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Update comments about the entries in .got.plt. 

The original comments were a bit inaccurate because there was no 4 addends.

llvm-svn: 259274
This commit is contained in:
Rui Ueyama 2016-01-29 23:58:03 +00:00
parent a06e8ca6c5
commit cf375935a9
1 changed files with 9 additions and 8 deletions
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17
lld/ELF/Target.cpp
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@ -302,7 +302,8 @@ void X86TargetInfo::writeGotPltHeader(uint8_t *Buf) const {
}
void X86TargetInfo::writeGotPlt(uint8_t *Buf, uint64_t Plt) const {
// Skip 6 bytes of "pushl (GOT+4)"
// Entries in .got.plt initially points back to the corresponding
// PLT entries with a fixed offset to skip the first instruction.
write32le(Buf, Plt + 6);
}
@ -335,8 +336,8 @@ void X86TargetInfo::writePltZero(uint8_t *Buf) const {
if (Config->Shared) {
const uint8_t V[] = {
0xff, 0xb3, 0x04, 0x00, 0x00, 0x00, // pushl 4(%ebx)
0xff, 0xa3, 0x08, 0x00, 0x00, 0x00, // jmp *8(%ebx)
0x90, 0x90, 0x90, 0x90 // nop;nop;nop;nop
0xff, 0xa3, 0x08, 0x00, 0x00, 0x00, // jmp *8(%ebx)
0x90, 0x90, 0x90, 0x90 // nop; nop; nop; nop
};
memcpy(Buf, V, sizeof(V));
return;
@ -344,13 +345,13 @@ void X86TargetInfo::writePltZero(uint8_t *Buf) const {
const uint8_t PltData[] = {
0xff, 0x35, 0x00, 0x00, 0x00, 0x00, // pushl (GOT+4)
0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmp *(GOT+8)
0x90, 0x90, 0x90, 0x90 // nop;nop;nop;nop
0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmp *(GOT+8)
0x90, 0x90, 0x90, 0x90 // nop; nop; nop; nop
};
memcpy(Buf, PltData, sizeof(PltData));
uint32_t Got = Out<ELF32LE>::GotPlt->getVA();
write32le(Buf + 2, Got + 4); // GOT+4
write32le(Buf + 8, Got + 8); // GOT+8
write32le(Buf + 2, Got + 4);
write32le(Buf + 8, Got + 8);
}
void X86TargetInfo::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
@ -609,7 +610,7 @@ void X86_64TargetInfo::writeGotPltHeader(uint8_t *Buf) const {
}
void X86_64TargetInfo::writeGotPlt(uint8_t *Buf, uint64_t Plt) const {
// Skip 6 bytes of "jmpq *got(%rip)"
// See comments in X86TargetInfo::writeGotPlt.
write32le(Buf, Plt + 6);
}