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Merge pull request #18010 from ziglang/elf-symtab-fixes

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elf: actually write synthetic globals to output symtab and other misc fixes
This commit is contained in:
Jakub Konka
2023-11-16 01:18:22 +01:00
committed by GitHub
parent 0c6cb8d8c8 6e4d7362ce
commit 359842f8d5
7 changed files with 220 additions and 101 deletions
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79
src/link/Elf.zig
View File

@@ -1208,14 +1208,15 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
}
}
try self.initOutputSections();
try self.addLinkerDefinedSymbols();
self.claimUnresolved();
// Scan and create missing synthetic entries such as GOT indirection.
try self.scanRelocs();
// Generate and emit non-incremental sections.
try self.initSections();
// Generate and emit synthetic sections.
try self.initSyntheticSections();
try self.initSpecialPhdrs();
try self.sortShdrs();
for (self.objects.items) |index| {
@@ -3210,21 +3211,18 @@ fn addLinkerDefinedSymbols(self: *Elf) !void {
self.rela_iplt_start_index = try linker_defined.addGlobal("__rela_iplt_start", self);
self.rela_iplt_end_index = try linker_defined.addGlobal("__rela_iplt_end", self);
for (self.objects.items) |index| {
const object = self.file(index).?.object;
for (object.atoms.items) |atom_index| {
if (self.getStartStopBasename(atom_index)) |name| {
const gpa = self.base.allocator;
try self.start_stop_indexes.ensureUnusedCapacity(gpa, 2);
for (self.shdrs.items) |shdr| {
if (self.getStartStopBasename(shdr)) |name| {
const gpa = self.base.allocator;
try self.start_stop_indexes.ensureUnusedCapacity(gpa, 2);
const start = try std.fmt.allocPrintZ(gpa, "__start_{s}", .{name});
defer gpa.free(start);
const stop = try std.fmt.allocPrintZ(gpa, "__stop_{s}", .{name});
defer gpa.free(stop);
const start = try std.fmt.allocPrintZ(gpa, "__start_{s}", .{name});
defer gpa.free(start);
const stop = try std.fmt.allocPrintZ(gpa, "__stop_{s}", .{name});
defer gpa.free(stop);
self.start_stop_indexes.appendAssumeCapacity(try linker_defined.addGlobal(start, self));
self.start_stop_indexes.appendAssumeCapacity(try linker_defined.addGlobal(stop, self));
}
self.start_stop_indexes.appendAssumeCapacity(try linker_defined.addGlobal(start, self));
self.start_stop_indexes.appendAssumeCapacity(try linker_defined.addGlobal(stop, self));
}
}
@@ -3354,12 +3352,14 @@ fn allocateLinkerDefinedSymbols(self: *Elf) void {
}
}
fn initSections(self: *Elf) !void {
const ptr_size = self.ptrWidthBytes();
fn initOutputSections(self: *Elf) !void {
for (self.objects.items) |index| {
try self.file(index).?.object.initOutputSections(self);
}
}
fn initSyntheticSections(self: *Elf) !void {
const ptr_size = self.ptrWidthBytes();
const needs_eh_frame = for (self.objects.items) |index| {
if (self.file(index).?.object.cies.items.len > 0) break true;
@@ -3394,6 +3394,14 @@ fn initSections(self: *Elf) !void {
});
}
self.got_plt_section_index = try self.addSection(.{
.name = ".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.zig_got.flags.needs_rela or self.copy_rel.symbols.items.len > 0) break :blk true;
@@ -3424,13 +3432,6 @@ fn initSections(self: *Elf) !void {
.addralign = 16,
.offset = std.math.maxInt(u64),
});
self.got_plt_section_index = try self.addSection(.{
.name = ".got.plt",
.type = elf.SHT_PROGBITS,
.flags = elf.SHF_ALLOC | elf.SHF_WRITE,
.addralign = @alignOf(u64),
.offset = std.math.maxInt(u64),
});
self.rela_plt_section_index = try self.addSection(.{
.name = ".rela.plt",
.type = elf.SHT_RELA,
@@ -4819,15 +4820,12 @@ fn updateSymtabSize(self: *Elf) !void {
const gpa = self.base.allocator;
var files = std.ArrayList(File.Index).init(gpa);
defer files.deinit();
try files.ensureTotalCapacityPrecise(self.objects.items.len + self.shared_objects.items.len + 1);
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);
}
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
for (self.output_sections.keys()) |_| {
@@ -5166,6 +5164,11 @@ fn writeSymtab(self: *Elf) !void {
file_ptr.writeSymtab(self);
}
if (self.linker_defined_index) |index| {
const file_ptr = self.file(index).?;
file_ptr.writeSymtab(self);
}
if (self.zig_got_section_index) |_| {
self.zig_got.writeSymtab(self);
}
@@ -5182,11 +5185,6 @@ fn writeSymtab(self: *Elf) !void {
self.plt_got.writeSymtab(self);
}
if (self.linker_defined_index) |index| {
const file_ptr = self.file(index).?;
file_ptr.writeSymtab(self);
}
const foreign_endian = self.base.options.target.cpu.arch.endian() != builtin.cpu.arch.endian();
switch (self.ptr_width) {
.p32 => {
@@ -5750,10 +5748,9 @@ pub fn isCIdentifier(name: []const u8) bool {
return true;
}
fn getStartStopBasename(self: *Elf, atom_index: Atom.Index) ?[]const u8 {
const atom_ptr = self.atom(atom_index) orelse return null;
const name = atom_ptr.name(self);
if (atom_ptr.inputShdr(self).sh_flags & elf.SHF_ALLOC != 0 and name.len > 0) {
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 (isCIdentifier(name)) return name;
}
return null;

34
src/link/Elf/LinkerDefined.zig
View File

@@ -48,10 +48,42 @@ pub fn resolveSymbols(self: *LinkerDefined, elf_file: *Elf) void {
}
}
pub fn globals(self: *LinkerDefined) []const Symbol.Index {
pub fn globals(self: LinkerDefined) []const Symbol.Index {
return self.symbols.items;
}
pub fn updateSymtabSize(self: *LinkerDefined, elf_file: *Elf) !void {
for (self.globals()) |global_index| {
const global = elf_file.symbol(global_index);
const file_ptr = global.file(elf_file) orelse continue;
if (file_ptr.index() != self.index) continue;
global.flags.output_symtab = true;
if (global.isLocal(elf_file)) {
try global.setOutputSymtabIndex(self.output_symtab_ctx.nlocals, elf_file);
self.output_symtab_ctx.nlocals += 1;
} else {
try global.setOutputSymtabIndex(self.output_symtab_ctx.nglobals, elf_file);
self.output_symtab_ctx.nglobals += 1;
}
self.output_symtab_ctx.strsize += @as(u32, @intCast(global.name(elf_file).len)) + 1;
}
}
pub fn writeSymtab(self: LinkerDefined, elf_file: *Elf) void {
for (self.globals()) |global_index| {
const global = elf_file.symbol(global_index);
const file_ptr = global.file(elf_file) orelse continue;
if (file_ptr.index() != self.index) continue;
const idx = global.outputSymtabIndex(elf_file) orelse continue;
const st_name = @as(u32, @intCast(elf_file.strtab.items.len));
elf_file.strtab.appendSliceAssumeCapacity(global.name(elf_file));
elf_file.strtab.appendAssumeCapacity(0);
const out_sym = &elf_file.symtab.items[idx];
out_sym.st_name = st_name;
global.setOutputSym(elf_file, out_sym);
}
}
pub fn asFile(self: *LinkerDefined) File {
return .{ .linker_defined = self };
}

57
src/link/Elf/Object.zig
View File

@@ -741,6 +741,63 @@ pub fn writeAr(self: Object, writer: anytype) !void {
try writer.writeAll(self.data);
}
pub fn updateSymtabSize(self: *Object, elf_file: *Elf) !void {
for (self.locals()) |local_index| {
const local = elf_file.symbol(local_index);
if (local.atom(elf_file)) |atom| if (!atom.flags.alive) continue;
const esym = local.elfSym(elf_file);
switch (esym.st_type()) {
elf.STT_SECTION, elf.STT_NOTYPE => continue,
else => {},
}
local.flags.output_symtab = true;
try local.setOutputSymtabIndex(self.output_symtab_ctx.nlocals, elf_file);
self.output_symtab_ctx.nlocals += 1;
self.output_symtab_ctx.strsize += @as(u32, @intCast(local.name(elf_file).len)) + 1;
}
for (self.globals()) |global_index| {
const global = elf_file.symbol(global_index);
const file_ptr = global.file(elf_file) orelse continue;
if (file_ptr.index() != self.index) continue;
if (global.atom(elf_file)) |atom| if (!atom.flags.alive) continue;
global.flags.output_symtab = true;
if (global.isLocal(elf_file)) {
try global.setOutputSymtabIndex(self.output_symtab_ctx.nlocals, elf_file);
self.output_symtab_ctx.nlocals += 1;
} else {
try global.setOutputSymtabIndex(self.output_symtab_ctx.nglobals, elf_file);
self.output_symtab_ctx.nglobals += 1;
}
self.output_symtab_ctx.strsize += @as(u32, @intCast(global.name(elf_file).len)) + 1;
}
}
pub fn writeSymtab(self: Object, elf_file: *Elf) void {
for (self.locals()) |local_index| {
const local = elf_file.symbol(local_index);
const idx = local.outputSymtabIndex(elf_file) orelse continue;
const out_sym = &elf_file.symtab.items[idx];
out_sym.st_name = @intCast(elf_file.strtab.items.len);
elf_file.strtab.appendSliceAssumeCapacity(local.name(elf_file));
elf_file.strtab.appendAssumeCapacity(0);
local.setOutputSym(elf_file, out_sym);
}
for (self.globals()) |global_index| {
const global = elf_file.symbol(global_index);
const file_ptr = global.file(elf_file) orelse continue;
if (file_ptr.index() != self.index) continue;
const idx = global.outputSymtabIndex(elf_file) orelse continue;
const st_name = @as(u32, @intCast(elf_file.strtab.items.len));
elf_file.strtab.appendSliceAssumeCapacity(global.name(elf_file));
elf_file.strtab.appendAssumeCapacity(0);
const out_sym = &elf_file.symtab.items[idx];
out_sym.st_name = st_name;
global.setOutputSym(elf_file, out_sym);
}
}
pub fn locals(self: Object) []const Symbol.Index {
if (self.symbols.items.len == 0) return &[0]Symbol.Index{};
const end = self.first_global orelse self.symbols.items.len;

28
src/link/Elf/SharedObject.zig
View File

@@ -191,6 +191,34 @@ pub fn globals(self: SharedObject) []const Symbol.Index {
return self.symbols.items;
}
pub fn updateSymtabSize(self: *SharedObject, elf_file: *Elf) !void {
for (self.globals()) |global_index| {
const global = elf_file.symbol(global_index);
const file_ptr = global.file(elf_file) orelse continue;
if (file_ptr.index() != self.index) continue;
if (global.isLocal(elf_file)) continue;
global.flags.output_symtab = true;
try global.setOutputSymtabIndex(self.output_symtab_ctx.nglobals, elf_file);
self.output_symtab_ctx.nglobals += 1;
self.output_symtab_ctx.strsize += @as(u32, @intCast(global.name(elf_file).len)) + 1;
}
}
pub fn writeSymtab(self: SharedObject, elf_file: *Elf) void {
for (self.globals()) |global_index| {
const global = elf_file.symbol(global_index);
const file_ptr = global.file(elf_file) orelse continue;
if (file_ptr.index() != self.index) continue;
const idx = global.outputSymtabIndex(elf_file) orelse continue;
const st_name = @as(u32, @intCast(elf_file.strtab.items.len));
elf_file.strtab.appendSliceAssumeCapacity(global.name(elf_file));
elf_file.strtab.appendAssumeCapacity(0);
const out_sym = &elf_file.symtab.items[idx];
out_sym.st_name = st_name;
global.setOutputSym(elf_file, out_sym);
}
}
pub fn shdrContents(self: SharedObject, index: u16) []const u8 {
const shdr = self.shdrs.items[index];
return self.data[shdr.sh_offset..][0..shdr.sh_size];

57
src/link/Elf/ZigObject.zig
View File

@@ -528,6 +528,63 @@ pub fn globals(self: ZigObject) []const Symbol.Index {
return self.global_symbols.items;
}
pub fn updateSymtabSize(self: *ZigObject, elf_file: *Elf) !void {
for (self.locals()) |local_index| {
const local = elf_file.symbol(local_index);
if (local.atom(elf_file)) |atom| if (!atom.flags.alive) continue;
const esym = local.elfSym(elf_file);
switch (esym.st_type()) {
elf.STT_SECTION, elf.STT_NOTYPE => continue,
else => {},
}
local.flags.output_symtab = true;
try local.setOutputSymtabIndex(self.output_symtab_ctx.nlocals, elf_file);
self.output_symtab_ctx.nlocals += 1;
self.output_symtab_ctx.strsize += @as(u32, @intCast(local.name(elf_file).len)) + 1;
}
for (self.globals()) |global_index| {
const global = elf_file.symbol(global_index);
const file_ptr = global.file(elf_file) orelse continue;
if (file_ptr.index() != self.index) continue;
if (global.atom(elf_file)) |atom| if (!atom.flags.alive) continue;
global.flags.output_symtab = true;
if (global.isLocal(elf_file)) {
try global.setOutputSymtabIndex(self.output_symtab_ctx.nlocals, elf_file);
self.output_symtab_ctx.nlocals += 1;
} else {
try global.setOutputSymtabIndex(self.output_symtab_ctx.nglobals, elf_file);
self.output_symtab_ctx.nglobals += 1;
}
self.output_symtab_ctx.strsize += @as(u32, @intCast(global.name(elf_file).len)) + 1;
}
}
pub fn writeSymtab(self: ZigObject, elf_file: *Elf) void {
for (self.locals()) |local_index| {
const local = elf_file.symbol(local_index);
const idx = local.outputSymtabIndex(elf_file) orelse continue;
const out_sym = &elf_file.symtab.items[idx];
out_sym.st_name = @intCast(elf_file.strtab.items.len);
elf_file.strtab.appendSliceAssumeCapacity(local.name(elf_file));
elf_file.strtab.appendAssumeCapacity(0);
local.setOutputSym(elf_file, out_sym);
}
for (self.globals()) |global_index| {
const global = elf_file.symbol(global_index);
const file_ptr = global.file(elf_file) orelse continue;
if (file_ptr.index() != self.index) continue;
const idx = global.outputSymtabIndex(elf_file) orelse continue;
const st_name = @as(u32, @intCast(elf_file.strtab.items.len));
elf_file.strtab.appendSliceAssumeCapacity(global.name(elf_file));
elf_file.strtab.appendAssumeCapacity(0);
const out_sym = &elf_file.symtab.items[idx];
out_sym.st_name = st_name;
global.setOutputSym(elf_file, out_sym);
}
}
pub fn asFile(self: *ZigObject) File {
return .{ .zig_object = self };
}

58
src/link/Elf/file.zig
View File

@@ -128,63 +128,15 @@ pub const File = union(enum) {
}
pub fn updateSymtabSize(file: File, elf_file: *Elf) !void {
const output_symtab_ctx = switch (file) {
inline else => |x| &x.output_symtab_ctx,
return switch (file) {
inline else => |x| x.updateSymtabSize(elf_file),
};
for (file.locals()) |local_index| {
const local = elf_file.symbol(local_index);
if (local.atom(elf_file)) |atom| if (!atom.flags.alive) continue;
const esym = local.elfSym(elf_file);
switch (esym.st_type()) {
elf.STT_SECTION, elf.STT_NOTYPE => continue,
else => {},
}
local.flags.output_symtab = true;
try local.setOutputSymtabIndex(output_symtab_ctx.nlocals, elf_file);
output_symtab_ctx.nlocals += 1;
output_symtab_ctx.strsize += @as(u32, @intCast(local.name(elf_file).len)) + 1;
}
for (file.globals()) |global_index| {
const global = elf_file.symbol(global_index);
const file_ptr = global.file(elf_file) orelse continue;
if (file_ptr.index() != file.index()) continue;
if (global.atom(elf_file)) |atom| if (!atom.flags.alive) continue;
global.flags.output_symtab = true;
if (global.isLocal(elf_file)) {
try global.setOutputSymtabIndex(output_symtab_ctx.nlocals, elf_file);
output_symtab_ctx.nlocals += 1;
} else {
try global.setOutputSymtabIndex(output_symtab_ctx.nglobals, elf_file);
output_symtab_ctx.nglobals += 1;
}
output_symtab_ctx.strsize += @as(u32, @intCast(global.name(elf_file).len)) + 1;
}
}
pub fn writeSymtab(file: File, elf_file: *Elf) void {
for (file.locals()) |local_index| {
const local = elf_file.symbol(local_index);
const idx = local.outputSymtabIndex(elf_file) orelse continue;
const out_sym = &elf_file.symtab.items[idx];
out_sym.st_name = @intCast(elf_file.strtab.items.len);
elf_file.strtab.appendSliceAssumeCapacity(local.name(elf_file));
elf_file.strtab.appendAssumeCapacity(0);
local.setOutputSym(elf_file, out_sym);
}
for (file.globals()) |global_index| {
const global = elf_file.symbol(global_index);
const file_ptr = global.file(elf_file) orelse continue;
if (file_ptr.index() != file.index()) continue;
const idx = global.outputSymtabIndex(elf_file) orelse continue;
const st_name = @as(u32, @intCast(elf_file.strtab.items.len));
elf_file.strtab.appendSliceAssumeCapacity(global.name(elf_file));
elf_file.strtab.appendAssumeCapacity(0);
const out_sym = &elf_file.symtab.items[idx];
out_sym.st_name = st_name;
global.setOutputSym(elf_file, out_sym);
}
return switch (file) {
inline else => |x| x.writeSymtab(elf_file),
};
}
pub fn updateArSymtab(file: File, ar_symtab: *Archive.ArSymtab, elf_file: *Elf) !void {

8
src/link/Elf/synthetic_sections.zig
View File

@@ -917,8 +917,7 @@ pub const PltSection = struct {
}
pub fn writeSymtab(plt: PltSection, elf_file: *Elf) void {
var ilocal = plt.output_symtab_ctx.ilocal;
for (plt.symbols.items) |sym_index| {
for (plt.symbols.items, plt.output_symtab_ctx.ilocal..) |sym_index, ilocal| {
const sym = elf_file.symbol(sym_index);
const st_name = @as(u32, @intCast(elf_file.strtab.items.len));
elf_file.strtab.appendSliceAssumeCapacity(sym.name(elf_file));
@@ -932,7 +931,6 @@ pub const PltSection = struct {
.st_value = sym.pltAddress(elf_file),
.st_size = 16,
};
ilocal += 1;
}
}
@@ -1046,8 +1044,7 @@ pub const PltGotSection = struct {
}
pub fn writeSymtab(plt_got: PltGotSection, elf_file: *Elf) void {
var ilocal = plt_got.output_symtab_ctx.ilocal;
for (plt_got.symbols.items) |sym_index| {
for (plt_got.symbols.items, plt_got.output_symtab_ctx.ilocal..) |sym_index, ilocal| {
const sym = elf_file.symbol(sym_index);
const st_name = @as(u32, @intCast(elf_file.strtab.items.len));
elf_file.strtab.appendSliceAssumeCapacity(sym.name(elf_file));
@@ -1061,7 +1058,6 @@ pub const PltGotSection = struct {
.st_value = sym.pltGotAddress(elf_file),
.st_size = 16,
};
ilocal += 1;
}
}
};