base: link.File, rpath_table: std.StringArrayHashMapUnmanaged(void), image_base: u64, emit_relocs: bool, z_nodelete: bool, z_notext: bool, z_defs: bool, z_origin: bool, z_nocopyreloc: bool, z_now: bool, z_relro: bool, /// TODO make this non optional and resolve the default in open() z_common_page_size: ?u64, /// TODO make this non optional and resolve the default in open() z_max_page_size: ?u64, lib_dirs: []const []const u8, hash_style: HashStyle, compress_debug_sections: CompressDebugSections, symbol_wrap_set: std.StringArrayHashMapUnmanaged(void), sort_section: ?SortSection, soname: ?[]const u8, bind_global_refs_locally: bool, linker_script: ?[]const u8, version_script: ?[]const u8, allow_undefined_version: bool, enable_new_dtags: ?bool, print_icf_sections: bool, print_map: bool, entry_name: ?[]const u8, ptr_width: PtrWidth, /// If this is not null, an object file is created by LLVM and emitted to zcu_object_sub_path. llvm_object: ?LlvmObject.Ptr = null, /// A list of all input files. /// Index of each input file also encodes the priority or precedence of one input file /// over another. files: std.MultiArrayList(File.Entry) = .{}, /// Long-lived list of all file descriptors. /// We store them globally rather than per actual File so that we can re-use /// one file handle per every object file within an archive. file_handles: std.ArrayListUnmanaged(File.Handle) = .empty, zig_object_index: ?File.Index = null, linker_defined_index: ?File.Index = null, objects: std.ArrayListUnmanaged(File.Index) = .empty, shared_objects: std.ArrayListUnmanaged(File.Index) = .empty, /// List of all output sections and their associated metadata. sections: std.MultiArrayList(Section) = .{}, /// File offset into the shdr table. shdr_table_offset: ?u64 = null, /// Stored in native-endian format, depending on target endianness needs to be bswapped on read/write. /// Same order as in the file. phdrs: std.ArrayListUnmanaged(elf.Elf64_Phdr) = .empty, /// Special program headers /// PT_PHDR phdr_table_index: ?u16 = null, /// PT_LOAD for PHDR table /// We add this special load segment to ensure the EHDR and PHDR table are always /// loaded into memory. phdr_table_load_index: ?u16 = null, /// PT_INTERP phdr_interp_index: ?u16 = null, /// PT_DYNAMIC phdr_dynamic_index: ?u16 = null, /// PT_GNU_EH_FRAME phdr_gnu_eh_frame_index: ?u16 = null, /// PT_GNU_STACK phdr_gnu_stack_index: ?u16 = null, /// PT_TLS /// TODO I think ELF permits multiple TLS segments but for now, assume one per file. phdr_tls_index: ?u16 = null, page_size: u32, default_sym_version: elf.Elf64_Versym, /// .shstrtab buffer shstrtab: std.ArrayListUnmanaged(u8) = .empty, /// .symtab buffer symtab: std.ArrayListUnmanaged(elf.Elf64_Sym) = .empty, /// .strtab buffer strtab: std.ArrayListUnmanaged(u8) = .empty, /// Dynamic symbol table. Only populated and emitted when linking dynamically. dynsym: DynsymSection = .{}, /// .dynstrtab buffer dynstrtab: std.ArrayListUnmanaged(u8) = .empty, /// Version symbol table. Only populated and emitted when linking dynamically. versym: std.ArrayListUnmanaged(elf.Elf64_Versym) = .empty, /// .verneed section verneed: VerneedSection = .{}, /// .got section got: GotSection = .{}, /// .rela.dyn section rela_dyn: std.ArrayListUnmanaged(elf.Elf64_Rela) = .empty, /// .dynamic section dynamic: DynamicSection = .{}, /// .hash section hash: HashSection = .{}, /// .gnu.hash section gnu_hash: GnuHashSection = .{}, /// .plt section plt: PltSection = .{}, /// .got.plt section got_plt: GotPltSection = .{}, /// .plt.got section plt_got: PltGotSection = .{}, /// .copyrel section copy_rel: CopyRelSection = .{}, /// .rela.plt section rela_plt: std.ArrayListUnmanaged(elf.Elf64_Rela) = .empty, /// SHT_GROUP sections /// Applies only to a relocatable. comdat_group_sections: std.ArrayListUnmanaged(ComdatGroupSection) = .empty, copy_rel_section_index: ?u32 = null, dynamic_section_index: ?u32 = null, dynstrtab_section_index: ?u32 = null, dynsymtab_section_index: ?u32 = null, eh_frame_section_index: ?u32 = null, eh_frame_rela_section_index: ?u32 = null, eh_frame_hdr_section_index: ?u32 = null, hash_section_index: ?u32 = null, gnu_hash_section_index: ?u32 = null, got_section_index: ?u32 = null, got_plt_section_index: ?u32 = null, interp_section_index: ?u32 = null, plt_section_index: ?u32 = null, plt_got_section_index: ?u32 = null, rela_dyn_section_index: ?u32 = null, rela_plt_section_index: ?u32 = null, versym_section_index: ?u32 = null, verneed_section_index: ?u32 = null, shstrtab_section_index: ?u32 = null, strtab_section_index: ?u32 = null, symtab_section_index: ?u32 = null, resolver: SymbolResolver = .{}, has_text_reloc: bool = false, num_ifunc_dynrelocs: usize = 0, /// List of range extension thunks. thunks: std.ArrayListUnmanaged(Thunk) = .empty, /// List of output merge sections with deduped contents. merge_sections: std.ArrayListUnmanaged(MergeSection) = .empty, comment_merge_section_index: ?MergeSection.Index = null, first_eflags: ?elf.Elf64_Word = null, /// When allocating, the ideal_capacity is calculated by /// actual_capacity + (actual_capacity / ideal_factor) const ideal_factor = 3; /// In order for a slice of bytes to be considered eligible to keep metadata pointing at /// it as a possible place to put new symbols, it must have enough room for this many bytes /// (plus extra for reserved capacity). const minimum_atom_size = 64; pub const min_text_capacity = padToIdeal(minimum_atom_size); pub const PtrWidth = enum { p32, p64 }; pub const HashStyle = enum { sysv, gnu, both }; pub const CompressDebugSections = enum { none, zlib, zstd }; pub const SortSection = enum { name, alignment }; pub fn createEmpty( arena: Allocator, comp: *Compilation, emit: Path, options: link.File.OpenOptions, ) !*Elf { const target = comp.root_mod.resolved_target.result; assert(target.ofmt == .elf); const use_lld = build_options.have_llvm and comp.config.use_lld; const use_llvm = comp.config.use_llvm; const opt_zcu = comp.zcu; const output_mode = comp.config.output_mode; const link_mode = comp.config.link_mode; const optimize_mode = comp.root_mod.optimize_mode; const is_native_os = comp.root_mod.resolved_target.is_native_os; const ptr_width: PtrWidth = switch (target.ptrBitWidth()) { 0...32 => .p32, 33...64 => .p64, else => return error.UnsupportedELFArchitecture, }; // This is the max page size that the target system can run with, aka the ABI page size. Not to // be confused with the common page size, which is the page size that's used in practice on most // systems. const page_size: u32 = switch (target.cpu.arch) { .bpfel, .bpfeb, .sparc64, => 0x100000, .aarch64, .aarch64_be, .amdgcn, .hexagon, .mips, .mipsel, .mips64, .mips64el, .powerpc, .powerpcle, .powerpc64, .powerpc64le, .sparc, => 0x10000, .loongarch32, .loongarch64, => 0x4000, .arc, .m68k, => 0x2000, .msp430, => 0x4, .avr, => 0x1, else => 0x1000, }; const is_dyn_lib = output_mode == .Lib and link_mode == .dynamic; const default_sym_version: elf.Elf64_Versym = if (is_dyn_lib or comp.config.rdynamic) elf.VER_NDX_GLOBAL else elf.VER_NDX_LOCAL; // If using LLD to link, this code should produce an object file so that it // can be passed to LLD. // If using LLVM to generate the object file for the zig compilation unit, // we need a place to put the object file so that it can be subsequently // handled. const zcu_object_sub_path = if (!use_lld and !use_llvm) null else try std.fmt.allocPrint(arena, "{s}.o", .{emit.sub_path}); var rpath_table: std.StringArrayHashMapUnmanaged(void) = .empty; try rpath_table.entries.resize(arena, options.rpath_list.len); @memcpy(rpath_table.entries.items(.key), options.rpath_list); try rpath_table.reIndex(arena); const self = try arena.create(Elf); self.* = .{ .base = .{ .tag = .elf, .comp = comp, .emit = emit, .zcu_object_sub_path = zcu_object_sub_path, .gc_sections = options.gc_sections orelse (optimize_mode != .Debug and output_mode != .Obj), .print_gc_sections = options.print_gc_sections, .stack_size = options.stack_size orelse 16777216, .allow_shlib_undefined = options.allow_shlib_undefined orelse !is_native_os, .file = null, .disable_lld_caching = options.disable_lld_caching, .build_id = options.build_id, }, .rpath_table = rpath_table, .ptr_width = ptr_width, .page_size = page_size, .default_sym_version = default_sym_version, .entry_name = switch (options.entry) { .disabled => null, .default => if (output_mode != .Exe) null else defaultEntrySymbolName(target.cpu.arch), .enabled => defaultEntrySymbolName(target.cpu.arch), .named => |name| name, }, .image_base = b: { if (is_dyn_lib) break :b 0; if (output_mode == .Exe and comp.config.pie) break :b 0; break :b options.image_base orelse switch (ptr_width) { .p32 => 0x10000, .p64 => 0x1000000, }; }, .emit_relocs = options.emit_relocs, .z_nodelete = options.z_nodelete, .z_notext = options.z_notext, .z_defs = options.z_defs, .z_origin = options.z_origin, .z_nocopyreloc = options.z_nocopyreloc, .z_now = options.z_now, .z_relro = options.z_relro, .z_common_page_size = options.z_common_page_size, .z_max_page_size = options.z_max_page_size, .lib_dirs = options.lib_dirs, .hash_style = options.hash_style, .compress_debug_sections = options.compress_debug_sections, .symbol_wrap_set = options.symbol_wrap_set, .sort_section = options.sort_section, .soname = options.soname, .bind_global_refs_locally = options.bind_global_refs_locally, .linker_script = options.linker_script, .version_script = options.version_script, .allow_undefined_version = options.allow_undefined_version, .enable_new_dtags = options.enable_new_dtags, .print_icf_sections = options.print_icf_sections, .print_map = options.print_map, }; if (use_llvm and comp.config.have_zcu) { self.llvm_object = try LlvmObject.create(arena, comp); } errdefer self.base.destroy(); if (use_lld and (use_llvm or !comp.config.have_zcu)) { // LLVM emits the object file (if any); LLD links it into the final product. return self; } const is_obj = output_mode == .Obj; const is_obj_or_ar = is_obj or (output_mode == .Lib and link_mode == .static); // What path should this ELF linker code output to? // If using LLD to link, this code should produce an object file so that it // can be passed to LLD. const sub_path = if (use_lld) zcu_object_sub_path.? else emit.sub_path; self.base.file = try emit.root_dir.handle.createFile(sub_path, .{ .truncate = true, .read = true, .mode = link.File.determineMode(use_lld, output_mode, link_mode), }); const gpa = comp.gpa; // Append null file at index 0 try self.files.append(gpa, .null); // Append null byte to string tables try self.shstrtab.append(gpa, 0); try self.strtab.append(gpa, 0); // There must always be a null shdr in index 0 _ = try self.addSection(.{}); // Append null symbol in output symtab try self.symtab.append(gpa, null_sym); if (!is_obj_or_ar) { try self.dynstrtab.append(gpa, 0); // Initialize PT_PHDR program header const p_align: u16 = switch (self.ptr_width) { .p32 => @alignOf(elf.Elf32_Phdr), .p64 => @alignOf(elf.Elf64_Phdr), }; const ehsize: u64 = switch (self.ptr_width) { .p32 => @sizeOf(elf.Elf32_Ehdr), .p64 => @sizeOf(elf.Elf64_Ehdr), }; const phsize: u64 = switch (self.ptr_width) { .p32 => @sizeOf(elf.Elf32_Phdr), .p64 => @sizeOf(elf.Elf64_Phdr), }; const max_nphdrs = comptime getMaxNumberOfPhdrs(); const reserved: u64 = mem.alignForward(u64, padToIdeal(max_nphdrs * phsize), self.page_size); self.phdr_table_index = try self.addPhdr(.{ .type = elf.PT_PHDR, .flags = elf.PF_R, .@"align" = p_align, .addr = self.image_base + ehsize, .offset = ehsize, .filesz = reserved, .memsz = reserved, }); self.phdr_table_load_index = try self.addPhdr(.{ .type = elf.PT_LOAD, .flags = elf.PF_R, .@"align" = self.page_size, .addr = self.image_base, .offset = 0, .filesz = reserved + ehsize, .memsz = reserved + ehsize, }); } if (opt_zcu) |zcu| { if (!use_llvm) { const index: File.Index = @intCast(try self.files.addOne(gpa)); self.files.set(index, .{ .zig_object = .{ .index = index, .path = try std.fmt.allocPrint(arena, "{s}.o", .{fs.path.stem( zcu.main_mod.root_src_path, )}), } }); self.zig_object_index = index; try self.zigObjectPtr().?.init(self, .{ .symbol_count_hint = options.symbol_count_hint, .program_code_size_hint = options.program_code_size_hint, }); } } return self; } pub fn open( arena: Allocator, comp: *Compilation, emit: Path, options: link.File.OpenOptions, ) !*Elf { // TODO: restore saved linker state, don't truncate the file, and // participate in incremental compilation. return createEmpty(arena, comp, emit, options); } pub fn deinit(self: *Elf) void { const gpa = self.base.comp.gpa; if (self.llvm_object) |llvm_object| llvm_object.deinit(); for (self.file_handles.items) |fh| { fh.close(); } self.file_handles.deinit(gpa); for (self.files.items(.tags), self.files.items(.data)) |tag, *data| switch (tag) { .null => {}, .zig_object => data.zig_object.deinit(gpa), .linker_defined => data.linker_defined.deinit(gpa), .object => data.object.deinit(gpa), .shared_object => data.shared_object.deinit(gpa), }; self.files.deinit(gpa); self.objects.deinit(gpa); self.shared_objects.deinit(gpa); for (self.sections.items(.atom_list_2), self.sections.items(.atom_list), self.sections.items(.free_list)) |*atom_list, *atoms, *free_list| { atom_list.deinit(gpa); atoms.deinit(gpa); free_list.deinit(gpa); } self.sections.deinit(gpa); self.phdrs.deinit(gpa); self.shstrtab.deinit(gpa); self.symtab.deinit(gpa); self.strtab.deinit(gpa); self.resolver.deinit(gpa); for (self.thunks.items) |*th| { th.deinit(gpa); } self.thunks.deinit(gpa); for (self.merge_sections.items) |*sect| { sect.deinit(gpa); } self.merge_sections.deinit(gpa); self.got.deinit(gpa); self.plt.deinit(gpa); self.plt_got.deinit(gpa); self.dynsym.deinit(gpa); self.dynstrtab.deinit(gpa); self.dynamic.deinit(gpa); self.hash.deinit(gpa); self.versym.deinit(gpa); self.verneed.deinit(gpa); self.copy_rel.deinit(gpa); self.rela_dyn.deinit(gpa); self.rela_plt.deinit(gpa); self.comdat_group_sections.deinit(gpa); } pub fn getNavVAddr(self: *Elf, pt: Zcu.PerThread, nav_index: InternPool.Nav.Index, reloc_info: link.File.RelocInfo) !u64 { assert(self.llvm_object == null); return self.zigObjectPtr().?.getNavVAddr(self, pt, nav_index, reloc_info); } pub fn lowerUav( self: *Elf, pt: Zcu.PerThread, uav: InternPool.Index, explicit_alignment: InternPool.Alignment, src_loc: Zcu.LazySrcLoc, ) !codegen.GenResult { return self.zigObjectPtr().?.lowerUav(self, pt, uav, explicit_alignment, src_loc); } pub fn getUavVAddr(self: *Elf, uav: InternPool.Index, reloc_info: link.File.RelocInfo) !u64 { assert(self.llvm_object == null); return self.zigObjectPtr().?.getUavVAddr(self, uav, reloc_info); } /// Returns end pos of collision, if any. fn detectAllocCollision(self: *Elf, start: u64, size: u64) !?u64 { const small_ptr = self.ptr_width == .p32; const ehdr_size: u64 = if (small_ptr) @sizeOf(elf.Elf32_Ehdr) else @sizeOf(elf.Elf64_Ehdr); if (start < ehdr_size) return ehdr_size; var at_end = true; const end = start + padToIdeal(size); if (self.shdr_table_offset) |off| { const shdr_size: u64 = if (small_ptr) @sizeOf(elf.Elf32_Shdr) else @sizeOf(elf.Elf64_Shdr); const tight_size = self.sections.items(.shdr).len * shdr_size; const increased_size = padToIdeal(tight_size); const test_end = off +| increased_size; if (start < test_end) { if (end > off) return test_end; if (test_end < std.math.maxInt(u64)) at_end = false; } } for (self.sections.items(.shdr)) |shdr| { if (shdr.sh_type == elf.SHT_NOBITS) continue; const increased_size = padToIdeal(shdr.sh_size); const test_end = shdr.sh_offset +| increased_size; if (start < test_end) { if (end > shdr.sh_offset) return test_end; if (test_end < std.math.maxInt(u64)) at_end = false; } } for (self.phdrs.items) |phdr| { if (phdr.p_type != elf.PT_LOAD) continue; const increased_size = padToIdeal(phdr.p_filesz); const test_end = phdr.p_offset +| increased_size; if (start < test_end) { if (end > phdr.p_offset) return test_end; if (test_end < std.math.maxInt(u64)) at_end = false; } } if (at_end) try self.base.file.?.setEndPos(end); return null; } pub fn allocatedSize(self: *Elf, start: u64) u64 { if (start == 0) return 0; var min_pos: u64 = std.math.maxInt(u64); if (self.shdr_table_offset) |off| { if (off > start and off < min_pos) min_pos = off; } for (self.sections.items(.shdr)) |section| { if (section.sh_offset <= start) continue; if (section.sh_offset < min_pos) min_pos = section.sh_offset; } for (self.phdrs.items) |phdr| { if (phdr.p_offset <= start) continue; if (phdr.p_offset < min_pos) min_pos = phdr.p_offset; } return min_pos - start; } pub fn findFreeSpace(self: *Elf, object_size: u64, min_alignment: u64) !u64 { var start: u64 = 0; while (try self.detectAllocCollision(start, object_size)) |item_end| { start = mem.alignForward(u64, item_end, min_alignment); } return start; } pub fn growSection(self: *Elf, shdr_index: u32, needed_size: u64, min_alignment: u64) !void { const shdr = &self.sections.items(.shdr)[shdr_index]; if (shdr.sh_type != elf.SHT_NOBITS) { const allocated_size = self.allocatedSize(shdr.sh_offset); log.debug("allocated size {x} of '{s}', needed size {x}", .{ allocated_size, self.getShString(shdr.sh_name), needed_size, }); if (needed_size > allocated_size) { const existing_size = shdr.sh_size; shdr.sh_size = 0; // Must move the entire section. const new_offset = try self.findFreeSpace(needed_size, min_alignment); log.debug("new '{s}' file offset 0x{x} to 0x{x}", .{ self.getShString(shdr.sh_name), new_offset, new_offset + existing_size, }); const amt = try self.base.file.?.copyRangeAll( shdr.sh_offset, self.base.file.?, new_offset, existing_size, ); // TODO figure out what to about this error condition - how to communicate it up. if (amt != existing_size) return error.InputOutput; shdr.sh_offset = new_offset; } else if (shdr.sh_offset + allocated_size == std.math.maxInt(u64)) { try self.base.file.?.setEndPos(shdr.sh_offset + needed_size); } } shdr.sh_size = needed_size; self.markDirty(shdr_index); } fn markDirty(self: *Elf, shdr_index: u32) void { if (self.zigObjectPtr()) |zo| { for ([_]?Symbol.Index{ zo.debug_info_index, zo.debug_abbrev_index, zo.debug_aranges_index, zo.debug_str_index, zo.debug_line_index, zo.debug_line_str_index, zo.debug_loclists_index, zo.debug_rnglists_index, }, [_]*bool{ &zo.debug_info_section_dirty, &zo.debug_abbrev_section_dirty, &zo.debug_aranges_section_dirty, &zo.debug_str_section_dirty, &zo.debug_line_section_dirty, &zo.debug_line_str_section_dirty, &zo.debug_loclists_section_dirty, &zo.debug_rnglists_section_dirty, }) |maybe_sym_index, dirty| { const sym_index = maybe_sym_index orelse continue; if (zo.symbol(sym_index).atom(self).?.output_section_index == shdr_index) { dirty.* = true; break; } } } } const AllocateChunkResult = struct { value: u64, placement: Ref, }; pub fn allocateChunk(self: *Elf, args: struct { size: u64, shndx: u32, alignment: Atom.Alignment, requires_padding: bool = true, }) !AllocateChunkResult { const slice = self.sections.slice(); const shdr = &slice.items(.shdr)[args.shndx]; const free_list = &slice.items(.free_list)[args.shndx]; const last_atom_ref = &slice.items(.last_atom)[args.shndx]; const new_atom_ideal_capacity = if (args.requires_padding) padToIdeal(args.size) else args.size; // First we look for an appropriately sized free list node. // The list is unordered. We'll just take the first thing that works. const res: AllocateChunkResult = blk: { var i: usize = if (self.base.child_pid == null) 0 else free_list.items.len; while (i < free_list.items.len) { const big_atom_ref = free_list.items[i]; const big_atom = self.atom(big_atom_ref).?; // We now have a pointer to a live atom that has too much capacity. // Is it enough that we could fit this new atom? const cap = big_atom.capacity(self); const ideal_capacity = if (args.requires_padding) padToIdeal(cap) else cap; const ideal_capacity_end_vaddr = std.math.add(u64, @intCast(big_atom.value), ideal_capacity) catch ideal_capacity; const capacity_end_vaddr = @as(u64, @intCast(big_atom.value)) + cap; const new_start_vaddr_unaligned = capacity_end_vaddr - new_atom_ideal_capacity; const new_start_vaddr = args.alignment.backward(new_start_vaddr_unaligned); if (new_start_vaddr < ideal_capacity_end_vaddr) { // Additional bookkeeping here to notice if this free list node // should be deleted because the block that it points to has grown to take up // more of the extra capacity. if (!big_atom.freeListEligible(self)) { _ = free_list.swapRemove(i); } else { i += 1; } continue; } // At this point we know that we will place the new block here. But the // remaining question is whether there is still yet enough capacity left // over for there to still be a free list node. const remaining_capacity = new_start_vaddr - ideal_capacity_end_vaddr; const keep_free_list_node = remaining_capacity >= min_text_capacity; if (!keep_free_list_node) { _ = free_list.swapRemove(i); } break :blk .{ .value = new_start_vaddr, .placement = big_atom_ref }; } else if (self.atom(last_atom_ref.*)) |last_atom| { const ideal_capacity = if (args.requires_padding) padToIdeal(last_atom.size) else last_atom.size; const ideal_capacity_end_vaddr = @as(u64, @intCast(last_atom.value)) + ideal_capacity; const new_start_vaddr = args.alignment.forward(ideal_capacity_end_vaddr); break :blk .{ .value = new_start_vaddr, .placement = last_atom.ref() }; } else { break :blk .{ .value = 0, .placement = .{} }; } }; log.debug("allocated chunk (size({x}),align({x})) at 0x{x} (file(0x{x}))", .{ args.size, args.alignment.toByteUnits().?, shdr.sh_addr + res.value, shdr.sh_offset + res.value, }); const expand_section = if (self.atom(res.placement)) |placement_atom| placement_atom.nextAtom(self) == null else true; if (expand_section) { const needed_size = res.value + args.size; try self.growSection(args.shndx, needed_size, args.alignment.toByteUnits().?); } return res; } pub fn flush(self: *Elf, arena: Allocator, tid: Zcu.PerThread.Id, prog_node: std.Progress.Node) link.File.FlushError!void { const use_lld = build_options.have_llvm and self.base.comp.config.use_lld; if (use_lld) { return self.linkWithLLD(arena, tid, prog_node); } try self.flushModule(arena, tid, prog_node); } pub fn flushModule(self: *Elf, arena: Allocator, tid: Zcu.PerThread.Id, prog_node: std.Progress.Node) link.File.FlushError!void { const tracy = trace(@src()); defer tracy.end(); const comp = self.base.comp; const gpa = comp.gpa; if (self.llvm_object) |llvm_object| { try self.base.emitLlvmObject(arena, llvm_object, prog_node); const use_lld = build_options.have_llvm and comp.config.use_lld; if (use_lld) return; } const sub_prog_node = prog_node.start("ELF Flush", 0); defer sub_prog_node.end(); const target = self.getTarget(); const link_mode = comp.config.link_mode; const directory = self.base.emit.root_dir; // Just an alias to make it shorter to type. const module_obj_path: ?[]const u8 = if (self.base.zcu_object_sub_path) |path| blk: { const full_out_path = try directory.join(arena, &[_][]const u8{self.base.emit.sub_path}); if (fs.path.dirname(full_out_path)) |dirname| { break :blk try fs.path.join(arena, &.{ dirname, path }); } else { break :blk path; } } else null; // --verbose-link if (comp.verbose_link) try self.dumpArgv(comp); if (self.zigObjectPtr()) |zig_object| try zig_object.flushModule(self, tid); if (self.base.isStaticLib()) return relocatable.flushStaticLib(self, comp, module_obj_path); if (self.base.isObject()) return relocatable.flushObject(self, comp, module_obj_path); const csu = try CsuObjects.init(arena, comp); // csu prelude if (csu.crt0) |path| try parseObjectReportingFailure(self, path); if (csu.crti) |path| try parseObjectReportingFailure(self, path); if (csu.crtbegin) |path| try parseObjectReportingFailure(self, path); for (comp.objects) |obj| { if (obj.isObject()) { try parseObjectReportingFailure(self, obj.path); } else { try parseLibraryReportingFailure(self, .{ .path = obj.path }, obj.must_link); } } // This is a set of object files emitted by clang in a single `build-exe` invocation. // For instance, the implicit `a.o` as compiled by `zig build-exe a.c` will end up // in this set. for (comp.c_object_table.keys()) |key| { try parseObjectReportingFailure(self, key.status.success.object_path); } if (module_obj_path) |path| try parseObjectReportingFailure(self, path); if (comp.config.any_sanitize_thread) try parseCrtFileReportingFailure(self, comp.tsan_lib.?); if (comp.config.any_fuzz) try parseCrtFileReportingFailure(self, comp.fuzzer_lib.?); // libc if (!comp.skip_linker_dependencies and !comp.config.link_libc) { if (comp.libc_static_lib) |lib| try parseCrtFileReportingFailure(self, lib); } var system_libs = std.ArrayList(SystemLib).init(arena); try system_libs.ensureUnusedCapacity(comp.system_libs.values().len); for (comp.system_libs.values()) |lib_info| { system_libs.appendAssumeCapacity(.{ .needed = lib_info.needed, .path = lib_info.path.? }); } // libc++ dep if (comp.config.link_libcpp) { try system_libs.ensureUnusedCapacity(2); system_libs.appendAssumeCapacity(.{ .path = comp.libcxxabi_static_lib.?.full_object_path }); system_libs.appendAssumeCapacity(.{ .path = comp.libcxx_static_lib.?.full_object_path }); } // libunwind dep if (comp.config.link_libunwind) { try system_libs.append(.{ .path = comp.libunwind_static_lib.?.full_object_path }); } // libc dep comp.link_error_flags.missing_libc = false; if (comp.config.link_libc) { if (comp.libc_installation) |lc| { const flags = target_util.libcFullLinkFlags(target); try system_libs.ensureUnusedCapacity(flags.len); var test_path = std.ArrayList(u8).init(arena); var checked_paths = std.ArrayList([]const u8).init(arena); for (flags) |flag| { checked_paths.clearRetainingCapacity(); const lib_name = flag["-l".len..]; success: { if (!self.base.isStatic()) { if (try self.accessLibPath(arena, &test_path, &checked_paths, lc.crt_dir.?, lib_name, .dynamic)) break :success; } if (try self.accessLibPath(arena, &test_path, &checked_paths, lc.crt_dir.?, lib_name, .static)) break :success; try self.reportMissingLibraryError( checked_paths.items, "missing system library: '{s}' was not found", .{lib_name}, ); continue; } const resolved_path = try arena.dupe(u8, test_path.items); system_libs.appendAssumeCapacity(.{ .path = resolved_path }); } } else if (target.isGnuLibC()) { try system_libs.ensureUnusedCapacity(glibc.libs.len + 1); for (glibc.libs) |lib| { if (lib.removed_in) |rem_in| { if (target.os.version_range.linux.glibc.order(rem_in) != .lt) continue; } const lib_path = try std.fmt.allocPrint(arena, "{s}{c}lib{s}.so.{d}", .{ comp.glibc_so_files.?.dir_path, fs.path.sep, lib.name, lib.sover, }); system_libs.appendAssumeCapacity(.{ .path = lib_path }); } system_libs.appendAssumeCapacity(.{ .path = try comp.get_libc_crt_file(arena, "libc_nonshared.a"), }); } else if (target.isMusl()) { const path = try comp.get_libc_crt_file(arena, switch (link_mode) { .static => "libc.a", .dynamic => "libc.so", }); try system_libs.append(.{ .path = path }); } else { comp.link_error_flags.missing_libc = true; } } for (system_libs.items) |lib| { try self.parseLibraryReportingFailure(lib, false); } // Finally, as the last input objects we add compiler_rt and CSU postlude (if any). // compiler-rt. Since compiler_rt exports symbols like `memset`, it needs // to be after the shared libraries, so they are picked up from the shared // libraries, not libcompiler_rt. if (comp.compiler_rt_lib) |crt_file| { try parseLibraryReportingFailure(self, .{ .path = crt_file.full_object_path }, false); } else if (comp.compiler_rt_obj) |crt_file| { try parseObjectReportingFailure(self, crt_file.full_object_path); } // csu postlude if (csu.crtend) |path| try parseObjectReportingFailure(self, path); if (csu.crtn) |path| try parseObjectReportingFailure(self, path); if (self.base.hasErrors()) return error.FlushFailure; // Dedup shared objects { var seen_dsos = std.StringHashMap(void).init(gpa); defer seen_dsos.deinit(); try seen_dsos.ensureTotalCapacity(@as(u32, @intCast(self.shared_objects.items.len))); var i: usize = 0; while (i < self.shared_objects.items.len) { const index = self.shared_objects.items[i]; const shared_object = self.file(index).?.shared_object; const soname = shared_object.soname(); const gop = seen_dsos.getOrPutAssumeCapacity(soname); if (gop.found_existing) { _ = self.shared_objects.orderedRemove(i); } else i += 1; } } // If we haven't already, create a linker-generated input file comprising of // linker-defined synthetic symbols only such as `_DYNAMIC`, etc. if (self.linker_defined_index == null) { const index = @as(File.Index, @intCast(try self.files.addOne(gpa))); self.files.set(index, .{ .linker_defined = .{ .index = index } }); self.linker_defined_index = index; const object = self.linkerDefinedPtr().?; try object.init(gpa); try object.initSymbols(self); } // Now, we are ready to resolve the symbols across all input files. // We will first resolve the files in the ZigObject, next in the parsed // input Object files. // Any qualifing unresolved symbol will be upgraded to an absolute, weak // symbol for potential resolution at load-time. try self.resolveSymbols(); self.markEhFrameAtomsDead(); try self.resolveMergeSections(); for (self.objects.items) |index| { try self.file(index).?.object.convertCommonSymbols(self); } self.markImportsExports(); if (self.base.gc_sections) { try gc.gcAtoms(self); if (self.base.print_gc_sections) { try gc.dumpPrunedAtoms(self); } } self.checkDuplicates() catch |err| switch (err) { error.HasDuplicates => return error.FlushFailure, else => |e| return e, }; try self.addCommentString(); try self.finalizeMergeSections(); try self.initOutputSections(); if (self.linkerDefinedPtr()) |obj| { try obj.initStartStopSymbols(self); } self.claimUnresolved(); // Scan and create missing synthetic entries such as GOT indirection. try self.scanRelocs(); // Generate and emit synthetic sections. try self.initSyntheticSections(); try self.initSpecialPhdrs(); try self.sortShdrs(); try self.setDynamicSection(self.rpath_table.keys()); self.sortDynamicSymtab(); try self.setHashSections(); try self.setVersionSymtab(); try self.sortInitFini(); try self.updateMergeSectionSizes(); try self.updateSectionSizes(); try self.addLoadPhdrs(); try self.allocatePhdrTable(); try self.allocateAllocSections(); try self.sortPhdrs(); try self.allocateNonAllocSections(); self.allocateSpecialPhdrs(); if (self.linkerDefinedPtr()) |obj| { obj.allocateSymbols(self); } // Dump the state for easy debugging. // State can be dumped via `--debug-log link_state`. if (build_options.enable_logging) { state_log.debug("{}", .{self.dumpState()}); } // Beyond this point, everything has been allocated a virtual address and we can resolve // the relocations, and commit objects to file. for (self.objects.items) |index| { self.file(index).?.object.dirty = false; } // TODO: would state tracking be more appropriate here? perhaps even custom relocation type? self.rela_dyn.clearRetainingCapacity(); self.rela_plt.clearRetainingCapacity(); if (self.zigObjectPtr()) |zo| { var has_reloc_errors = false; for (zo.atoms_indexes.items) |atom_index| { const atom_ptr = zo.atom(atom_index) orelse continue; if (!atom_ptr.alive) continue; const out_shndx = atom_ptr.output_section_index; const shdr = &self.sections.items(.shdr)[out_shndx]; if (shdr.sh_type == elf.SHT_NOBITS) continue; const code = try zo.codeAlloc(self, atom_index); defer gpa.free(code); const file_offset = atom_ptr.offset(self); atom_ptr.resolveRelocsAlloc(self, code) catch |err| switch (err) { error.RelocFailure, error.RelaxFailure => has_reloc_errors = true, error.UnsupportedCpuArch => { try self.reportUnsupportedCpuArch(); return error.FlushFailure; }, else => |e| return e, }; try self.base.file.?.pwriteAll(code, file_offset); } if (has_reloc_errors) return error.FlushFailure; } try self.writePhdrTable(); try self.writeShdrTable(); try self.writeAtoms(); try self.writeMergeSections(); self.writeSyntheticSections() catch |err| switch (err) { error.RelocFailure => return error.FlushFailure, error.UnsupportedCpuArch => { try self.reportUnsupportedCpuArch(); return error.FlushFailure; }, else => |e| return e, }; if (self.base.isExe() and self.linkerDefinedPtr().?.entry_index == null) { log.debug("flushing. no_entry_point_found = true", .{}); comp.link_error_flags.no_entry_point_found = true; } else { log.debug("flushing. no_entry_point_found = false", .{}); comp.link_error_flags.no_entry_point_found = false; try self.writeElfHeader(); } if (self.base.hasErrors()) return error.FlushFailure; } /// --verbose-link output fn dumpArgv(self: *Elf, comp: *Compilation) !void { const gpa = self.base.comp.gpa; var arena_allocator = std.heap.ArenaAllocator.init(gpa); defer arena_allocator.deinit(); const arena = arena_allocator.allocator(); const target = self.getTarget(); const link_mode = self.base.comp.config.link_mode; const directory = self.base.emit.root_dir; // Just an alias to make it shorter to type. const full_out_path = try directory.join(arena, &[_][]const u8{self.base.emit.sub_path}); const module_obj_path: ?[]const u8 = if (self.base.zcu_object_sub_path) |path| blk: { if (fs.path.dirname(full_out_path)) |dirname| { break :blk try fs.path.join(arena, &.{ dirname, path }); } else { break :blk path; } } else null; const csu = try CsuObjects.init(arena, comp); const compiler_rt_path: ?[]const u8 = blk: { if (comp.compiler_rt_lib) |x| break :blk x.full_object_path; if (comp.compiler_rt_obj) |x| break :blk x.full_object_path; break :blk null; }; var argv = std.ArrayList([]const u8).init(arena); try argv.append("zig"); if (self.base.isStaticLib()) { try argv.append("ar"); } else { try argv.append("ld"); } if (self.base.isObject()) { try argv.append("-r"); } try argv.append("-o"); try argv.append(full_out_path); if (self.base.isRelocatable()) { for (comp.objects) |obj| { try argv.append(obj.path); } for (comp.c_object_table.keys()) |key| { try argv.append(key.status.success.object_path); } if (module_obj_path) |p| { try argv.append(p); } } else { if (!self.base.isStatic()) { if (target.dynamic_linker.get()) |path| { try argv.append("-dynamic-linker"); try argv.append(path); } } if (self.base.isDynLib()) { if (self.soname) |name| { try argv.append("-soname"); try argv.append(name); } } if (self.entry_name) |name| { try argv.appendSlice(&.{ "--entry", name }); } for (self.rpath_table.keys()) |rpath| { try argv.appendSlice(&.{ "-rpath", rpath }); } try argv.appendSlice(&.{ "-z", try std.fmt.allocPrint(arena, "stack-size={d}", .{self.base.stack_size}), }); try argv.append(try std.fmt.allocPrint(arena, "--image-base={d}", .{self.image_base})); if (self.base.gc_sections) { try argv.append("--gc-sections"); } if (self.base.print_gc_sections) { try argv.append("--print-gc-sections"); } if (comp.link_eh_frame_hdr) { try argv.append("--eh-frame-hdr"); } if (comp.config.rdynamic) { try argv.append("--export-dynamic"); } if (self.z_notext) { try argv.append("-z"); try argv.append("notext"); } if (self.z_nocopyreloc) { try argv.append("-z"); try argv.append("nocopyreloc"); } if (self.z_now) { try argv.append("-z"); try argv.append("now"); } if (self.base.isStatic()) { try argv.append("-static"); } else if (self.isEffectivelyDynLib()) { try argv.append("-shared"); } if (comp.config.pie and self.base.isExe()) { try argv.append("-pie"); } if (comp.config.debug_format == .strip) { try argv.append("-s"); } // csu prelude if (csu.crt0) |v| try argv.append(v); if (csu.crti) |v| try argv.append(v); if (csu.crtbegin) |v| try argv.append(v); for (self.lib_dirs) |lib_dir| { try argv.append("-L"); try argv.append(lib_dir); } if (comp.config.link_libc) { if (self.base.comp.libc_installation) |libc_installation| { try argv.append("-L"); try argv.append(libc_installation.crt_dir.?); } } var whole_archive = false; for (comp.objects) |obj| { if (obj.must_link and !whole_archive) { try argv.append("-whole-archive"); whole_archive = true; } else if (!obj.must_link and whole_archive) { try argv.append("-no-whole-archive"); whole_archive = false; } if (obj.loption) { assert(obj.path[0] == ':'); try argv.append("-l"); } try argv.append(obj.path); } if (whole_archive) { try argv.append("-no-whole-archive"); whole_archive = false; } for (comp.c_object_table.keys()) |key| { try argv.append(key.status.success.object_path); } if (module_obj_path) |p| { try argv.append(p); } if (comp.config.any_sanitize_thread) { try argv.append(comp.tsan_lib.?.full_object_path); } if (comp.config.any_fuzz) { try argv.append(comp.fuzzer_lib.?.full_object_path); } // libc if (!comp.skip_linker_dependencies and !comp.config.link_libc) { if (comp.libc_static_lib) |lib| { try argv.append(lib.full_object_path); } } // Shared libraries. // Worst-case, we need an --as-needed argument for every lib, as well // as one before and one after. try argv.ensureUnusedCapacity(self.base.comp.system_libs.keys().len * 2 + 2); argv.appendAssumeCapacity("--as-needed"); var as_needed = true; for (self.base.comp.system_libs.values()) |lib_info| { const lib_as_needed = !lib_info.needed; switch ((@as(u2, @intFromBool(lib_as_needed)) << 1) | @intFromBool(as_needed)) { 0b00, 0b11 => {}, 0b01 => { argv.appendAssumeCapacity("--no-as-needed"); as_needed = false; }, 0b10 => { argv.appendAssumeCapacity("--as-needed"); as_needed = true; }, } argv.appendAssumeCapacity(lib_info.path.?); } if (!as_needed) { argv.appendAssumeCapacity("--as-needed"); as_needed = true; } // libc++ dep if (comp.config.link_libcpp) { try argv.append(comp.libcxxabi_static_lib.?.full_object_path); try argv.append(comp.libcxx_static_lib.?.full_object_path); } // libunwind dep if (comp.config.link_libunwind) { try argv.append(comp.libunwind_static_lib.?.full_object_path); } // libc dep if (comp.config.link_libc) { if (self.base.comp.libc_installation != null) { const needs_grouping = link_mode == .static; if (needs_grouping) try argv.append("--start-group"); try argv.appendSlice(target_util.libcFullLinkFlags(target)); if (needs_grouping) try argv.append("--end-group"); } else if (target.isGnuLibC()) { for (glibc.libs) |lib| { if (lib.removed_in) |rem_in| { if (target.os.version_range.linux.glibc.order(rem_in) != .lt) continue; } const lib_path = try std.fmt.allocPrint(arena, "{s}{c}lib{s}.so.{d}", .{ comp.glibc_so_files.?.dir_path, fs.path.sep, lib.name, lib.sover, }); try argv.append(lib_path); } try argv.append(try comp.get_libc_crt_file(arena, "libc_nonshared.a")); } else if (target.isMusl()) { try argv.append(try comp.get_libc_crt_file(arena, switch (link_mode) { .static => "libc.a", .dynamic => "libc.so", })); } } // compiler-rt if (compiler_rt_path) |p| { try argv.append(p); } // crt postlude if (csu.crtend) |v| try argv.append(v); if (csu.crtn) |v| try argv.append(v); } Compilation.dump_argv(argv.items); } pub const ParseError = error{ /// Indicates the error is already reported on `Compilation.link_errors`. LinkFailure, OutOfMemory, Overflow, InputOutput, EndOfStream, FileSystem, NotSupported, InvalidCharacter, UnknownFileType, } || LdScript.Error || fs.Dir.AccessError || fs.File.SeekError || fs.File.OpenError || fs.File.ReadError; fn parseCrtFileReportingFailure(self: *Elf, crt_file: Compilation.CRTFile) error{OutOfMemory}!void { if (crt_file.isObject()) { try parseObjectReportingFailure(self, crt_file.full_object_path); } else { try parseLibraryReportingFailure(self, .{ .path = crt_file.full_object_path }, false); } } pub fn parseObjectReportingFailure(self: *Elf, path: []const u8) error{OutOfMemory}!void { self.parseObject(path) catch |err| switch (err) { error.LinkFailure => return, // already reported error.OutOfMemory => return error.OutOfMemory, else => |e| try self.addParseError(path, "unable to parse object: {s}", .{@errorName(e)}), }; } pub fn parseLibraryReportingFailure(self: *Elf, lib: SystemLib, must_link: bool) error{OutOfMemory}!void { self.parseLibrary(lib, must_link) catch |err| switch (err) { error.LinkFailure => return, // already reported error.OutOfMemory => return error.OutOfMemory, else => |e| try self.addParseError(lib.path, "unable to parse library: {s}", .{@errorName(e)}), }; } fn parseLibrary(self: *Elf, lib: SystemLib, must_link: bool) ParseError!void { const tracy = trace(@src()); defer tracy.end(); if (try Archive.isArchive(lib.path)) { try self.parseArchive(lib.path, must_link); } else if (try SharedObject.isSharedObject(lib.path)) { try self.parseSharedObject(lib); } else { try self.parseLdScript(lib); } } fn parseObject(self: *Elf, path: []const u8) ParseError!void { const tracy = trace(@src()); defer tracy.end(); const gpa = self.base.comp.gpa; const handle = try fs.cwd().openFile(path, .{}); const fh = try self.addFileHandle(handle); const index = @as(File.Index, @intCast(try self.files.addOne(gpa))); self.files.set(index, .{ .object = .{ .path = try gpa.dupe(u8, path), .file_handle = fh, .index = index, } }); try self.objects.append(gpa, index); const object = self.file(index).?.object; try object.parse(self); } fn parseArchive(self: *Elf, path: []const u8, must_link: bool) ParseError!void { const tracy = trace(@src()); defer tracy.end(); const gpa = self.base.comp.gpa; const handle = try fs.cwd().openFile(path, .{}); const fh = try self.addFileHandle(handle); var archive = Archive{}; defer archive.deinit(gpa); try archive.parse(self, path, fh); const objects = try archive.objects.toOwnedSlice(gpa); defer gpa.free(objects); for (objects) |extracted| { const index = @as(File.Index, @intCast(try self.files.addOne(gpa))); self.files.set(index, .{ .object = extracted }); const object = &self.files.items(.data)[index].object; object.index = index; object.alive = must_link; try object.parse(self); try self.objects.append(gpa, index); } } fn parseSharedObject(self: *Elf, lib: SystemLib) ParseError!void { const tracy = trace(@src()); defer tracy.end(); const gpa = self.base.comp.gpa; const handle = try fs.cwd().openFile(lib.path, .{}); defer handle.close(); const index = @as(File.Index, @intCast(try self.files.addOne(gpa))); self.files.set(index, .{ .shared_object = .{ .path = try gpa.dupe(u8, lib.path), .index = index, .needed = lib.needed, .alive = lib.needed, } }); try self.shared_objects.append(gpa, index); const shared_object = self.file(index).?.shared_object; try shared_object.parse(self, handle); } fn parseLdScript(self: *Elf, lib: SystemLib) ParseError!void { const tracy = trace(@src()); defer tracy.end(); const gpa = self.base.comp.gpa; const in_file = try fs.cwd().openFile(lib.path, .{}); defer in_file.close(); const data = try in_file.readToEndAlloc(gpa, std.math.maxInt(u32)); defer gpa.free(data); var script = LdScript{ .path = lib.path }; defer script.deinit(gpa); try script.parse(data, self); var arena_allocator = std.heap.ArenaAllocator.init(gpa); defer arena_allocator.deinit(); const arena = arena_allocator.allocator(); var test_path = std.ArrayList(u8).init(arena); var checked_paths = std.ArrayList([]const u8).init(arena); for (script.args.items) |scr_obj| { checked_paths.clearRetainingCapacity(); success: { if (mem.startsWith(u8, scr_obj.path, "-l")) { const lib_name = scr_obj.path["-l".len..]; // TODO I think technically we should re-use the mechanism used by the frontend here. // Maybe we should hoist search-strategy all the way here? for (self.lib_dirs) |lib_dir| { if (!self.base.isStatic()) { if (try self.accessLibPath(arena, &test_path, &checked_paths, lib_dir, lib_name, .dynamic)) break :success; } if (try self.accessLibPath(arena, &test_path, &checked_paths, lib_dir, lib_name, .static)) break :success; } } else { var buffer: [fs.max_path_bytes]u8 = undefined; if (fs.realpath(scr_obj.path, &buffer)) |path| { test_path.clearRetainingCapacity(); try test_path.writer().writeAll(path); break :success; } else |_| {} try checked_paths.append(try arena.dupe(u8, scr_obj.path)); for (self.lib_dirs) |lib_dir| { if (try self.accessLibPath(arena, &test_path, &checked_paths, lib_dir, scr_obj.path, null)) break :success; } } try self.reportMissingLibraryError( checked_paths.items, "missing library dependency: GNU ld script '{s}' requires '{s}', but file not found", .{ lib.path, scr_obj.path, }, ); continue; } const full_path = test_path.items; self.parseLibrary(.{ .needed = scr_obj.needed, .path = full_path, }, false) catch |err| switch (err) { error.LinkFailure => continue, // already reported else => |e| try self.addParseError( full_path, "unexpected error: parsing library failed with error {s}", .{@errorName(e)}, ), }; } } pub fn validateEFlags(self: *Elf, file_index: File.Index, e_flags: elf.Elf64_Word) !void { if (self.first_eflags == null) { self.first_eflags = e_flags; return; // there isn't anything to conflict with yet } const self_eflags: *elf.Elf64_Word = &self.first_eflags.?; switch (self.getTarget().cpu.arch) { .riscv64 => { if (e_flags != self_eflags.*) { const riscv_eflags: riscv.RiscvEflags = @bitCast(e_flags); const self_riscv_eflags: *riscv.RiscvEflags = @ptrCast(self_eflags); self_riscv_eflags.rvc = self_riscv_eflags.rvc or riscv_eflags.rvc; self_riscv_eflags.tso = self_riscv_eflags.tso or riscv_eflags.tso; var any_errors: bool = false; if (self_riscv_eflags.fabi != riscv_eflags.fabi) { any_errors = true; try self.addFileError( file_index, "cannot link object files with different float-point ABIs", .{}, ); } if (self_riscv_eflags.rve != riscv_eflags.rve) { any_errors = true; try self.addFileError( file_index, "cannot link object files with different RVEs", .{}, ); } if (any_errors) return error.LinkFailure; } }, else => {}, } } fn accessLibPath( self: *Elf, arena: Allocator, test_path: *std.ArrayList(u8), checked_paths: ?*std.ArrayList([]const u8), lib_dir_path: []const u8, lib_name: []const u8, link_mode: ?std.builtin.LinkMode, ) !bool { const sep = fs.path.sep_str; const target = self.getTarget(); test_path.clearRetainingCapacity(); const prefix = if (link_mode != null) "lib" else ""; const suffix = if (link_mode) |mode| switch (mode) { .static => target.staticLibSuffix(), .dynamic => target.dynamicLibSuffix(), } else ""; try test_path.writer().print("{s}" ++ sep ++ "{s}{s}{s}", .{ lib_dir_path, prefix, lib_name, suffix, }); if (checked_paths) |cpaths| { try cpaths.append(try arena.dupe(u8, test_path.items)); } fs.cwd().access(test_path.items, .{}) catch |err| switch (err) { error.FileNotFound => return false, else => |e| return e, }; return true; } /// When resolving symbols, we approach the problem similarly to `mold`. /// 1. Resolve symbols across all objects (including those preemptively extracted archives). /// 2. Resolve symbols across all shared objects. /// 3. Mark live objects (see `Elf.markLive`) /// 4. Reset state of all resolved globals since we will redo this bit on the pruned set. /// 5. Remove references to dead objects/shared objects /// 6. Re-run symbol resolution on pruned objects and shared objects sets. pub fn resolveSymbols(self: *Elf) !void { // Resolve symbols in the ZigObject. For now, we assume that it's always live. if (self.zigObjectPtr()) |zo| try zo.asFile().resolveSymbols(self); // Resolve symbols on the set of all objects and shared objects (even if some are unneeded). for (self.objects.items) |index| try self.file(index).?.resolveSymbols(self); for (self.shared_objects.items) |index| try self.file(index).?.resolveSymbols(self); if (self.linkerDefinedPtr()) |obj| try obj.asFile().resolveSymbols(self); // Mark live objects. self.markLive(); // Reset state of all globals after marking live objects. self.resolver.reset(); // Prune dead objects and shared objects. var i: usize = 0; while (i < self.objects.items.len) { const index = self.objects.items[i]; if (!self.file(index).?.isAlive()) { _ = self.objects.orderedRemove(i); } else i += 1; } i = 0; while (i < self.shared_objects.items.len) { const index = self.shared_objects.items[i]; if (!self.file(index).?.isAlive()) { _ = self.shared_objects.orderedRemove(i); } else i += 1; } { // Dedup comdat groups. var table = std.StringHashMap(Ref).init(self.base.comp.gpa); defer table.deinit(); for (self.objects.items) |index| { try self.file(index).?.object.resolveComdatGroups(self, &table); } for (self.objects.items) |index| { self.file(index).?.object.markComdatGroupsDead(self); } } // Re-resolve the symbols. if (self.zigObjectPtr()) |zo| try zo.asFile().resolveSymbols(self); for (self.objects.items) |index| try self.file(index).?.resolveSymbols(self); for (self.shared_objects.items) |index| try self.file(index).?.resolveSymbols(self); if (self.linkerDefinedPtr()) |obj| try obj.asFile().resolveSymbols(self); } /// Traverses all objects and shared objects marking any object referenced by /// a live object/shared object as alive itself. /// This routine will prune unneeded objects extracted from archives and /// unneeded shared objects. fn markLive(self: *Elf) void { if (self.zigObjectPtr()) |zig_object| zig_object.asFile().markLive(self); for (self.objects.items) |index| { const file_ptr = self.file(index).?; if (file_ptr.isAlive()) file_ptr.markLive(self); } for (self.shared_objects.items) |index| { const file_ptr = self.file(index).?; if (file_ptr.isAlive()) file_ptr.markLive(self); } } pub fn markEhFrameAtomsDead(self: *Elf) void { for (self.objects.items) |index| { const file_ptr = self.file(index).?; if (!file_ptr.isAlive()) continue; file_ptr.object.markEhFrameAtomsDead(self); } } fn markImportsExports(self: *Elf) void { if (self.zigObjectPtr()) |zo| { zo.markImportsExports(self); } for (self.objects.items) |index| { self.file(index).?.object.markImportsExports(self); } if (!self.isEffectivelyDynLib()) { for (self.shared_objects.items) |index| { self.file(index).?.shared_object.markImportExports(self); } } } fn claimUnresolved(self: *Elf) void { if (self.zigObjectPtr()) |zig_object| { zig_object.claimUnresolved(self); } for (self.objects.items) |index| { self.file(index).?.object.claimUnresolved(self); } } /// In scanRelocs we will go over all live atoms and scan their relocs. /// This will help us work out what synthetics to emit, GOT indirection, etc. /// This is also the point where we will report undefined symbols for any /// alloc sections. fn scanRelocs(self: *Elf) !void { const gpa = self.base.comp.gpa; var undefs = std.AutoArrayHashMap(SymbolResolver.Index, std.ArrayList(Ref)).init(gpa); defer { for (undefs.values()) |*refs| { refs.deinit(); } undefs.deinit(); } var has_reloc_errors = false; if (self.zigObjectPtr()) |zo| { zo.asFile().scanRelocs(self, &undefs) catch |err| switch (err) { error.RelaxFailure => unreachable, error.UnsupportedCpuArch => { try self.reportUnsupportedCpuArch(); return error.FlushFailure; }, error.RelocFailure => has_reloc_errors = true, else => |e| return e, }; } for (self.objects.items) |index| { self.file(index).?.scanRelocs(self, &undefs) catch |err| switch (err) { error.RelaxFailure => unreachable, error.UnsupportedCpuArch => { try self.reportUnsupportedCpuArch(); return error.FlushFailure; }, error.RelocFailure => has_reloc_errors = true, else => |e| return e, }; } try self.reportUndefinedSymbols(&undefs); if (has_reloc_errors) return error.FlushFailure; if (self.zigObjectPtr()) |zo| { try zo.asFile().createSymbolIndirection(self); } for (self.objects.items) |index| { try self.file(index).?.createSymbolIndirection(self); } for (self.shared_objects.items) |index| { try self.file(index).?.createSymbolIndirection(self); } if (self.linkerDefinedPtr()) |obj| { try obj.asFile().createSymbolIndirection(self); } if (self.got.flags.needs_tlsld) { log.debug("program needs TLSLD", .{}); try self.got.addTlsLdSymbol(self); } } pub fn initOutputSection(self: *Elf, args: struct { name: [:0]const u8, flags: u64, type: u32, }) error{OutOfMemory}!u32 { const name = blk: { if (self.base.isRelocatable()) break :blk args.name; if (args.flags & elf.SHF_MERGE != 0) break :blk args.name; const name_prefixes: []const [:0]const u8 = &.{ ".text", ".data.rel.ro", ".data", ".rodata", ".bss.rel.ro", ".bss", ".init_array", ".fini_array", ".tbss", ".tdata", ".gcc_except_table", ".ctors", ".dtors", ".gnu.warning", }; inline for (name_prefixes) |prefix| { if (std.mem.eql(u8, args.name, prefix) or std.mem.startsWith(u8, args.name, prefix ++ ".")) { break :blk prefix; } } break :blk args.name; }; const @"type" = tt: { if (self.getTarget().cpu.arch == .x86_64 and args.type == elf.SHT_X86_64_UNWIND) break :tt elf.SHT_PROGBITS; switch (args.type) { elf.SHT_NULL => unreachable, elf.SHT_PROGBITS => { if (std.mem.eql(u8, args.name, ".init_array") or std.mem.startsWith(u8, args.name, ".init_array.")) break :tt elf.SHT_INIT_ARRAY; if (std.mem.eql(u8, args.name, ".fini_array") or std.mem.startsWith(u8, args.name, ".fini_array.")) break :tt elf.SHT_FINI_ARRAY; break :tt args.type; }, else => break :tt args.type, } }; const flags = blk: { var flags = args.flags; if (!self.base.isRelocatable()) { flags &= ~@as(u64, elf.SHF_COMPRESSED | elf.SHF_GROUP | elf.SHF_GNU_RETAIN); } break :blk switch (@"type") { elf.SHT_INIT_ARRAY, elf.SHT_FINI_ARRAY => flags | elf.SHF_WRITE, else => flags, }; }; const out_shndx = self.sectionByName(name) orelse try self.addSection(.{ .type = @"type", .flags = flags, .name = try self.insertShString(name), }); return out_shndx; } fn linkWithLLD(self: *Elf, arena: Allocator, tid: Zcu.PerThread.Id, prog_node: std.Progress.Node) !void { dev.check(.lld_linker); const tracy = trace(@src()); defer tracy.end(); const comp = self.base.comp; const gpa = comp.gpa; const directory = self.base.emit.root_dir; // Just an alias to make it shorter to type. const full_out_path = try directory.join(arena, &[_][]const u8{self.base.emit.sub_path}); // If there is no Zig code to compile, then we should skip flushing the output file because it // will not be part of the linker line anyway. const module_obj_path: ?[]const u8 = if (comp.zcu != null) blk: { try self.flushModule(arena, tid, prog_node); if (fs.path.dirname(full_out_path)) |dirname| { break :blk try fs.path.join(arena, &.{ dirname, self.base.zcu_object_sub_path.? }); } else { break :blk self.base.zcu_object_sub_path.?; } } else null; const sub_prog_node = prog_node.start("LLD Link", 0); defer sub_prog_node.end(); const output_mode = comp.config.output_mode; const is_obj = output_mode == .Obj; const is_lib = output_mode == .Lib; const link_mode = comp.config.link_mode; const is_dyn_lib = link_mode == .dynamic and is_lib; const is_exe_or_dyn_lib = is_dyn_lib or output_mode == .Exe; const have_dynamic_linker = comp.config.link_libc and link_mode == .dynamic and is_exe_or_dyn_lib; const target = self.getTarget(); const compiler_rt_path: ?[]const u8 = blk: { if (comp.compiler_rt_lib) |x| break :blk x.full_object_path; if (comp.compiler_rt_obj) |x| break :blk x.full_object_path; break :blk null; }; // Here we want to determine whether we can save time by not invoking LLD when the // output is unchanged. None of the linker options or the object files that are being // linked are in the hash that namespaces the directory we are outputting to. Therefore, // we must hash those now, and the resulting digest will form the "id" of the linking // job we are about to perform. // After a successful link, we store the id in the metadata of a symlink named "lld.id" in // the artifact directory. So, now, we check if this symlink exists, and if it matches // our digest. If so, we can skip linking. Otherwise, we proceed with invoking LLD. const id_symlink_basename = "lld.id"; var man: Cache.Manifest = undefined; defer if (!self.base.disable_lld_caching) man.deinit(); var digest: [Cache.hex_digest_len]u8 = undefined; if (!self.base.disable_lld_caching) { man = comp.cache_parent.obtain(); // We are about to obtain this lock, so here we give other processes a chance first. self.base.releaseLock(); comptime assert(Compilation.link_hash_implementation_version == 14); try man.addOptionalFile(self.linker_script); try man.addOptionalFile(self.version_script); man.hash.add(self.allow_undefined_version); man.hash.addOptional(self.enable_new_dtags); for (comp.objects) |obj| { _ = try man.addFile(obj.path, null); man.hash.add(obj.must_link); man.hash.add(obj.loption); } for (comp.c_object_table.keys()) |key| { _ = try man.addFile(key.status.success.object_path, null); } try man.addOptionalFile(module_obj_path); try man.addOptionalFile(compiler_rt_path); try man.addOptionalFile(if (comp.tsan_lib) |l| l.full_object_path else null); try man.addOptionalFile(if (comp.fuzzer_lib) |l| l.full_object_path else null); // We can skip hashing libc and libc++ components that we are in charge of building from Zig // installation sources because they are always a product of the compiler version + target information. man.hash.addOptionalBytes(self.entry_name); man.hash.add(self.image_base); man.hash.add(self.base.gc_sections); man.hash.addOptional(self.sort_section); man.hash.add(comp.link_eh_frame_hdr); man.hash.add(self.emit_relocs); man.hash.add(comp.config.rdynamic); man.hash.addListOfBytes(self.lib_dirs); man.hash.addListOfBytes(self.rpath_table.keys()); if (output_mode == .Exe) { man.hash.add(self.base.stack_size); man.hash.add(self.base.build_id); } man.hash.addListOfBytes(self.symbol_wrap_set.keys()); man.hash.add(comp.skip_linker_dependencies); man.hash.add(self.z_nodelete); man.hash.add(self.z_notext); man.hash.add(self.z_defs); man.hash.add(self.z_origin); man.hash.add(self.z_nocopyreloc); man.hash.add(self.z_now); man.hash.add(self.z_relro); man.hash.add(self.z_common_page_size orelse 0); man.hash.add(self.z_max_page_size orelse 0); man.hash.add(self.hash_style); // strip does not need to go into the linker hash because it is part of the hash namespace if (comp.config.link_libc) { man.hash.add(comp.libc_installation != null); if (comp.libc_installation) |libc_installation| { man.hash.addBytes(libc_installation.crt_dir.?); } if (have_dynamic_linker) { man.hash.addOptionalBytes(target.dynamic_linker.get()); } } man.hash.addOptionalBytes(self.soname); man.hash.addOptional(comp.version); try link.hashAddSystemLibs(&man, comp.system_libs); man.hash.addListOfBytes(comp.force_undefined_symbols.keys()); man.hash.add(self.base.allow_shlib_undefined); man.hash.add(self.bind_global_refs_locally); man.hash.add(self.compress_debug_sections); man.hash.add(comp.config.any_sanitize_thread); man.hash.add(comp.config.any_fuzz); man.hash.addOptionalBytes(comp.sysroot); // We don't actually care whether it's a cache hit or miss; we just need the digest and the lock. _ = try man.hit(); digest = man.final(); var prev_digest_buf: [digest.len]u8 = undefined; const prev_digest: []u8 = Cache.readSmallFile( directory.handle, id_symlink_basename, &prev_digest_buf, ) catch |err| blk: { log.debug("ELF LLD new_digest={s} error: {s}", .{ std.fmt.fmtSliceHexLower(&digest), @errorName(err) }); // Handle this as a cache miss. break :blk prev_digest_buf[0..0]; }; if (mem.eql(u8, prev_digest, &digest)) { log.debug("ELF LLD digest={s} match - skipping invocation", .{std.fmt.fmtSliceHexLower(&digest)}); // Hot diggity dog! The output binary is already there. self.base.lock = man.toOwnedLock(); return; } log.debug("ELF LLD prev_digest={s} new_digest={s}", .{ std.fmt.fmtSliceHexLower(prev_digest), std.fmt.fmtSliceHexLower(&digest) }); // We are about to change the output file to be different, so we invalidate the build hash now. directory.handle.deleteFile(id_symlink_basename) catch |err| switch (err) { error.FileNotFound => {}, else => |e| return e, }; } // Due to a deficiency in LLD, we need to special-case BPF to a simple file // copy when generating relocatables. Normally, we would expect `lld -r` to work. // However, because LLD wants to resolve BPF relocations which it shouldn't, it fails // before even generating the relocatable. if (output_mode == .Obj and (comp.config.lto or target.isBpfFreestanding())) { // In this case we must do a simple file copy // here. TODO: think carefully about how we can avoid this redundant operation when doing // build-obj. See also the corresponding TODO in linkAsArchive. const the_object_path = blk: { if (comp.objects.len != 0) break :blk comp.objects[0].path; if (comp.c_object_table.count() != 0) break :blk comp.c_object_table.keys()[0].status.success.object_path; if (module_obj_path) |p| break :blk p; // TODO I think this is unreachable. Audit this situation when solving the above TODO // regarding eliding redundant object -> object transformations. return error.NoObjectsToLink; }; // This can happen when using --enable-cache and using the stage1 backend. In this case // we can skip the file copy. if (!mem.eql(u8, the_object_path, full_out_path)) { try fs.cwd().copyFile(the_object_path, fs.cwd(), full_out_path, .{}); } } else { // Create an LLD command line and invoke it. var argv = std.ArrayList([]const u8).init(gpa); defer argv.deinit(); // We will invoke ourselves as a child process to gain access to LLD. // This is necessary because LLD does not behave properly as a library - // it calls exit() and does not reset all global data between invocations. const linker_command = "ld.lld"; try argv.appendSlice(&[_][]const u8{ comp.self_exe_path.?, linker_command }); if (is_obj) { try argv.append("-r"); } try argv.append("--error-limit=0"); if (comp.sysroot) |sysroot| { try argv.append(try std.fmt.allocPrint(arena, "--sysroot={s}", .{sysroot})); } if (comp.config.lto) { switch (comp.root_mod.optimize_mode) { .Debug => {}, .ReleaseSmall => try argv.append("--lto-O2"), .ReleaseFast, .ReleaseSafe => try argv.append("--lto-O3"), } } switch (comp.root_mod.optimize_mode) { .Debug => {}, .ReleaseSmall => try argv.append("-O2"), .ReleaseFast, .ReleaseSafe => try argv.append("-O3"), } if (self.entry_name) |name| { try argv.appendSlice(&.{ "--entry", name }); } for (comp.force_undefined_symbols.keys()) |sym| { try argv.append("-u"); try argv.append(sym); } switch (self.hash_style) { .gnu => try argv.append("--hash-style=gnu"), .sysv => try argv.append("--hash-style=sysv"), .both => {}, // this is the default } if (output_mode == .Exe) { try argv.appendSlice(&.{ "-z", try std.fmt.allocPrint(arena, "stack-size={d}", .{self.base.stack_size}), }); switch (self.base.build_id) { .none => {}, .fast, .uuid, .sha1, .md5 => { try argv.append(try std.fmt.allocPrint(arena, "--build-id={s}", .{ @tagName(self.base.build_id), })); }, .hexstring => |hs| { try argv.append(try std.fmt.allocPrint(arena, "--build-id=0x{s}", .{ std.fmt.fmtSliceHexLower(hs.toSlice()), })); }, } } try argv.append(try std.fmt.allocPrint(arena, "--image-base={d}", .{self.image_base})); if (self.linker_script) |linker_script| { try argv.append("-T"); try argv.append(linker_script); } if (self.sort_section) |how| { const arg = try std.fmt.allocPrint(arena, "--sort-section={s}", .{@tagName(how)}); try argv.append(arg); } if (self.base.gc_sections) { try argv.append("--gc-sections"); } if (self.base.print_gc_sections) { try argv.append("--print-gc-sections"); } if (self.print_icf_sections) { try argv.append("--print-icf-sections"); } if (self.print_map) { try argv.append("--print-map"); } if (comp.link_eh_frame_hdr) { try argv.append("--eh-frame-hdr"); } if (self.emit_relocs) { try argv.append("--emit-relocs"); } if (comp.config.rdynamic) { try argv.append("--export-dynamic"); } if (comp.config.debug_format == .strip) { try argv.append("-s"); } if (self.z_nodelete) { try argv.append("-z"); try argv.append("nodelete"); } if (self.z_notext) { try argv.append("-z"); try argv.append("notext"); } if (self.z_defs) { try argv.append("-z"); try argv.append("defs"); } if (self.z_origin) { try argv.append("-z"); try argv.append("origin"); } if (self.z_nocopyreloc) { try argv.append("-z"); try argv.append("nocopyreloc"); } if (self.z_now) { // LLD defaults to -zlazy try argv.append("-znow"); } if (!self.z_relro) { // LLD defaults to -zrelro try argv.append("-znorelro"); } if (self.z_common_page_size) |size| { try argv.append("-z"); try argv.append(try std.fmt.allocPrint(arena, "common-page-size={d}", .{size})); } if (self.z_max_page_size) |size| { try argv.append("-z"); try argv.append(try std.fmt.allocPrint(arena, "max-page-size={d}", .{size})); } if (getLDMOption(target)) |ldm| { try argv.append("-m"); try argv.append(ldm); } if (link_mode == .static) { if (target.cpu.arch.isArmOrThumb()) { try argv.append("-Bstatic"); } else { try argv.append("-static"); } } else if (switch (target.os.tag) { else => is_dyn_lib, .haiku => is_exe_or_dyn_lib, }) { try argv.append("-shared"); } if (comp.config.pie and output_mode == .Exe) { try argv.append("-pie"); } if (is_exe_or_dyn_lib and target.os.tag == .netbsd) { // Add options to produce shared objects with only 2 PT_LOAD segments. // NetBSD expects 2 PT_LOAD segments in a shared object, otherwise // ld.elf_so fails loading dynamic libraries with "not found" error. // See https://github.com/ziglang/zig/issues/9109 . try argv.append("--no-rosegment"); try argv.append("-znorelro"); } try argv.append("-o"); try argv.append(full_out_path); // csu prelude const csu = try CsuObjects.init(arena, comp); if (csu.crt0) |v| try argv.append(v); if (csu.crti) |v| try argv.append(v); if (csu.crtbegin) |v| try argv.append(v); for (self.rpath_table.keys()) |rpath| { try argv.appendSlice(&.{ "-rpath", rpath }); } for (self.symbol_wrap_set.keys()) |symbol_name| { try argv.appendSlice(&.{ "-wrap", symbol_name }); } for (self.lib_dirs) |lib_dir| { try argv.append("-L"); try argv.append(lib_dir); } if (comp.config.link_libc) { if (comp.libc_installation) |libc_installation| { try argv.append("-L"); try argv.append(libc_installation.crt_dir.?); } if (have_dynamic_linker) { if (target.dynamic_linker.get()) |dynamic_linker| { try argv.append("-dynamic-linker"); try argv.append(dynamic_linker); } } } if (is_dyn_lib) { if (self.soname) |soname| { try argv.append("-soname"); try argv.append(soname); } if (self.version_script) |version_script| { try argv.append("-version-script"); try argv.append(version_script); } if (self.allow_undefined_version) { try argv.append("--undefined-version"); } else { try argv.append("--no-undefined-version"); } if (self.enable_new_dtags) |enable_new_dtags| { if (enable_new_dtags) { try argv.append("--enable-new-dtags"); } else { try argv.append("--disable-new-dtags"); } } } // Positional arguments to the linker such as object files. var whole_archive = false; for (comp.objects) |obj| { if (obj.must_link and !whole_archive) { try argv.append("-whole-archive"); whole_archive = true; } else if (!obj.must_link and whole_archive) { try argv.append("-no-whole-archive"); whole_archive = false; } if (obj.loption) { assert(obj.path[0] == ':'); try argv.append("-l"); } try argv.append(obj.path); } if (whole_archive) { try argv.append("-no-whole-archive"); whole_archive = false; } for (comp.c_object_table.keys()) |key| { try argv.append(key.status.success.object_path); } if (module_obj_path) |p| { try argv.append(p); } if (comp.tsan_lib) |lib| { assert(comp.config.any_sanitize_thread); try argv.append(lib.full_object_path); } if (comp.fuzzer_lib) |lib| { assert(comp.config.any_fuzz); try argv.append(lib.full_object_path); } // libc if (is_exe_or_dyn_lib and !comp.skip_linker_dependencies and !comp.config.link_libc) { if (comp.libc_static_lib) |lib| { try argv.append(lib.full_object_path); } } // Shared libraries. if (is_exe_or_dyn_lib) { const system_libs = comp.system_libs.keys(); const system_libs_values = comp.system_libs.values(); // Worst-case, we need an --as-needed argument for every lib, as well // as one before and one after. try argv.ensureUnusedCapacity(system_libs.len * 2 + 2); argv.appendAssumeCapacity("--as-needed"); var as_needed = true; for (system_libs_values) |lib_info| { const lib_as_needed = !lib_info.needed; switch ((@as(u2, @intFromBool(lib_as_needed)) << 1) | @intFromBool(as_needed)) { 0b00, 0b11 => {}, 0b01 => { argv.appendAssumeCapacity("--no-as-needed"); as_needed = false; }, 0b10 => { argv.appendAssumeCapacity("--as-needed"); as_needed = true; }, } // By this time, we depend on these libs being dynamically linked // libraries and not static libraries (the check for that needs to be earlier), // but they could be full paths to .so files, in which case we // want to avoid prepending "-l". argv.appendAssumeCapacity(lib_info.path.?); } if (!as_needed) { argv.appendAssumeCapacity("--as-needed"); as_needed = true; } // libc++ dep if (comp.config.link_libcpp) { try argv.append(comp.libcxxabi_static_lib.?.full_object_path); try argv.append(comp.libcxx_static_lib.?.full_object_path); } // libunwind dep if (comp.config.link_libunwind) { try argv.append(comp.libunwind_static_lib.?.full_object_path); } // libc dep comp.link_error_flags.missing_libc = false; if (comp.config.link_libc) { if (comp.libc_installation != null) { const needs_grouping = link_mode == .static; if (needs_grouping) try argv.append("--start-group"); try argv.appendSlice(target_util.libcFullLinkFlags(target)); if (needs_grouping) try argv.append("--end-group"); } else if (target.isGnuLibC()) { for (glibc.libs) |lib| { if (lib.removed_in) |rem_in| { if (target.os.version_range.linux.glibc.order(rem_in) != .lt) continue; } const lib_path = try std.fmt.allocPrint(arena, "{s}{c}lib{s}.so.{d}", .{ comp.glibc_so_files.?.dir_path, fs.path.sep, lib.name, lib.sover, }); try argv.append(lib_path); } try argv.append(try comp.get_libc_crt_file(arena, "libc_nonshared.a")); } else if (target.isMusl()) { try argv.append(try comp.get_libc_crt_file(arena, switch (link_mode) { .static => "libc.a", .dynamic => "libc.so", })); } else { comp.link_error_flags.missing_libc = true; } } } // compiler-rt. Since compiler_rt exports symbols like `memset`, it needs // to be after the shared libraries, so they are picked up from the shared // libraries, not libcompiler_rt. if (compiler_rt_path) |p| { try argv.append(p); } // crt postlude if (csu.crtend) |v| try argv.append(v); if (csu.crtn) |v| try argv.append(v); if (self.base.allow_shlib_undefined) { try argv.append("--allow-shlib-undefined"); } switch (self.compress_debug_sections) { .none => {}, .zlib => try argv.append("--compress-debug-sections=zlib"), .zstd => try argv.append("--compress-debug-sections=zstd"), } if (self.bind_global_refs_locally) { try argv.append("-Bsymbolic"); } try link.spawnLld(comp, arena, argv.items); } if (!self.base.disable_lld_caching) { // Update the file with the digest. If it fails we can continue; it only // means that the next invocation will have an unnecessary cache miss. Cache.writeSmallFile(directory.handle, id_symlink_basename, &digest) catch |err| { log.warn("failed to save linking hash digest file: {s}", .{@errorName(err)}); }; // Again failure here only means an unnecessary cache miss. man.writeManifest() catch |err| { log.warn("failed to write cache manifest when linking: {s}", .{@errorName(err)}); }; // We hang on to this lock so that the output file path can be used without // other processes clobbering it. self.base.lock = man.toOwnedLock(); } } pub fn writeShdrTable(self: *Elf) !void { const gpa = self.base.comp.gpa; const target_endian = self.getTarget().cpu.arch.endian(); const foreign_endian = target_endian != builtin.cpu.arch.endian(); const shsize: u64 = switch (self.ptr_width) { .p32 => @sizeOf(elf.Elf32_Shdr), .p64 => @sizeOf(elf.Elf64_Shdr), }; const shalign: u16 = switch (self.ptr_width) { .p32 => @alignOf(elf.Elf32_Shdr), .p64 => @alignOf(elf.Elf64_Shdr), }; const shoff = self.shdr_table_offset orelse 0; const needed_size = self.sections.items(.shdr).len * shsize; if (needed_size > self.allocatedSize(shoff)) { self.shdr_table_offset = null; self.shdr_table_offset = try self.findFreeSpace(needed_size, shalign); } log.debug("writing section headers from 0x{x} to 0x{x}", .{ self.shdr_table_offset.?, self.shdr_table_offset.? + needed_size, }); switch (self.ptr_width) { .p32 => { const buf = try gpa.alloc(elf.Elf32_Shdr, self.sections.items(.shdr).len); defer gpa.free(buf); for (buf, 0..) |*shdr, i| { assert(self.sections.items(.shdr)[i].sh_offset != math.maxInt(u64)); shdr.* = shdrTo32(self.sections.items(.shdr)[i]); if (foreign_endian) { mem.byteSwapAllFields(elf.Elf32_Shdr, shdr); } } try self.base.file.?.pwriteAll(mem.sliceAsBytes(buf), self.shdr_table_offset.?); }, .p64 => { const buf = try gpa.alloc(elf.Elf64_Shdr, self.sections.items(.shdr).len); defer gpa.free(buf); for (buf, 0..) |*shdr, i| { assert(self.sections.items(.shdr)[i].sh_offset != math.maxInt(u64)); shdr.* = self.sections.items(.shdr)[i]; if (foreign_endian) { mem.byteSwapAllFields(elf.Elf64_Shdr, shdr); } } try self.base.file.?.pwriteAll(mem.sliceAsBytes(buf), self.shdr_table_offset.?); }, } } fn writePhdrTable(self: *Elf) !void { const gpa = self.base.comp.gpa; const target_endian = self.getTarget().cpu.arch.endian(); const foreign_endian = target_endian != builtin.cpu.arch.endian(); const phdr_table = &self.phdrs.items[self.phdr_table_index.?]; log.debug("writing program headers from 0x{x} to 0x{x}", .{ phdr_table.p_offset, phdr_table.p_offset + phdr_table.p_filesz, }); switch (self.ptr_width) { .p32 => { const buf = try gpa.alloc(elf.Elf32_Phdr, self.phdrs.items.len); defer gpa.free(buf); for (buf, 0..) |*phdr, i| { phdr.* = phdrTo32(self.phdrs.items[i]); if (foreign_endian) { mem.byteSwapAllFields(elf.Elf32_Phdr, phdr); } } try self.base.file.?.pwriteAll(mem.sliceAsBytes(buf), phdr_table.p_offset); }, .p64 => { const buf = try gpa.alloc(elf.Elf64_Phdr, self.phdrs.items.len); defer gpa.free(buf); for (buf, 0..) |*phdr, i| { phdr.* = self.phdrs.items[i]; if (foreign_endian) { mem.byteSwapAllFields(elf.Elf64_Phdr, phdr); } } try self.base.file.?.pwriteAll(mem.sliceAsBytes(buf), phdr_table.p_offset); }, } } pub fn writeElfHeader(self: *Elf) !void { if (self.base.hasErrors()) return; // We had errors, so skip flushing to render the output unusable const comp = self.base.comp; var hdr_buf: [@sizeOf(elf.Elf64_Ehdr)]u8 = undefined; var index: usize = 0; hdr_buf[0..4].* = elf.MAGIC.*; index += 4; hdr_buf[index] = switch (self.ptr_width) { .p32 => elf.ELFCLASS32, .p64 => elf.ELFCLASS64, }; index += 1; const target = self.getTarget(); const endian = target.cpu.arch.endian(); hdr_buf[index] = switch (endian) { .little => elf.ELFDATA2LSB, .big => elf.ELFDATA2MSB, }; index += 1; hdr_buf[index] = 1; // ELF version index += 1; hdr_buf[index] = @intFromEnum(@as(elf.OSABI, switch (target.cpu.arch) { .amdgcn => switch (target.os.tag) { .amdhsa => .AMDGPU_HSA, .amdpal => .AMDGPU_PAL, .mesa3d => .AMDGPU_MESA3D, else => .NONE, }, .msp430 => .STANDALONE, else => switch (target.os.tag) { .freebsd, .ps4 => .FREEBSD, .hermit => .STANDALONE, .illumos, .solaris => .SOLARIS, .openbsd => .OPENBSD, else => .NONE, }, })); index += 1; // ABI Version, possibly used by glibc but not by static executables // padding @memset(hdr_buf[index..][0..8], 0); index += 8; assert(index == 16); const output_mode = comp.config.output_mode; const link_mode = comp.config.link_mode; const elf_type: elf.ET = switch (output_mode) { .Exe => if (comp.config.pie or target.os.tag == .haiku) .DYN else .EXEC, .Obj => .REL, .Lib => switch (link_mode) { .static => @as(elf.ET, .REL), .dynamic => .DYN, }, }; mem.writeInt(u16, hdr_buf[index..][0..2], @intFromEnum(elf_type), endian); index += 2; const machine = target.toElfMachine(); mem.writeInt(u16, hdr_buf[index..][0..2], @intFromEnum(machine), endian); index += 2; // ELF Version, again mem.writeInt(u32, hdr_buf[index..][0..4], 1, endian); index += 4; const e_entry: u64 = if (self.linkerDefinedPtr()) |obj| blk: { const entry_sym = obj.entrySymbol(self) orelse break :blk 0; break :blk @intCast(entry_sym.address(.{}, self)); } else 0; const phdr_table_offset = if (self.phdr_table_index) |phndx| self.phdrs.items[phndx].p_offset else 0; switch (self.ptr_width) { .p32 => { mem.writeInt(u32, hdr_buf[index..][0..4], @as(u32, @intCast(e_entry)), endian); index += 4; // e_phoff mem.writeInt(u32, hdr_buf[index..][0..4], @as(u32, @intCast(phdr_table_offset)), endian); index += 4; // e_shoff mem.writeInt(u32, hdr_buf[index..][0..4], @as(u32, @intCast(self.shdr_table_offset.?)), endian); index += 4; }, .p64 => { // e_entry mem.writeInt(u64, hdr_buf[index..][0..8], e_entry, endian); index += 8; // e_phoff mem.writeInt(u64, hdr_buf[index..][0..8], phdr_table_offset, endian); index += 8; // e_shoff mem.writeInt(u64, hdr_buf[index..][0..8], self.shdr_table_offset.?, endian); index += 8; }, } const e_flags = 0; mem.writeInt(u32, hdr_buf[index..][0..4], e_flags, endian); index += 4; const e_ehsize: u16 = switch (self.ptr_width) { .p32 => @sizeOf(elf.Elf32_Ehdr), .p64 => @sizeOf(elf.Elf64_Ehdr), }; mem.writeInt(u16, hdr_buf[index..][0..2], e_ehsize, endian); index += 2; const e_phentsize: u16 = switch (self.ptr_width) { .p32 => @sizeOf(elf.Elf32_Phdr), .p64 => @sizeOf(elf.Elf64_Phdr), }; mem.writeInt(u16, hdr_buf[index..][0..2], e_phentsize, endian); index += 2; const e_phnum = @as(u16, @intCast(self.phdrs.items.len)); mem.writeInt(u16, hdr_buf[index..][0..2], e_phnum, endian); index += 2; const e_shentsize: u16 = switch (self.ptr_width) { .p32 => @sizeOf(elf.Elf32_Shdr), .p64 => @sizeOf(elf.Elf64_Shdr), }; mem.writeInt(u16, hdr_buf[index..][0..2], e_shentsize, endian); index += 2; const e_shnum = @as(u16, @intCast(self.sections.items(.shdr).len)); mem.writeInt(u16, hdr_buf[index..][0..2], e_shnum, endian); index += 2; mem.writeInt(u16, hdr_buf[index..][0..2], @intCast(self.shstrtab_section_index.?), endian); index += 2; assert(index == e_ehsize); try self.base.file.?.pwriteAll(hdr_buf[0..index], 0); } pub fn freeNav(self: *Elf, nav: InternPool.Nav.Index) void { if (self.llvm_object) |llvm_object| return llvm_object.freeNav(nav); return self.zigObjectPtr().?.freeNav(self, nav); } pub fn updateFunc(self: *Elf, pt: Zcu.PerThread, func_index: InternPool.Index, air: Air, liveness: Liveness) !void { if (build_options.skip_non_native and builtin.object_format != .elf) { @panic("Attempted to compile for object format that was disabled by build configuration"); } if (self.llvm_object) |llvm_object| return llvm_object.updateFunc(pt, func_index, air, liveness); return self.zigObjectPtr().?.updateFunc(self, pt, func_index, air, liveness); } pub fn updateNav( self: *Elf, pt: Zcu.PerThread, nav: InternPool.Nav.Index, ) link.File.UpdateNavError!void { if (build_options.skip_non_native and builtin.object_format != .elf) { @panic("Attempted to compile for object format that was disabled by build configuration"); } if (self.llvm_object) |llvm_object| return llvm_object.updateNav(pt, nav); return self.zigObjectPtr().?.updateNav(self, pt, nav); } pub fn updateContainerType( self: *Elf, pt: Zcu.PerThread, ty: InternPool.Index, ) link.File.UpdateNavError!void { if (build_options.skip_non_native and builtin.object_format != .elf) { @panic("Attempted to compile for object format that was disabled by build configuration"); } if (self.llvm_object) |_| return; return self.zigObjectPtr().?.updateContainerType(pt, ty); } pub fn updateExports( self: *Elf, pt: Zcu.PerThread, exported: Zcu.Exported, export_indices: []const u32, ) link.File.UpdateExportsError!void { if (build_options.skip_non_native and builtin.object_format != .elf) { @panic("Attempted to compile for object format that was disabled by build configuration"); } if (self.llvm_object) |llvm_object| return llvm_object.updateExports(pt, exported, export_indices); return self.zigObjectPtr().?.updateExports(self, pt, exported, export_indices); } pub fn updateNavLineNumber(self: *Elf, pt: Zcu.PerThread, nav: InternPool.Nav.Index) !void { if (self.llvm_object) |_| return; return self.zigObjectPtr().?.updateNavLineNumber(pt, nav); } pub fn deleteExport( self: *Elf, exported: Zcu.Exported, name: InternPool.NullTerminatedString, ) void { if (self.llvm_object) |_| return; return self.zigObjectPtr().?.deleteExport(self, exported, name); } fn checkDuplicates(self: *Elf) !void { const gpa = self.base.comp.gpa; var dupes = std.AutoArrayHashMap(SymbolResolver.Index, std.ArrayListUnmanaged(File.Index)).init(gpa); defer { for (dupes.values()) |*list| { list.deinit(gpa); } dupes.deinit(); } if (self.zigObjectPtr()) |zig_object| { try zig_object.checkDuplicates(&dupes, self); } for (self.objects.items) |index| { try self.file(index).?.object.checkDuplicates(&dupes, self); } try self.reportDuplicates(dupes); } pub fn addCommentString(self: *Elf) !void { const gpa = self.base.comp.gpa; if (self.comment_merge_section_index != null) return; const msec_index = try self.getOrCreateMergeSection(".comment", elf.SHF_MERGE | elf.SHF_STRINGS, elf.SHT_PROGBITS); const msec = self.mergeSection(msec_index); const res = try msec.insertZ(gpa, "zig " ++ builtin.zig_version_string); if (res.found_existing) return; const msub_index = try msec.addMergeSubsection(gpa); const msub = msec.mergeSubsection(msub_index); msub.merge_section_index = msec_index; msub.string_index = res.key.pos; msub.alignment = .@"1"; msub.size = res.key.len; msub.entsize = 1; msub.alive = true; res.sub.* = msub_index; self.comment_merge_section_index = msec_index; } pub fn resolveMergeSections(self: *Elf) !void { const tracy = trace(@src()); defer tracy.end(); var has_errors = false; for (self.objects.items) |index| { const object = self.file(index).?.object; if (!object.alive) continue; if (!object.dirty) continue; object.initInputMergeSections(self) catch |err| switch (err) { error.LinkFailure => has_errors = true, else => |e| return e, }; } if (has_errors) return error.FlushFailure; for (self.objects.items) |index| { const object = self.file(index).?.object; if (!object.alive) continue; if (!object.dirty) continue; try object.initOutputMergeSections(self); } for (self.objects.items) |index| { const object = self.file(index).?.object; if (!object.alive) continue; if (!object.dirty) continue; object.resolveMergeSubsections(self) catch |err| switch (err) { error.LinkFailure => has_errors = true, else => |e| return e, }; } if (has_errors) return error.LinkFailure; } pub fn finalizeMergeSections(self: *Elf) !void { for (self.merge_sections.items) |*msec| { try msec.finalize(self.base.comp.gpa); } } pub fn updateMergeSectionSizes(self: *Elf) !void { for (self.merge_sections.items) |*msec| { msec.updateSize(); } for (self.merge_sections.items) |*msec| { const shdr = &self.sections.items(.shdr)[msec.output_section_index]; const offset = msec.alignment.forward(shdr.sh_size); const padding = offset - shdr.sh_size; msec.value = @intCast(offset); shdr.sh_size += padding + msec.size; shdr.sh_addralign = @max(shdr.sh_addralign, msec.alignment.toByteUnits() orelse 1); shdr.sh_entsize = if (shdr.sh_entsize == 0) msec.entsize else @min(shdr.sh_entsize, msec.entsize); } } pub fn writeMergeSections(self: *Elf) !void { const gpa = self.base.comp.gpa; var buffer = std.ArrayList(u8).init(gpa); defer buffer.deinit(); for (self.merge_sections.items) |*msec| { const shdr = self.sections.items(.shdr)[msec.output_section_index]; const fileoff = math.cast(usize, msec.value + shdr.sh_offset) orelse return error.Overflow; const size = math.cast(usize, msec.size) orelse return error.Overflow; try buffer.ensureTotalCapacity(size); buffer.appendNTimesAssumeCapacity(0, size); for (msec.finalized_subsections.items) |msub_index| { const msub = msec.mergeSubsection(msub_index); assert(msub.alive); const string = msub.getString(self); const off = math.cast(usize, msub.value) orelse return error.Overflow; @memcpy(buffer.items[off..][0..string.len], string); } try self.base.file.?.pwriteAll(buffer.items, fileoff); buffer.clearRetainingCapacity(); } } fn initOutputSections(self: *Elf) !void { for (self.objects.items) |index| { try self.file(index).?.object.initOutputSections(self); } for (self.merge_sections.items) |*msec| { if (msec.finalized_subsections.items.len == 0) continue; try msec.initOutputSection(self); } } fn initSyntheticSections(self: *Elf) !void { const comp = self.base.comp; const target = self.getTarget(); const ptr_size = self.ptrWidthBytes(); const needs_eh_frame = blk: { if (self.zigObjectPtr()) |zo| if (zo.eh_frame_index != null) break :blk true; break :blk for (self.objects.items) |index| { if (self.file(index).?.object.cies.items.len > 0) break true; } else false; }; if (needs_eh_frame) { if (self.eh_frame_section_index == null) { self.eh_frame_section_index = self.sectionByName(".eh_frame") orelse try self.addSection(.{ .name = try self.insertShString(".eh_frame"), .type = if (target.cpu.arch == .x86_64) elf.SHT_X86_64_UNWIND else elf.SHT_PROGBITS, .flags = elf.SHF_ALLOC, .addralign = ptr_size, .offset = std.math.maxInt(u64), }); } if (comp.link_eh_frame_hdr and self.eh_frame_hdr_section_index == null) { self.eh_frame_hdr_section_index = try self.addSection(.{ .name = try self.insertShString(".eh_frame_hdr"), .type = elf.SHT_PROGBITS, .flags = elf.SHF_ALLOC, .addralign = 4, .offset = std.math.maxInt(u64), }); } } if (self.got.entries.items.len > 0 and self.got_section_index == null) { self.got_section_index = try self.addSection(.{ .name = try self.insertShString(".got"), .type = elf.SHT_PROGBITS, .flags = elf.SHF_ALLOC | elf.SHF_WRITE, .addralign = ptr_size, .offset = std.math.maxInt(u64), }); } if (self.got_plt_section_index == null) { self.got_plt_section_index = try self.addSection(.{ .name = try self.insertShString(".got.plt"), .type = elf.SHT_PROGBITS, .flags = elf.SHF_ALLOC | elf.SHF_WRITE, .addralign = @alignOf(u64), .offset = std.math.maxInt(u64), }); } const needs_rela_dyn = blk: { if (self.got.flags.needs_rela or self.got.flags.needs_tlsld or self.copy_rel.symbols.items.len > 0) break :blk true; if (self.zigObjectPtr()) |zig_object| { if (zig_object.num_dynrelocs > 0) break :blk true; } for (self.objects.items) |index| { if (self.file(index).?.object.num_dynrelocs > 0) break :blk true; } break :blk false; }; if (needs_rela_dyn and self.rela_dyn_section_index == null) { self.rela_dyn_section_index = try self.addSection(.{ .name = try self.insertShString(".rela.dyn"), .type = elf.SHT_RELA, .flags = elf.SHF_ALLOC, .addralign = @alignOf(elf.Elf64_Rela), .entsize = @sizeOf(elf.Elf64_Rela), .offset = std.math.maxInt(u64), }); } if (self.plt.symbols.items.len > 0) { if (self.plt_section_index == null) { self.plt_section_index = try self.addSection(.{ .name = try self.insertShString(".plt"), .type = elf.SHT_PROGBITS, .flags = elf.SHF_ALLOC | elf.SHF_EXECINSTR, .addralign = 16, .offset = std.math.maxInt(u64), }); } if (self.rela_plt_section_index == null) { self.rela_plt_section_index = try self.addSection(.{ .name = try self.insertShString(".rela.plt"), .type = elf.SHT_RELA, .flags = elf.SHF_ALLOC, .addralign = @alignOf(elf.Elf64_Rela), .entsize = @sizeOf(elf.Elf64_Rela), .offset = std.math.maxInt(u64), }); } } if (self.plt_got.symbols.items.len > 0 and self.plt_got_section_index == null) { self.plt_got_section_index = try self.addSection(.{ .name = try self.insertShString(".plt.got"), .type = elf.SHT_PROGBITS, .flags = elf.SHF_ALLOC | elf.SHF_EXECINSTR, .addralign = 16, .offset = std.math.maxInt(u64), }); } if (self.copy_rel.symbols.items.len > 0 and self.copy_rel_section_index == null) { self.copy_rel_section_index = try self.addSection(.{ .name = try self.insertShString(".copyrel"), .type = elf.SHT_NOBITS, .flags = elf.SHF_ALLOC | elf.SHF_WRITE, .offset = std.math.maxInt(u64), }); } const needs_interp = blk: { // On Ubuntu with musl-gcc, we get a weird combo of options looking like this: // -dynamic-linker= -static // In this case, if we do generate .interp section and segment, we will get // a segfault in the dynamic linker trying to load a binary that is static // and doesn't contain .dynamic section. if (self.base.isStatic() and !comp.config.pie) break :blk false; break :blk target.dynamic_linker.get() != null; }; if (needs_interp and self.interp_section_index == null) { self.interp_section_index = try self.addSection(.{ .name = try self.insertShString(".interp"), .type = elf.SHT_PROGBITS, .flags = elf.SHF_ALLOC, .addralign = 1, .offset = std.math.maxInt(u64), }); } if (self.isEffectivelyDynLib() or self.shared_objects.items.len > 0 or comp.config.pie) { if (self.dynstrtab_section_index == null) { self.dynstrtab_section_index = try self.addSection(.{ .name = try self.insertShString(".dynstr"), .flags = elf.SHF_ALLOC, .type = elf.SHT_STRTAB, .entsize = 1, .addralign = 1, .offset = std.math.maxInt(u64), }); } if (self.dynamic_section_index == null) { self.dynamic_section_index = try self.addSection(.{ .name = try self.insertShString(".dynamic"), .flags = elf.SHF_ALLOC | elf.SHF_WRITE, .type = elf.SHT_DYNAMIC, .entsize = @sizeOf(elf.Elf64_Dyn), .addralign = @alignOf(elf.Elf64_Dyn), .offset = std.math.maxInt(u64), }); } if (self.dynsymtab_section_index == null) { self.dynsymtab_section_index = try self.addSection(.{ .name = try self.insertShString(".dynsym"), .flags = elf.SHF_ALLOC, .type = elf.SHT_DYNSYM, .addralign = @alignOf(elf.Elf64_Sym), .entsize = @sizeOf(elf.Elf64_Sym), .info = 1, .offset = std.math.maxInt(u64), }); } if (self.hash_section_index == null) { self.hash_section_index = try self.addSection(.{ .name = try self.insertShString(".hash"), .flags = elf.SHF_ALLOC, .type = elf.SHT_HASH, .addralign = 4, .entsize = 4, .offset = std.math.maxInt(u64), }); } if (self.gnu_hash_section_index == null) { self.gnu_hash_section_index = try self.addSection(.{ .name = try self.insertShString(".gnu.hash"), .flags = elf.SHF_ALLOC, .type = elf.SHT_GNU_HASH, .addralign = 8, .offset = std.math.maxInt(u64), }); } const needs_versions = for (self.dynsym.entries.items) |entry| { const sym = self.symbol(entry.ref).?; if (sym.flags.import and sym.version_index & elf.VERSYM_VERSION > elf.VER_NDX_GLOBAL) break true; } else false; if (needs_versions) { if (self.versym_section_index == null) { self.versym_section_index = try self.addSection(.{ .name = try self.insertShString(".gnu.version"), .flags = elf.SHF_ALLOC, .type = elf.SHT_GNU_VERSYM, .addralign = @alignOf(elf.Elf64_Versym), .entsize = @sizeOf(elf.Elf64_Versym), .offset = std.math.maxInt(u64), }); } if (self.verneed_section_index == null) { self.verneed_section_index = try self.addSection(.{ .name = try self.insertShString(".gnu.version_r"), .flags = elf.SHF_ALLOC, .type = elf.SHT_GNU_VERNEED, .addralign = @alignOf(elf.Elf64_Verneed), .offset = std.math.maxInt(u64), }); } } } try self.initSymtab(); try self.initShStrtab(); } pub fn initSymtab(self: *Elf) !void { const small_ptr = switch (self.ptr_width) { .p32 => true, .p64 => false, }; if (self.symtab_section_index == null) { self.symtab_section_index = try self.addSection(.{ .name = try self.insertShString(".symtab"), .type = elf.SHT_SYMTAB, .addralign = if (small_ptr) @alignOf(elf.Elf32_Sym) else @alignOf(elf.Elf64_Sym), .entsize = if (small_ptr) @sizeOf(elf.Elf32_Sym) else @sizeOf(elf.Elf64_Sym), .offset = std.math.maxInt(u64), }); } if (self.strtab_section_index == null) { self.strtab_section_index = try self.addSection(.{ .name = try self.insertShString(".strtab"), .type = elf.SHT_STRTAB, .entsize = 1, .addralign = 1, .offset = std.math.maxInt(u64), }); } } pub fn initShStrtab(self: *Elf) !void { if (self.shstrtab_section_index == null) { self.shstrtab_section_index = try self.addSection(.{ .name = try self.insertShString(".shstrtab"), .type = elf.SHT_STRTAB, .entsize = 1, .addralign = 1, .offset = std.math.maxInt(u64), }); } } fn initSpecialPhdrs(self: *Elf) !void { comptime assert(max_number_of_special_phdrs == 5); if (self.interp_section_index != null and self.phdr_interp_index == null) { self.phdr_interp_index = try self.addPhdr(.{ .type = elf.PT_INTERP, .flags = elf.PF_R, .@"align" = 1, }); } if (self.dynamic_section_index != null and self.phdr_dynamic_index == null) { self.phdr_dynamic_index = try self.addPhdr(.{ .type = elf.PT_DYNAMIC, .flags = elf.PF_R | elf.PF_W, }); } if (self.eh_frame_hdr_section_index != null and self.phdr_gnu_eh_frame_index == null) { self.phdr_gnu_eh_frame_index = try self.addPhdr(.{ .type = elf.PT_GNU_EH_FRAME, .flags = elf.PF_R, }); } if (self.phdr_gnu_stack_index == null) { self.phdr_gnu_stack_index = try self.addPhdr(.{ .type = elf.PT_GNU_STACK, .flags = elf.PF_W | elf.PF_R, .memsz = self.base.stack_size, .@"align" = 1, }); } const has_tls = for (self.sections.items(.shdr)) |shdr| { if (shdr.sh_flags & elf.SHF_TLS != 0) break true; } else false; if (has_tls and self.phdr_tls_index == null) { self.phdr_tls_index = try self.addPhdr(.{ .type = elf.PT_TLS, .flags = elf.PF_R, .@"align" = 1, }); } } /// We need to sort constructors/destuctors in the following sections: /// * .init_array /// * .fini_array /// * .preinit_array /// * .ctors /// * .dtors /// The prority of inclusion is defined as part of the input section's name. For example, .init_array.10000. /// If no priority value has been specified, /// * for .init_array, .fini_array and .preinit_array, we automatically assign that section max value of maxInt(i32) /// and push it to the back of the queue, /// * for .ctors and .dtors, we automatically assign that section min value of -1 /// and push it to the front of the queue, /// crtbegin and ctrend are assigned minInt(i32) and maxInt(i32) respectively. /// Ties are broken by the file prority which corresponds to the inclusion of input sections in this output section /// we are about to sort. fn sortInitFini(self: *Elf) !void { const gpa = self.base.comp.gpa; const slice = self.sections.slice(); const Entry = struct { priority: i32, atom_ref: Ref, pub fn lessThan(ctx: *Elf, lhs: @This(), rhs: @This()) bool { if (lhs.priority == rhs.priority) { return ctx.atom(lhs.atom_ref).?.priority(ctx) < ctx.atom(rhs.atom_ref).?.priority(ctx); } return lhs.priority < rhs.priority; } }; for (slice.items(.shdr), slice.items(.atom_list_2)) |shdr, *atom_list| { if (shdr.sh_flags & elf.SHF_ALLOC == 0) continue; if (atom_list.atoms.keys().len == 0) continue; var is_init_fini = false; var is_ctor_dtor = false; switch (shdr.sh_type) { elf.SHT_PREINIT_ARRAY, elf.SHT_INIT_ARRAY, elf.SHT_FINI_ARRAY, => is_init_fini = true, else => { const name = self.getShString(shdr.sh_name); is_ctor_dtor = mem.indexOf(u8, name, ".ctors") != null or mem.indexOf(u8, name, ".dtors") != null; }, } if (!is_init_fini and !is_ctor_dtor) continue; var entries = std.ArrayList(Entry).init(gpa); try entries.ensureTotalCapacityPrecise(atom_list.atoms.keys().len); defer entries.deinit(); for (atom_list.atoms.keys()) |ref| { const atom_ptr = self.atom(ref).?; const object = atom_ptr.file(self).?.object; const priority = blk: { if (is_ctor_dtor) { if (mem.indexOf(u8, object.path, "crtbegin") != null) break :blk std.math.minInt(i32); if (mem.indexOf(u8, object.path, "crtend") != null) break :blk std.math.maxInt(i32); } const default: i32 = if (is_ctor_dtor) -1 else std.math.maxInt(i32); const name = atom_ptr.name(self); var it = mem.splitBackwardsScalar(u8, name, '.'); const priority = std.fmt.parseUnsigned(u16, it.first(), 10) catch default; break :blk priority; }; entries.appendAssumeCapacity(.{ .priority = priority, .atom_ref = ref }); } mem.sort(Entry, entries.items, self, Entry.lessThan); atom_list.atoms.clearRetainingCapacity(); for (entries.items) |entry| { _ = atom_list.atoms.getOrPutAssumeCapacity(entry.atom_ref); } } } fn setDynamicSection(self: *Elf, rpaths: []const []const u8) !void { if (self.dynamic_section_index == null) return; for (self.shared_objects.items) |index| { const shared_object = self.file(index).?.shared_object; if (!shared_object.alive) continue; try self.dynamic.addNeeded(shared_object, self); } if (self.isEffectivelyDynLib()) { if (self.soname) |soname| { try self.dynamic.setSoname(soname, self); } } try self.dynamic.setRpath(rpaths, self); } fn sortDynamicSymtab(self: *Elf) void { if (self.gnu_hash_section_index == null) return; self.dynsym.sort(self); } fn setVersionSymtab(self: *Elf) !void { const gpa = self.base.comp.gpa; if (self.versym_section_index == null) return; try self.versym.resize(gpa, self.dynsym.count()); self.versym.items[0] = elf.VER_NDX_LOCAL; for (self.dynsym.entries.items, 1..) |entry, i| { const sym = self.symbol(entry.ref).?; self.versym.items[i] = sym.version_index; } if (self.verneed_section_index) |shndx| { try self.verneed.generate(self); const shdr = &self.sections.items(.shdr)[shndx]; shdr.sh_info = @as(u32, @intCast(self.verneed.verneed.items.len)); } } fn setHashSections(self: *Elf) !void { if (self.hash_section_index != null) { try self.hash.generate(self); } if (self.gnu_hash_section_index != null) { try self.gnu_hash.calcSize(self); } } fn phdrRank(phdr: elf.Elf64_Phdr) u8 { switch (phdr.p_type) { elf.PT_NULL => return 0, elf.PT_PHDR => return 1, elf.PT_INTERP => return 2, elf.PT_LOAD => return 3, elf.PT_DYNAMIC, elf.PT_TLS => return 4, elf.PT_GNU_EH_FRAME => return 5, elf.PT_GNU_STACK => return 6, else => return 7, } } fn sortPhdrs(self: *Elf) error{OutOfMemory}!void { const Entry = struct { phndx: u16, pub fn lessThan(elf_file: *Elf, lhs: @This(), rhs: @This()) bool { const lhs_phdr = elf_file.phdrs.items[lhs.phndx]; const rhs_phdr = elf_file.phdrs.items[rhs.phndx]; const lhs_rank = phdrRank(lhs_phdr); const rhs_rank = phdrRank(rhs_phdr); if (lhs_rank == rhs_rank) return lhs_phdr.p_vaddr < rhs_phdr.p_vaddr; return lhs_rank < rhs_rank; } }; const gpa = self.base.comp.gpa; var entries = try std.ArrayList(Entry).initCapacity(gpa, self.phdrs.items.len); defer entries.deinit(); for (0..self.phdrs.items.len) |phndx| { entries.appendAssumeCapacity(.{ .phndx = @as(u16, @intCast(phndx)) }); } mem.sort(Entry, entries.items, self, Entry.lessThan); const backlinks = try gpa.alloc(u16, entries.items.len); defer gpa.free(backlinks); for (entries.items, 0..) |entry, i| { backlinks[entry.phndx] = @as(u16, @intCast(i)); } const slice = try self.phdrs.toOwnedSlice(gpa); defer gpa.free(slice); try self.phdrs.ensureTotalCapacityPrecise(gpa, slice.len); for (entries.items) |sorted| { self.phdrs.appendAssumeCapacity(slice[sorted.phndx]); } for (&[_]*?u16{ &self.phdr_table_index, &self.phdr_table_load_index, &self.phdr_interp_index, &self.phdr_dynamic_index, &self.phdr_gnu_eh_frame_index, &self.phdr_tls_index, }) |maybe_index| { if (maybe_index.*) |*index| { index.* = backlinks[index.*]; } } for (self.sections.items(.phndx)) |*maybe_phndx| { if (maybe_phndx.*) |*index| { index.* = backlinks[index.*]; } } } fn shdrRank(self: *Elf, shndx: u32) u8 { const shdr = self.sections.items(.shdr)[shndx]; const name = self.getShString(shdr.sh_name); const flags = shdr.sh_flags; switch (shdr.sh_type) { elf.SHT_NULL => return 0, elf.SHT_DYNSYM => return 2, elf.SHT_HASH => return 3, elf.SHT_GNU_HASH => return 3, elf.SHT_GNU_VERSYM => return 4, elf.SHT_GNU_VERDEF => return 4, elf.SHT_GNU_VERNEED => return 4, elf.SHT_PREINIT_ARRAY, elf.SHT_INIT_ARRAY, elf.SHT_FINI_ARRAY, => return 0xf1, elf.SHT_DYNAMIC => return 0xf2, elf.SHT_RELA, elf.SHT_GROUP => return 0xf, elf.SHT_PROGBITS => if (flags & elf.SHF_ALLOC != 0) { if (flags & elf.SHF_EXECINSTR != 0) { return 0xf0; } else if (flags & elf.SHF_WRITE != 0) { return if (flags & elf.SHF_TLS != 0) 0xf3 else 0xf5; } else if (mem.eql(u8, name, ".interp")) { return 1; } else if (mem.startsWith(u8, name, ".eh_frame")) { return 0xe1; } else { return 0xe0; } } else { if (mem.startsWith(u8, name, ".debug")) { return 0xf7; } else { return 0xf8; } }, elf.SHT_X86_64_UNWIND => return 0xe1, elf.SHT_NOBITS => return if (flags & elf.SHF_TLS != 0) 0xf4 else 0xf6, elf.SHT_SYMTAB => return 0xf9, elf.SHT_STRTAB => return if (mem.eql(u8, name, ".dynstr")) 0x4 else 0xfa, else => return 0xff, } } pub fn sortShdrs(self: *Elf) !void { const Entry = struct { shndx: u32, pub fn lessThan(elf_file: *Elf, lhs: @This(), rhs: @This()) bool { return elf_file.shdrRank(lhs.shndx) < elf_file.shdrRank(rhs.shndx); } }; const gpa = self.base.comp.gpa; var entries = try std.ArrayList(Entry).initCapacity(gpa, self.sections.items(.shdr).len); defer entries.deinit(); for (0..self.sections.items(.shdr).len) |shndx| { entries.appendAssumeCapacity(.{ .shndx = @intCast(shndx) }); } mem.sort(Entry, entries.items, self, Entry.lessThan); const backlinks = try gpa.alloc(u32, entries.items.len); defer gpa.free(backlinks); for (entries.items, 0..) |entry, i| { backlinks[entry.shndx] = @intCast(i); } var slice = self.sections.toOwnedSlice(); defer slice.deinit(gpa); try self.sections.ensureTotalCapacity(gpa, slice.len); for (entries.items) |sorted| { self.sections.appendAssumeCapacity(slice.get(sorted.shndx)); } self.resetShdrIndexes(backlinks); } fn resetShdrIndexes(self: *Elf, backlinks: []const u32) void { for (&[_]*?u32{ &self.eh_frame_section_index, &self.eh_frame_rela_section_index, &self.eh_frame_hdr_section_index, &self.got_section_index, &self.symtab_section_index, &self.strtab_section_index, &self.shstrtab_section_index, &self.interp_section_index, &self.dynamic_section_index, &self.dynsymtab_section_index, &self.dynstrtab_section_index, &self.hash_section_index, &self.gnu_hash_section_index, &self.plt_section_index, &self.got_plt_section_index, &self.plt_got_section_index, &self.rela_dyn_section_index, &self.rela_plt_section_index, &self.copy_rel_section_index, &self.versym_section_index, &self.verneed_section_index, }) |maybe_index| { if (maybe_index.*) |*index| { index.* = backlinks[index.*]; } } for (self.merge_sections.items) |*msec| { msec.output_section_index = backlinks[msec.output_section_index]; } const slice = self.sections.slice(); for (slice.items(.shdr), slice.items(.atom_list_2)) |*shdr, *atom_list| { atom_list.output_section_index = backlinks[atom_list.output_section_index]; for (atom_list.atoms.keys()) |ref| { self.atom(ref).?.output_section_index = atom_list.output_section_index; } if (shdr.sh_type == elf.SHT_RELA) { // FIXME:JK we should spin up .symtab potentially earlier, or set all non-dynamic RELA sections // to point at symtab // shdr.sh_link = backlinks[shdr.sh_link]; shdr.sh_link = self.symtab_section_index.?; shdr.sh_info = backlinks[shdr.sh_info]; } } if (self.zigObjectPtr()) |zo| { for (zo.atoms_indexes.items) |atom_index| { const atom_ptr = zo.atom(atom_index) orelse continue; atom_ptr.output_section_index = backlinks[atom_ptr.output_section_index]; } } for (self.comdat_group_sections.items) |*cg| { cg.shndx = backlinks[cg.shndx]; } if (self.symtab_section_index) |index| { const shdr = &slice.items(.shdr)[index]; shdr.sh_link = self.strtab_section_index.?; } if (self.dynamic_section_index) |index| { const shdr = &slice.items(.shdr)[index]; shdr.sh_link = self.dynstrtab_section_index.?; } if (self.dynsymtab_section_index) |index| { const shdr = &slice.items(.shdr)[index]; shdr.sh_link = self.dynstrtab_section_index.?; } if (self.hash_section_index) |index| { const shdr = &slice.items(.shdr)[index]; shdr.sh_link = self.dynsymtab_section_index.?; } if (self.gnu_hash_section_index) |index| { const shdr = &slice.items(.shdr)[index]; shdr.sh_link = self.dynsymtab_section_index.?; } if (self.versym_section_index) |index| { const shdr = &slice.items(.shdr)[index]; shdr.sh_link = self.dynsymtab_section_index.?; } if (self.verneed_section_index) |index| { const shdr = &slice.items(.shdr)[index]; shdr.sh_link = self.dynstrtab_section_index.?; } if (self.rela_dyn_section_index) |index| { const shdr = &slice.items(.shdr)[index]; shdr.sh_link = self.dynsymtab_section_index orelse 0; } if (self.rela_plt_section_index) |index| { const shdr = &slice.items(.shdr)[index]; shdr.sh_link = self.dynsymtab_section_index.?; shdr.sh_info = self.plt_section_index.?; } if (self.eh_frame_rela_section_index) |index| { const shdr = &slice.items(.shdr)[index]; shdr.sh_link = self.symtab_section_index.?; shdr.sh_info = self.eh_frame_section_index.?; } } fn updateSectionSizes(self: *Elf) !void { const slice = self.sections.slice(); for (slice.items(.shdr), slice.items(.atom_list_2)) |shdr, *atom_list| { if (atom_list.atoms.keys().len == 0) continue; if (!atom_list.dirty) continue; if (self.requiresThunks() and shdr.sh_flags & elf.SHF_EXECINSTR != 0) continue; atom_list.updateSize(self); try atom_list.allocate(self); atom_list.dirty = false; } if (self.requiresThunks()) { for (slice.items(.shdr), slice.items(.atom_list_2)) |shdr, *atom_list| { if (shdr.sh_flags & elf.SHF_EXECINSTR == 0) continue; if (atom_list.atoms.keys().len == 0) continue; if (!atom_list.dirty) continue; // Create jump/branch range extenders if needed. try self.createThunks(atom_list); try atom_list.allocate(self); atom_list.dirty = false; } // FIXME:JK this will hopefully not be needed once we create a link from Atom/Thunk to AtomList. for (self.thunks.items) |*th| { th.value += slice.items(.atom_list_2)[th.output_section_index].value; } } const shdrs = slice.items(.shdr); if (self.eh_frame_section_index) |index| { shdrs[index].sh_size = try eh_frame.calcEhFrameSize(self); } if (self.eh_frame_hdr_section_index) |index| { shdrs[index].sh_size = eh_frame.calcEhFrameHdrSize(self); } if (self.got_section_index) |index| { shdrs[index].sh_size = self.got.size(self); } if (self.plt_section_index) |index| { shdrs[index].sh_size = self.plt.size(self); } if (self.got_plt_section_index) |index| { shdrs[index].sh_size = self.got_plt.size(self); } if (self.plt_got_section_index) |index| { shdrs[index].sh_size = self.plt_got.size(self); } if (self.rela_dyn_section_index) |shndx| { var num = self.got.numRela(self) + self.copy_rel.numRela(); if (self.zigObjectPtr()) |zig_object| { num += zig_object.num_dynrelocs; } for (self.objects.items) |index| { num += self.file(index).?.object.num_dynrelocs; } shdrs[shndx].sh_size = num * @sizeOf(elf.Elf64_Rela); } if (self.rela_plt_section_index) |index| { shdrs[index].sh_size = self.plt.numRela() * @sizeOf(elf.Elf64_Rela); } if (self.copy_rel_section_index) |index| { try self.copy_rel.updateSectionSize(index, self); } if (self.interp_section_index) |index| { shdrs[index].sh_size = self.getTarget().dynamic_linker.get().?.len + 1; } if (self.hash_section_index) |index| { shdrs[index].sh_size = self.hash.size(); } if (self.gnu_hash_section_index) |index| { shdrs[index].sh_size = self.gnu_hash.size(); } if (self.dynamic_section_index) |index| { shdrs[index].sh_size = self.dynamic.size(self); } if (self.dynsymtab_section_index) |index| { shdrs[index].sh_size = self.dynsym.size(); } if (self.dynstrtab_section_index) |index| { shdrs[index].sh_size = self.dynstrtab.items.len; } if (self.versym_section_index) |index| { shdrs[index].sh_size = self.versym.items.len * @sizeOf(elf.Elf64_Versym); } if (self.verneed_section_index) |index| { shdrs[index].sh_size = self.verneed.size(); } try self.updateSymtabSize(); self.updateShStrtabSize(); } // FIXME:JK this is very much obsolete, remove! pub fn updateShStrtabSize(self: *Elf) void { if (self.shstrtab_section_index) |index| { self.sections.items(.shdr)[index].sh_size = self.shstrtab.items.len; } } fn shdrToPhdrFlags(sh_flags: u64) u32 { const write = sh_flags & elf.SHF_WRITE != 0; const exec = sh_flags & elf.SHF_EXECINSTR != 0; var out_flags: u32 = elf.PF_R; if (write) out_flags |= elf.PF_W; if (exec) out_flags |= elf.PF_X; return out_flags; } /// Returns maximum number of program headers that may be emitted by the linker. /// (This is an upper bound so that we can reserve enough space for the header and progam header /// table without running out of space and being forced to move things around.) fn getMaxNumberOfPhdrs() u64 { // The estimated maximum number of segments the linker can emit for input sections are: var num: u64 = max_number_of_object_segments; // Any other non-loadable program headers, including TLS, DYNAMIC, GNU_STACK, GNU_EH_FRAME, INTERP: num += max_number_of_special_phdrs; // PHDR program header and corresponding read-only load segment: num += 2; return num; } fn addLoadPhdrs(self: *Elf) error{OutOfMemory}!void { for (self.sections.items(.shdr)) |shdr| { if (shdr.sh_type == elf.SHT_NULL) continue; if (shdr.sh_flags & elf.SHF_ALLOC == 0) continue; const flags = shdrToPhdrFlags(shdr.sh_flags); if (self.getPhdr(.{ .flags = flags, .type = elf.PT_LOAD }) == null) { _ = try self.addPhdr(.{ .flags = flags, .type = elf.PT_LOAD }); } } } /// Allocates PHDR table in virtual memory and in file. fn allocatePhdrTable(self: *Elf) error{OutOfMemory}!void { const phdr_table = &self.phdrs.items[self.phdr_table_index.?]; const phdr_table_load = &self.phdrs.items[self.phdr_table_load_index.?]; const ehsize: u64 = switch (self.ptr_width) { .p32 => @sizeOf(elf.Elf32_Ehdr), .p64 => @sizeOf(elf.Elf64_Ehdr), }; const phsize: u64 = switch (self.ptr_width) { .p32 => @sizeOf(elf.Elf32_Phdr), .p64 => @sizeOf(elf.Elf64_Phdr), }; const needed_size = self.phdrs.items.len * phsize; const available_space = self.allocatedSize(phdr_table.p_offset); if (needed_size > available_space) { // In this case, we have two options: // 1. increase the available padding for EHDR + PHDR table so that we don't overflow it // (revisit getMaxNumberOfPhdrs()) // 2. shift everything in file to free more space for EHDR + PHDR table // TODO verify `getMaxNumberOfPhdrs()` is accurate and convert this into no-op var err = try self.base.addErrorWithNotes(1); try err.addMsg("fatal linker error: not enough space reserved for EHDR and PHDR table", .{}); try err.addNote("required 0x{x}, available 0x{x}", .{ needed_size, available_space }); } phdr_table_load.p_filesz = needed_size + ehsize; phdr_table_load.p_memsz = needed_size + ehsize; phdr_table.p_filesz = needed_size; phdr_table.p_memsz = needed_size; } /// Allocates alloc sections and creates load segments for sections /// extracted from input object files. pub fn allocateAllocSections(self: *Elf) !void { // We use this struct to track maximum alignment of all TLS sections. // According to https://github.com/rui314/mold/commit/bd46edf3f0fe9e1a787ea453c4657d535622e61f in mold, // in-file offsets have to be aligned against the start of TLS program header. // If that's not ensured, then in a multi-threaded context, TLS variables across a shared object // boundary may not get correctly loaded at an aligned address. const Align = struct { tls_start_align: u64 = 1, first_tls_index: ?usize = null, fn isFirstTlsShdr(this: @This(), other: usize) bool { if (this.first_tls_index) |index| return index == other; return false; } fn @"align"(this: @This(), index: usize, sh_addralign: u64, addr: u64) u64 { const alignment = if (this.isFirstTlsShdr(index)) this.tls_start_align else sh_addralign; return mem.alignForward(u64, addr, alignment); } }; const slice = self.sections.slice(); var alignment = Align{}; for (slice.items(.shdr), 0..) |shdr, i| { if (shdr.sh_type == elf.SHT_NULL) continue; if (shdr.sh_flags & elf.SHF_TLS == 0) continue; if (alignment.first_tls_index == null) alignment.first_tls_index = i; alignment.tls_start_align = @max(alignment.tls_start_align, shdr.sh_addralign); } // Next, calculate segment covers by scanning all alloc sections. // If a section matches segment flags with the preceeding section, // we put it in the same segment. Otherwise, we create a new cover. // This algorithm is simple but suboptimal in terms of space re-use: // normally we would also take into account any gaps in allocated // virtual and file offsets. However, the simple one will do for one // as we are more interested in quick turnaround and compatibility // with `findFreeSpace` mechanics than anything else. const Cover = std.ArrayList(u32); const gpa = self.base.comp.gpa; var covers: [max_number_of_object_segments]Cover = undefined; for (&covers) |*cover| { cover.* = Cover.init(gpa); } defer for (&covers) |*cover| { cover.deinit(); }; for (slice.items(.shdr), 0..) |shdr, shndx| { if (shdr.sh_type == elf.SHT_NULL) continue; if (shdr.sh_flags & elf.SHF_ALLOC == 0) continue; const flags = shdrToPhdrFlags(shdr.sh_flags); try covers[flags - 1].append(@intCast(shndx)); } // Now we can proceed with allocating the sections in virtual memory. // As the base address we take the end address of the PHDR table. // When allocating we first find the largest required alignment // of any section that is contained in a cover and use it to align // the start address of the segement (and first section). const phdr_table = &self.phdrs.items[self.phdr_table_load_index.?]; var addr = phdr_table.p_vaddr + phdr_table.p_memsz; for (covers) |cover| { if (cover.items.len == 0) continue; var @"align": u64 = self.page_size; for (cover.items) |shndx| { const shdr = slice.items(.shdr)[shndx]; if (shdr.sh_type == elf.SHT_NOBITS and shdr.sh_flags & elf.SHF_TLS != 0) continue; @"align" = @max(@"align", shdr.sh_addralign); } addr = mem.alignForward(u64, addr, @"align"); var memsz: u64 = 0; var filesz: u64 = 0; var i: usize = 0; while (i < cover.items.len) : (i += 1) { const shndx = cover.items[i]; const shdr = &slice.items(.shdr)[shndx]; if (shdr.sh_type == elf.SHT_NOBITS and shdr.sh_flags & elf.SHF_TLS != 0) { // .tbss is a little special as it's used only by the loader meaning it doesn't // need to be actually mmap'ed at runtime. We still need to correctly increment // the addresses of every TLS zerofill section tho. Thus, we hack it so that // we increment the start address like normal, however, after we are done, // the next ALLOC section will get its start address allocated within the same // range as the .tbss sections. We will get something like this: // // ... // .tbss 0x10 // .tcommon 0x20 // .data 0x10 // ... var tbss_addr = addr; while (i < cover.items.len and slice.items(.shdr)[cover.items[i]].sh_type == elf.SHT_NOBITS and slice.items(.shdr)[cover.items[i]].sh_flags & elf.SHF_TLS != 0) : (i += 1) { const tbss_shndx = cover.items[i]; const tbss_shdr = &slice.items(.shdr)[tbss_shndx]; tbss_addr = alignment.@"align"(tbss_shndx, tbss_shdr.sh_addralign, tbss_addr); tbss_shdr.sh_addr = tbss_addr; tbss_addr += tbss_shdr.sh_size; } i -= 1; continue; } const next = alignment.@"align"(shndx, shdr.sh_addralign, addr); const padding = next - addr; addr = next; shdr.sh_addr = addr; if (shdr.sh_type != elf.SHT_NOBITS) { filesz += padding + shdr.sh_size; } memsz += padding + shdr.sh_size; addr += shdr.sh_size; } const first = slice.items(.shdr)[cover.items[0]]; const phndx = self.getPhdr(.{ .type = elf.PT_LOAD, .flags = shdrToPhdrFlags(first.sh_flags) }).?; const phdr = &self.phdrs.items[phndx]; const allocated_size = self.allocatedSize(phdr.p_offset); if (filesz > allocated_size) { const old_offset = phdr.p_offset; phdr.p_offset = 0; var new_offset = try self.findFreeSpace(filesz, @"align"); phdr.p_offset = new_offset; log.debug("moving phdr({d}) from 0x{x} to 0x{x}", .{ phndx, old_offset, new_offset }); for (cover.items) |shndx| { const shdr = &slice.items(.shdr)[shndx]; slice.items(.phndx)[shndx] = phndx; if (shdr.sh_type == elf.SHT_NOBITS) { shdr.sh_offset = 0; continue; } new_offset = alignment.@"align"(shndx, shdr.sh_addralign, new_offset); log.debug("moving {s} from 0x{x} to 0x{x}", .{ self.getShString(shdr.sh_name), shdr.sh_offset, new_offset, }); if (shdr.sh_offset > 0) { // Get size actually commited to the output file. const existing_size = self.sectionSize(shndx); const amt = try self.base.file.?.copyRangeAll( shdr.sh_offset, self.base.file.?, new_offset, existing_size, ); if (amt != existing_size) return error.InputOutput; } shdr.sh_offset = new_offset; new_offset += shdr.sh_size; } } phdr.p_vaddr = first.sh_addr; phdr.p_paddr = first.sh_addr; phdr.p_memsz = memsz; phdr.p_filesz = filesz; phdr.p_align = @"align"; addr = mem.alignForward(u64, addr, self.page_size); } } /// Allocates non-alloc sections (debug info, symtabs, etc.). pub fn allocateNonAllocSections(self: *Elf) !void { for (self.sections.items(.shdr), 0..) |*shdr, shndx| { if (shdr.sh_type == elf.SHT_NULL) continue; if (shdr.sh_flags & elf.SHF_ALLOC != 0) continue; const needed_size = shdr.sh_size; if (needed_size > self.allocatedSize(shdr.sh_offset)) { shdr.sh_size = 0; const new_offset = try self.findFreeSpace(needed_size, shdr.sh_addralign); if (self.zigObjectPtr()) |zo| blk: { const existing_size = for ([_]?Symbol.Index{ zo.debug_info_index, zo.debug_abbrev_index, zo.debug_aranges_index, zo.debug_str_index, zo.debug_line_index, zo.debug_line_str_index, zo.debug_loclists_index, zo.debug_rnglists_index, }) |maybe_sym_index| { const sym_index = maybe_sym_index orelse continue; const sym = zo.symbol(sym_index); const atom_ptr = sym.atom(self).?; if (atom_ptr.output_section_index == shndx) break atom_ptr.size; } else break :blk; log.debug("moving {s} from 0x{x} to 0x{x}", .{ self.getShString(shdr.sh_name), shdr.sh_offset, new_offset, }); const amt = try self.base.file.?.copyRangeAll( shdr.sh_offset, self.base.file.?, new_offset, existing_size, ); if (amt != existing_size) return error.InputOutput; } shdr.sh_offset = new_offset; shdr.sh_size = needed_size; } } } fn allocateSpecialPhdrs(self: *Elf) void { const slice = self.sections.slice(); for (&[_]struct { ?u16, ?u32 }{ .{ self.phdr_interp_index, self.interp_section_index }, .{ self.phdr_dynamic_index, self.dynamic_section_index }, .{ self.phdr_gnu_eh_frame_index, self.eh_frame_hdr_section_index }, }) |pair| { if (pair[0]) |index| { const shdr = slice.items(.shdr)[pair[1].?]; const phdr = &self.phdrs.items[index]; phdr.p_align = shdr.sh_addralign; phdr.p_offset = shdr.sh_offset; phdr.p_vaddr = shdr.sh_addr; phdr.p_paddr = shdr.sh_addr; phdr.p_filesz = shdr.sh_size; phdr.p_memsz = shdr.sh_size; } } // Set the TLS segment boundaries. // We assume TLS sections are laid out contiguously and that there is // a single TLS segment. if (self.phdr_tls_index) |index| { const shdrs = slice.items(.shdr); const phdr = &self.phdrs.items[index]; var shndx: u32 = 0; while (shndx < shdrs.len) { const shdr = shdrs[shndx]; if (shdr.sh_flags & elf.SHF_TLS == 0) { shndx += 1; continue; } phdr.p_offset = shdr.sh_offset; phdr.p_vaddr = shdr.sh_addr; phdr.p_paddr = shdr.sh_addr; phdr.p_align = shdr.sh_addralign; shndx += 1; phdr.p_align = @max(phdr.p_align, shdr.sh_addralign); if (shdr.sh_type != elf.SHT_NOBITS) { phdr.p_filesz = shdr.sh_offset + shdr.sh_size - phdr.p_offset; } phdr.p_memsz = shdr.sh_addr + shdr.sh_size - phdr.p_vaddr; while (shndx < shdrs.len) : (shndx += 1) { const next = shdrs[shndx]; if (next.sh_flags & elf.SHF_TLS == 0) break; phdr.p_align = @max(phdr.p_align, next.sh_addralign); if (next.sh_type != elf.SHT_NOBITS) { phdr.p_filesz = next.sh_offset + next.sh_size - phdr.p_offset; } phdr.p_memsz = next.sh_addr + next.sh_size - phdr.p_vaddr; } } } } fn writeAtoms(self: *Elf) !void { const gpa = self.base.comp.gpa; var undefs = std.AutoArrayHashMap(SymbolResolver.Index, std.ArrayList(Ref)).init(gpa); defer { for (undefs.values()) |*refs| { refs.deinit(); } undefs.deinit(); } var buffer = std.ArrayList(u8).init(gpa); defer buffer.deinit(); const slice = self.sections.slice(); var has_reloc_errors = false; for (slice.items(.shdr), slice.items(.atom_list_2)) |shdr, atom_list| { if (shdr.sh_type == elf.SHT_NOBITS) continue; if (atom_list.atoms.keys().len == 0) continue; atom_list.write(&buffer, &undefs, self) catch |err| switch (err) { error.UnsupportedCpuArch => { try self.reportUnsupportedCpuArch(); return error.FlushFailure; }, error.RelocFailure, error.RelaxFailure => has_reloc_errors = true, else => |e| return e, }; } try self.reportUndefinedSymbols(&undefs); if (has_reloc_errors) return error.FlushFailure; if (self.requiresThunks()) { for (self.thunks.items) |th| { const thunk_size = th.size(self); try buffer.ensureUnusedCapacity(thunk_size); const shdr = slice.items(.shdr)[th.output_section_index]; const offset = @as(u64, @intCast(th.value)) + shdr.sh_offset; try th.write(self, buffer.writer()); assert(buffer.items.len == thunk_size); try self.base.file.?.pwriteAll(buffer.items, offset); buffer.clearRetainingCapacity(); } } } pub fn updateSymtabSize(self: *Elf) !void { var nlocals: u32 = 0; var nglobals: u32 = 0; var strsize: u32 = 0; const gpa = self.base.comp.gpa; var files = std.ArrayList(File.Index).init(gpa); defer files.deinit(); try files.ensureTotalCapacityPrecise(self.objects.items.len + self.shared_objects.items.len + 2); if (self.zig_object_index) |index| files.appendAssumeCapacity(index); for (self.objects.items) |index| files.appendAssumeCapacity(index); for (self.shared_objects.items) |index| files.appendAssumeCapacity(index); if (self.linker_defined_index) |index| files.appendAssumeCapacity(index); // Section symbols nlocals += @intCast(self.sections.slice().len); if (self.requiresThunks()) for (self.thunks.items) |*th| { th.output_symtab_ctx.reset(); th.output_symtab_ctx.ilocal = nlocals; th.calcSymtabSize(self); nlocals += th.output_symtab_ctx.nlocals; strsize += th.output_symtab_ctx.strsize; }; for (files.items) |index| { const file_ptr = self.file(index).?; const ctx = switch (file_ptr) { inline else => |x| &x.output_symtab_ctx, }; ctx.reset(); ctx.ilocal = nlocals; ctx.iglobal = nglobals; try file_ptr.updateSymtabSize(self); nlocals += ctx.nlocals; nglobals += ctx.nglobals; strsize += ctx.strsize; } if (self.got_section_index) |_| { self.got.output_symtab_ctx.reset(); self.got.output_symtab_ctx.ilocal = nlocals; self.got.updateSymtabSize(self); nlocals += self.got.output_symtab_ctx.nlocals; strsize += self.got.output_symtab_ctx.strsize; } if (self.plt_section_index) |_| { self.plt.output_symtab_ctx.reset(); self.plt.output_symtab_ctx.ilocal = nlocals; self.plt.updateSymtabSize(self); nlocals += self.plt.output_symtab_ctx.nlocals; strsize += self.plt.output_symtab_ctx.strsize; } if (self.plt_got_section_index) |_| { self.plt_got.output_symtab_ctx.reset(); self.plt_got.output_symtab_ctx.ilocal = nlocals; self.plt_got.updateSymtabSize(self); nlocals += self.plt_got.output_symtab_ctx.nlocals; strsize += self.plt_got.output_symtab_ctx.strsize; } for (files.items) |index| { const file_ptr = self.file(index).?; const ctx = switch (file_ptr) { inline else => |x| &x.output_symtab_ctx, }; ctx.iglobal += nlocals; } const slice = self.sections.slice(); const symtab_shdr = &slice.items(.shdr)[self.symtab_section_index.?]; symtab_shdr.sh_info = nlocals; symtab_shdr.sh_link = self.strtab_section_index.?; const sym_size: u64 = switch (self.ptr_width) { .p32 => @sizeOf(elf.Elf32_Sym), .p64 => @sizeOf(elf.Elf64_Sym), }; const needed_size = (nlocals + nglobals) * sym_size; symtab_shdr.sh_size = needed_size; const strtab = &slice.items(.shdr)[self.strtab_section_index.?]; strtab.sh_size = strsize + 1; } fn writeSyntheticSections(self: *Elf) !void { const gpa = self.base.comp.gpa; const slice = self.sections.slice(); if (self.interp_section_index) |shndx| { var buffer: [256]u8 = undefined; const interp = self.getTarget().dynamic_linker.get().?; @memcpy(buffer[0..interp.len], interp); buffer[interp.len] = 0; const contents = buffer[0 .. interp.len + 1]; const shdr = slice.items(.shdr)[shndx]; assert(shdr.sh_size == contents.len); try self.base.file.?.pwriteAll(contents, shdr.sh_offset); } if (self.hash_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; try self.base.file.?.pwriteAll(self.hash.buffer.items, shdr.sh_offset); } if (self.gnu_hash_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; var buffer = try std.ArrayList(u8).initCapacity(gpa, self.gnu_hash.size()); defer buffer.deinit(); try self.gnu_hash.write(self, buffer.writer()); try self.base.file.?.pwriteAll(buffer.items, shdr.sh_offset); } if (self.versym_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; try self.base.file.?.pwriteAll(mem.sliceAsBytes(self.versym.items), shdr.sh_offset); } if (self.verneed_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; var buffer = try std.ArrayList(u8).initCapacity(gpa, self.verneed.size()); defer buffer.deinit(); try self.verneed.write(buffer.writer()); try self.base.file.?.pwriteAll(buffer.items, shdr.sh_offset); } if (self.dynamic_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; var buffer = try std.ArrayList(u8).initCapacity(gpa, self.dynamic.size(self)); defer buffer.deinit(); try self.dynamic.write(self, buffer.writer()); try self.base.file.?.pwriteAll(buffer.items, shdr.sh_offset); } if (self.dynsymtab_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; var buffer = try std.ArrayList(u8).initCapacity(gpa, self.dynsym.size()); defer buffer.deinit(); try self.dynsym.write(self, buffer.writer()); try self.base.file.?.pwriteAll(buffer.items, shdr.sh_offset); } if (self.dynstrtab_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; try self.base.file.?.pwriteAll(self.dynstrtab.items, shdr.sh_offset); } if (self.eh_frame_section_index) |shndx| { const existing_size = existing_size: { const zo = self.zigObjectPtr() orelse break :existing_size 0; const sym = zo.symbol(zo.eh_frame_index orelse break :existing_size 0); break :existing_size sym.atom(self).?.size; }; const shdr = slice.items(.shdr)[shndx]; const sh_size = math.cast(usize, shdr.sh_size) orelse return error.Overflow; var buffer = try std.ArrayList(u8).initCapacity(gpa, @intCast(sh_size - existing_size)); defer buffer.deinit(); try eh_frame.writeEhFrame(self, buffer.writer()); assert(buffer.items.len == sh_size - existing_size); try self.base.file.?.pwriteAll(buffer.items, shdr.sh_offset + existing_size); } if (self.eh_frame_hdr_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; const sh_size = math.cast(usize, shdr.sh_size) orelse return error.Overflow; var buffer = try std.ArrayList(u8).initCapacity(gpa, sh_size); defer buffer.deinit(); try eh_frame.writeEhFrameHdr(self, buffer.writer()); try self.base.file.?.pwriteAll(buffer.items, shdr.sh_offset); } if (self.got_section_index) |index| { const shdr = slice.items(.shdr)[index]; var buffer = try std.ArrayList(u8).initCapacity(gpa, self.got.size(self)); defer buffer.deinit(); try self.got.write(self, buffer.writer()); try self.base.file.?.pwriteAll(buffer.items, shdr.sh_offset); } if (self.rela_dyn_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; try self.got.addRela(self); try self.copy_rel.addRela(self); self.sortRelaDyn(); try self.base.file.?.pwriteAll(mem.sliceAsBytes(self.rela_dyn.items), shdr.sh_offset); } if (self.plt_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; var buffer = try std.ArrayList(u8).initCapacity(gpa, self.plt.size(self)); defer buffer.deinit(); try self.plt.write(self, buffer.writer()); try self.base.file.?.pwriteAll(buffer.items, shdr.sh_offset); } if (self.got_plt_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; var buffer = try std.ArrayList(u8).initCapacity(gpa, self.got_plt.size(self)); defer buffer.deinit(); try self.got_plt.write(self, buffer.writer()); try self.base.file.?.pwriteAll(buffer.items, shdr.sh_offset); } if (self.plt_got_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; var buffer = try std.ArrayList(u8).initCapacity(gpa, self.plt_got.size(self)); defer buffer.deinit(); try self.plt_got.write(self, buffer.writer()); try self.base.file.?.pwriteAll(buffer.items, shdr.sh_offset); } if (self.rela_plt_section_index) |shndx| { const shdr = slice.items(.shdr)[shndx]; try self.plt.addRela(self); try self.base.file.?.pwriteAll(mem.sliceAsBytes(self.rela_plt.items), shdr.sh_offset); } try self.writeSymtab(); try self.writeShStrtab(); } // FIXME:JK again, why is this needed? pub fn writeShStrtab(self: *Elf) !void { if (self.shstrtab_section_index) |index| { const shdr = self.sections.items(.shdr)[index]; log.debug("writing .shstrtab from 0x{x} to 0x{x}", .{ shdr.sh_offset, shdr.sh_offset + shdr.sh_size }); try self.base.file.?.pwriteAll(self.shstrtab.items, shdr.sh_offset); } } pub fn writeSymtab(self: *Elf) !void { const gpa = self.base.comp.gpa; const slice = self.sections.slice(); const symtab_shdr = slice.items(.shdr)[self.symtab_section_index.?]; const strtab_shdr = slice.items(.shdr)[self.strtab_section_index.?]; const sym_size: u64 = switch (self.ptr_width) { .p32 => @sizeOf(elf.Elf32_Sym), .p64 => @sizeOf(elf.Elf64_Sym), }; const nsyms = math.cast(usize, @divExact(symtab_shdr.sh_size, sym_size)) orelse return error.Overflow; log.debug("writing {d} symbols in .symtab from 0x{x} to 0x{x}", .{ nsyms, symtab_shdr.sh_offset, symtab_shdr.sh_offset + symtab_shdr.sh_size, }); log.debug("writing .strtab from 0x{x} to 0x{x}", .{ strtab_shdr.sh_offset, strtab_shdr.sh_offset + strtab_shdr.sh_size, }); try self.symtab.resize(gpa, nsyms); const needed_strtab_size = math.cast(usize, strtab_shdr.sh_size - 1) orelse return error.Overflow; // TODO we could resize instead and in ZigObject/Object always access as slice self.strtab.clearRetainingCapacity(); self.strtab.appendAssumeCapacity(0); try self.strtab.ensureUnusedCapacity(gpa, needed_strtab_size); for (slice.items(.shdr), 0..) |shdr, shndx| { const out_sym = &self.symtab.items[shndx]; out_sym.* = .{ .st_name = 0, .st_value = shdr.sh_addr, .st_info = if (shdr.sh_type == elf.SHT_NULL) elf.STT_NOTYPE else elf.STT_SECTION, .st_shndx = @intCast(shndx), .st_size = 0, .st_other = 0, }; } if (self.requiresThunks()) for (self.thunks.items) |th| { th.writeSymtab(self); }; if (self.zigObjectPtr()) |zig_object| { zig_object.asFile().writeSymtab(self); } for (self.objects.items) |index| { const file_ptr = self.file(index).?; file_ptr.writeSymtab(self); } for (self.shared_objects.items) |index| { const file_ptr = self.file(index).?; file_ptr.writeSymtab(self); } if (self.linkerDefinedPtr()) |obj| { obj.asFile().writeSymtab(self); } if (self.got_section_index) |_| { self.got.writeSymtab(self); } if (self.plt_section_index) |_| { self.plt.writeSymtab(self); } if (self.plt_got_section_index) |_| { self.plt_got.writeSymtab(self); } const foreign_endian = self.getTarget().cpu.arch.endian() != builtin.cpu.arch.endian(); switch (self.ptr_width) { .p32 => { const buf = try gpa.alloc(elf.Elf32_Sym, self.symtab.items.len); defer gpa.free(buf); for (buf, self.symtab.items) |*out, sym| { out.* = .{ .st_name = sym.st_name, .st_info = sym.st_info, .st_other = sym.st_other, .st_shndx = sym.st_shndx, .st_value = @as(u32, @intCast(sym.st_value)), .st_size = @as(u32, @intCast(sym.st_size)), }; if (foreign_endian) mem.byteSwapAllFields(elf.Elf32_Sym, out); } try self.base.file.?.pwriteAll(mem.sliceAsBytes(buf), symtab_shdr.sh_offset); }, .p64 => { if (foreign_endian) { for (self.symtab.items) |*sym| mem.byteSwapAllFields(elf.Elf64_Sym, sym); } try self.base.file.?.pwriteAll(mem.sliceAsBytes(self.symtab.items), symtab_shdr.sh_offset); }, } try self.base.file.?.pwriteAll(self.strtab.items, strtab_shdr.sh_offset); } /// Always 4 or 8 depending on whether this is 32-bit ELF or 64-bit ELF. pub fn ptrWidthBytes(self: Elf) u8 { return switch (self.ptr_width) { .p32 => 4, .p64 => 8, }; } /// Does not necessarily match `ptrWidthBytes` for example can be 2 bytes /// in a 32-bit ELF file. pub fn archPtrWidthBytes(self: Elf) u8 { return @intCast(@divExact(self.getTarget().ptrBitWidth(), 8)); } fn phdrTo32(phdr: elf.Elf64_Phdr) elf.Elf32_Phdr { return .{ .p_type = phdr.p_type, .p_flags = phdr.p_flags, .p_offset = @as(u32, @intCast(phdr.p_offset)), .p_vaddr = @as(u32, @intCast(phdr.p_vaddr)), .p_paddr = @as(u32, @intCast(phdr.p_paddr)), .p_filesz = @as(u32, @intCast(phdr.p_filesz)), .p_memsz = @as(u32, @intCast(phdr.p_memsz)), .p_align = @as(u32, @intCast(phdr.p_align)), }; } fn shdrTo32(shdr: elf.Elf64_Shdr) elf.Elf32_Shdr { return .{ .sh_name = shdr.sh_name, .sh_type = shdr.sh_type, .sh_flags = @as(u32, @intCast(shdr.sh_flags)), .sh_addr = @as(u32, @intCast(shdr.sh_addr)), .sh_offset = @as(u32, @intCast(shdr.sh_offset)), .sh_size = @as(u32, @intCast(shdr.sh_size)), .sh_link = shdr.sh_link, .sh_info = shdr.sh_info, .sh_addralign = @as(u32, @intCast(shdr.sh_addralign)), .sh_entsize = @as(u32, @intCast(shdr.sh_entsize)), }; } fn getLDMOption(target: std.Target) ?[]const u8 { // This should only return emulations understood by LLD's parseEmulation(). return switch (target.cpu.arch) { .aarch64 => switch (target.os.tag) { .linux => "aarch64linux", else => "aarch64elf", }, .aarch64_be => switch (target.os.tag) { .linux => "aarch64linuxb", else => "aarch64elfb", }, .amdgcn => "elf64_amdgpu", .arm, .thumb => switch (target.os.tag) { .linux => "armelf_linux_eabi", else => "armelf", }, .armeb, .thumbeb => switch (target.os.tag) { .linux => "armelfb_linux_eabi", else => "armelfb", }, .hexagon => "hexagonelf", .loongarch32 => "elf32loongarch", .loongarch64 => "elf64loongarch", .mips => switch (target.os.tag) { .freebsd => "elf32btsmip_fbsd", else => "elf32btsmip", }, .mipsel => switch (target.os.tag) { .freebsd => "elf32ltsmip_fbsd", else => "elf32ltsmip", }, .mips64 => switch (target.os.tag) { .freebsd => switch (target.abi) { .gnuabin32 => "elf32btsmipn32_fbsd", else => "elf64btsmip_fbsd", }, else => switch (target.abi) { .gnuabin32 => "elf32btsmipn32", else => "elf64btsmip", }, }, .mips64el => switch (target.os.tag) { .freebsd => switch (target.abi) { .gnuabin32 => "elf32ltsmipn32_fbsd", else => "elf64ltsmip_fbsd", }, else => switch (target.abi) { .gnuabin32 => "elf32ltsmipn32", else => "elf64ltsmip", }, }, .msp430 => "msp430elf", .powerpc => switch (target.os.tag) { .freebsd => "elf32ppc_fbsd", .linux => "elf32ppclinux", else => "elf32ppc", }, .powerpcle => switch (target.os.tag) { .linux => "elf32lppclinux", else => "elf32lppc", }, .powerpc64 => "elf64ppc", .powerpc64le => "elf64lppc", .riscv32 => "elf32lriscv", .riscv64 => "elf64lriscv", .s390x => "elf64_s390", .sparc64 => "elf64_sparc", .x86 => switch (target.os.tag) { .elfiamcu => "elf_iamcu", .freebsd => "elf_i386_fbsd", else => "elf_i386", }, .x86_64 => switch (target.abi) { .gnux32, .muslx32 => "elf32_x86_64", else => "elf_x86_64", }, else => null, }; } pub fn padToIdeal(actual_size: anytype) @TypeOf(actual_size) { return actual_size +| (actual_size / ideal_factor); } // Provide a blueprint of csu (c-runtime startup) objects for supported // link modes. // // This is for cross-mode targets only. For host-mode targets the system // compiler can be probed to produce a robust blueprint. // // Targets requiring a libc for which zig does not bundle a libc are // host-mode targets. Unfortunately, host-mode probes are not yet // implemented. For now the data is hard-coded here. Such targets are // { freebsd, netbsd, openbsd, dragonfly }. const CsuObjects = struct { crt0: ?[]const u8 = null, crti: ?[]const u8 = null, crtbegin: ?[]const u8 = null, crtend: ?[]const u8 = null, crtn: ?[]const u8 = null, const InitArgs = struct {}; fn init(arena: Allocator, comp: *const Compilation) !CsuObjects { // crt objects are only required for libc. if (!comp.config.link_libc) return .{}; var result: CsuObjects = .{}; // Flatten crt cases. const mode: enum { dynamic_lib, dynamic_exe, dynamic_pie, static_exe, static_pie, } = switch (comp.config.output_mode) { .Obj => return CsuObjects{}, .Lib => switch (comp.config.link_mode) { .dynamic => .dynamic_lib, .static => return CsuObjects{}, }, .Exe => switch (comp.config.link_mode) { .dynamic => if (comp.config.pie) .dynamic_pie else .dynamic_exe, .static => if (comp.config.pie) .static_pie else .static_exe, }, }; const target = comp.root_mod.resolved_target.result; if (target.isAndroid()) { switch (mode) { // zig fmt: off .dynamic_lib => result.set( null, null, "crtbegin_so.o", "crtend_so.o", null ), .dynamic_exe, .dynamic_pie => result.set( null, null, "crtbegin_dynamic.o", "crtend_android.o", null ), .static_exe, .static_pie => result.set( null, null, "crtbegin_static.o", "crtend_android.o", null ), // zig fmt: on } } else { switch (target.os.tag) { .linux => { switch (mode) { // zig fmt: off .dynamic_lib => result.set( null, "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), .dynamic_exe => result.set( "crt1.o", "crti.o", "crtbegin.o", "crtend.o", "crtn.o" ), .dynamic_pie => result.set( "Scrt1.o", "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), .static_exe => result.set( "crt1.o", "crti.o", "crtbeginT.o", "crtend.o", "crtn.o" ), .static_pie => result.set( "rcrt1.o", "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), // zig fmt: on } if (comp.libc_installation) |_| { // hosted-glibc provides crtbegin/end objects in platform/compiler-specific dirs // and they are not known at comptime. For now null-out crtbegin/end objects; // there is no feature loss, zig has never linked those objects in before. result.crtbegin = null; result.crtend = null; } else { // Bundled glibc only has Scrt1.o . if (result.crt0 != null and target.isGnuLibC()) result.crt0 = "Scrt1.o"; } }, .dragonfly => switch (mode) { // zig fmt: off .dynamic_lib => result.set( null, "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), .dynamic_exe => result.set( "crt1.o", "crti.o", "crtbegin.o", "crtend.o", "crtn.o" ), .dynamic_pie => result.set( "Scrt1.o", "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), .static_exe => result.set( "crt1.o", "crti.o", "crtbegin.o", "crtend.o", "crtn.o" ), .static_pie => result.set( "Scrt1.o", "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), // zig fmt: on }, .freebsd => switch (mode) { // zig fmt: off .dynamic_lib => result.set( null, "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), .dynamic_exe => result.set( "crt1.o", "crti.o", "crtbegin.o", "crtend.o", "crtn.o" ), .dynamic_pie => result.set( "Scrt1.o", "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), .static_exe => result.set( "crt1.o", "crti.o", "crtbeginT.o", "crtend.o", "crtn.o" ), .static_pie => result.set( "Scrt1.o", "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), // zig fmt: on }, .netbsd => switch (mode) { // zig fmt: off .dynamic_lib => result.set( null, "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), .dynamic_exe => result.set( "crt0.o", "crti.o", "crtbegin.o", "crtend.o", "crtn.o" ), .dynamic_pie => result.set( "crt0.o", "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), .static_exe => result.set( "crt0.o", "crti.o", "crtbeginT.o", "crtend.o", "crtn.o" ), .static_pie => result.set( "crt0.o", "crti.o", "crtbeginT.o", "crtendS.o", "crtn.o" ), // zig fmt: on }, .openbsd => switch (mode) { // zig fmt: off .dynamic_lib => result.set( null, null, "crtbeginS.o", "crtendS.o", null ), .dynamic_exe, .dynamic_pie => result.set( "crt0.o", null, "crtbegin.o", "crtend.o", null ), .static_exe, .static_pie => result.set( "rcrt0.o", null, "crtbegin.o", "crtend.o", null ), // zig fmt: on }, .haiku => switch (mode) { // zig fmt: off .dynamic_lib => result.set( null, "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), .dynamic_exe => result.set( "start_dyn.o", "crti.o", "crtbegin.o", "crtend.o", "crtn.o" ), .dynamic_pie => result.set( "start_dyn.o", "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), .static_exe => result.set( "start_dyn.o", "crti.o", "crtbegin.o", "crtend.o", "crtn.o" ), .static_pie => result.set( "start_dyn.o", "crti.o", "crtbeginS.o", "crtendS.o", "crtn.o" ), // zig fmt: on }, .solaris, .illumos => switch (mode) { // zig fmt: off .dynamic_lib => result.set( null, "crti.o", null, null, "crtn.o" ), .dynamic_exe, .dynamic_pie => result.set( "crt1.o", "crti.o", null, null, "crtn.o" ), .static_exe, .static_pie => result.set( null, null, null, null, null ), // zig fmt: on }, else => {}, } } // Convert each object to a full pathname. if (comp.libc_installation) |lci| { const crt_dir_path = lci.crt_dir orelse return error.LibCInstallationMissingCRTDir; switch (target.os.tag) { .dragonfly => { if (result.crt0) |*obj| obj.* = try fs.path.join(arena, &[_][]const u8{ crt_dir_path, obj.* }); if (result.crti) |*obj| obj.* = try fs.path.join(arena, &[_][]const u8{ crt_dir_path, obj.* }); if (result.crtn) |*obj| obj.* = try fs.path.join(arena, &[_][]const u8{ crt_dir_path, obj.* }); var gccv: []const u8 = undefined; if (target.os.version_range.semver.isAtLeast(.{ .major = 5, .minor = 4, .patch = 0 }) orelse true) { gccv = "gcc80"; } else { gccv = "gcc54"; } if (result.crtbegin) |*obj| obj.* = try fs.path.join(arena, &[_][]const u8{ crt_dir_path, gccv, obj.* }); if (result.crtend) |*obj| obj.* = try fs.path.join(arena, &[_][]const u8{ crt_dir_path, gccv, obj.* }); }, .haiku => { const gcc_dir_path = lci.gcc_dir orelse return error.LibCInstallationMissingCRTDir; if (result.crt0) |*obj| obj.* = try fs.path.join(arena, &[_][]const u8{ crt_dir_path, obj.* }); if (result.crti) |*obj| obj.* = try fs.path.join(arena, &[_][]const u8{ crt_dir_path, obj.* }); if (result.crtn) |*obj| obj.* = try fs.path.join(arena, &[_][]const u8{ crt_dir_path, obj.* }); if (result.crtbegin) |*obj| obj.* = try fs.path.join(arena, &[_][]const u8{ gcc_dir_path, obj.* }); if (result.crtend) |*obj| obj.* = try fs.path.join(arena, &[_][]const u8{ gcc_dir_path, obj.* }); }, else => { inline for (std.meta.fields(@TypeOf(result))) |f| { if (@field(result, f.name)) |*obj| { obj.* = try fs.path.join(arena, &[_][]const u8{ crt_dir_path, obj.* }); } } }, } } else { inline for (std.meta.fields(@TypeOf(result))) |f| { if (@field(result, f.name)) |*obj| { if (comp.crt_files.get(obj.*)) |crtf| { obj.* = crtf.full_object_path; } else { @field(result, f.name) = null; } } } } return result; } fn set( self: *CsuObjects, crt0: ?[]const u8, crti: ?[]const u8, crtbegin: ?[]const u8, crtend: ?[]const u8, crtn: ?[]const u8, ) void { self.crt0 = crt0; self.crti = crti; self.crtbegin = crtbegin; self.crtend = crtend; self.crtn = crtn; } }; /// If a target compiles other output modes as dynamic libraries, /// this function returns true for those too. pub fn isEffectivelyDynLib(self: Elf) bool { if (self.base.isDynLib()) return true; return switch (self.getTarget().os.tag) { .haiku => self.base.isExe(), else => false, }; } fn getPhdr(self: *Elf, opts: struct { type: u32 = 0, flags: u32 = 0, }) ?u16 { for (self.phdrs.items, 0..) |phdr, phndx| { if (self.phdr_table_load_index) |index| { if (phndx == index) continue; } if (phdr.p_type == opts.type and phdr.p_flags == opts.flags) return @intCast(phndx); } return null; } fn addPhdr(self: *Elf, opts: struct { type: u32 = 0, flags: u32 = 0, @"align": u64 = 0, offset: u64 = 0, addr: u64 = 0, filesz: u64 = 0, memsz: u64 = 0, }) error{OutOfMemory}!u16 { const gpa = self.base.comp.gpa; const index = @as(u16, @intCast(self.phdrs.items.len)); try self.phdrs.append(gpa, .{ .p_type = opts.type, .p_flags = opts.flags, .p_offset = opts.offset, .p_vaddr = opts.addr, .p_paddr = opts.addr, .p_filesz = opts.filesz, .p_memsz = opts.memsz, .p_align = opts.@"align", }); return index; } pub fn addRelaShdr(self: *Elf, name: u32, shndx: u32) !u32 { const entsize: u64 = switch (self.ptr_width) { .p32 => @sizeOf(elf.Elf32_Rela), .p64 => @sizeOf(elf.Elf64_Rela), }; const addralign: u64 = switch (self.ptr_width) { .p32 => @alignOf(elf.Elf32_Rela), .p64 => @alignOf(elf.Elf64_Rela), }; return self.addSection(.{ .name = name, .type = elf.SHT_RELA, .flags = elf.SHF_INFO_LINK, .entsize = entsize, .info = shndx, .addralign = addralign, .offset = std.math.maxInt(u64), }); } pub const AddSectionOpts = struct { name: u32 = 0, type: u32 = elf.SHT_NULL, flags: u64 = 0, link: u32 = 0, info: u32 = 0, addralign: u64 = 0, entsize: u64 = 0, offset: u64 = 0, }; pub fn addSection(self: *Elf, opts: AddSectionOpts) !u32 { const gpa = self.base.comp.gpa; const index: u32 = @intCast(try self.sections.addOne(gpa)); self.sections.set(index, .{ .shdr = .{ .sh_name = opts.name, .sh_type = opts.type, .sh_flags = opts.flags, .sh_addr = 0, .sh_offset = opts.offset, .sh_size = 0, .sh_link = opts.link, .sh_info = opts.info, .sh_addralign = opts.addralign, .sh_entsize = opts.entsize, }, }); return index; } pub fn sectionByName(self: *Elf, name: [:0]const u8) ?u32 { for (self.sections.items(.shdr), 0..) |*shdr, i| { const this_name = self.getShString(shdr.sh_name); if (mem.eql(u8, this_name, name)) return @intCast(i); } else return null; } const RelaDyn = struct { offset: u64, sym: u64 = 0, type: u32, addend: i64 = 0, target: ?*const Symbol = null, }; pub fn addRelaDyn(self: *Elf, opts: RelaDyn) !void { try self.rela_dyn.ensureUnusedCapacity(self.base.alloctor, 1); self.addRelaDynAssumeCapacity(opts); } pub fn addRelaDynAssumeCapacity(self: *Elf, opts: RelaDyn) void { relocs_log.debug(" {s}: [{x} => {d}({s})] + {x}", .{ relocation.fmtRelocType(opts.type, self.getTarget().cpu.arch), opts.offset, opts.sym, if (opts.target) |sym| sym.name(self) else "", opts.addend, }); self.rela_dyn.appendAssumeCapacity(.{ .r_offset = opts.offset, .r_info = (opts.sym << 32) | opts.type, .r_addend = opts.addend, }); } fn sortRelaDyn(self: *Elf) void { const Sort = struct { fn rank(rel: elf.Elf64_Rela, ctx: *Elf) u2 { const cpu_arch = ctx.getTarget().cpu.arch; const r_type = rel.r_type(); const r_kind = relocation.decode(r_type, cpu_arch).?; return switch (r_kind) { .rel => 0, .irel => 2, else => 1, }; } pub fn lessThan(ctx: *Elf, lhs: elf.Elf64_Rela, rhs: elf.Elf64_Rela) bool { if (rank(lhs, ctx) == rank(rhs, ctx)) { if (lhs.r_sym() == rhs.r_sym()) return lhs.r_offset < rhs.r_offset; return lhs.r_sym() < rhs.r_sym(); } return rank(lhs, ctx) < rank(rhs, ctx); } }; mem.sort(elf.Elf64_Rela, self.rela_dyn.items, self, Sort.lessThan); } pub fn calcNumIRelativeRelocs(self: *Elf) usize { var count: usize = self.num_ifunc_dynrelocs; for (self.got.entries.items) |entry| { if (entry.tag != .got) continue; const sym = self.symbol(entry.ref).?; if (sym.isIFunc(self)) count += 1; } return count; } pub fn getStartStopBasename(self: Elf, shdr: elf.Elf64_Shdr) ?[]const u8 { const name = self.getShString(shdr.sh_name); if (shdr.sh_flags & elf.SHF_ALLOC != 0 and name.len > 0) { if (Elf.isCIdentifier(name)) return name; } return null; } pub fn isCIdentifier(name: []const u8) bool { if (name.len == 0) return false; const first_c = name[0]; if (!std.ascii.isAlphabetic(first_c) and first_c != '_') return false; for (name[1..]) |c| { if (!std.ascii.isAlphanumeric(c) and c != '_') return false; } return true; } pub fn addThunk(self: *Elf) !Thunk.Index { const index = @as(Thunk.Index, @intCast(self.thunks.items.len)); const th = try self.thunks.addOne(self.base.comp.gpa); th.* = .{}; return index; } pub fn thunk(self: *Elf, index: Thunk.Index) *Thunk { assert(index < self.thunks.items.len); return &self.thunks.items[index]; } pub fn file(self: *Elf, index: File.Index) ?File { const tag = self.files.items(.tags)[index]; return switch (tag) { .null => null, .linker_defined => .{ .linker_defined = &self.files.items(.data)[index].linker_defined }, .zig_object => .{ .zig_object = &self.files.items(.data)[index].zig_object }, .object => .{ .object = &self.files.items(.data)[index].object }, .shared_object => .{ .shared_object = &self.files.items(.data)[index].shared_object }, }; } pub fn addFileHandle(self: *Elf, handle: fs.File) !File.HandleIndex { const gpa = self.base.comp.gpa; const index: File.HandleIndex = @intCast(self.file_handles.items.len); const fh = try self.file_handles.addOne(gpa); fh.* = handle; return index; } pub fn fileHandle(self: Elf, index: File.HandleIndex) File.Handle { assert(index < self.file_handles.items.len); return self.file_handles.items[index]; } pub fn atom(self: *Elf, ref: Ref) ?*Atom { const file_ptr = self.file(ref.file) orelse return null; return file_ptr.atom(ref.index); } pub fn comdatGroup(self: *Elf, ref: Ref) *ComdatGroup { return self.file(ref.file).?.comdatGroup(ref.index); } pub fn symbol(self: *Elf, ref: Ref) ?*Symbol { const file_ptr = self.file(ref.file) orelse return null; return file_ptr.symbol(ref.index); } pub fn getGlobalSymbol(self: *Elf, name: []const u8, lib_name: ?[]const u8) !u32 { return self.zigObjectPtr().?.getGlobalSymbol(self, name, lib_name); } pub fn zigObjectPtr(self: *Elf) ?*ZigObject { const index = self.zig_object_index orelse return null; return self.file(index).?.zig_object; } pub fn linkerDefinedPtr(self: *Elf) ?*LinkerDefined { const index = self.linker_defined_index orelse return null; return self.file(index).?.linker_defined; } pub fn getOrCreateMergeSection(self: *Elf, name: [:0]const u8, flags: u64, @"type": u32) !MergeSection.Index { const gpa = self.base.comp.gpa; const out_name = name: { if (self.base.isRelocatable()) break :name name; if (mem.eql(u8, name, ".rodata") or mem.startsWith(u8, name, ".rodata")) break :name if (flags & elf.SHF_STRINGS != 0) ".rodata.str" else ".rodata.cst"; break :name name; }; for (self.merge_sections.items, 0..) |msec, index| { if (mem.eql(u8, msec.name(self), out_name)) return @intCast(index); } const out_off = try self.insertShString(out_name); const out_flags = flags & ~@as(u64, elf.SHF_COMPRESSED | elf.SHF_GROUP); const index = @as(MergeSection.Index, @intCast(self.merge_sections.items.len)); const msec = try self.merge_sections.addOne(gpa); msec.* = .{ .name_offset = out_off, .flags = out_flags, .type = @"type", }; return index; } pub fn mergeSection(self: *Elf, index: MergeSection.Index) *MergeSection { assert(index < self.merge_sections.items.len); return &self.merge_sections.items[index]; } pub fn gotAddress(self: *Elf) i64 { const shndx = blk: { if (self.getTarget().cpu.arch == .x86_64 and self.got_plt_section_index != null) break :blk self.got_plt_section_index.?; break :blk if (self.got_section_index) |shndx| shndx else null; }; return if (shndx) |index| @intCast(self.sections.items(.shdr)[index].sh_addr) else 0; } pub fn tpAddress(self: *Elf) i64 { const index = self.phdr_tls_index orelse return 0; const phdr = self.phdrs.items[index]; const addr = switch (self.getTarget().cpu.arch) { .x86_64 => mem.alignForward(u64, phdr.p_vaddr + phdr.p_memsz, phdr.p_align), .aarch64 => mem.alignBackward(u64, phdr.p_vaddr - 16, phdr.p_align), .riscv64 => phdr.p_vaddr, else => |arch| std.debug.panic("TODO implement getTpAddress for {s}", .{@tagName(arch)}), }; return @intCast(addr); } pub fn dtpAddress(self: *Elf) i64 { const index = self.phdr_tls_index orelse return 0; const phdr = self.phdrs.items[index]; return @intCast(phdr.p_vaddr); } pub fn tlsAddress(self: *Elf) i64 { const index = self.phdr_tls_index orelse return 0; const phdr = self.phdrs.items[index]; return @intCast(phdr.p_vaddr); } pub fn getShString(self: Elf, off: u32) [:0]const u8 { assert(off < self.shstrtab.items.len); return mem.sliceTo(@as([*:0]const u8, @ptrCast(self.shstrtab.items.ptr + off)), 0); } pub fn insertShString(self: *Elf, name: [:0]const u8) error{OutOfMemory}!u32 { const gpa = self.base.comp.gpa; const off = @as(u32, @intCast(self.shstrtab.items.len)); try self.shstrtab.ensureUnusedCapacity(gpa, name.len + 1); self.shstrtab.writer(gpa).print("{s}\x00", .{name}) catch unreachable; return off; } pub fn getDynString(self: Elf, off: u32) [:0]const u8 { assert(off < self.dynstrtab.items.len); return mem.sliceTo(@as([*:0]const u8, @ptrCast(self.dynstrtab.items.ptr + off)), 0); } pub fn insertDynString(self: *Elf, name: []const u8) error{OutOfMemory}!u32 { const gpa = self.base.comp.gpa; const off = @as(u32, @intCast(self.dynstrtab.items.len)); try self.dynstrtab.ensureUnusedCapacity(gpa, name.len + 1); self.dynstrtab.writer(gpa).print("{s}\x00", .{name}) catch unreachable; return off; } fn reportUndefinedSymbols(self: *Elf, undefs: anytype) !void { const gpa = self.base.comp.gpa; const max_notes = 4; try self.base.comp.link_errors.ensureUnusedCapacity(gpa, undefs.count()); for (undefs.keys(), undefs.values()) |key, refs| { const undef_sym = self.resolver.keys.items[key - 1]; const nrefs = @min(refs.items.len, max_notes); const nnotes = nrefs + @intFromBool(refs.items.len > max_notes); var err = try self.base.addErrorWithNotesAssumeCapacity(nnotes); try err.addMsg("undefined symbol: {s}", .{undef_sym.name(self)}); for (refs.items[0..nrefs]) |ref| { const atom_ptr = self.atom(ref).?; const file_ptr = atom_ptr.file(self).?; try err.addNote("referenced by {s}:{s}", .{ file_ptr.fmtPath(), atom_ptr.name(self) }); } if (refs.items.len > max_notes) { const remaining = refs.items.len - max_notes; try err.addNote("referenced {d} more times", .{remaining}); } } } fn reportDuplicates(self: *Elf, dupes: anytype) error{ HasDuplicates, OutOfMemory }!void { if (dupes.keys().len == 0) return; // Nothing to do const max_notes = 3; for (dupes.keys(), dupes.values()) |key, notes| { const sym = self.resolver.keys.items[key - 1]; const nnotes = @min(notes.items.len, max_notes) + @intFromBool(notes.items.len > max_notes); var err = try self.base.addErrorWithNotes(nnotes + 1); try err.addMsg("duplicate symbol definition: {s}", .{sym.name(self)}); try err.addNote("defined by {}", .{sym.file(self).?.fmtPath()}); var inote: usize = 0; while (inote < @min(notes.items.len, max_notes)) : (inote += 1) { const file_ptr = self.file(notes.items[inote]).?; try err.addNote("defined by {}", .{file_ptr.fmtPath()}); } if (notes.items.len > max_notes) { const remaining = notes.items.len - max_notes; try err.addNote("defined {d} more times", .{remaining}); } } return error.HasDuplicates; } fn reportMissingLibraryError( self: *Elf, checked_paths: []const []const u8, comptime format: []const u8, args: anytype, ) error{OutOfMemory}!void { var err = try self.base.addErrorWithNotes(checked_paths.len); try err.addMsg(format, args); for (checked_paths) |path| { try err.addNote("tried {s}", .{path}); } } fn reportUnsupportedCpuArch(self: *Elf) error{OutOfMemory}!void { var err = try self.base.addErrorWithNotes(0); try err.addMsg("fatal linker error: unsupported CPU architecture {s}", .{ @tagName(self.getTarget().cpu.arch), }); } pub fn addParseError( self: *Elf, path: []const u8, comptime format: []const u8, args: anytype, ) error{OutOfMemory}!void { var err = try self.base.addErrorWithNotes(1); try err.addMsg(format, args); try err.addNote("while parsing {s}", .{path}); } pub fn addFileError( self: *Elf, file_index: File.Index, comptime format: []const u8, args: anytype, ) error{OutOfMemory}!void { var err = try self.base.addErrorWithNotes(1); try err.addMsg(format, args); try err.addNote("while parsing {}", .{self.file(file_index).?.fmtPath()}); } pub fn failFile( self: *Elf, file_index: File.Index, comptime format: []const u8, args: anytype, ) error{ OutOfMemory, LinkFailure } { try addFileError(self, file_index, format, args); return error.LinkFailure; } pub fn failParse( self: *Elf, path: []const u8, comptime format: []const u8, args: anytype, ) error{ OutOfMemory, LinkFailure } { try addParseError(self, path, format, args); return error.LinkFailure; } const FormatShdrCtx = struct { elf_file: *Elf, shdr: elf.Elf64_Shdr, }; fn fmtShdr(self: *Elf, shdr: elf.Elf64_Shdr) std.fmt.Formatter(formatShdr) { return .{ .data = .{ .shdr = shdr, .elf_file = self, } }; } fn formatShdr( ctx: FormatShdrCtx, comptime unused_fmt_string: []const u8, options: std.fmt.FormatOptions, writer: anytype, ) !void { _ = options; _ = unused_fmt_string; const shdr = ctx.shdr; try writer.print("{s} : @{x} ({x}) : align({x}) : size({x}) : entsize({x}) : flags({})", .{ ctx.elf_file.getShString(shdr.sh_name), shdr.sh_offset, shdr.sh_addr, shdr.sh_addralign, shdr.sh_size, shdr.sh_entsize, fmtShdrFlags(shdr.sh_flags), }); } pub fn fmtShdrFlags(sh_flags: u64) std.fmt.Formatter(formatShdrFlags) { return .{ .data = sh_flags }; } fn formatShdrFlags( sh_flags: u64, comptime unused_fmt_string: []const u8, options: std.fmt.FormatOptions, writer: anytype, ) !void { _ = unused_fmt_string; _ = options; if (elf.SHF_WRITE & sh_flags != 0) { try writer.writeAll("W"); } if (elf.SHF_ALLOC & sh_flags != 0) { try writer.writeAll("A"); } if (elf.SHF_EXECINSTR & sh_flags != 0) { try writer.writeAll("X"); } if (elf.SHF_MERGE & sh_flags != 0) { try writer.writeAll("M"); } if (elf.SHF_STRINGS & sh_flags != 0) { try writer.writeAll("S"); } if (elf.SHF_INFO_LINK & sh_flags != 0) { try writer.writeAll("I"); } if (elf.SHF_LINK_ORDER & sh_flags != 0) { try writer.writeAll("L"); } if (elf.SHF_EXCLUDE & sh_flags != 0) { try writer.writeAll("E"); } if (elf.SHF_COMPRESSED & sh_flags != 0) { try writer.writeAll("C"); } if (elf.SHF_GROUP & sh_flags != 0) { try writer.writeAll("G"); } if (elf.SHF_OS_NONCONFORMING & sh_flags != 0) { try writer.writeAll("O"); } if (elf.SHF_TLS & sh_flags != 0) { try writer.writeAll("T"); } if (elf.SHF_X86_64_LARGE & sh_flags != 0) { try writer.writeAll("l"); } if (elf.SHF_MIPS_ADDR & sh_flags != 0 or elf.SHF_ARM_PURECODE & sh_flags != 0) { try writer.writeAll("p"); } } const FormatPhdrCtx = struct { elf_file: *Elf, phdr: elf.Elf64_Phdr, }; fn fmtPhdr(self: *Elf, phdr: elf.Elf64_Phdr) std.fmt.Formatter(formatPhdr) { return .{ .data = .{ .phdr = phdr, .elf_file = self, } }; } fn formatPhdr( ctx: FormatPhdrCtx, comptime unused_fmt_string: []const u8, options: std.fmt.FormatOptions, writer: anytype, ) !void { _ = options; _ = unused_fmt_string; const phdr = ctx.phdr; const write = phdr.p_flags & elf.PF_W != 0; const read = phdr.p_flags & elf.PF_R != 0; const exec = phdr.p_flags & elf.PF_X != 0; var flags: [3]u8 = [_]u8{'_'} ** 3; if (exec) flags[0] = 'X'; if (write) flags[1] = 'W'; if (read) flags[2] = 'R'; const p_type = switch (phdr.p_type) { elf.PT_LOAD => "LOAD", elf.PT_TLS => "TLS", elf.PT_GNU_EH_FRAME => "GNU_EH_FRAME", elf.PT_GNU_STACK => "GNU_STACK", elf.PT_DYNAMIC => "DYNAMIC", elf.PT_INTERP => "INTERP", elf.PT_NULL => "NULL", elf.PT_PHDR => "PHDR", elf.PT_NOTE => "NOTE", else => "UNKNOWN", }; try writer.print("{s} : {s} : @{x} ({x}) : align({x}) : filesz({x}) : memsz({x})", .{ p_type, flags, phdr.p_offset, phdr.p_vaddr, phdr.p_align, phdr.p_filesz, phdr.p_memsz, }); } pub fn dumpState(self: *Elf) std.fmt.Formatter(fmtDumpState) { return .{ .data = self }; } fn fmtDumpState( self: *Elf, comptime unused_fmt_string: []const u8, options: std.fmt.FormatOptions, writer: anytype, ) !void { _ = unused_fmt_string; _ = options; if (self.zigObjectPtr()) |zig_object| { try writer.print("zig_object({d}) : {s}\n", .{ zig_object.index, zig_object.path }); try writer.print("{}{}", .{ zig_object.fmtAtoms(self), zig_object.fmtSymtab(self), }); try writer.writeByte('\n'); } for (self.objects.items) |index| { const object = self.file(index).?.object; try writer.print("object({d}) : {}", .{ index, object.fmtPath() }); if (!object.alive) try writer.writeAll(" : [*]"); try writer.writeByte('\n'); try writer.print("{}{}{}{}{}\n", .{ object.fmtAtoms(self), object.fmtCies(self), object.fmtFdes(self), object.fmtSymtab(self), object.fmtComdatGroups(self), }); } for (self.shared_objects.items) |index| { const shared_object = self.file(index).?.shared_object; try writer.print("shared_object({d}) : ", .{index}); try writer.print("{s}", .{shared_object.path}); try writer.print(" : needed({})", .{shared_object.needed}); if (!shared_object.alive) try writer.writeAll(" : [*]"); try writer.writeByte('\n'); try writer.print("{}\n", .{shared_object.fmtSymtab(self)}); } if (self.linker_defined_index) |index| { const linker_defined = self.file(index).?.linker_defined; try writer.print("linker_defined({d}) : (linker defined)\n", .{index}); try writer.print("{}\n", .{linker_defined.fmtSymtab(self)}); } const slice = self.sections.slice(); { try writer.writeAll("atom lists\n"); for (slice.items(.shdr), slice.items(.atom_list_2), 0..) |shdr, atom_list, shndx| { try writer.print("shdr({d}) : {s} : {}\n", .{ shndx, self.getShString(shdr.sh_name), atom_list.fmt(self) }); } } if (self.requiresThunks()) { try writer.writeAll("thunks\n"); for (self.thunks.items, 0..) |th, index| { try writer.print("thunk({d}) : {}\n", .{ index, th.fmt(self) }); } } try writer.print("{}\n", .{self.got.fmt(self)}); try writer.print("{}\n", .{self.plt.fmt(self)}); try writer.writeAll("Output COMDAT groups\n"); for (self.comdat_group_sections.items) |cg| { try writer.print(" shdr({d}) : COMDAT({})\n", .{ cg.shndx, cg.cg_ref }); } try writer.writeAll("\nOutput merge sections\n"); for (self.merge_sections.items) |msec| { try writer.print(" shdr({d}) : {}\n", .{ msec.output_section_index, msec.fmt(self) }); } try writer.writeAll("\nOutput shdrs\n"); for (slice.items(.shdr), slice.items(.phndx), 0..) |shdr, phndx, shndx| { try writer.print(" shdr({d}) : phdr({?d}) : {}\n", .{ shndx, phndx, self.fmtShdr(shdr), }); } try writer.writeAll("\nOutput phdrs\n"); for (self.phdrs.items, 0..) |phdr, phndx| { try writer.print(" phdr({d}) : {}\n", .{ phndx, self.fmtPhdr(phdr) }); } } /// Caller owns the memory. pub fn preadAllAlloc(allocator: Allocator, handle: fs.File, offset: u64, size: u64) ![]u8 { const buffer = try allocator.alloc(u8, math.cast(usize, size) orelse return error.Overflow); errdefer allocator.free(buffer); const amt = try handle.preadAll(buffer, offset); if (amt != size) return error.InputOutput; return buffer; } /// Binary search pub fn bsearch(comptime T: type, haystack: []align(1) const T, predicate: anytype) usize { if (!@hasDecl(@TypeOf(predicate), "predicate")) @compileError("Predicate is required to define fn predicate(@This(), T) bool"); var min: usize = 0; var max: usize = haystack.len; while (min < max) { const index = (min + max) / 2; const curr = haystack[index]; if (predicate.predicate(curr)) { min = index + 1; } else { max = index; } } return min; } /// Linear search pub fn lsearch(comptime T: type, haystack: []align(1) const T, predicate: anytype) usize { if (!@hasDecl(@TypeOf(predicate), "predicate")) @compileError("Predicate is required to define fn predicate(@This(), T) bool"); var i: usize = 0; while (i < haystack.len) : (i += 1) { if (predicate.predicate(haystack[i])) break; } return i; } pub fn getTarget(self: Elf) std.Target { return self.base.comp.root_mod.resolved_target.result; } fn requiresThunks(self: Elf) bool { return switch (self.getTarget().cpu.arch) { .aarch64 => true, .x86_64, .riscv64 => false, else => @panic("TODO unimplemented architecture"), }; } /// The following three values are only observed at compile-time and used to emit a compile error /// to remind the programmer to update expected maximum numbers of different program header types /// so that we reserve enough space for the program header table up-front. /// Bump these numbers when adding or deleting a Zig specific pre-allocated segment, or adding /// more special-purpose program headers. const max_number_of_object_segments = 9; const max_number_of_special_phdrs = 5; const default_entry_addr = 0x8000000; pub const base_tag: link.File.Tag = .elf; pub const ComdatGroup = struct { signature_off: u32, file_index: File.Index, shndx: u32, members_start: u32, members_len: u32, alive: bool = true, pub fn file(cg: ComdatGroup, elf_file: *Elf) File { return elf_file.file(cg.file_index).?; } pub fn signature(cg: ComdatGroup, elf_file: *Elf) [:0]const u8 { return cg.file(elf_file).object.getString(cg.signature_off); } pub fn comdatGroupMembers(cg: ComdatGroup, elf_file: *Elf) []const u32 { const object = cg.file(elf_file).object; return object.comdat_group_data.items[cg.members_start..][0..cg.members_len]; } pub const Index = u32; }; pub const SymtabCtx = struct { ilocal: u32 = 0, iglobal: u32 = 0, nlocals: u32 = 0, nglobals: u32 = 0, strsize: u32 = 0, pub fn reset(ctx: *SymtabCtx) void { ctx.ilocal = 0; ctx.iglobal = 0; ctx.nlocals = 0; ctx.nglobals = 0; ctx.strsize = 0; } }; pub const null_sym = elf.Elf64_Sym{ .st_name = 0, .st_info = 0, .st_other = 0, .st_shndx = 0, .st_value = 0, .st_size = 0, }; pub const null_shdr = elf.Elf64_Shdr{ .sh_name = 0, .sh_type = 0, .sh_flags = 0, .sh_addr = 0, .sh_offset = 0, .sh_size = 0, .sh_link = 0, .sh_info = 0, .sh_addralign = 0, .sh_entsize = 0, }; pub const SystemLib = struct { needed: bool = false, path: []const u8, }; pub const Ref = struct { index: u32 = 0, file: u32 = 0, pub fn eql(ref: Ref, other: Ref) bool { return ref.index == other.index and ref.file == other.file; } pub fn format( ref: Ref, comptime unused_fmt_string: []const u8, options: std.fmt.FormatOptions, writer: anytype, ) !void { _ = unused_fmt_string; _ = options; try writer.print("ref({},{})", .{ ref.index, ref.file }); } }; pub const SymbolResolver = struct { keys: std.ArrayListUnmanaged(Key) = .empty, values: std.ArrayListUnmanaged(Ref) = .empty, table: std.AutoArrayHashMapUnmanaged(void, void) = .empty, const Result = struct { found_existing: bool, index: Index, ref: *Ref, }; pub fn deinit(resolver: *SymbolResolver, allocator: Allocator) void { resolver.keys.deinit(allocator); resolver.values.deinit(allocator); resolver.table.deinit(allocator); } pub fn getOrPut( resolver: *SymbolResolver, allocator: Allocator, ref: Ref, elf_file: *Elf, ) !Result { const adapter = Adapter{ .keys = resolver.keys.items, .elf_file = elf_file }; const key = Key{ .index = ref.index, .file_index = ref.file }; const gop = try resolver.table.getOrPutAdapted(allocator, key, adapter); if (!gop.found_existing) { try resolver.keys.append(allocator, key); _ = try resolver.values.addOne(allocator); } return .{ .found_existing = gop.found_existing, .index = @intCast(gop.index + 1), .ref = &resolver.values.items[gop.index], }; } pub fn get(resolver: SymbolResolver, index: Index) ?Ref { if (index == 0) return null; return resolver.values.items[index - 1]; } pub fn reset(resolver: *SymbolResolver) void { resolver.keys.clearRetainingCapacity(); resolver.values.clearRetainingCapacity(); resolver.table.clearRetainingCapacity(); } const Key = struct { index: Symbol.Index, file_index: File.Index, fn name(key: Key, elf_file: *Elf) [:0]const u8 { const ref = Ref{ .index = key.index, .file = key.file_index }; return elf_file.symbol(ref).?.name(elf_file); } fn file(key: Key, elf_file: *Elf) ?File { return elf_file.file(key.file_index); } fn eql(key: Key, other: Key, elf_file: *Elf) bool { const key_name = key.name(elf_file); const other_name = other.name(elf_file); return mem.eql(u8, key_name, other_name); } fn hash(key: Key, elf_file: *Elf) u32 { return @truncate(Hash.hash(0, key.name(elf_file))); } }; const Adapter = struct { keys: []const Key, elf_file: *Elf, pub fn eql(ctx: @This(), key: Key, b_void: void, b_map_index: usize) bool { _ = b_void; const other = ctx.keys[b_map_index]; return key.eql(other, ctx.elf_file); } pub fn hash(ctx: @This(), key: Key) u32 { return key.hash(ctx.elf_file); } }; pub const Index = u32; }; const Section = struct { /// Section header. shdr: elf.Elf64_Shdr, /// Assigned program header index if any. phndx: ?u32 = null, /// List of atoms contributing to this section. /// TODO currently this is only used for relocations tracking in relocatable mode /// but will be merged with atom_list_2. atom_list: std.ArrayListUnmanaged(Ref) = .empty, /// List of atoms contributing to this section. /// This can be used by sections that require special handling such as init/fini array, etc. atom_list_2: AtomList = .{}, /// Index of the last allocated atom in this section. last_atom: Ref = .{ .index = 0, .file = 0 }, /// A list of atoms that have surplus capacity. This list can have false /// positives, as functions grow and shrink over time, only sometimes being added /// or removed from the freelist. /// /// An atom has surplus capacity when its overcapacity value is greater than /// padToIdeal(minimum_atom_size). That is, when it has so /// much extra capacity, that we could fit a small new symbol in it, itself with /// ideal_capacity or more. /// /// Ideal capacity is defined by size + (size / ideal_factor) /// /// Overcapacity is measured by actual_capacity - ideal_capacity. Note that /// overcapacity can be negative. A simple way to have negative overcapacity is to /// allocate a fresh text block, which will have ideal capacity, and then grow it /// by 1 byte. It will then have -1 overcapacity. free_list: std.ArrayListUnmanaged(Ref) = .empty, }; pub fn sectionSize(self: *Elf, shndx: u32) u64 { const last_atom_ref = self.sections.items(.last_atom)[shndx]; const atom_ptr = self.atom(last_atom_ref) orelse return 0; return @as(u64, @intCast(atom_ptr.value)) + atom_ptr.size; } fn defaultEntrySymbolName(cpu_arch: std.Target.Cpu.Arch) []const u8 { return switch (cpu_arch) { .mips, .mipsel, .mips64, .mips64el => "__start", else => "_start", }; } fn createThunks(elf_file: *Elf, atom_list: *AtomList) !void { const gpa = elf_file.base.comp.gpa; const cpu_arch = elf_file.getTarget().cpu.arch; // A branch will need an extender if its target is larger than // `2^(jump_bits - 1) - margin` where margin is some arbitrary number. const max_distance = switch (cpu_arch) { .aarch64 => 0x500_000, .x86_64, .riscv64 => unreachable, else => @panic("unhandled arch"), }; const advance = struct { fn advance(list: *AtomList, size: u64, alignment: Atom.Alignment) !i64 { const offset = alignment.forward(list.size); const padding = offset - list.size; list.size += padding + size; list.alignment = list.alignment.max(alignment); return @intCast(offset); } }.advance; for (atom_list.atoms.keys()) |ref| { elf_file.atom(ref).?.value = -1; } var i: usize = 0; while (i < atom_list.atoms.keys().len) { const start = i; const start_atom = elf_file.atom(atom_list.atoms.keys()[start]).?; assert(start_atom.alive); start_atom.value = try advance(atom_list, start_atom.size, start_atom.alignment); i += 1; while (i < atom_list.atoms.keys().len) : (i += 1) { const atom_ptr = elf_file.atom(atom_list.atoms.keys()[i]).?; assert(atom_ptr.alive); if (@as(i64, @intCast(atom_ptr.alignment.forward(atom_list.size))) - start_atom.value >= max_distance) break; atom_ptr.value = try advance(atom_list, atom_ptr.size, atom_ptr.alignment); } // Insert a thunk at the group end const thunk_index = try elf_file.addThunk(); const thunk_ptr = elf_file.thunk(thunk_index); thunk_ptr.output_section_index = atom_list.output_section_index; // Scan relocs in the group and create trampolines for any unreachable callsite for (atom_list.atoms.keys()[start..i]) |ref| { const atom_ptr = elf_file.atom(ref).?; const file_ptr = atom_ptr.file(elf_file).?; log.debug("atom({}) {s}", .{ ref, atom_ptr.name(elf_file) }); for (atom_ptr.relocs(elf_file)) |rel| { const is_reachable = switch (cpu_arch) { .aarch64 => r: { const r_type: elf.R_AARCH64 = @enumFromInt(rel.r_type()); if (r_type != .CALL26 and r_type != .JUMP26) break :r true; const target_ref = file_ptr.resolveSymbol(rel.r_sym(), elf_file); const target = elf_file.symbol(target_ref).?; if (target.flags.has_plt) break :r false; if (atom_ptr.output_section_index != target.output_section_index) break :r false; const target_atom = target.atom(elf_file).?; if (target_atom.value == -1) break :r false; const saddr = atom_ptr.address(elf_file) + @as(i64, @intCast(rel.r_offset)); const taddr = target.address(.{}, elf_file); _ = math.cast(i28, taddr + rel.r_addend - saddr) orelse break :r false; break :r true; }, .x86_64, .riscv64 => unreachable, else => @panic("unsupported arch"), }; if (is_reachable) continue; const target = file_ptr.resolveSymbol(rel.r_sym(), elf_file); try thunk_ptr.symbols.put(gpa, target, {}); } atom_ptr.addExtra(.{ .thunk = thunk_index }, elf_file); } thunk_ptr.value = try advance(atom_list, thunk_ptr.size(elf_file), Atom.Alignment.fromNonzeroByteUnits(2)); log.debug("thunk({d}) : {}", .{ thunk_index, thunk_ptr.fmt(elf_file) }); } } const std = @import("std"); const build_options = @import("build_options"); const builtin = @import("builtin"); const assert = std.debug.assert; const elf = std.elf; const fs = std.fs; const log = std.log.scoped(.link); const relocs_log = std.log.scoped(.link_relocs); const state_log = std.log.scoped(.link_state); const math = std.math; const mem = std.mem; const codegen = @import("../codegen.zig"); const dev = @import("../dev.zig"); const eh_frame = @import("Elf/eh_frame.zig"); const gc = @import("Elf/gc.zig"); const glibc = @import("../glibc.zig"); const link = @import("../link.zig"); const merge_section = @import("Elf/merge_section.zig"); const musl = @import("../musl.zig"); const relocatable = @import("Elf/relocatable.zig"); const relocation = @import("Elf/relocation.zig"); const target_util = @import("../target.zig"); const trace = @import("../tracy.zig").trace; const synthetic_sections = @import("Elf/synthetic_sections.zig"); const Air = @import("../Air.zig"); const Allocator = std.mem.Allocator; const Archive = @import("Elf/Archive.zig"); pub const Atom = @import("Elf/Atom.zig"); const AtomList = @import("Elf/AtomList.zig"); const Cache = std.Build.Cache; const Path = Cache.Path; const Compilation = @import("../Compilation.zig"); const ComdatGroupSection = synthetic_sections.ComdatGroupSection; const CopyRelSection = synthetic_sections.CopyRelSection; const DynamicSection = synthetic_sections.DynamicSection; const DynsymSection = synthetic_sections.DynsymSection; const Dwarf = @import("Dwarf.zig"); const Elf = @This(); const File = @import("Elf/file.zig").File; const GnuHashSection = synthetic_sections.GnuHashSection; const GotSection = synthetic_sections.GotSection; const GotPltSection = synthetic_sections.GotPltSection; const Hash = std.hash.Wyhash; const HashSection = synthetic_sections.HashSection; const InputMergeSection = merge_section.InputMergeSection; const LdScript = @import("Elf/LdScript.zig"); const LinkerDefined = @import("Elf/LinkerDefined.zig"); const Liveness = @import("../Liveness.zig"); const LlvmObject = @import("../codegen/llvm.zig").Object; const MergeSection = merge_section.MergeSection; const MergeSubsection = merge_section.MergeSubsection; const Zcu = @import("../Zcu.zig"); const Object = @import("Elf/Object.zig"); const InternPool = @import("../InternPool.zig"); const PltSection = synthetic_sections.PltSection; const PltGotSection = synthetic_sections.PltGotSection; const SharedObject = @import("Elf/SharedObject.zig"); const Symbol = @import("Elf/Symbol.zig"); const StringTable = @import("StringTable.zig"); const Thunk = @import("Elf/Thunk.zig"); const Value = @import("../Value.zig"); const VerneedSection = synthetic_sections.VerneedSection; const ZigObject = @import("Elf/ZigObject.zig"); const riscv = @import("riscv.zig");