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mold/arch_i386.cc
Rui Ueyama 12790e554f wip
2021-03-31 12:48:27 +09:00

365 lines
10 KiB
C++
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#include "mold.h"
template <>
void PltSection<I386>::copy_buf(Context<I386> &ctx) {
u8 *buf = ctx.buf + this->shdr.sh_offset;
// Write PLT header
if (ctx.arg.pic) {
static const u8 plt0[] = {
0xff, 0xb3, 0x04, 0, 0, 0, // pushl 4(%ebx)
0xff, 0xa3, 0x08, 0, 0, 0, // jmp *8(%ebx)
0x90, 0x90, 0x90, 0x90, // nop
};
memcpy(buf, plt0, sizeof(plt0));
} else {
static const u8 plt0[] = {
0xff, 0x35, 0, 0, 0, 0, // pushl (GOTPLT+4)
0xff, 0x25, 0, 0, 0, 0, // jmp *(GOTPLT+8)
0x90, 0x90, 0x90, 0x90, // nop
};
memcpy(buf, plt0, sizeof(plt0));
*(u32 *)(buf + 2) = ctx.gotplt->shdr.sh_addr + 4;
*(u32 *)(buf + 8) = ctx.gotplt->shdr.sh_addr + 8;
}
// Write PLT entries
i64 relplt_idx = 0;
for (Symbol<I386> *sym : symbols) {
u8 *ent = buf + sym->plt_idx * I386::plt_size;
if (ctx.arg.pic) {
static const uint8_t data[] = {
0xff, 0xa3, 0, 0, 0, 0, // jmp *foo@GOT(%ebx)
0x68, 0, 0, 0, 0, // pushl $reloc_offset
0xe9, 0, 0, 0, 0, // jmp .PLT0@PC
};
memcpy(ent, data, sizeof(data));
*(u32 *)(ent + 2) = sym->get_gotplt_addr(ctx) - sym->get_plt_addr(ctx);
} else {
static const uint8_t data[] = {
0xff, 0x25, 0, 0, 0, 0, // jmp *foo@GOT
0x68, 0, 0, 0, 0, // pushl $reloc_offset
0xe9, 0, 0, 0, 0, // jmp .PLT0@PC
};
memcpy(ent, data, sizeof(data));
*(u32 *)(ent + 2) = sym->get_gotplt_addr(ctx);
}
*(u32 *)(ent + 7) = relplt_idx++;
*(u32 *)(ent + 12) = this->shdr.sh_addr - sym->get_plt_addr(ctx) - 16;
}
}
template <>
std::string rel_to_string<I386>(u32 r_type) {
switch (r_type) {
case R_386_NONE: return "R_386_NONE";
case R_386_32: return "R_386_32";
case R_386_PC32: return "R_386_PC32";
case R_386_GOT32: return "R_386_GOT32";
case R_386_PLT32: return "R_386_PLT32";
case R_386_COPY: return "R_386_COPY";
case R_386_GLOB_DAT: return "R_386_GLOB_DAT";
case R_386_JUMP_SLOT: return "R_386_JUMP_SLOT";
case R_386_RELATIVE: return "R_386_RELATIVE";
case R_386_GOTOFF: return "R_386_GOTOFF";
case R_386_GOTPC: return "R_386_GOTPC";
case R_386_32PLT: return "R_386_32PLT";
case R_386_TLS_TPOFF: return "R_386_TLS_TPOFF";
case R_386_TLS_IE: return "R_386_TLS_IE";
case R_386_TLS_GOTIE: return "R_386_TLS_GOTIE";
case R_386_TLS_LE: return "R_386_TLS_LE";
case R_386_TLS_GD: return "R_386_TLS_GD";
case R_386_TLS_LDM: return "R_386_TLS_LDM";
case R_386_16: return "R_386_16";
case R_386_PC16: return "R_386_PC16";
case R_386_8: return "R_386_8";
case R_386_PC8: return "R_386_PC8";
case R_386_TLS_GD_32: return "R_386_TLS_GD_32";
case R_386_TLS_GD_PUSH: return "R_386_TLS_GD_PUSH";
case R_386_TLS_GD_CALL: return "R_386_TLS_GD_CALL";
case R_386_TLS_GD_POP: return "R_386_TLS_GD_POP";
case R_386_TLS_LDM_32: return "R_386_TLS_LDM_32";
case R_386_TLS_LDM_PUSH: return "R_386_TLS_LDM_PUSH";
case R_386_TLS_LDM_CALL: return "R_386_TLS_LDM_CALL";
case R_386_TLS_LDM_POP: return "R_386_TLS_LDM_POP";
case R_386_TLS_LDO_32: return "R_386_TLS_LDO_32";
case R_386_TLS_IE_32: return "R_386_TLS_IE_32";
case R_386_TLS_LE_32: return "R_386_TLS_LE_32";
case R_386_TLS_DTPMOD32: return "R_386_TLS_DTPMOD32";
case R_386_TLS_DTPOFF32: return "R_386_TLS_DTPOFF32";
case R_386_TLS_TPOFF32: return "R_386_TLS_TPOFF32";
case R_386_TLS_GOTDESC: return "R_386_TLS_GOTDESC";
case R_386_TLS_DESC_CALL: return "R_386_TLS_DESC_CALL";
case R_386_TLS_DESC: return "R_386_TLS_DESC";
case R_386_IRELATIVE: return "R_386_IRELATIVE";
case R_386_GOT32X: return "R_386_GOT32X";
}
return "unknown (" + std::to_string(r_type) + ")";
}
static void write_val(Context<I386> &ctx, u64 r_type, u8 *loc, u64 val) {
switch (r_type) {
case R_386_NONE:
return;
case R_386_8:
case R_386_PC8:
*loc += val;
return;
case R_386_16:
case R_386_PC16:
*(u16 *)loc += val;
return;
case R_386_32:
case R_386_PC32:
case R_386_GOT32:
case R_386_GOT32X:
case R_386_PLT32:
case R_386_GOTOFF:
case R_386_GOTPC:
case R_386_SIZE32:
*(u32 *)loc += val;
return;
}
unreachable(ctx);
}
template <>
void InputSection<I386>::apply_reloc_alloc(Context<I386> &ctx, u8 *base) {
i64 ref_idx = 0;
ElfRel<I386> *dynrel = nullptr;
if (ctx.reldyn)
dynrel = (ElfRel<I386> *)(ctx.buf + ctx.reldyn->shdr.sh_offset +
file.reldyn_offset + this->reldyn_offset);
for (i64 i = 0; i < rels.size(); i++) {
const ElfRel<I386> &rel = rels[i];
Symbol<I386> &sym = *file.symbols[rel.r_sym];
u8 *loc = base + rel.r_offset;
const SectionFragmentRef<I386> *ref = nullptr;
if (has_fragments[i])
ref = &rel_fragments[ref_idx++];
auto write = [&](u64 val) {
write_val(ctx, rel.r_type, loc, val);
};
#define S (ref ? ref->frag->get_addr(ctx) : sym.get_addr(ctx))
#define A (ref ? ref->addend : 0)
#define P (output_section->shdr.sh_addr + offset + rel.r_offset)
#define G (sym.get_got_addr(ctx) - ctx.got->shdr.sh_addr)
#define GOT ctx.got->shdr.sh_addr
switch (rel_types[i]) {
case R_NONE:
break;
case R_ABS:
write(S + A);
break;
case R_BASEREL:
*dynrel++ = {P, R_386_RELATIVE, 0};
*(u32 *)loc += S + A;
break;
case R_DYN:
*dynrel++ = {P, R_386_32, sym.dynsym_idx};
*(u32 *)loc += A;
break;
case R_PC:
write(S + A - P);
break;
case R_GOT:
write(G + A);
break;
case R_GOTOFF:
write(S + A - GOT);
break;
case R_GOTPC:
write(GOT + A - P);
break;
case R_GOTPCREL:
write(G + GOT + A - P);
break;
case R_SIZE:
write(sym.esym->st_size + A);
break;
default:
unreachable(ctx);
}
#undef S
#undef A
#undef P
#undef G
#undef GOT
}
}
template <>
void InputSection<I386>::apply_reloc_nonalloc(Context<I386> &ctx, u8 *base) {
i64 ref_idx = 0;
for (i64 i = 0; i < rels.size(); i++) {
const ElfRel<I386> &rel = rels[i];
Symbol<I386> &sym = *file.symbols[rel.r_sym];
u8 *loc = base + rel.r_offset;
if (!sym.file) {
Error(ctx) << "undefined symbol: " << file << ": " << sym;
continue;
}
const SectionFragmentRef<I386> *ref = nullptr;
if (has_fragments[i])
ref = &rel_fragments[ref_idx++];
auto write = [&](u64 val) {
write_val(ctx, rel.r_type, loc, val);
};
switch (rel.r_type) {
case R_386_NONE:
return;
case R_386_8:
case R_386_16:
case R_386_32:
case R_386_PC8:
case R_386_PC16:
case R_386_PC32:
if (ref)
write(ref->frag->get_addr(ctx) + ref->addend);
else
write(sym.get_addr(ctx));
break;
case R_386_SIZE32:
write(sym.esym->st_size);
break;
default:
Fatal(ctx) << *this << ": invalid relocation for non-allocated sections: "
<< rel_to_string<I386>(rel.r_type);
break;
}
}
}
template <>
void InputSection<I386>::scan_relocations(Context<I386> &ctx) {
assert(shdr.sh_flags & SHF_ALLOC);
this->reldyn_offset = file.num_dynrel * sizeof(ElfRel<I386>);
// Scan relocations
for (i64 i = 0; i < rels.size(); i++) {
const ElfRel<I386> &rel = rels[i];
Symbol<I386> &sym = *file.symbols[rel.r_sym];
u8 *loc = (u8 *)(contents.data() + rel.r_offset);
if (!sym.file) {
Error(ctx) << "undefined symbol: " << file << ": " << sym;
continue;
}
if (sym.esym->st_type == STT_GNU_IFUNC)
sym.flags |= NEEDS_PLT;
switch (rel.r_type) {
case R_386_NONE:
rel_types[i] = R_NONE;
break;
case R_386_8:
case R_386_16: {
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, R_ABS, i);
break;
}
case R_386_32: {
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, R_ABS, i);
break;
}
case R_386_PC8:
case R_386_PC16: {
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, R_PC, i);
break;
}
case R_386_PC32: {
Action table[][4] = {
// Absolute Local Imported data Imported code
{ BASEREL, NONE, ERROR, ERROR }, // DSO
{ BASEREL, NONE, COPYREL, PLT }, // PIE
{ NONE, NONE, COPYREL, PLT }, // PDE
};
dispatch(ctx, table, R_PC, i);
break;
}
case R_386_GOT32:
case R_386_GOT32X:
sym.flags |= NEEDS_GOT;
rel_types[i] = R_GOT;
break;
case R_386_PLT32:
if (sym.is_imported)
sym.flags |= NEEDS_PLT;
rel_types[i] = R_PC;
break;
case R_386_GOTOFF:
rel_types[i] = R_GOTOFF;
break;
case R_386_GOTPC:
sym.flags |= NEEDS_GOT;
rel_types[i] = R_GOTPC;
break;
case R_386_TLS_TPOFF:
case R_386_TLS_IE:
case R_386_TLS_GOTIE:
case R_386_TLS_LE:
case R_386_TLS_GD:
case R_386_TLS_LDM:
case R_386_TLS_GD_32:
case R_386_TLS_GD_PUSH:
case R_386_TLS_GD_CALL:
case R_386_TLS_GD_POP:
case R_386_TLS_LDM_32:
case R_386_TLS_LDM_PUSH:
case R_386_TLS_LDM_CALL:
case R_386_TLS_LDM_POP:
case R_386_TLS_LDO_32:
case R_386_TLS_IE_32:
case R_386_TLS_LE_32:
case R_386_TLS_DTPMOD32:
case R_386_TLS_DTPOFF32:
case R_386_TLS_TPOFF32:
Fatal(ctx) << "TLS reloc is not supported yet";
case R_386_SIZE32:
rel_types[i] = R_SIZE;
break;
case R_386_TLS_GOTDESC:
case R_386_TLS_DESC_CALL:
case R_386_TLS_DESC:
Fatal(ctx) << "TLS reloc is not supported yet";
}
}
}
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