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https://github.com/ziglang/zig.git
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elf: emit .rela shdrs for output sections
This commit is contained in:
Jakub Konka
parent
0ee2ab413f
commit
21853bc310
155
src/link/Elf.zig
155
src/link/Elf.zig
@ -99,15 +99,20 @@ plt_got: PltGotSection = .{},
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copy_rel: CopyRelSection = .{},
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/// .rela.plt section
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rela_plt: std.ArrayListUnmanaged(elf.Elf64_Rela) = .{},
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/// .zig.got section
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/// .got.zig section
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zig_got: ZigGotSection = .{},
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/// Tracked section headers with incremental updates to Zig object
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/// Tracked section headers with incremental updates to Zig object.
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/// .rela.* sections are only used when emitting a relocatable object file.
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zig_text_section_index: ?u16 = null,
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zig_text_rela_section_index: ?u16 = null,
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zig_data_rel_ro_section_index: ?u16 = null,
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zig_data_rel_ro_rela_section_index: ?u16 = null,
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zig_data_section_index: ?u16 = null,
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zig_data_rela_section_index: ?u16 = null,
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zig_bss_section_index: ?u16 = null,
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zig_got_section_index: ?u16 = null,
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zig_got_rela_section_index: ?u16 = null,
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debug_info_section_index: ?u16 = null,
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debug_abbrev_section_index: ?u16 = null,
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@ -491,6 +496,21 @@ pub fn initMetadata(self: *Elf) !void {
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const ptr_bit_width = self.base.options.target.ptrBitWidth();
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const is_linux = self.base.options.target.os.tag == .linux;
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const fillSection = struct {
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fn fillSection(elf_file: *Elf, shdr: *elf.Elf64_Shdr, size: u64, phndx: ?u16) void {
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if (elf_file.isObject()) {
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const off = elf_file.findFreeSpace(size, shdr.sh_addralign);
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shdr.sh_offset = off;
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shdr.sh_size = size;
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} else {
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const phdr = elf_file.phdrs.items[phndx.?];
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shdr.sh_addr = phdr.p_vaddr;
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shdr.sh_offset = phdr.p_offset;
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shdr.sh_size = phdr.p_memsz;
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}
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}
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}.fillSection;
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comptime assert(number_of_zig_segments == 5);
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if (!self.isObject()) {
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@ -569,24 +589,25 @@ pub fn initMetadata(self: *Elf) !void {
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if (self.zig_text_section_index == null) {
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self.zig_text_section_index = try self.addSection(.{
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.name = ".zig.text",
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.name = ".text.zig",
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.type = elf.SHT_PROGBITS,
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.flags = elf.SHF_ALLOC | elf.SHF_EXECINSTR,
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.addralign = 1,
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.offset = std.math.maxInt(u64),
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});
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const shdr = &self.shdrs.items[self.zig_text_section_index.?];
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if (self.phdr_zig_load_re_index) |phndx| {
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const phdr = self.phdrs.items[phndx];
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shdr.sh_addr = phdr.p_vaddr;
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shdr.sh_offset = phdr.p_offset;
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shdr.sh_size = phdr.p_memsz;
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try self.phdr_to_shdr_table.putNoClobber(gpa, self.zig_text_section_index.?, phndx);
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fillSection(self, shdr, self.base.options.program_code_size_hint, self.phdr_zig_load_re_index);
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if (self.isObject()) {
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self.zig_text_rela_section_index = try self.addRelaShdr(
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".rela.text.zig",
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self.zig_text_section_index.?,
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);
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} else {
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const size = self.base.options.program_code_size_hint;
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const off = self.findFreeSpace(size, 1);
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shdr.sh_offset = off;
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shdr.sh_size = size;
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try self.phdr_to_shdr_table.putNoClobber(
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gpa,
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self.zig_text_section_index.?,
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self.phdr_zig_load_re_index.?,
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);
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}
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try self.last_atom_and_free_list_table.putNoClobber(gpa, self.zig_text_section_index.?, .{});
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}
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@ -594,78 +615,80 @@ pub fn initMetadata(self: *Elf) !void {
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if (self.zig_got_section_index == null) {
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// TODO we don't actually need this section in a relocatable object file
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self.zig_got_section_index = try self.addSection(.{
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.name = ".zig.got",
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.name = ".got.zig",
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.type = elf.SHT_PROGBITS,
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.addralign = ptr_size,
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.flags = elf.SHF_ALLOC | elf.SHF_WRITE,
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.offset = std.math.maxInt(u64),
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});
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const shdr = &self.shdrs.items[self.zig_got_section_index.?];
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if (self.phdr_zig_got_index) |phndx| {
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const phdr = self.phdrs.items[phndx];
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shdr.sh_addr = phdr.p_vaddr;
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shdr.sh_offset = phdr.p_offset;
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shdr.sh_size = phdr.p_memsz;
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try self.phdr_to_shdr_table.putNoClobber(gpa, self.zig_got_section_index.?, phndx);
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} else {
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const size = @as(u64, ptr_size) * self.base.options.symbol_count_hint;
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const off = self.findFreeSpace(size, ptr_size);
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shdr.sh_offset = off;
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shdr.sh_size = size;
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fillSection(
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self,
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shdr,
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@as(u64, ptr_size) * self.base.options.symbol_count_hint,
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self.phdr_zig_got_index,
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);
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if (self.isObject()) {
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self.zig_got_rela_section_index = try self.addRelaShdr(
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".rela.got.zig",
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self.zig_got_section_index.?,
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);
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}
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}
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if (self.zig_data_rel_ro_section_index == null) {
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self.zig_data_rel_ro_section_index = try self.addSection(.{
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.name = ".zig.data.rel.ro",
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.name = ".data.rel.ro.zig",
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.type = elf.SHT_PROGBITS,
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.addralign = 1,
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.flags = elf.SHF_ALLOC | elf.SHF_WRITE, // TODO rename this section to .data.rel.ro
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.offset = std.math.maxInt(u64),
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});
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const shdr = &self.shdrs.items[self.zig_data_rel_ro_section_index.?];
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if (self.phdr_zig_load_ro_index) |phndx| {
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const phdr = self.phdrs.items[phndx];
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shdr.sh_addr = phdr.p_vaddr;
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shdr.sh_offset = phdr.p_offset;
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shdr.sh_size = phdr.p_memsz;
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try self.phdr_to_shdr_table.putNoClobber(gpa, self.zig_data_rel_ro_section_index.?, phndx);
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fillSection(self, shdr, 1024, self.phdr_zig_load_ro_index);
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if (self.isObject()) {
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self.zig_data_rel_ro_rela_section_index = try self.addRelaShdr(
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".rela.data.rel.ro.zig",
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self.zig_data_rel_ro_section_index.?,
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);
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} else {
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const size: u64 = 1024;
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const off = self.findFreeSpace(size, 1);
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shdr.sh_offset = off;
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shdr.sh_size = size;
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try self.phdr_to_shdr_table.putNoClobber(
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gpa,
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self.zig_data_rel_ro_section_index.?,
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self.phdr_zig_load_ro_index.?,
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);
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}
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try self.last_atom_and_free_list_table.putNoClobber(gpa, self.zig_data_rel_ro_section_index.?, .{});
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}
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if (self.zig_data_section_index == null) {
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self.zig_data_section_index = try self.addSection(.{
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.name = ".zig.data",
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.name = ".data.zig",
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.type = elf.SHT_PROGBITS,
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.addralign = ptr_size,
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.flags = elf.SHF_ALLOC | elf.SHF_WRITE,
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.offset = std.math.maxInt(u64),
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});
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const shdr = &self.shdrs.items[self.zig_data_section_index.?];
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if (self.phdr_zig_load_rw_index) |phndx| {
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const phdr = self.phdrs.items[phndx];
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shdr.sh_addr = phdr.p_vaddr;
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shdr.sh_offset = phdr.p_offset;
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shdr.sh_size = phdr.p_memsz;
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try self.phdr_to_shdr_table.putNoClobber(gpa, self.zig_data_section_index.?, phndx);
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fillSection(self, shdr, 1024, self.phdr_zig_load_rw_index);
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if (self.isObject()) {
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self.zig_data_rela_section_index = try self.addRelaShdr(
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".rela.data.zig",
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self.zig_data_section_index.?,
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);
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} else {
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const size: u64 = 1024;
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const off = self.findFreeSpace(size, ptr_size);
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shdr.sh_offset = off;
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shdr.sh_size = size;
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try self.phdr_to_shdr_table.putNoClobber(
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gpa,
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self.zig_data_section_index.?,
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self.phdr_zig_load_rw_index.?,
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);
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}
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try self.last_atom_and_free_list_table.putNoClobber(gpa, self.zig_data_section_index.?, .{});
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}
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if (self.zig_bss_section_index == null) {
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self.zig_bss_section_index = try self.addSection(.{
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.name = ".zig.bss",
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.name = ".bss.zig",
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.type = elf.SHT_NOBITS,
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.addralign = ptr_size,
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.flags = elf.SHF_ALLOC | elf.SHF_WRITE,
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@ -3676,9 +3699,13 @@ fn sortShdrs(self: *Elf) !void {
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&self.versym_section_index,
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&self.verneed_section_index,
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&self.zig_text_section_index,
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&self.zig_text_rela_section_index,
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&self.zig_got_section_index,
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&self.zig_got_rela_section_index,
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&self.zig_data_rel_ro_section_index,
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&self.zig_data_rel_ro_rela_section_index,
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&self.zig_data_section_index,
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&self.zig_data_rela_section_index,
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&self.zig_bss_section_index,
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&self.debug_str_section_index,
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&self.debug_info_section_index,
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@ -3737,6 +3764,18 @@ fn sortShdrs(self: *Elf) !void {
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shdr.sh_info = self.plt_section_index.?;
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}
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for (&[_]?u16{
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self.zig_text_rela_section_index,
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self.zig_got_rela_section_index,
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self.zig_data_rel_ro_rela_section_index,
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self.zig_data_rela_section_index,
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}) |maybe_index| {
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const index = maybe_index orelse continue;
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const shdr = &self.shdrs.items[index];
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shdr.sh_link = self.symtab_section_index.?;
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shdr.sh_info = backlinks[shdr.sh_info];
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}
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{
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var phdr_to_shdr_table = try self.phdr_to_shdr_table.clone(gpa);
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defer phdr_to_shdr_table.deinit(gpa);
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@ -4955,6 +4994,26 @@ fn addPhdr(self: *Elf, opts: struct {
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return index;
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}
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fn addRelaShdr(self: *Elf, name: [:0]const u8, shndx: u16) !u16 {
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const entsize: u64 = switch (self.ptr_width) {
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.p32 => @sizeOf(elf.Elf32_Rela),
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.p64 => @sizeOf(elf.Elf64_Rela),
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};
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const addralign: u64 = switch (self.ptr_width) {
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.p32 => @alignOf(elf.Elf32_Rela),
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.p64 => @alignOf(elf.Elf64_Rela),
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};
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return self.addSection(.{
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.name = name,
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.type = elf.SHT_RELA,
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.flags = elf.SHF_INFO_LINK,
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.entsize = entsize,
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.info = shndx,
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.addralign = addralign,
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.offset = std.math.maxInt(u64),
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});
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}
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pub const AddSectionOpts = struct {
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name: [:0]const u8,
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type: u32 = elf.SHT_NULL,
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