mirror of
https://github.com/rui314/mold.git
synced 2024-12-26 01:44:29 +03:00
441 lines
11 KiB
C++
441 lines
11 KiB
C++
#include "mold.h"
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enum {
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R_TLS_GOTIE = R_END + 1,
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R_TLS_LE,
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R_TLS_GD,
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R_TLS_LD,
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R_TLS_GOTDESC,
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R_TLS_GOTDESC_RELAX,
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R_TLS_DESC_CALL_RELAX,
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R_TPOFF,
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};
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template <>
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void PltSection<I386>::copy_buf(Context<I386> &ctx) {
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u8 *buf = ctx.buf + this->shdr.sh_offset;
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// Write PLT header
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if (ctx.arg.pic) {
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static const u8 plt0[] = {
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0xff, 0xb3, 0x04, 0, 0, 0, // pushl 4(%ebx)
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0xff, 0xa3, 0x08, 0, 0, 0, // jmp *8(%ebx)
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0x90, 0x90, 0x90, 0x90, // nop
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};
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memcpy(buf, plt0, sizeof(plt0));
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} else {
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static const u8 plt0[] = {
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0xff, 0x35, 0, 0, 0, 0, // pushl (GOTPLT+4)
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0xff, 0x25, 0, 0, 0, 0, // jmp *(GOTPLT+8)
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0x90, 0x90, 0x90, 0x90, // 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 + 4;
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*(u32 *)(buf + 8) = ctx.gotplt->shdr.sh_addr + 8;
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}
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// Write PLT entries
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i64 relplt_idx = 0;
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for (Symbol<I386> *sym : symbols) {
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u8 *ent = buf + sym->get_plt_idx(ctx) * I386::plt_size;
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if (ctx.arg.pic) {
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static const u8 data[] = {
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0xff, 0xa3, 0, 0, 0, 0, // jmp *foo@GOT(%ebx)
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0x68, 0, 0, 0, 0, // pushl $reloc_offset
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0xe9, 0, 0, 0, 0, // jmp .PLT0@PC
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};
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memcpy(ent, data, sizeof(data));
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*(u32 *)(ent + 2) = sym->get_gotplt_addr(ctx) - ctx.gotplt->shdr.sh_addr;
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} else {
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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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0x68, 0, 0, 0, 0, // pushl $reloc_offset
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0xe9, 0, 0, 0, 0, // jmp .PLT0@PC
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};
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memcpy(ent, data, sizeof(data));
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*(u32 *)(ent + 2) = sym->get_gotplt_addr(ctx);
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}
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*(u32 *)(ent + 7) = relplt_idx++ * sizeof(ElfRel<I386>);
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*(u32 *)(ent + 12) = this->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 PltGotSection<I386>::copy_buf(Context<I386> &ctx) {
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u8 *buf = ctx.buf + this->shdr.sh_offset;
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if (ctx.arg.pic) {
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static const u8 data[] = {
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0xff, 0xa3, 0, 0, 0, 0, // jmp *foo@GOT(%ebx)
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0x66, 0x90, // nop
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};
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for (i64 i = 0; i < symbols.size(); i++) {
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u8 *ent = buf + i * sizeof(data);
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memcpy(ent, data, sizeof(data));
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*(u32 *)(ent + 2) = symbols[i]->get_got_addr(ctx) - ctx.gotplt->shdr.sh_addr;
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}
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} else {
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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 (i64 i = 0; i < symbols.size(); i++) {
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u8 *ent = buf + i * sizeof(data);
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memcpy(ent, data, sizeof(data));
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*(u32 *)(ent + 2) = symbols[i]->get_got_addr(ctx);
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}
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}
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}
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template <>
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void EhFrameSection<I386>::apply_reloc(Context<I386> &ctx,
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ElfRel<I386> &rel,
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u64 loc, u64 val) {
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u8 *base = ctx.buf + this->shdr.sh_offset;
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switch (rel.r_type) {
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case R_386_NONE:
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return;
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case R_386_32:
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*(u32 *)(base + loc) = val;
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return;
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case R_386_PC32:
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*(u32 *)(base + loc) = val - this->shdr.sh_addr - loc;
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return;
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}
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unreachable(ctx);
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}
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static void write_val(Context<I386> &ctx, u64 r_type, u8 *loc, u64 val) {
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switch (r_type) {
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case R_386_NONE:
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return;
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case R_386_8:
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case R_386_PC8:
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*loc += val;
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return;
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case R_386_16:
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case R_386_PC16:
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*(u16 *)loc += val;
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return;
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case R_386_32:
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case R_386_PC32:
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case R_386_GOT32:
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case R_386_GOT32X:
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case R_386_PLT32:
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case R_386_GOTOFF:
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case R_386_GOTPC:
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case R_386_TLS_LDM:
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case R_386_TLS_GOTIE:
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case R_386_TLS_LE:
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case R_386_TLS_GD:
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case R_386_TLS_LDO_32:
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case R_386_SIZE32:
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case R_386_TLS_GOTDESC:
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*(u32 *)loc += val;
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return;
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}
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unreachable(ctx);
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}
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template <>
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void InputSection<I386>::apply_reloc_alloc(Context<I386> &ctx, u8 *base) {
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ElfRel<I386> *dynrel = nullptr;
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std::span<ElfRel<I386>> 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<I386> *)(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<I386> &rel = rels[i];
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Symbol<I386> &sym = *file.symbols[rel.r_sym];
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u8 *loc = base + rel.r_offset;
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const SectionFragmentRef<I386> *ref = nullptr;
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if (rel_fragments && rel_fragments[frag_idx].idx == i)
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ref = &rel_fragments[frag_idx++];
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auto write = [&](u64 val) {
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write_val(ctx, rel.r_type, loc, val);
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};
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#define S (ref ? ref->frag->get_addr(ctx) : sym.get_addr(ctx))
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#define A (ref ? ref->addend : 0)
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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.got->shdr.sh_addr)
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#define GOTPLT ctx.gotplt->shdr.sh_addr
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switch (rel_types[i]) {
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case R_NONE:
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break;
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case R_ABS:
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write(S + A);
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break;
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case R_BASEREL:
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*dynrel++ = {P, R_386_RELATIVE, 0};
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*(u32 *)loc += S + A;
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break;
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case R_DYN:
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*dynrel++ = {P, R_386_32, (u32)sym.get_dynsym_idx(ctx)};
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*(u32 *)loc += A;
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break;
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case R_PC:
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write(S + A - P);
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break;
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case R_GOT:
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write(sym.get_got_addr(ctx) + A - GOTPLT);
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break;
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case R_GOTOFF:
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write(S + A - GOTPLT);
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break;
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case R_GOTPC:
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write(GOTPLT + A - P);
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break;
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case R_GOTPCREL:
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write(G + GOTPLT + A - P);
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break;
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case R_TLS_GOTIE:
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write(sym.get_gottp_addr(ctx) + A - GOTPLT);
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break;
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case R_TLS_LE:
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write(S + A - ctx.tls_end);
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break;
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case R_TLS_GD:
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write(sym.get_tlsgd_addr(ctx) + A - GOTPLT);
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break;
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case R_TLS_LD:
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write(ctx.got->get_tlsld_addr(ctx) + A - GOTPLT);
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break;
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case R_TPOFF:
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write(S + A - ctx.tls_begin);
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break;
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case R_TLS_GOTDESC:
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write(sym.get_tlsdesc_addr(ctx) + A - GOTPLT);
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break;
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case R_TLS_GOTDESC_RELAX: {
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static const u8 insn[] = {
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0x8d, 0x05, 0, 0, 0, 0, // lea 0, %eax
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};
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memcpy(loc - 2, insn, sizeof(insn));
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write(S + A - ctx.tls_end);
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break;
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}
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case R_TLS_DESC_CALL_RELAX:
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// call *(%rax) -> nop
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loc[0] = 0x66;
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loc[1] = 0x90;
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break;
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case R_SIZE:
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write(sym.esym().st_size + A);
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break;
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default:
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unreachable(ctx);
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}
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#undef S
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#undef A
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#undef P
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#undef G
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#undef GOTPLT
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}
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}
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template <>
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void InputSection<I386>::apply_reloc_nonalloc(Context<I386> &ctx, u8 *base) {
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std::span<ElfRel<I386>> rels = get_rels(ctx);
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i64 frag_idx = 0;
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for (i64 i = 0; i < rels.size(); i++) {
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const ElfRel<I386> &rel = rels[i];
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Symbol<I386> &sym = *file.symbols[rel.r_sym];
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u8 *loc = base + rel.r_offset;
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if (!sym.file) {
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report_undef(ctx, sym);
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continue;
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}
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const SectionFragmentRef<I386> *ref = nullptr;
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if (rel_fragments && rel_fragments[frag_idx].idx == i)
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ref = &rel_fragments[frag_idx++];
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auto write = [&](u64 val) {
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write_val(ctx, rel.r_type, loc, val);
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};
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switch (rel.r_type) {
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case R_386_NONE:
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return;
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case R_386_8:
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case R_386_16:
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case R_386_32:
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case R_386_PC8:
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case R_386_PC16:
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case R_386_PC32:
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if (ref)
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write(ref->frag->get_addr(ctx) + ref->addend);
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else
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write(sym.get_addr(ctx));
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break;
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case R_386_GOTOFF:
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write(sym.get_addr(ctx) - ctx.got->shdr.sh_addr);
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break;
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case R_386_TLS_LDO_32:
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write(sym.get_addr(ctx) - ctx.tls_begin);
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break;
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case R_386_SIZE32:
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write(sym.esym().st_size);
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break;
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default:
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Fatal(ctx) << *this << ": invalid relocation for non-allocated sections: "
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<< rel_to_string<I386>(rel.r_type);
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break;
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}
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}
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}
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template <>
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void InputSection<I386>::scan_relocations(Context<I386> &ctx) {
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assert(shdr.sh_flags & SHF_ALLOC);
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this->reldyn_offset = file.num_dynrel * sizeof(ElfRel<I386>);
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std::span<ElfRel<I386>> rels = get_rels(ctx);
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bool is_writable = (shdr.sh_flags & SHF_WRITE);
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// Scan relocations
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for (i64 i = 0; i < rels.size(); i++) {
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const ElfRel<I386> &rel = rels[i];
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if (rel.r_type == R_386_NONE) {
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rel_types[i] = R_NONE;
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break;
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}
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Symbol<I386> &sym = *file.symbols[rel.r_sym];
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u8 *loc = (u8 *)(contents.data() + rel.r_offset);
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if (!sym.file) {
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report_undef(ctx, sym);
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continue;
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}
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if (sym.get_type() == STT_GNU_IFUNC) {
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sym.flags |= NEEDS_GOT;
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sym.flags |= NEEDS_PLT;
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}
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switch (rel.r_type) {
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case R_386_8:
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case R_386_16: {
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Action table[][4] = {
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// Absolute Local Imported data Imported code
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{ NONE, ERROR, ERROR, ERROR }, // DSO
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{ NONE, ERROR, ERROR, ERROR }, // PIE
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{ NONE, NONE, COPYREL, PLT }, // PDE
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};
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dispatch(ctx, table, R_ABS, i);
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break;
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}
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case R_386_32: {
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Action act = is_writable ? DYNREL : COPYREL;
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Action table[][4] = {
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// Absolute Local Imported data Imported code
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{ NONE, BASEREL, DYNREL, DYNREL }, // DSO
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{ NONE, BASEREL, DYNREL, DYNREL }, // PIE
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{ NONE, NONE, act, PLT }, // PDE
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};
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dispatch(ctx, table, R_ABS, i);
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break;
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}
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case R_386_PC8:
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case R_386_PC16: {
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Action table[][4] = {
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// Absolute Local Imported data Imported code
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{ ERROR, NONE, ERROR, ERROR }, // DSO
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{ ERROR, NONE, COPYREL, PLT }, // PIE
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{ NONE, NONE, COPYREL, PLT }, // PDE
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};
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dispatch(ctx, table, R_PC, i);
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break;
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}
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case R_386_PC32: {
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Action table[][4] = {
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// Absolute Local Imported data Imported code
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{ BASEREL, NONE, ERROR, ERROR }, // DSO
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{ BASEREL, NONE, COPYREL, PLT }, // PIE
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{ NONE, NONE, COPYREL, PLT }, // PDE
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};
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dispatch(ctx, table, R_PC, i);
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break;
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}
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case R_386_GOT32:
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case R_386_GOT32X:
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sym.flags |= NEEDS_GOT;
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rel_types[i] = R_GOT;
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break;
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case R_386_PLT32:
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if (sym.is_imported)
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sym.flags |= NEEDS_PLT;
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rel_types[i] = R_PC;
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break;
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case R_386_GOTOFF:
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rel_types[i] = R_GOTOFF;
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break;
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case R_386_GOTPC:
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sym.flags |= NEEDS_GOT;
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rel_types[i] = R_GOTPC;
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break;
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case R_386_TLS_GOTIE:
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sym.flags |= NEEDS_GOTTP;
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rel_types[i] = R_TLS_GOTIE;
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break;
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case R_386_TLS_LE:
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sym.flags |= NEEDS_GOTTP;
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rel_types[i] = R_TLS_LE;
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break;
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case R_386_TLS_GD:
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sym.flags |= NEEDS_TLSGD;
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rel_types[i] = R_TLS_GD;
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break;
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case R_386_TLS_LDM:
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sym.flags |= NEEDS_TLSLD;
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rel_types[i] = R_TLS_LD;
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break;
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case R_386_TLS_LDO_32:
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rel_types[i] = R_TPOFF;
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break;
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case R_386_SIZE32:
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rel_types[i] = R_SIZE;
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break;
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case R_386_TLS_GOTDESC:
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if (ctx.arg.relax && !ctx.arg.shared) {
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rel_types[i] = R_TLS_GOTDESC_RELAX;
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} else {
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sym.flags |= NEEDS_TLSDESC;
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rel_types[i] = R_TLS_GOTDESC;
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}
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break;
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case R_386_TLS_DESC_CALL:
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if (ctx.arg.relax && !ctx.arg.shared)
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rel_types[i] = R_TLS_DESC_CALL_RELAX;
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else
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rel_types[i] = R_NONE;
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break;
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default:
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Error(ctx) << *this << ": unknown relocation: "
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<< rel_to_string<I386>(rel.r_type);
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}
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}
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}
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