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elf: lower TLS data into appropriate TLS section

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This commit is contained in:
Jakub Konka 2023-11-10 19:14:42 +01:00 committed by Jacob Young
parent 70d8baaec1
commit f34247c4bc
4 changed files with 135 additions and 78 deletions
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15
src/link/Elf.zig
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@ -4512,7 +4512,10 @@ fn allocateAllocSections(self: *Elf) error{OutOfMemory}!void {
for (cover.items) |shndx| {
const shdr = &self.shdrs.items[shndx];
if (shdr.sh_type == elf.SHT_NOBITS) continue;
if (shdr.sh_type == elf.SHT_NOBITS) {
shdr.sh_offset = 0;
continue;
}
off = alignment.@"align"(shndx, shdr.sh_addralign, off);
shdr.sh_offset = off;
off += shdr.sh_size;
@ -4640,6 +4643,9 @@ fn allocateSpecialPhdrs(self: *Elf) void {
}
fn allocateAtoms(self: *Elf) void {
if (self.zigObjectPtr()) |zig_object| {
zig_object.allocateTlvAtoms(self);
}
for (self.objects.items) |index| {
self.file(index).?.object.allocateAtoms(self);
}
@ -4698,7 +4704,6 @@ fn writeAtoms(self: *Elf) !void {
const atom_ptr = self.atom(atom_index).?;
assert(atom_ptr.flags.alive);
const object = atom_ptr.file(self).?.object;
const offset = math.cast(usize, atom_ptr.value - shdr.sh_addr - base_offset) orelse
return error.Overflow;
const size = math.cast(usize, atom_ptr.size) orelse return error.Overflow;
@ -4707,7 +4712,11 @@ fn writeAtoms(self: *Elf) !void {
// TODO decompress directly into provided buffer
const out_code = buffer[offset..][0..size];
const in_code = try object.codeDecompressAlloc(self, atom_index);
const in_code = switch (atom_ptr.file(self).?) {
.object => |x| try x.codeDecompressAlloc(self, atom_index),
.zig_object => |x| try x.codeAlloc(self, atom_index),
else => unreachable,
};
defer gpa.free(in_code);
@memcpy(out_code, in_code);

1
src/link/Elf/Object.zig
View File

@ -251,6 +251,7 @@ fn initOutputSection(self: Object, elf_file: *Elf, shdr: ElfShdr) error{OutOfMem
.type = @"type",
.flags = flags,
.name = name,
.offset = std.math.maxInt(u32),
});
return out_shndx;
}

195
src/link/Elf/ZigObject.zig
View File

@ -29,6 +29,9 @@ lazy_syms: LazySymbolTable = .{},
/// Table of tracked Decls.
decls: DeclTable = .{},
/// TLS variables indexed by Atom.Index.
tls_variables: TlsTable = .{},
/// Table of unnamed constants associated with a parent `Decl`.
/// We store them here so that we can free the constants whenever the `Decl`
/// needs updating or is freed.
@ -137,6 +140,11 @@ pub fn deinit(self: *ZigObject, allocator: Allocator) void {
self.anon_decls.deinit(allocator);
}
for (self.tls_variables.values()) |*tlv| {
tlv.deinit(allocator);
}
self.tls_variables.deinit(allocator);
if (self.dwarf) |*dw| {
dw.deinit();
}
@ -212,8 +220,6 @@ pub fn flushModule(self: *ZigObject, elf_file: *Elf) !void {
self.saveDebugSectionsSizes(elf_file);
}
try self.sortSymbols(elf_file);
// The point of flushModule() is to commit changes, so in theory, nothing should
// be dirty after this. However, it is possible for some things to remain
// dirty because they fail to be written in the event of compile errors,
@ -388,6 +394,19 @@ pub fn claimUnresolvedObject(self: ZigObject, elf_file: *Elf) void {
}
}
pub fn allocateTlvAtoms(self: ZigObject, elf_file: *Elf) void {
for (self.tls_variables.keys(), self.tls_variables.values()) |atom_index, tlv| {
const atom = elf_file.atom(atom_index) orelse continue;
if (!atom.flags.alive) continue;
const local = elf_file.symbol(tlv.symbol_index);
const shdr = elf_file.shdrs.items[atom.output_section_index];
atom.value += shdr.sh_addr;
local.value += shdr.sh_addr;
// TODO exported TLS vars
}
}
pub fn scanRelocs(self: *ZigObject, elf_file: *Elf, undefs: anytype) !void {
for (self.atoms.items) |atom_index| {
const atom = elf_file.atom(atom_index) orelse continue;
@ -421,72 +440,6 @@ pub fn markLive(self: *ZigObject, elf_file: *Elf) void {
}
}
fn sortSymbols(self: *ZigObject, elf_file: *Elf) error{OutOfMemory}!void {
_ = self;
_ = elf_file;
// const Entry = struct {
// index: Symbol.Index,
// const Ctx = struct {
// zobj: ZigObject,
// efile: *Elf,
// };
// pub fn lessThan(ctx: Ctx, lhs: @This(), rhs: @This()) bool {
// const lhs_sym = ctx.efile.symbol(zobj.symbol(lhs.index));
// const rhs_sym = ctx.efile.symbol(zobj.symbol(rhs.index));
// if (lhs_sym.outputShndx() != null and rhs_sym.outputShndx() != null) {
// if (lhs_sym.output_section_index == rhs_sym.output_section_index) {
// if (lhs_sym.value == rhs_sym.value) {
// return lhs_sym.name_offset < rhs_sym.name_offset;
// }
// return lhs_sym.value < rhs_sym.value;
// }
// return lhs_sym.output_section_index < rhs_sym.output_section_index;
// }
// if (lhs_sym.outputShndx() != null) {
// if (rhs_sym.isAbs(ctx.efile)) return false;
// return true;
// }
// return false;
// }
// };
// const gpa = elf_file.base.allocator;
// {
// const sorted = try gpa.alloc(Entry, self.local_symbols.items.len);
// defer gpa.free(sorted);
// for (0..self.local_symbols.items.len) |index| {
// sorted[i] = .{ .index = @as(Symbol.Index, @intCast(index)) };
// }
// mem.sort(Entry, sorted, .{ .zobj = self, .efile = elf_file }, Entry.lessThan);
// const backlinks = try gpa.alloc(Symbol.Index, sorted.len);
// defer gpa.free(backlinks);
// for (sorted, 0..) |entry, i| {
// backlinks[entry.index] = @as(Symbol.Index, @intCast(i));
// }
// const local_symbols = try self.local_symbols.toOwnedSlice(gpa);
// defer gpa.free(local_symbols);
// try self.local_symbols.ensureTotalCapacityPrecise(gpa, local_symbols.len);
// for (sorted) |entry| {
// self.local_symbols.appendAssumeCapacity(local_symbols[entry.index]);
// }
// for (self.)
// }
// const sorted_globals = try gpa.alloc(Entry, self.global_symbols.items.len);
// defer gpa.free(sorted_globals);
// for (self.global_symbols.items, 0..) |index, i| {
// sorted_globals[i] = .{ .index = index };
// }
// mem.sort(Entry, sorted_globals, elf_file, Entry.lessThan);
}
pub fn updateArSymtab(self: ZigObject, ar_symtab: *Archive.ArSymtab, elf_file: *Elf) error{OutOfMemory}!void {
const gpa = elf_file.base.allocator;
@ -583,6 +536,13 @@ pub fn codeAlloc(self: ZigObject, elf_file: *Elf, atom_index: Atom.Index) ![]u8
const atom = elf_file.atom(atom_index).?;
assert(atom.file_index == self.index);
const shdr = &elf_file.shdrs.items[atom.outputShndx().?];
if (shdr.sh_flags & elf.SHF_TLS != 0) {
const tlv = self.tls_variables.get(atom_index).?;
const code = try gpa.dupe(u8, tlv.code);
return code;
}
const file_offset = shdr.sh_offset + atom.value - shdr.sh_addr;
const size = std.math.cast(usize, atom.size) orelse return error.Overflow;
const code = try gpa.alloc(u8, size);
@ -765,15 +725,37 @@ pub fn getOrCreateMetadataForDecl(
return gop.value_ptr.symbol_index;
}
fn getDeclShdrIndex(self: *ZigObject, elf_file: *Elf, decl_index: Module.Decl.Index, code: []const u8) u16 {
fn getDeclShdrIndex(
self: *ZigObject,
elf_file: *Elf,
decl: *const Module.Decl,
code: []const u8,
) error{OutOfMemory}!u16 {
_ = self;
const mod = elf_file.base.options.module.?;
const decl = mod.declPtr(decl_index);
const single_threaded = elf_file.base.options.single_threaded;
const shdr_index = switch (decl.ty.zigTypeTag(mod)) {
// TODO: what if this is a function pointer?
.Fn => elf_file.zig_text_section_index.?,
else => blk: {
if (decl.getOwnedVariable(mod)) |variable| {
if (variable.is_threadlocal and !single_threaded) {
const is_all_zeroes = for (code) |byte| {
if (byte != 0) break false;
} else true;
if (is_all_zeroes) break :blk elf_file.sectionByName(".tbss") orelse try elf_file.addSection(.{
.type = elf.SHT_NOBITS,
.flags = elf.SHF_ALLOC | elf.SHF_WRITE | elf.SHF_TLS,
.name = ".tbss",
.offset = std.math.maxInt(u32),
});
break :blk elf_file.sectionByName(".tdata") orelse try elf_file.addSection(.{
.type = elf.SHT_PROGBITS,
.flags = elf.SHF_ALLOC | elf.SHF_WRITE | elf.SHF_TLS,
.name = ".tdata",
.offset = std.math.maxInt(u32),
});
}
if (variable.is_const) break :blk elf_file.zig_data_rel_ro_section_index.?;
if (variable.init.toValue().isUndefDeep(mod)) {
const mode = elf_file.base.options.optimize_mode;
@ -799,6 +781,7 @@ fn updateDeclCode(
elf_file: *Elf,
decl_index: Module.Decl.Index,
sym_index: Symbol.Index,
shdr_index: u16,
code: []const u8,
stt_bits: u8,
) !void {
@ -815,7 +798,6 @@ fn updateDeclCode(
const esym = &self.local_esyms.items(.elf_sym)[sym.esym_index];
const atom_ptr = sym.atom(elf_file).?;
const shdr_index = self.getDeclShdrIndex(elf_file, decl_index, code);
sym.output_section_index = shdr_index;
atom_ptr.output_section_index = shdr_index;
@ -893,6 +875,53 @@ fn updateDeclCode(
}
}
fn updateTlv(
self: *ZigObject,
elf_file: *Elf,
decl_index: Module.Decl.Index,
sym_index: Symbol.Index,
shndx: u16,
code: []const u8,
) !void {
const gpa = elf_file.base.allocator;
const mod = elf_file.base.options.module.?;
const decl = mod.declPtr(decl_index);
const decl_name = mod.intern_pool.stringToSlice(try decl.getFullyQualifiedName(mod));
log.debug("updateTlv {s}{*}", .{ decl_name, decl });
const required_alignment = decl.getAlignment(mod);
const sym = elf_file.symbol(sym_index);
const esym = &self.local_esyms.items(.elf_sym)[sym.esym_index];
const atom_ptr = sym.atom(elf_file).?;
sym.output_section_index = shndx;
atom_ptr.output_section_index = shndx;
sym.name_offset = try self.strtab.insert(gpa, decl_name);
atom_ptr.flags.alive = true;
atom_ptr.name_offset = sym.name_offset;
esym.st_name = sym.name_offset;
esym.st_info |= elf.STT_TLS;
esym.st_size = code.len;
atom_ptr.alignment = required_alignment;
atom_ptr.size = code.len;
{
const gop = try self.tls_variables.getOrPut(gpa, atom_ptr.atom_index);
assert(!gop.found_existing); // TODO incremental updates
gop.value_ptr.* = .{ .symbol_index = sym_index, .code = try gpa.dupe(u8, code) };
}
{
const gop = try elf_file.output_sections.getOrPut(gpa, atom_ptr.output_section_index);
if (!gop.found_existing) gop.value_ptr.* = .{};
try gop.value_ptr.append(gpa, atom_ptr.atom_index);
}
}
pub fn updateFunc(
self: *ZigObject,
elf_file: *Elf,
@ -947,7 +976,10 @@ pub fn updateFunc(
return;
},
};
try self.updateDeclCode(elf_file, decl_index, sym_index, code, elf.STT_FUNC);
const shndx = try self.getDeclShdrIndex(elf_file, decl, code);
try self.updateDeclCode(elf_file, decl_index, sym_index, shndx, code, elf.STT_FUNC);
if (decl_state) |*ds| {
const sym = elf_file.symbol(sym_index);
try self.dwarf.?.commitDeclState(
@ -1026,7 +1058,12 @@ pub fn updateDecl(
},
};
try self.updateDeclCode(elf_file, decl_index, sym_index, code, elf.STT_OBJECT);
const shndx = try self.getDeclShdrIndex(elf_file, decl, code);
if (elf_file.shdrs.items[shndx].sh_flags & elf.SHF_TLS != 0)
try self.updateTlv(elf_file, decl_index, sym_index, shndx, code)
else
try self.updateDeclCode(elf_file, decl_index, sym_index, shndx, code, elf.STT_OBJECT);
if (decl_state) |*ds| {
const sym = elf_file.symbol(sym_index);
try self.dwarf.?.commitDeclState(
@ -1454,11 +1491,21 @@ const DeclMetadata = struct {
}
};
const TlsVariable = struct {
symbol_index: Symbol.Index,
code: []const u8,
fn deinit(tlv: *TlsVariable, allocator: Allocator) void {
allocator.free(tlv.code);
}
};
const AtomList = std.ArrayListUnmanaged(Atom.Index);
const UnnamedConstTable = std.AutoHashMapUnmanaged(Module.Decl.Index, std.ArrayListUnmanaged(Symbol.Index));
const DeclTable = std.AutoHashMapUnmanaged(Module.Decl.Index, DeclMetadata);
const AnonDeclTable = std.AutoHashMapUnmanaged(InternPool.Index, DeclMetadata);
const LazySymbolTable = std.AutoArrayHashMapUnmanaged(Module.Decl.OptionalIndex, LazySymbolMetadata);
const TlsTable = std.AutoArrayHashMapUnmanaged(Atom.Index, TlsVariable);
const assert = std.debug.assert;
const builtin = @import("builtin");

2
src/target.zig
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@ -654,7 +654,7 @@ pub fn supportsTailCall(target: std.Target, backend: std.builtin.CompilerBackend
pub fn supportsThreads(target: std.Target, backend: std.builtin.CompilerBackend) bool {
return switch (backend) {
.stage2_x86_64 => target.ofmt == .macho,
.stage2_x86_64 => target.ofmt == .macho or target.ofmt == .elf,
else => true,
};
}