mirror of
https://github.com/ziglang/zig.git
synced 2025-12-29 09:33:18 +00:00
elf: write all symbols in bulk in flush
This avoids leaving undefined bytes in the output file in case a decl has been garbage collected before it's been committed into the binary. This should have minimal impact on performance since we have to write globals on every iteration anyway.
This commit is contained in:
Jakub Konka
parent
da56727e6a
commit
9bd60bef2a
133
src/link/Elf.zig
133
src/link/Elf.zig
@ -750,7 +750,6 @@ pub fn populateMissingMetadata(self: *Elf) !void {
|
||||
.phdr_index = undefined,
|
||||
});
|
||||
self.shdr_table_dirty = true;
|
||||
try self.writeSymbol(0);
|
||||
}
|
||||
|
||||
if (self.dwarf) |*dw| {
|
||||
@ -1134,9 +1133,7 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
|
||||
}
|
||||
}
|
||||
|
||||
// Unfortunately these have to be buffered and done at the end because ELF does not allow
|
||||
// mixing local and global symbols within a symbol table.
|
||||
try self.writeAllGlobalSymbols();
|
||||
try self.writeSymbols();
|
||||
|
||||
if (build_options.enable_logging) {
|
||||
self.logSymtab();
|
||||
@ -2551,9 +2548,6 @@ fn updateDeclCode(self: *Elf, decl_index: Module.Decl.Index, code: []const u8, s
|
||||
self.shrinkAtom(atom_index, code.len);
|
||||
}
|
||||
local_sym.st_size = code.len;
|
||||
|
||||
// TODO this write could be avoided if no fields of the symbol were changed.
|
||||
try self.writeSymbol(local_sym_index);
|
||||
} else {
|
||||
const local_sym = atom.getSymbolPtr(self);
|
||||
local_sym.* = .{
|
||||
@ -2571,7 +2565,6 @@ fn updateDeclCode(self: *Elf, decl_index: Module.Decl.Index, code: []const u8, s
|
||||
local_sym.st_value = vaddr;
|
||||
local_sym.st_size = code.len;
|
||||
|
||||
try self.writeSymbol(local_sym_index);
|
||||
const got_entry_index = try atom.getOrCreateOffsetTableEntry(self);
|
||||
try self.writeOffsetTableEntry(got_entry_index);
|
||||
}
|
||||
@ -2807,7 +2800,6 @@ fn updateLazySymbolAtom(
|
||||
local_sym.st_value = vaddr;
|
||||
local_sym.st_size = code.len;
|
||||
|
||||
try self.writeSymbol(local_sym_index);
|
||||
const got_entry_index = try atom.getOrCreateOffsetTableEntry(self);
|
||||
try self.writeOffsetTableEntry(got_entry_index);
|
||||
|
||||
@ -2870,7 +2862,6 @@ pub fn lowerUnnamedConst(self: *Elf, typed_value: TypedValue, decl_index: Module
|
||||
|
||||
log.debug("allocated text block for {s} at 0x{x}", .{ name, local_sym.st_value });
|
||||
|
||||
try self.writeSymbol(self.getAtom(atom_index).getSymbolIndex().?);
|
||||
try unnamed_consts.append(gpa, atom_index);
|
||||
|
||||
const section_offset = local_sym.st_value - self.program_headers.items[phdr_index].p_vaddr;
|
||||
@ -3096,63 +3087,20 @@ fn writeOffsetTableEntry(self: *Elf, index: @TypeOf(self.got_table).Index) !void
|
||||
}
|
||||
}
|
||||
|
||||
fn writeSymbol(self: *Elf, index: usize) !void {
|
||||
const tracy = trace(@src());
|
||||
defer tracy.end();
|
||||
|
||||
const syms_sect = &self.sections.items(.shdr)[self.symtab_section_index.?];
|
||||
// Make sure we are not pointlessly writing symbol data that will have to get relocated
|
||||
// due to running out of space.
|
||||
if (self.local_symbols.items.len != syms_sect.sh_info) {
|
||||
const sym_size: u64 = switch (self.ptr_width) {
|
||||
.p32 => @sizeOf(elf.Elf32_Sym),
|
||||
.p64 => @sizeOf(elf.Elf64_Sym),
|
||||
};
|
||||
const sym_align: u16 = switch (self.ptr_width) {
|
||||
.p32 => @alignOf(elf.Elf32_Sym),
|
||||
.p64 => @alignOf(elf.Elf64_Sym),
|
||||
};
|
||||
const needed_size = (self.local_symbols.items.len + self.global_symbols.items.len) * sym_size;
|
||||
try self.growNonAllocSection(self.symtab_section_index.?, needed_size, sym_align, true);
|
||||
syms_sect.sh_info = @as(u32, @intCast(self.local_symbols.items.len));
|
||||
}
|
||||
const foreign_endian = self.base.options.target.cpu.arch.endian() != builtin.cpu.arch.endian();
|
||||
const off = switch (self.ptr_width) {
|
||||
.p32 => syms_sect.sh_offset + @sizeOf(elf.Elf32_Sym) * index,
|
||||
.p64 => syms_sect.sh_offset + @sizeOf(elf.Elf64_Sym) * index,
|
||||
fn elf32SymFromSym(sym: elf.Elf64_Sym, out: *elf.Elf32_Sym) void {
|
||||
out.* = .{
|
||||
.st_name = sym.st_name,
|
||||
.st_value = @as(u32, @intCast(sym.st_value)),
|
||||
.st_size = @as(u32, @intCast(sym.st_size)),
|
||||
.st_info = sym.st_info,
|
||||
.st_other = sym.st_other,
|
||||
.st_shndx = sym.st_shndx,
|
||||
};
|
||||
const local = self.local_symbols.items[index];
|
||||
log.debug("writing symbol {d}, '{?s}' at 0x{x}", .{ index, self.strtab.get(local.st_name), off });
|
||||
log.debug(" ({})", .{local});
|
||||
switch (self.ptr_width) {
|
||||
.p32 => {
|
||||
var sym = [1]elf.Elf32_Sym{
|
||||
.{
|
||||
.st_name = local.st_name,
|
||||
.st_value = @as(u32, @intCast(local.st_value)),
|
||||
.st_size = @as(u32, @intCast(local.st_size)),
|
||||
.st_info = local.st_info,
|
||||
.st_other = local.st_other,
|
||||
.st_shndx = local.st_shndx,
|
||||
},
|
||||
};
|
||||
if (foreign_endian) {
|
||||
mem.byteSwapAllFields(elf.Elf32_Sym, &sym[0]);
|
||||
}
|
||||
try self.base.file.?.pwriteAll(mem.sliceAsBytes(sym[0..1]), off);
|
||||
},
|
||||
.p64 => {
|
||||
var sym = [1]elf.Elf64_Sym{local};
|
||||
if (foreign_endian) {
|
||||
mem.byteSwapAllFields(elf.Elf64_Sym, &sym[0]);
|
||||
}
|
||||
try self.base.file.?.pwriteAll(mem.sliceAsBytes(sym[0..1]), off);
|
||||
},
|
||||
}
|
||||
}
|
||||
|
||||
fn writeAllGlobalSymbols(self: *Elf) !void {
|
||||
const syms_sect = &self.sections.items(.shdr)[self.symtab_section_index.?];
|
||||
fn writeSymbols(self: *Elf) !void {
|
||||
const gpa = self.base.allocator;
|
||||
const shdr = &self.sections.items(.shdr)[self.symtab_section_index.?];
|
||||
const sym_size: u64 = switch (self.ptr_width) {
|
||||
.p32 => @sizeOf(elf.Elf32_Sym),
|
||||
.p64 => @sizeOf(elf.Elf64_Sym),
|
||||
@ -3161,52 +3109,49 @@ fn writeAllGlobalSymbols(self: *Elf) !void {
|
||||
.p32 => @alignOf(elf.Elf32_Sym),
|
||||
.p64 => @alignOf(elf.Elf64_Sym),
|
||||
};
|
||||
const needed_size = (self.local_symbols.items.len + self.global_symbols.items.len) * sym_size;
|
||||
const nsyms = self.local_symbols.items.len + self.global_symbols.items.len;
|
||||
const needed_size = nsyms * sym_size;
|
||||
try self.growNonAllocSection(self.symtab_section_index.?, needed_size, sym_align, true);
|
||||
|
||||
const foreign_endian = self.base.options.target.cpu.arch.endian() != builtin.cpu.arch.endian();
|
||||
const global_syms_off = syms_sect.sh_offset + self.local_symbols.items.len * sym_size;
|
||||
log.debug("writing {d} global symbols at 0x{x}", .{ self.global_symbols.items.len, global_syms_off });
|
||||
log.debug("writing {d} symbols at 0x{x}", .{ nsyms, shdr.sh_offset });
|
||||
switch (self.ptr_width) {
|
||||
.p32 => {
|
||||
const buf = try self.base.allocator.alloc(elf.Elf32_Sym, self.global_symbols.items.len);
|
||||
defer self.base.allocator.free(buf);
|
||||
const buf = try gpa.alloc(elf.Elf32_Sym, nsyms);
|
||||
defer gpa.free(buf);
|
||||
|
||||
for (buf, 0..) |*sym, i| {
|
||||
const global = self.global_symbols.items[i];
|
||||
sym.* = .{
|
||||
.st_name = global.st_name,
|
||||
.st_value = @as(u32, @intCast(global.st_value)),
|
||||
.st_size = @as(u32, @intCast(global.st_size)),
|
||||
.st_info = global.st_info,
|
||||
.st_other = global.st_other,
|
||||
.st_shndx = global.st_shndx,
|
||||
};
|
||||
for (buf[0..self.local_symbols.items.len], self.local_symbols.items) |*sym, local| {
|
||||
elf32SymFromSym(local, sym);
|
||||
if (foreign_endian) {
|
||||
mem.byteSwapAllFields(elf.Elf32_Sym, sym);
|
||||
}
|
||||
}
|
||||
try self.base.file.?.pwriteAll(mem.sliceAsBytes(buf), global_syms_off);
|
||||
|
||||
for (buf[self.local_symbols.items.len..], self.global_symbols.items) |*sym, global| {
|
||||
elf32SymFromSym(global, sym);
|
||||
if (foreign_endian) {
|
||||
mem.byteSwapAllFields(elf.Elf32_Sym, sym);
|
||||
}
|
||||
}
|
||||
try self.base.file.?.pwriteAll(mem.sliceAsBytes(buf), shdr.sh_offset);
|
||||
},
|
||||
.p64 => {
|
||||
const buf = try self.base.allocator.alloc(elf.Elf64_Sym, self.global_symbols.items.len);
|
||||
defer self.base.allocator.free(buf);
|
||||
|
||||
for (buf, 0..) |*sym, i| {
|
||||
const global = self.global_symbols.items[i];
|
||||
sym.* = .{
|
||||
.st_name = global.st_name,
|
||||
.st_value = global.st_value,
|
||||
.st_size = global.st_size,
|
||||
.st_info = global.st_info,
|
||||
.st_other = global.st_other,
|
||||
.st_shndx = global.st_shndx,
|
||||
};
|
||||
const buf = try gpa.alloc(elf.Elf64_Sym, nsyms);
|
||||
defer gpa.free(buf);
|
||||
for (buf[0..self.local_symbols.items.len], self.local_symbols.items) |*sym, local| {
|
||||
sym.* = local;
|
||||
if (foreign_endian) {
|
||||
mem.byteSwapAllFields(elf.Elf64_Sym, sym);
|
||||
}
|
||||
}
|
||||
try self.base.file.?.pwriteAll(mem.sliceAsBytes(buf), global_syms_off);
|
||||
|
||||
for (buf[self.local_symbols.items.len..], self.global_symbols.items) |*sym, global| {
|
||||
sym.* = global;
|
||||
if (foreign_endian) {
|
||||
mem.byteSwapAllFields(elf.Elf64_Sym, sym);
|
||||
}
|
||||
}
|
||||
try self.base.file.?.pwriteAll(mem.sliceAsBytes(buf), shdr.sh_offset);
|
||||
},
|
||||
}
|
||||
}
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user