diff options
Diffstat (limited to 'ELF/Arch/X86.cpp')
| -rw-r--r-- | ELF/Arch/X86.cpp | 144 |
1 files changed, 141 insertions, 3 deletions
diff --git a/ELF/Arch/X86.cpp b/ELF/Arch/X86.cpp index 10517bef14f38..09c16db53e4b7 100644 --- a/ELF/Arch/X86.cpp +++ b/ELF/Arch/X86.cpp @@ -21,7 +21,7 @@ using namespace lld; using namespace lld::elf; namespace { -class X86 final : public TargetInfo { +class X86 : public TargetInfo { public: X86(); RelExpr getRelExpr(RelType Type, const Symbol &S, @@ -399,7 +399,145 @@ void X86::relaxTlsLdToLe(uint8_t *Loc, RelType Type, uint64_t Val) const { memcpy(Loc - 2, Inst, sizeof(Inst)); } +namespace { +class RetpolinePic : public X86 { +public: + RetpolinePic(); + void writeGotPlt(uint8_t *Buf, const Symbol &S) const override; + void writePltHeader(uint8_t *Buf) const override; + void writePlt(uint8_t *Buf, uint64_t GotPltEntryAddr, uint64_t PltEntryAddr, + int32_t Index, unsigned RelOff) const override; +}; + +class RetpolineNoPic : public X86 { +public: + RetpolineNoPic(); + void writeGotPlt(uint8_t *Buf, const Symbol &S) const override; + void writePltHeader(uint8_t *Buf) const override; + void writePlt(uint8_t *Buf, uint64_t GotPltEntryAddr, uint64_t PltEntryAddr, + int32_t Index, unsigned RelOff) const override; +}; +} // namespace + +RetpolinePic::RetpolinePic() { + PltHeaderSize = 48; + PltEntrySize = 32; +} + +void RetpolinePic::writeGotPlt(uint8_t *Buf, const Symbol &S) const { + write32le(Buf, S.getPltVA() + 17); +} + +void RetpolinePic::writePltHeader(uint8_t *Buf) const { + const uint8_t Insn[] = { + 0xff, 0xb3, 0, 0, 0, 0, // 0: pushl GOTPLT+4(%ebx) + 0x50, // 6: pushl %eax + 0x8b, 0x83, 0, 0, 0, 0, // 7: mov GOTPLT+8(%ebx), %eax + 0xe8, 0x0e, 0x00, 0x00, 0x00, // d: call next + 0xf3, 0x90, // 12: loop: pause + 0x0f, 0xae, 0xe8, // 14: lfence + 0xeb, 0xf9, // 17: jmp loop + 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, // 19: int3; .align 16 + 0x89, 0x0c, 0x24, // 20: next: mov %ecx, (%esp) + 0x8b, 0x4c, 0x24, 0x04, // 23: mov 0x4(%esp), %ecx + 0x89, 0x44, 0x24, 0x04, // 27: mov %eax ,0x4(%esp) + 0x89, 0xc8, // 2b: mov %ecx, %eax + 0x59, // 2d: pop %ecx + 0xc3, // 2e: ret + }; + memcpy(Buf, Insn, sizeof(Insn)); + + uint32_t Ebx = InX::Got->getVA() + InX::Got->getSize(); + uint32_t GotPlt = InX::GotPlt->getVA() - Ebx; + write32le(Buf + 2, GotPlt + 4); + write32le(Buf + 9, GotPlt + 8); +} + +void RetpolinePic::writePlt(uint8_t *Buf, uint64_t GotPltEntryAddr, + uint64_t PltEntryAddr, int32_t Index, + unsigned RelOff) const { + const uint8_t Insn[] = { + 0x50, // pushl %eax + 0x8b, 0x83, 0, 0, 0, 0, // mov foo@GOT(%ebx), %eax + 0xe8, 0, 0, 0, 0, // call plt+0x20 + 0xe9, 0, 0, 0, 0, // jmp plt+0x12 + 0x68, 0, 0, 0, 0, // pushl $reloc_offset + 0xe9, 0, 0, 0, 0, // jmp plt+0 + }; + memcpy(Buf, Insn, sizeof(Insn)); + + uint32_t Ebx = InX::Got->getVA() + InX::Got->getSize(); + write32le(Buf + 3, GotPltEntryAddr - Ebx); + write32le(Buf + 8, -Index * PltEntrySize - PltHeaderSize - 12 + 32); + write32le(Buf + 13, -Index * PltEntrySize - PltHeaderSize - 17 + 18); + write32le(Buf + 18, RelOff); + write32le(Buf + 23, -Index * PltEntrySize - PltHeaderSize - 27); +} + +RetpolineNoPic::RetpolineNoPic() { + PltHeaderSize = 48; + PltEntrySize = 32; +} + +void RetpolineNoPic::writeGotPlt(uint8_t *Buf, const Symbol &S) const { + write32le(Buf, S.getPltVA() + 16); +} + +void RetpolineNoPic::writePltHeader(uint8_t *Buf) const { + const uint8_t PltData[] = { + 0xff, 0x35, 0, 0, 0, 0, // 0: pushl GOTPLT+4 + 0x50, // 6: pushl %eax + 0xa1, 0, 0, 0, 0, // 7: mov GOTPLT+8, %eax + 0xe8, 0x0f, 0x00, 0x00, 0x00, // c: call next + 0xf3, 0x90, // 11: loop: pause + 0x0f, 0xae, 0xe8, // 13: lfence + 0xeb, 0xf9, // 16: jmp loop + 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, // 18: int3 + 0xcc, 0xcc, 0xcc, // 1f: int3; .align 16 + 0x89, 0x0c, 0x24, // 20: next: mov %ecx, (%esp) + 0x8b, 0x4c, 0x24, 0x04, // 23: mov 0x4(%esp), %ecx + 0x89, 0x44, 0x24, 0x04, // 27: mov %eax ,0x4(%esp) + 0x89, 0xc8, // 2b: mov %ecx, %eax + 0x59, // 2d: pop %ecx + 0xc3, // 2e: ret + }; + memcpy(Buf, PltData, sizeof(PltData)); + + uint32_t GotPlt = InX::GotPlt->getVA(); + write32le(Buf + 2, GotPlt + 4); + write32le(Buf + 8, GotPlt + 8); +} + +void RetpolineNoPic::writePlt(uint8_t *Buf, uint64_t GotPltEntryAddr, + uint64_t PltEntryAddr, int32_t Index, + unsigned RelOff) const { + const uint8_t Insn[] = { + 0x50, // 0: pushl %eax + 0xa1, 0, 0, 0, 0, // 1: mov foo_in_GOT, %eax + 0xe8, 0, 0, 0, 0, // 6: call plt+0x20 + 0xe9, 0, 0, 0, 0, // b: jmp plt+0x11 + 0x68, 0, 0, 0, 0, // 10: pushl $reloc_offset + 0xe9, 0, 0, 0, 0, // 15: jmp plt+0 + }; + memcpy(Buf, Insn, sizeof(Insn)); + + write32le(Buf + 2, GotPltEntryAddr); + write32le(Buf + 7, -Index * PltEntrySize - PltHeaderSize - 11 + 32); + write32le(Buf + 12, -Index * PltEntrySize - PltHeaderSize - 16 + 17); + write32le(Buf + 17, RelOff); + write32le(Buf + 22, -Index * PltEntrySize - PltHeaderSize - 26); +} + TargetInfo *elf::getX86TargetInfo() { - static X86 Target; - return &Target; + if (Config->ZRetpolineplt) { + if (Config->Pic) { + static RetpolinePic T; + return &T; + } + static RetpolineNoPic T; + return &T; + } + + static X86 T; + return &T; } |