mirror of
https://github.com/rui314/mold.git
synced 2024-10-05 09:07:10 +03:00
800 lines
24 KiB
C++
800 lines
24 KiB
C++
#include "mold.h"
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namespace mold::elf {
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using E = X86_64;
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// The compact PLT format is used when `-z now` is given. If the flag
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// is given, all PLT symbols are resolved eagerly on startup, so we
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// can omit code for lazy symbol resolution from PLT in that case.
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static void write_compact_plt(Context<E> &ctx) {
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u8 *buf = ctx.buf + ctx.plt->shdr.sh_offset;
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static const u8 data[] = {
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0xff, 0x25, 0, 0, 0, 0, // jmp *foo@GOT
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0x66, 0x90, // nop
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};
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for (Symbol<E> *sym : ctx.plt->symbols) {
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u8 *ent = buf + sym->get_plt_idx(ctx) * ctx.plt_size;
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memcpy(ent, data, sizeof(data));
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*(u32 *)(ent + 2) = sym->get_gotplt_addr(ctx) - sym->get_plt_addr(ctx) - 6;
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}
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}
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// The IBTPLT is a security-enhanced version of the regular PLT.
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// It uses Indirect Branch Tracking (IBT) feature which is part of
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// Intel Control-Flow Enforcement (CET).
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//
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// Note that our IBTPLT instruction sequence is different from the one
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// used in GNU ld. GNU's IBTPLT implementation uses two separate
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// sections (.plt and .plt.sec) in which one PLT entry takes 32 bytes
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// in total. Our PLT consists of just .plt and each entry is 16 bytes
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// long.
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//
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// Our PLT entry clobbers r11, but that's fine because the resolver
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// function (_dl_runtime_resolve) does not preserve r11 anyway.
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static void write_ibtplt(Context<E> &ctx) {
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u8 *buf = ctx.buf + ctx.plt->shdr.sh_offset;
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// Write PLT header
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static const u8 plt0[] = {
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0xf3, 0x0f, 0x1e, 0xfa, // endbr64
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0x41, 0x53, // push %r11
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0xff, 0x35, 0, 0, 0, 0, // push GOTPLT+8(%rip)
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0xff, 0x25, 0, 0, 0, 0, // jmp *GOTPLT+16(%rip)
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0x0f, 0x1f, 0x40, 0x00, // nop
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0x0f, 0x1f, 0x40, 0x00, // nop
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0x0f, 0x1f, 0x40, 0x00, // nop
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0x66, 0x90, // nop
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};
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memcpy(buf, plt0, sizeof(plt0));
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*(u32 *)(buf + 8) = ctx.gotplt->shdr.sh_addr - ctx.plt->shdr.sh_addr - 4;
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*(u32 *)(buf + 14) = ctx.gotplt->shdr.sh_addr - ctx.plt->shdr.sh_addr - 2;
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// Write PLT entries
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i64 relplt_idx = 0;
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static const u8 data[] = {
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0xf3, 0x0f, 0x1e, 0xfa, // endbr64
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0x41, 0xbb, 0, 0, 0, 0, // mov $index_in_relplt, %r11d
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0xff, 0x25, 0, 0, 0, 0, // jmp *foo@GOTPLT
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};
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for (Symbol<E> *sym : ctx.plt->symbols) {
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u8 *ent = buf + ctx.plt_hdr_size + sym->get_plt_idx(ctx) * ctx.plt_size;
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memcpy(ent, data, sizeof(data));
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*(u32 *)(ent + 6) = relplt_idx++;
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*(u32 *)(ent + 12) = sym->get_gotplt_addr(ctx) - sym->get_plt_addr(ctx) - 16;
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}
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}
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// The regular PLT.
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static void write_plt(Context<E> &ctx) {
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u8 *buf = ctx.buf + ctx.plt->shdr.sh_offset;
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// Write PLT header
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static const u8 plt0[] = {
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0xff, 0x35, 0, 0, 0, 0, // pushq GOTPLT+8(%rip)
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0xff, 0x25, 0, 0, 0, 0, // jmp *GOTPLT+16(%rip)
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0x0f, 0x1f, 0x40, 0x00, // nop
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};
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memcpy(buf, plt0, sizeof(plt0));
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*(u32 *)(buf + 2) = ctx.gotplt->shdr.sh_addr - ctx.plt->shdr.sh_addr + 2;
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*(u32 *)(buf + 8) = ctx.gotplt->shdr.sh_addr - ctx.plt->shdr.sh_addr + 4;
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// Write PLT entries
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i64 relplt_idx = 0;
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static const u8 data[] = {
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0xff, 0x25, 0, 0, 0, 0, // jmp *foo@GOTPLT
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0x68, 0, 0, 0, 0, // push $index_in_relplt
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0xe9, 0, 0, 0, 0, // jmp PLT[0]
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};
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for (Symbol<E> *sym : ctx.plt->symbols) {
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u8 *ent = buf + ctx.plt_hdr_size + sym->get_plt_idx(ctx) * ctx.plt_size;
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memcpy(ent, data, sizeof(data));
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*(u32 *)(ent + 2) = sym->get_gotplt_addr(ctx) - sym->get_plt_addr(ctx) - 6;
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*(u32 *)(ent + 7) = relplt_idx++;
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*(u32 *)(ent + 12) = ctx.plt->shdr.sh_addr - sym->get_plt_addr(ctx) - 16;
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}
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}
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template <>
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void PltSection<E>::copy_buf(Context<E> &ctx) {
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if (ctx.arg.z_now)
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write_compact_plt(ctx);
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else if (ctx.arg.z_ibtplt)
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write_ibtplt(ctx);
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else
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write_plt(ctx);
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}
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template <>
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void PltGotSection<E>::copy_buf(Context<E> &ctx) {
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u8 *buf = ctx.buf + this->shdr.sh_offset;
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static const u8 data[] = {
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0xff, 0x25, 0, 0, 0, 0, // jmp *foo@GOT
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0x66, 0x90, // nop
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};
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for (Symbol<E> *sym : symbols) {
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u8 *ent = buf + sym->get_pltgot_idx(ctx) * X86_64::pltgot_size;
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memcpy(ent, data, sizeof(data));
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*(u32 *)(ent + 2) = sym->get_got_addr(ctx) - sym->get_plt_addr(ctx) - 6;
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}
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}
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template <>
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void EhFrameSection<E>::apply_reloc(Context<E> &ctx, ElfRel<E> &rel,
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u64 offset, u64 val) {
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u8 *loc = ctx.buf + this->shdr.sh_offset + offset;
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switch (rel.r_type) {
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case R_X86_64_NONE:
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return;
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case R_X86_64_32:
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*(u32 *)loc = val;
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return;
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case R_X86_64_64:
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*(u64 *)loc = val;
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return;
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case R_X86_64_PC32:
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*(u32 *)loc = val - this->shdr.sh_addr - offset;
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return;
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case R_X86_64_PC64:
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*(u64 *)loc = val - this->shdr.sh_addr - offset;
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return;
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}
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unreachable();
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}
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static u32 relax_gotpcrelx(u8 *loc) {
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switch ((loc[0] << 8) | loc[1]) {
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case 0xff15: return 0x90e8; // call *0(%rip) -> call 0
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case 0xff25: return 0x90e9; // jmp *0(%rip) -> jmp 0
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}
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return 0;
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}
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static u32 relax_rex_gotpcrelx(u8 *loc) {
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switch ((loc[0] << 16) | (loc[1] << 8) | loc[2]) {
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case 0x488b05: return 0x488d05; // mov 0(%rip), %rax -> lea 0(%rip), %rax
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case 0x488b0d: return 0x488d0d; // mov 0(%rip), %rcx -> lea 0(%rip), %rcx
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case 0x488b15: return 0x488d15; // mov 0(%rip), %rdx -> lea 0(%rip), %rdx
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case 0x488b1d: return 0x488d1d; // mov 0(%rip), %rbx -> lea 0(%rip), %rbx
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case 0x488b25: return 0x488d25; // mov 0(%rip), %rsp -> lea 0(%rip), %rsp
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case 0x488b2d: return 0x488d2d; // mov 0(%rip), %rbp -> lea 0(%rip), %rbp
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case 0x488b35: return 0x488d35; // mov 0(%rip), %rsi -> lea 0(%rip), %rsi
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case 0x488b3d: return 0x488d3d; // mov 0(%rip), %rdi -> lea 0(%rip), %rdi
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case 0x4c8b05: return 0x4c8d05; // mov 0(%rip), %r8 -> lea 0(%rip), %r8
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case 0x4c8b0d: return 0x4c8d0d; // mov 0(%rip), %r9 -> lea 0(%rip), %r9
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case 0x4c8b15: return 0x4c8d15; // mov 0(%rip), %r10 -> lea 0(%rip), %r10
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case 0x4c8b1d: return 0x4c8d1d; // mov 0(%rip), %r11 -> lea 0(%rip), %r11
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case 0x4c8b25: return 0x4c8d25; // mov 0(%rip), %r12 -> lea 0(%rip), %r12
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case 0x4c8b2d: return 0x4c8d2d; // mov 0(%rip), %r13 -> lea 0(%rip), %r13
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case 0x4c8b35: return 0x4c8d35; // mov 0(%rip), %r14 -> lea 0(%rip), %r14
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case 0x4c8b3d: return 0x4c8d3d; // mov 0(%rip), %r15 -> lea 0(%rip), %r15
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}
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return 0;
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}
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static u32 relax_gottpoff(u8 *loc) {
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switch ((loc[0] << 16) | (loc[1] << 8) | loc[2]) {
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case 0x488b05: return 0x48c7c0; // mov 0(%rip), %rax -> mov $0, %rax
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case 0x488b0d: return 0x48c7c1; // mov 0(%rip), %rcx -> mov $0, %rcx
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case 0x488b15: return 0x48c7c2; // mov 0(%rip), %rdx -> mov $0, %rdx
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case 0x488b1d: return 0x48c7c3; // mov 0(%rip), %rbx -> mov $0, %rbx
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case 0x488b25: return 0x48c7c4; // mov 0(%rip), %rsp -> mov $0, %rsp
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case 0x488b2d: return 0x48c7c5; // mov 0(%rip), %rbp -> mov $0, %rbp
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case 0x488b35: return 0x48c7c6; // mov 0(%rip), %rsi -> mov $0, %rsi
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case 0x488b3d: return 0x48c7c7; // mov 0(%rip), %rdi -> mov $0, %rdi
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case 0x4c8b05: return 0x49c7c0; // mov 0(%rip), %r8 -> mov $0, %r8
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case 0x4c8b0d: return 0x49c7c1; // mov 0(%rip), %r9 -> mov $0, %r9
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case 0x4c8b15: return 0x49c7c2; // mov 0(%rip), %r10 -> mov $0, %r10
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case 0x4c8b1d: return 0x49c7c3; // mov 0(%rip), %r11 -> mov $0, %r11
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case 0x4c8b25: return 0x49c7c4; // mov 0(%rip), %r12 -> mov $0, %r12
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case 0x4c8b2d: return 0x49c7c5; // mov 0(%rip), %r13 -> mov $0, %r13
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case 0x4c8b35: return 0x49c7c6; // mov 0(%rip), %r14 -> mov $0, %r14
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case 0x4c8b3d: return 0x49c7c7; // mov 0(%rip), %r15 -> mov $0, %r15
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}
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return 0;
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}
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// Apply relocations to SHF_ALLOC sections (i.e. sections that are
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// mapped to memory at runtime) based on the result of
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// scan_relocations().
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template <>
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void InputSection<E>::apply_reloc_alloc(Context<E> &ctx, u8 *base) {
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ElfRel<E> *dynrel = nullptr;
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std::span<ElfRel<E>> rels = get_rels(ctx);
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i64 frag_idx = 0;
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if (ctx.reldyn)
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dynrel = (ElfRel<E> *)(ctx.buf + ctx.reldyn->shdr.sh_offset +
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file.reldyn_offset + this->reldyn_offset);
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for (i64 i = 0; i < rels.size(); i++) {
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const ElfRel<E> &rel = rels[i];
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if (rel.r_type == R_X86_64_NONE)
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continue;
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Symbol<E> &sym = *file.symbols[rel.r_sym];
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u8 *loc = base + rel.r_offset;
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const SectionFragmentRef<E> *frag_ref = nullptr;
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if (rel_fragments && rel_fragments[frag_idx].idx == i)
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frag_ref = &rel_fragments[frag_idx++];
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auto overflow_check = [&](i64 val, i64 lo, i64 hi) {
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if (val < lo || hi <= val)
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Error(ctx) << *this << ": relocation " << rel << " against "
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<< sym << " out of range: " << val << " is not in ["
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<< lo << ", " << hi << ")";
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};
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auto write8 = [&](u64 val) {
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overflow_check(val, 0, 1 << 8);
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*loc = val;
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};
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auto write8s = [&](u64 val) {
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overflow_check(val, -(1 << 7), 1 << 7);
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*loc = val;
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};
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auto write16 = [&](u64 val) {
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overflow_check(val, 0, 1 << 16);
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*(u16 *)loc = val;
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};
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auto write16s = [&](u64 val) {
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overflow_check(val, -(1 << 15), 1 << 15);
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*(u16 *)loc = val;
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};
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auto write32 = [&](u64 val) {
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overflow_check(val, 0, (i64)1 << 32);
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*(u32 *)loc = val;
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};
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auto write32s = [&](u64 val) {
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overflow_check(val, -((i64)1 << 31), (i64)1 << 31);
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*(u32 *)loc = val;
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};
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auto write64 = [&](u64 val) {
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*(u64 *)loc = val;
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};
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#define S (frag_ref ? frag_ref->frag->get_addr(ctx) : sym.get_addr(ctx))
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#define A (frag_ref ? frag_ref->addend : rel.r_addend)
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#define P (output_section->shdr.sh_addr + offset + rel.r_offset)
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#define G (sym.get_got_addr(ctx) - ctx.gotplt->shdr.sh_addr)
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#define GOT ctx.gotplt->shdr.sh_addr
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switch (rel.r_type) {
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case R_X86_64_8:
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write8(S + A);
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continue;
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case R_X86_64_16:
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write16(S + A);
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continue;
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case R_X86_64_32:
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write32(S + A);
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continue;
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case R_X86_64_32S:
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write32s(S + A);
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continue;
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case R_X86_64_64:
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if (sym.is_absolute() || !ctx.arg.pic) {
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write64(S + A);
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} else if (sym.is_imported) {
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*dynrel++ = {P, R_X86_64_64, (u32)sym.get_dynsym_idx(ctx), A};
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write64(A);
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} else {
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if (!is_relr_reloc(ctx, rel))
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*dynrel++ = {P, R_X86_64_RELATIVE, 0, (i64)(S + A)};
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write64(S + A);
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}
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continue;
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case R_X86_64_PC8:
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write8s(S + A - P);
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continue;
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case R_X86_64_PC16:
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write16s(S + A - P);
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continue;
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case R_X86_64_PC32:
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write32s(S + A - P);
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continue;
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case R_X86_64_PC64:
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if (sym.is_absolute() || !sym.is_imported || !ctx.arg.shared) {
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write64(S + A - P);
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} else {
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*dynrel++ = {P, R_X86_64_64, (u32)sym.get_dynsym_idx(ctx), A};
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write64(A);
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}
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continue;
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case R_X86_64_PLT32:
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write32s(S + A - P);
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continue;
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case R_X86_64_PLTOFF64:
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write64(S + A - GOT);
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break;
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case R_X86_64_GOT32:
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write32s(G + A);
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continue;
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case R_X86_64_GOT64:
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write64(G + A);
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continue;
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case R_X86_64_GOTOFF64:
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write64(S + A - GOT);
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continue;
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case R_X86_64_GOTPC32:
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write32s(GOT + A - P);
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continue;
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case R_X86_64_GOTPC64:
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write64(GOT + A - P);
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continue;
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case R_X86_64_GOTPCREL:
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write32s(G + GOT + A - P);
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continue;
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case R_X86_64_GOTPCREL64:
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write64(G + GOT + A - P);
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continue;
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case R_X86_64_GOTPCRELX:
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if (sym.get_got_idx(ctx) == -1) {
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u32 insn = relax_gotpcrelx(loc - 2);
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loc[-2] = insn >> 8;
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loc[-1] = insn;
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write32s(S + A - P);
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} else {
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write32s(G + GOT + A - P);
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}
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continue;
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case R_X86_64_REX_GOTPCRELX:
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if (sym.get_got_idx(ctx) == -1) {
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u32 insn = relax_rex_gotpcrelx(loc - 3);
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loc[-3] = insn >> 16;
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loc[-2] = insn >> 8;
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loc[-1] = insn;
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write32s(S + A - P);
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} else {
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write32s(G + GOT + A - P);
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}
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continue;
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case R_X86_64_TLSGD:
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if (sym.get_tlsgd_idx(ctx) == -1) {
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// Relax GD to LE
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i64 val = S - ctx.tls_end + A + 4;
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overflow_check(val, -((i64)1 << 31), (i64)1 << 31);
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switch (rels[i + 1].r_type) {
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case R_X86_64_PLT32:
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case R_X86_64_GOTPCREL:
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case R_X86_64_GOTPCRELX: {
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static const u8 insn[] = {
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0x64, 0x48, 0x8b, 0x04, 0x25, 0, 0, 0, 0, // mov %fs:0, %rax
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0x48, 0x8d, 0x80, 0, 0, 0, 0, // lea 0(%rax), %rax
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};
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memcpy(loc - 4, insn, sizeof(insn));
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*(u32 *)(loc + 8) = val;
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break;
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}
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case R_X86_64_PLTOFF64: {
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static const u8 insn[] = {
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0x64, 0x48, 0x8b, 0x04, 0x25, 0, 0, 0, 0, // mov %fs:0, %rax
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0x48, 0x8d, 0x80, 0, 0, 0, 0, // lea 0(%rax), %rax
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0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00, // nop
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};
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memcpy(loc - 3, insn, sizeof(insn));
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*(u32 *)(loc + 9) = val;
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break;
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}
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default:
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unreachable();
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}
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i++;
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} else {
|
|
write32s(sym.get_tlsgd_addr(ctx) + A - P);
|
|
}
|
|
continue;
|
|
case R_X86_64_TLSLD:
|
|
if (ctx.got->tlsld_idx == -1) {
|
|
// Relax LD to LE
|
|
switch (rels[i + 1].r_type) {
|
|
case R_X86_64_PLT32: {
|
|
static const u8 insn[] = {
|
|
0x66, 0x66, 0x66, // (padding)
|
|
0x64, 0x48, 0x8b, 0x04, 0x25, 0, 0, 0, 0, // mov %fs:0, %rax
|
|
};
|
|
memcpy(loc - 3, insn, sizeof(insn));
|
|
break;
|
|
}
|
|
case R_X86_64_GOTPCREL:
|
|
case R_X86_64_GOTPCRELX: {
|
|
static const u8 insn[] = {
|
|
0x66, 0x66, 0x66, // (padding)
|
|
0x64, 0x48, 0x8b, 0x04, 0x25, 0, 0, 0, 0, // mov %fs:0, %rax
|
|
0x90, // nop
|
|
};
|
|
memcpy(loc - 3, insn, sizeof(insn));
|
|
break;
|
|
}
|
|
case R_X86_64_PLTOFF64: {
|
|
static const u8 insn[] = {
|
|
0x66, 0x66, 0x66, // (padding)
|
|
0x64, 0x48, 0x8b, 0x04, 0x25, 0, 0, 0, 0, // mov %fs:0, %rax
|
|
0x66, 0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00, // nop
|
|
};
|
|
memcpy(loc - 3, insn, sizeof(insn));
|
|
break;
|
|
}
|
|
default:
|
|
unreachable();
|
|
}
|
|
|
|
i++;
|
|
} else {
|
|
write32s(ctx.got->get_tlsld_addr(ctx) + A - P);
|
|
}
|
|
continue;
|
|
case R_X86_64_DTPOFF32:
|
|
if (ctx.arg.relax && !ctx.arg.shared)
|
|
write32s(S + A - ctx.tls_end);
|
|
else
|
|
write32s(S + A - ctx.tls_begin);
|
|
continue;
|
|
case R_X86_64_DTPOFF64:
|
|
if (ctx.arg.relax && !ctx.arg.shared)
|
|
write64(S + A - ctx.tls_end);
|
|
else
|
|
write64(S + A - ctx.tls_begin);
|
|
continue;
|
|
case R_X86_64_TPOFF32:
|
|
write32s(S + A - ctx.tls_end);
|
|
continue;
|
|
case R_X86_64_TPOFF64:
|
|
write64(S + A - ctx.tls_end);
|
|
continue;
|
|
case R_X86_64_GOTTPOFF:
|
|
if (sym.get_gottp_idx(ctx) == -1) {
|
|
u32 insn = relax_gottpoff(loc - 3);
|
|
loc[-3] = insn >> 16;
|
|
loc[-2] = insn >> 8;
|
|
loc[-1] = insn;
|
|
write32s(S + A - ctx.tls_end + 4);
|
|
} else {
|
|
write32s(sym.get_gottp_addr(ctx) + A - P);
|
|
}
|
|
continue;
|
|
case R_X86_64_GOTPC32_TLSDESC:
|
|
if (sym.get_tlsdesc_idx(ctx) == -1) {
|
|
static const u8 insn[] = {
|
|
0x48, 0xc7, 0xc0, 0, 0, 0, 0, // mov $0, %rax
|
|
};
|
|
memcpy(loc - 3, insn, sizeof(insn));
|
|
write32s(S + A - ctx.tls_end + 4);
|
|
} else {
|
|
write32s(sym.get_tlsdesc_addr(ctx) + A - P);
|
|
}
|
|
continue;
|
|
case R_X86_64_SIZE32:
|
|
write32(sym.esym().st_size + A);
|
|
continue;
|
|
case R_X86_64_SIZE64:
|
|
write64(sym.esym().st_size + A);
|
|
continue;
|
|
case R_X86_64_TLSDESC_CALL:
|
|
if (sym.get_tlsdesc_idx(ctx) == -1) {
|
|
// call *(%rax) -> nop
|
|
loc[0] = 0x66;
|
|
loc[1] = 0x90;
|
|
}
|
|
continue;
|
|
default:
|
|
unreachable();
|
|
}
|
|
|
|
#undef S
|
|
#undef A
|
|
#undef P
|
|
#undef G
|
|
#undef GOT
|
|
}
|
|
}
|
|
|
|
// This function is responsible for applying relocations against
|
|
// non-SHF_ALLOC sections (i.e. sections that are not mapped to memory
|
|
// at runtime).
|
|
//
|
|
// Relocations against non-SHF_ALLOC sections are much easier to
|
|
// handle than that against SHF_ALLOC sections. It is because, since
|
|
// they are not mapped to memory, they don't contain any variable or
|
|
// function and never need PLT or GOT. Non-SHF_ALLOC sections are
|
|
// mostly debug info sections.
|
|
//
|
|
// Relocations against non-SHF_ALLOC sections are not scanned by
|
|
// scan_relocations.
|
|
template <>
|
|
void InputSection<E>::apply_reloc_nonalloc(Context<E> &ctx, u8 *base) {
|
|
std::span<ElfRel<E>> rels = get_rels(ctx);
|
|
|
|
for (i64 i = 0; i < rels.size(); i++) {
|
|
const ElfRel<E> &rel = rels[i];
|
|
if (rel.r_type == R_X86_64_NONE)
|
|
continue;
|
|
|
|
Symbol<E> &sym = *file.symbols[rel.r_sym];
|
|
u8 *loc = base + rel.r_offset;
|
|
|
|
if (!sym.file) {
|
|
report_undef(ctx, file, sym);
|
|
continue;
|
|
}
|
|
|
|
SectionFragment<E> *frag;
|
|
i64 addend;
|
|
std::tie(frag, addend) = get_fragment(ctx, rel);
|
|
|
|
auto overflow_check = [&](i64 val, i64 lo, i64 hi) {
|
|
if (val < lo || hi <= val)
|
|
Error(ctx) << *this << ": relocation " << rel << " against "
|
|
<< sym << " out of range: " << val << " is not in ["
|
|
<< lo << ", " << hi << ")";
|
|
};
|
|
|
|
auto write8 = [&](u64 val) {
|
|
overflow_check(val, 0, 1 << 8);
|
|
*loc = val;
|
|
};
|
|
|
|
auto write16 = [&](u64 val) {
|
|
overflow_check(val, 0, 1 << 16);
|
|
*(u16 *)loc = val;
|
|
};
|
|
|
|
auto write32 = [&](u64 val) {
|
|
overflow_check(val, 0, (i64)1 << 32);
|
|
*(u32 *)loc = val;
|
|
};
|
|
|
|
auto write32s = [&](u64 val) {
|
|
overflow_check(val, -((i64)1 << 31), (i64)1 << 31);
|
|
*(u32 *)loc = val;
|
|
};
|
|
|
|
#define S (frag ? frag->get_addr(ctx) : sym.get_addr(ctx))
|
|
#define A (frag ? addend : rel.r_addend)
|
|
|
|
switch (rel.r_type) {
|
|
case R_X86_64_8:
|
|
write8(S + A);
|
|
break;
|
|
case R_X86_64_16:
|
|
write16(S + A);
|
|
break;
|
|
case R_X86_64_32:
|
|
write32(S + A);
|
|
break;
|
|
case R_X86_64_32S:
|
|
write32s(S + A);
|
|
break;
|
|
case R_X86_64_64:
|
|
*(u64 *)loc = S + A;
|
|
break;
|
|
case R_X86_64_DTPOFF32:
|
|
write32s(S + A - ctx.tls_begin);
|
|
break;
|
|
case R_X86_64_DTPOFF64:
|
|
*(u64 *)loc = S + A - ctx.tls_begin;
|
|
break;
|
|
case R_X86_64_SIZE32:
|
|
write32(sym.esym().st_size + A);
|
|
break;
|
|
case R_X86_64_SIZE64:
|
|
*(u64 *)loc = sym.esym().st_size + A;
|
|
break;
|
|
default:
|
|
Fatal(ctx) << *this << ": invalid relocation for non-allocated sections: "
|
|
<< rel;
|
|
break;
|
|
}
|
|
|
|
#undef S
|
|
#undef A
|
|
}
|
|
}
|
|
|
|
// Linker has to create data structures in an output file to apply
|
|
// some type of relocations. For example, if a relocation refers a GOT
|
|
// or a PLT entry of a symbol, linker has to create an entry in .got
|
|
// or in .plt for that symbol. In order to fix the file layout, we
|
|
// need to scan relocations.
|
|
template <>
|
|
void InputSection<E>::scan_relocations(Context<E> &ctx) {
|
|
assert(shdr().sh_flags & SHF_ALLOC);
|
|
|
|
this->reldyn_offset = file.num_dynrel * sizeof(ElfRel<E>);
|
|
std::span<ElfRel<E>> rels = get_rels(ctx);
|
|
|
|
// Scan relocations
|
|
for (i64 i = 0; i < rels.size(); i++) {
|
|
const ElfRel<E> &rel = rels[i];
|
|
if (rel.r_type == R_X86_64_NONE)
|
|
continue;
|
|
|
|
Symbol<E> &sym = *file.symbols[rel.r_sym];
|
|
u8 *loc = (u8 *)(contents.data() + rel.r_offset);
|
|
|
|
if (!sym.file) {
|
|
report_undef(ctx, file, sym);
|
|
continue;
|
|
}
|
|
|
|
if (sym.get_type() == STT_GNU_IFUNC) {
|
|
sym.flags |= NEEDS_GOT;
|
|
sym.flags |= NEEDS_PLT;
|
|
}
|
|
|
|
switch (rel.r_type) {
|
|
case R_X86_64_8:
|
|
case R_X86_64_16:
|
|
case R_X86_64_32:
|
|
case R_X86_64_32S: {
|
|
// Dynamic linker does not support 8, 16 or 32-bit dynamic
|
|
// relocations for these types of relocations. We report an
|
|
// error if we cannot relocate them even at load-time.
|
|
Action table[][4] = {
|
|
// Absolute Local Imported data Imported code
|
|
{ NONE, ERROR, ERROR, ERROR }, // DSO
|
|
{ NONE, ERROR, ERROR, ERROR }, // PIE
|
|
{ NONE, NONE, COPYREL, PLT }, // PDE
|
|
};
|
|
dispatch(ctx, table, i, rel, sym);
|
|
break;
|
|
}
|
|
case R_X86_64_64: {
|
|
// Unlike the above, we can use R_X86_64_RELATIVE and R_86_64_64
|
|
// relocations.
|
|
Action table[][4] = {
|
|
// Absolute Local Imported data Imported code
|
|
{ NONE, BASEREL, DYNREL, DYNREL }, // DSO
|
|
{ NONE, BASEREL, DYNREL, DYNREL }, // PIE
|
|
{ NONE, NONE, COPYREL, PLT }, // PDE
|
|
};
|
|
dispatch(ctx, table, i, rel, sym);
|
|
break;
|
|
}
|
|
case R_X86_64_PC8:
|
|
case R_X86_64_PC16:
|
|
case R_X86_64_PC32: {
|
|
Action table[][4] = {
|
|
// Absolute Local Imported data Imported code
|
|
{ ERROR, NONE, ERROR, ERROR }, // DSO
|
|
{ ERROR, NONE, COPYREL, PLT }, // PIE
|
|
{ NONE, NONE, COPYREL, PLT }, // PDE
|
|
};
|
|
dispatch(ctx, table, i, rel, sym);
|
|
break;
|
|
}
|
|
case R_X86_64_PC64: {
|
|
Action table[][4] = {
|
|
// Absolute Local Imported data Imported code
|
|
{ ERROR, NONE, DYNREL, DYNREL }, // DSO
|
|
{ ERROR, NONE, COPYREL, PLT }, // PIE
|
|
{ NONE, NONE, COPYREL, PLT }, // PDE
|
|
};
|
|
dispatch(ctx, table, i, rel, sym);
|
|
break;
|
|
}
|
|
case R_X86_64_GOT32:
|
|
case R_X86_64_GOT64:
|
|
case R_X86_64_GOTPC32:
|
|
case R_X86_64_GOTPC64:
|
|
case R_X86_64_GOTPCREL:
|
|
case R_X86_64_GOTPCREL64:
|
|
sym.flags |= NEEDS_GOT;
|
|
break;
|
|
case R_X86_64_GOTPCRELX: {
|
|
if (rel.r_addend != -4)
|
|
Fatal(ctx) << *this << ": bad r_addend for R_X86_64_GOTPCRELX";
|
|
|
|
bool do_relax = ctx.arg.relax && !sym.is_imported &&
|
|
sym.is_relative() && relax_gotpcrelx(loc - 2);
|
|
if (!do_relax)
|
|
sym.flags |= NEEDS_GOT;
|
|
break;
|
|
}
|
|
case R_X86_64_REX_GOTPCRELX: {
|
|
if (rel.r_addend != -4)
|
|
Fatal(ctx) << *this << ": bad r_addend for R_X86_64_REX_GOTPCRELX";
|
|
|
|
bool do_relax = ctx.arg.relax && !sym.is_imported &&
|
|
sym.is_relative() && relax_rex_gotpcrelx(loc - 3);
|
|
if (!do_relax)
|
|
sym.flags |= NEEDS_GOT;
|
|
break;
|
|
}
|
|
case R_X86_64_PLT32:
|
|
case R_X86_64_PLTOFF64: {
|
|
Action table[][4] = {
|
|
// Absolute Local Imported data Imported code
|
|
{ NONE, NONE, PLT, PLT }, // DSO
|
|
{ NONE, NONE, PLT, PLT }, // PIE
|
|
{ NONE, NONE, PLT, PLT }, // PDE
|
|
};
|
|
dispatch(ctx, table, i, rel, sym);
|
|
break;
|
|
}
|
|
case R_X86_64_TLSGD: {
|
|
if (i + 1 == rels.size())
|
|
Fatal(ctx) << *this << ": TLSGD reloc must be followed by PLT or GOTPCREL";
|
|
|
|
if (u32 ty = rels[i + 1].r_type;
|
|
ty != R_X86_64_PLT32 && ty != R_X86_64_PLTOFF64 &&
|
|
ty != R_X86_64_GOTPCREL && ty != R_X86_64_GOTPCRELX)
|
|
Fatal(ctx) << *this << ": TLSGD reloc must be followed by PLT or GOTPCREL";
|
|
|
|
if (ctx.arg.relax && !ctx.arg.shared && !sym.is_imported)
|
|
i++;
|
|
else
|
|
sym.flags |= NEEDS_TLSGD;
|
|
break;
|
|
}
|
|
case R_X86_64_TLSLD: {
|
|
if (i + 1 == rels.size())
|
|
Fatal(ctx) << *this << ": TLSLD reloc must be followed by PLT or GOTPCREL";
|
|
|
|
if (u32 ty = rels[i + 1].r_type;
|
|
ty != R_X86_64_PLT32 && ty != R_X86_64_PLTOFF64 &&
|
|
ty != R_X86_64_GOTPCREL && ty != R_X86_64_GOTPCRELX)
|
|
Fatal(ctx) << *this << ": TLSLD reloc must be followed by PLT or GOTPCREL";
|
|
|
|
if (ctx.arg.relax && !ctx.arg.shared)
|
|
i++;
|
|
else
|
|
ctx.needs_tlsld = true;
|
|
break;
|
|
}
|
|
case R_X86_64_GOTTPOFF: {
|
|
ctx.has_gottp_rel = true;
|
|
|
|
bool do_relax = ctx.arg.relax && !ctx.arg.shared &&
|
|
!sym.is_imported && relax_gottpoff(loc - 3);
|
|
if (!do_relax)
|
|
sym.flags |= NEEDS_GOTTP;
|
|
break;
|
|
}
|
|
case R_X86_64_GOTPC32_TLSDESC: {
|
|
if (memcmp(loc - 3, "\x48\x8d\x05", 3))
|
|
Fatal(ctx) << *this << ": GOTPC32_TLSDESC relocation is used"
|
|
<< " against an invalid code sequence";
|
|
|
|
bool do_relax = ctx.relax_tlsdesc && !sym.is_imported;
|
|
if (!do_relax)
|
|
sym.flags |= NEEDS_TLSDESC;
|
|
break;
|
|
}
|
|
case R_X86_64_GOTOFF64:
|
|
case R_X86_64_DTPOFF32:
|
|
case R_X86_64_DTPOFF64:
|
|
case R_X86_64_TPOFF32:
|
|
case R_X86_64_TPOFF64:
|
|
case R_X86_64_SIZE32:
|
|
case R_X86_64_SIZE64:
|
|
case R_X86_64_TLSDESC_CALL:
|
|
break;
|
|
default:
|
|
Error(ctx) << *this << ": unknown relocation: " << rel;
|
|
}
|
|
}
|
|
}
|
|
|
|
} // namespace mold::elf
|