Files
zig/src/link/MachO/DebugSymbols.zig

604 lines
22 KiB
Zig

const DebugSymbols = @This();
const std = @import("std");
const build_options = @import("build_options");
const assert = std.debug.assert;
const fs = std.fs;
const link = @import("../../link.zig");
const log = std.log.scoped(.dsym);
const macho = std.macho;
const makeStaticString = MachO.makeStaticString;
const math = std.math;
const mem = std.mem;
const padToIdeal = MachO.padToIdeal;
const trace = @import("../../tracy.zig").trace;
const Allocator = mem.Allocator;
const Dwarf = @import("../Dwarf.zig");
const MachO = @import("../MachO.zig");
const Module = @import("../../Module.zig");
const StringTable = @import("../strtab.zig").StringTable;
const TextBlock = MachO.TextBlock;
const Type = @import("../../type.zig").Type;
base: *MachO,
dwarf: Dwarf,
file: fs.File,
segments: std.ArrayListUnmanaged(macho.segment_command_64) = .{},
sections: std.ArrayListUnmanaged(macho.section_64) = .{},
linkedit_segment_cmd_index: ?u8 = null,
dwarf_segment_cmd_index: ?u8 = null,
debug_info_section_index: ?u8 = null,
debug_abbrev_section_index: ?u8 = null,
debug_str_section_index: ?u8 = null,
debug_aranges_section_index: ?u8 = null,
debug_line_section_index: ?u8 = null,
debug_string_table_dirty: bool = false,
debug_abbrev_section_dirty: bool = false,
debug_aranges_section_dirty: bool = false,
debug_info_header_dirty: bool = false,
debug_line_header_dirty: bool = false,
strtab: StringTable(.strtab) = .{},
relocs: std.ArrayListUnmanaged(Reloc) = .{},
pub const Reloc = struct {
@"type": enum {
direct_load,
got_load,
},
target: u32,
offset: u64,
addend: u32,
prev_vaddr: u64,
};
/// You must call this function *after* `MachO.populateMissingMetadata()`
/// has been called to get a viable debug symbols output.
pub fn populateMissingMetadata(self: *DebugSymbols, allocator: Allocator) !void {
if (self.linkedit_segment_cmd_index == null) {
self.linkedit_segment_cmd_index = @intCast(u8, self.segments.items.len);
const fileoff = @intCast(u64, self.base.page_size);
const needed_size = @intCast(u64, self.base.page_size) * 2;
log.debug("found __LINKEDIT segment free space 0x{x} to 0x{x}", .{ fileoff, needed_size });
// TODO this needs reworking
try self.segments.append(allocator, .{
.segname = makeStaticString("__LINKEDIT"),
.vmaddr = fileoff,
.vmsize = needed_size,
.fileoff = fileoff,
.filesize = needed_size,
.maxprot = macho.PROT.READ,
.initprot = macho.PROT.READ,
.cmdsize = @sizeOf(macho.segment_command_64),
});
}
if (self.dwarf_segment_cmd_index == null) {
self.dwarf_segment_cmd_index = @intCast(u8, self.segments.items.len);
const linkedit = self.segments.items[self.linkedit_segment_cmd_index.?];
const ideal_size: u16 = 200 + 128 + 160 + 250;
const needed_size = mem.alignForwardGeneric(u64, padToIdeal(ideal_size), self.base.page_size);
const fileoff = linkedit.fileoff + linkedit.filesize;
const vmaddr = linkedit.vmaddr + linkedit.vmsize;
log.debug("found __DWARF segment free space 0x{x} to 0x{x}", .{ fileoff, fileoff + needed_size });
try self.segments.append(allocator, .{
.segname = makeStaticString("__DWARF"),
.vmaddr = vmaddr,
.vmsize = needed_size,
.fileoff = fileoff,
.filesize = needed_size,
.cmdsize = @sizeOf(macho.segment_command_64),
});
}
if (self.debug_str_section_index == null) {
assert(self.dwarf.strtab.items.len == 0);
self.debug_str_section_index = try self.allocateSection(
"__debug_str",
@intCast(u32, self.dwarf.strtab.items.len),
0,
);
self.debug_string_table_dirty = true;
}
if (self.debug_info_section_index == null) {
self.debug_info_section_index = try self.allocateSection("__debug_info", 200, 0);
self.debug_info_header_dirty = true;
}
if (self.debug_abbrev_section_index == null) {
self.debug_abbrev_section_index = try self.allocateSection("__debug_abbrev", 128, 0);
self.debug_abbrev_section_dirty = true;
}
if (self.debug_aranges_section_index == null) {
self.debug_aranges_section_index = try self.allocateSection("__debug_aranges", 160, 4);
self.debug_aranges_section_dirty = true;
}
if (self.debug_line_section_index == null) {
self.debug_line_section_index = try self.allocateSection("__debug_line", 250, 0);
self.debug_line_header_dirty = true;
}
}
fn allocateSection(self: *DebugSymbols, sectname: []const u8, size: u64, alignment: u16) !u8 {
const segment = &self.segments.items[self.dwarf_segment_cmd_index.?];
var sect = macho.section_64{
.sectname = makeStaticString(sectname),
.segname = segment.segname,
.size = @intCast(u32, size),
.@"align" = alignment,
};
const alignment_pow_2 = try math.powi(u32, 2, alignment);
const off = self.findFreeSpace(size, alignment_pow_2);
assert(off + size <= segment.fileoff + segment.filesize); // TODO expand
log.debug("found {s},{s} section free space 0x{x} to 0x{x}", .{
sect.segName(),
sect.sectName(),
off,
off + size,
});
sect.addr = segment.vmaddr + off - segment.fileoff;
sect.offset = @intCast(u32, off);
const index = @intCast(u8, self.sections.items.len);
try self.sections.append(self.base.base.allocator, sect);
segment.cmdsize += @sizeOf(macho.section_64);
segment.nsects += 1;
return index;
}
fn detectAllocCollision(self: *DebugSymbols, start: u64, size: u64) ?u64 {
const end = start + padToIdeal(size);
for (self.sections.items) |section| {
const increased_size = padToIdeal(section.size);
const test_end = section.offset + increased_size;
if (end > section.offset and start < test_end) {
return test_end;
}
}
return null;
}
pub fn findFreeSpace(self: *DebugSymbols, object_size: u64, min_alignment: u64) u64 {
const segment = self.segments.items[self.dwarf_segment_cmd_index.?];
var offset: u64 = segment.fileoff;
while (self.detectAllocCollision(offset, object_size)) |item_end| {
offset = mem.alignForwardGeneric(u64, item_end, min_alignment);
}
return offset;
}
pub fn flushModule(self: *DebugSymbols, allocator: Allocator, options: link.Options) !void {
// TODO This linker code currently assumes there is only 1 compilation unit and it corresponds to the
// Zig source code.
const module = options.module orelse return error.LinkingWithoutZigSourceUnimplemented;
for (self.relocs.items) |*reloc| {
const sym = switch (reloc.@"type") {
.direct_load => self.base.getSymbol(.{ .sym_index = reloc.target, .file = null }),
.got_load => blk: {
const got_index = self.base.got_entries_table.get(.{
.sym_index = reloc.target,
.file = null,
}).?;
const got_entry = self.base.got_entries.items[got_index];
break :blk got_entry.getSymbol(self.base);
},
};
if (sym.n_value == reloc.prev_vaddr) continue;
const sym_name = switch (reloc.@"type") {
.direct_load => self.base.getSymbolName(.{ .sym_index = reloc.target, .file = null }),
.got_load => blk: {
const got_index = self.base.got_entries_table.get(.{
.sym_index = reloc.target,
.file = null,
}).?;
const got_entry = self.base.got_entries.items[got_index];
break :blk got_entry.getName(self.base);
},
};
const sect = &self.sections.items[self.debug_info_section_index.?];
const file_offset = sect.offset + reloc.offset;
log.debug("resolving relocation: {d}@{x} ('{s}') at offset {x}", .{
reloc.target,
sym.n_value,
sym_name,
file_offset,
});
try self.file.pwriteAll(mem.asBytes(&sym.n_value), file_offset);
reloc.prev_vaddr = sym.n_value;
}
if (self.debug_abbrev_section_dirty) {
try self.dwarf.writeDbgAbbrev(&self.base.base);
self.debug_abbrev_section_dirty = false;
}
if (self.debug_info_header_dirty) {
// Currently only one compilation unit is supported, so the address range is simply
// identical to the main program header virtual address and memory size.
const text_section = self.base.sections.items(.header)[self.base.text_section_index.?];
const low_pc = text_section.addr;
const high_pc = text_section.addr + text_section.size;
try self.dwarf.writeDbgInfoHeader(&self.base.base, module, low_pc, high_pc);
self.debug_info_header_dirty = false;
}
if (self.debug_aranges_section_dirty) {
// Currently only one compilation unit is supported, so the address range is simply
// identical to the main program header virtual address and memory size.
const text_section = self.base.sections.items(.header)[self.base.text_section_index.?];
try self.dwarf.writeDbgAranges(&self.base.base, text_section.addr, text_section.size);
self.debug_aranges_section_dirty = false;
}
if (self.debug_line_header_dirty) {
try self.dwarf.writeDbgLineHeader(&self.base.base, module);
self.debug_line_header_dirty = false;
}
{
const dwarf_segment = &self.segments.items[self.dwarf_segment_cmd_index.?];
const debug_strtab_sect = &self.sections.items[self.debug_str_section_index.?];
if (self.debug_string_table_dirty or self.dwarf.strtab.items.len != debug_strtab_sect.size) {
const allocated_size = self.allocatedSize(debug_strtab_sect.offset);
const needed_size = self.dwarf.strtab.items.len;
if (needed_size > allocated_size) {
debug_strtab_sect.size = 0; // free the space
const new_offset = self.findFreeSpace(needed_size, 1);
debug_strtab_sect.addr = dwarf_segment.vmaddr + new_offset - dwarf_segment.fileoff;
debug_strtab_sect.offset = @intCast(u32, new_offset);
}
debug_strtab_sect.size = @intCast(u32, needed_size);
log.debug("__debug_strtab start=0x{x} end=0x{x}", .{
debug_strtab_sect.offset,
debug_strtab_sect.offset + needed_size,
});
try self.file.pwriteAll(self.dwarf.strtab.items, debug_strtab_sect.offset);
self.debug_string_table_dirty = false;
}
}
var lc_buffer = std.ArrayList(u8).init(allocator);
defer lc_buffer.deinit();
const lc_writer = lc_buffer.writer();
var ncmds: u32 = 0;
self.updateDwarfSegment();
try self.writeLinkeditSegmentData(&ncmds, lc_writer);
self.updateDwarfSegment();
{
try lc_writer.writeStruct(self.base.uuid);
ncmds += 1;
}
var headers_buf = std.ArrayList(u8).init(allocator);
defer headers_buf.deinit();
try self.writeSegmentHeaders(&ncmds, headers_buf.writer());
try self.file.pwriteAll(headers_buf.items, @sizeOf(macho.mach_header_64));
try self.file.pwriteAll(lc_buffer.items, @sizeOf(macho.mach_header_64) + headers_buf.items.len);
try self.writeHeader(ncmds, @intCast(u32, lc_buffer.items.len + headers_buf.items.len));
assert(!self.debug_abbrev_section_dirty);
assert(!self.debug_aranges_section_dirty);
assert(!self.debug_string_table_dirty);
}
pub fn deinit(self: *DebugSymbols, allocator: Allocator) void {
self.segments.deinit(allocator);
self.sections.deinit(allocator);
self.dwarf.deinit();
self.strtab.deinit(allocator);
self.relocs.deinit(allocator);
}
pub fn swapRemoveRelocs(self: *DebugSymbols, target: u32) void {
// TODO re-implement using a hashmap with free lists
var last_index: usize = 0;
while (last_index < self.relocs.items.len) {
const reloc = self.relocs.items[last_index];
if (reloc.target == target) {
_ = self.relocs.swapRemove(last_index);
} else {
last_index += 1;
}
}
}
fn updateDwarfSegment(self: *DebugSymbols) void {
const linkedit = self.segments.items[self.linkedit_segment_cmd_index.?];
const dwarf_segment = &self.segments.items[self.dwarf_segment_cmd_index.?];
const new_start_aligned = linkedit.vmaddr + linkedit.vmsize;
const old_start_aligned = dwarf_segment.vmaddr;
const diff = new_start_aligned - old_start_aligned;
if (diff > 0) {
dwarf_segment.vmaddr = new_start_aligned;
}
var max_offset: u64 = 0;
for (self.sections.items) |*sect| {
sect.addr += diff;
log.debug(" {s},{s} - 0x{x}-0x{x} - 0x{x}-0x{x}", .{
sect.segName(),
sect.sectName(),
sect.offset,
sect.offset + sect.size,
sect.addr,
sect.addr + sect.size,
});
if (sect.offset + sect.size > max_offset) {
max_offset = sect.offset + sect.size;
}
}
const file_size = max_offset - dwarf_segment.fileoff;
log.debug("__DWARF size 0x{x}", .{file_size});
if (file_size != dwarf_segment.filesize) {
dwarf_segment.filesize = file_size;
dwarf_segment.vmsize = mem.alignForwardGeneric(u64, dwarf_segment.filesize, self.base.page_size);
}
}
fn writeSegmentHeaders(self: *DebugSymbols, ncmds: *u32, writer: anytype) !void {
// Write segment/section headers from the binary file first.
const end = self.base.linkedit_segment_cmd_index.?;
for (self.base.segments.items[0..end]) |seg, i| {
const indexes = self.base.getSectionIndexes(@intCast(u8, i));
var out_seg = seg;
out_seg.fileoff = 0;
out_seg.filesize = 0;
out_seg.cmdsize = @sizeOf(macho.segment_command_64);
out_seg.nsects = 0;
// Update section headers count; any section with size of 0 is excluded
// since it doesn't have any data in the final binary file.
for (self.base.sections.items(.header)[indexes.start..indexes.end]) |header| {
if (header.size == 0) continue;
out_seg.cmdsize += @sizeOf(macho.section_64);
out_seg.nsects += 1;
}
if (out_seg.nsects == 0 and
(mem.eql(u8, out_seg.segName(), "__DATA_CONST") or
mem.eql(u8, out_seg.segName(), "__DATA"))) continue;
try writer.writeStruct(out_seg);
for (self.base.sections.items(.header)[indexes.start..indexes.end]) |header| {
if (header.size == 0) continue;
var out_header = header;
out_header.offset = 0;
try writer.writeStruct(out_header);
}
ncmds.* += 1;
}
// Next, commit DSYM's __LINKEDIT and __DWARF segments headers.
for (self.segments.items) |seg| {
try writer.writeStruct(seg);
ncmds.* += 1;
}
for (self.sections.items) |header| {
try writer.writeStruct(header);
}
}
fn writeHeader(self: *DebugSymbols, ncmds: u32, sizeofcmds: u32) !void {
var header: macho.mach_header_64 = .{};
header.filetype = macho.MH_DSYM;
switch (self.base.base.options.target.cpu.arch) {
.aarch64 => {
header.cputype = macho.CPU_TYPE_ARM64;
header.cpusubtype = macho.CPU_SUBTYPE_ARM_ALL;
},
.x86_64 => {
header.cputype = macho.CPU_TYPE_X86_64;
header.cpusubtype = macho.CPU_SUBTYPE_X86_64_ALL;
},
else => return error.UnsupportedCpuArchitecture,
}
header.ncmds = ncmds;
header.sizeofcmds = sizeofcmds;
log.debug("writing Mach-O header {}", .{header});
try self.file.pwriteAll(mem.asBytes(&header), 0);
}
pub fn allocatedSize(self: *DebugSymbols, start: u64) u64 {
const seg = self.segments.items[self.dwarf_segment_cmd_index.?];
assert(start >= seg.fileoff);
var min_pos: u64 = std.math.maxInt(u64);
for (self.sections.items) |section| {
if (section.offset <= start) continue;
if (section.offset < min_pos) min_pos = section.offset;
}
return min_pos - start;
}
fn writeLinkeditSegmentData(self: *DebugSymbols, ncmds: *u32, lc_writer: anytype) !void {
const tracy = trace(@src());
defer tracy.end();
const source_vmaddr = self.base.segments.items[self.base.linkedit_segment_cmd_index.?].vmaddr;
const seg = &self.segments.items[self.linkedit_segment_cmd_index.?];
seg.vmaddr = source_vmaddr;
var symtab_cmd = macho.symtab_command{
.cmdsize = @sizeOf(macho.symtab_command),
.symoff = 0,
.nsyms = 0,
.stroff = 0,
.strsize = 0,
};
try self.writeSymtab(&symtab_cmd);
try self.writeStrtab(&symtab_cmd);
try lc_writer.writeStruct(symtab_cmd);
ncmds.* += 1;
const aligned_size = mem.alignForwardGeneric(u64, seg.filesize, self.base.page_size);
seg.filesize = aligned_size;
seg.vmsize = aligned_size;
}
fn writeSymtab(self: *DebugSymbols, lc: *macho.symtab_command) !void {
const tracy = trace(@src());
defer tracy.end();
const gpa = self.base.base.allocator;
var locals = std.ArrayList(macho.nlist_64).init(gpa);
defer locals.deinit();
for (self.base.locals.items) |sym, sym_id| {
if (sym.n_strx == 0) continue; // no name, skip
if (sym.n_desc == MachO.N_DESC_GCED) continue; // GCed, skip
const sym_loc = MachO.SymbolWithLoc{ .sym_index = @intCast(u32, sym_id), .file = null };
if (self.base.symbolIsTemp(sym_loc)) continue; // local temp symbol, skip
if (self.base.globals.contains(self.base.getSymbolName(sym_loc))) continue; // global symbol is either an export or import, skip
var out_sym = sym;
out_sym.n_strx = try self.strtab.insert(gpa, self.base.getSymbolName(sym_loc));
try locals.append(out_sym);
}
var exports = std.ArrayList(macho.nlist_64).init(gpa);
defer exports.deinit();
for (self.base.globals.values()) |global| {
const sym = self.base.getSymbol(global);
if (sym.undf()) continue; // import, skip
if (sym.n_desc == MachO.N_DESC_GCED) continue; // GCed, skip
var out_sym = sym;
out_sym.n_strx = try self.strtab.insert(gpa, self.base.getSymbolName(global));
try exports.append(out_sym);
}
const nlocals = locals.items.len;
const nexports = exports.items.len;
const nsyms = nlocals + nexports;
const seg = &self.segments.items[self.linkedit_segment_cmd_index.?];
const offset = mem.alignForwardGeneric(u64, seg.fileoff, @alignOf(macho.nlist_64));
const needed_size = nsyms * @sizeOf(macho.nlist_64);
if (needed_size > seg.filesize) {
const aligned_size = mem.alignForwardGeneric(u64, needed_size, self.base.page_size);
const diff = @intCast(u32, aligned_size - seg.filesize);
const dwarf_seg = &self.segments.items[self.dwarf_segment_cmd_index.?];
seg.filesize = aligned_size;
try MachO.copyRangeAllOverlappingAlloc(
self.base.base.allocator,
self.file,
dwarf_seg.fileoff,
dwarf_seg.fileoff + diff,
math.cast(usize, dwarf_seg.filesize) orelse return error.Overflow,
);
const old_seg_fileoff = dwarf_seg.fileoff;
dwarf_seg.fileoff += diff;
log.debug(" (moving __DWARF segment from 0x{x} to 0x{x})", .{ old_seg_fileoff, dwarf_seg.fileoff });
for (self.sections.items) |*sect| {
const old_offset = sect.offset;
sect.offset += diff;
log.debug(" (moving {s},{s} from 0x{x} to 0x{x})", .{
sect.segName(),
sect.sectName(),
old_offset,
sect.offset,
});
}
}
lc.symoff = @intCast(u32, offset);
lc.nsyms = @intCast(u32, nsyms);
const locals_off = lc.symoff;
const locals_size = nlocals * @sizeOf(macho.nlist_64);
const exports_off = locals_off + locals_size;
const exports_size = nexports * @sizeOf(macho.nlist_64);
log.debug("writing local symbols from 0x{x} to 0x{x}", .{ locals_off, locals_size + locals_off });
try self.file.pwriteAll(mem.sliceAsBytes(locals.items), locals_off);
log.debug("writing exported symbols from 0x{x} to 0x{x}", .{ exports_off, exports_size + exports_off });
try self.file.pwriteAll(mem.sliceAsBytes(exports.items), exports_off);
}
fn writeStrtab(self: *DebugSymbols, lc: *macho.symtab_command) !void {
const tracy = trace(@src());
defer tracy.end();
const seg = &self.segments.items[self.linkedit_segment_cmd_index.?];
const symtab_size = @intCast(u32, lc.nsyms * @sizeOf(macho.nlist_64));
const offset = mem.alignForwardGeneric(u64, lc.symoff + symtab_size, @alignOf(u64));
lc.stroff = @intCast(u32, offset);
const needed_size = mem.alignForwardGeneric(u64, self.strtab.buffer.items.len, @alignOf(u64));
lc.strsize = @intCast(u32, needed_size);
if (symtab_size + needed_size > seg.filesize) {
const aligned_size = mem.alignForwardGeneric(u64, offset + needed_size, self.base.page_size);
const diff = @intCast(u32, aligned_size - seg.filesize);
const dwarf_seg = &self.segments.items[self.dwarf_segment_cmd_index.?];
seg.filesize = aligned_size;
try MachO.copyRangeAllOverlappingAlloc(
self.base.base.allocator,
self.file,
dwarf_seg.fileoff,
dwarf_seg.fileoff + diff,
math.cast(usize, dwarf_seg.filesize) orelse return error.Overflow,
);
const old_seg_fileoff = dwarf_seg.fileoff;
dwarf_seg.fileoff += diff;
log.debug(" (moving __DWARF segment from 0x{x} to 0x{x})", .{ old_seg_fileoff, dwarf_seg.fileoff });
for (self.sections.items) |*sect| {
const old_offset = sect.offset;
sect.offset += diff;
log.debug(" (moving {s},{s} from 0x{x} to 0x{x})", .{
sect.segName(),
sect.sectName(),
old_offset,
sect.offset,
});
}
}
log.debug("writing string table from 0x{x} to 0x{x}", .{ lc.stroff, lc.stroff + lc.strsize });
try self.file.pwriteAll(self.strtab.buffer.items, lc.stroff);
}