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ld: fix Mach-O X86_64_RELOC_SIGNED relocations

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Fixes #1658.

R=rsc
CC=golang-dev
https://golang.org/cl/4344066
This commit is contained in:
Mikkel Krautz 2011-04-07 14:20:42 -04:00 committed by Russ Cox
parent cf3323f511
commit 2aceea630f
1 changed files with 24 additions and 2 deletions
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26
src/cmd/ld/ldmacho.c
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@ -422,6 +422,7 @@ void
ldmacho(Biobuf *f, char *pkg, int64 len, char *pn)
{
int i, j, is64;
uint64 secaddr;
uchar hdr[7*4], *cmdp;
uchar tmp[4];
uchar *dat;
@ -754,8 +755,29 @@ ldmacho(Biobuf *f, char *pkg, int64 len, char *pn)
rp->siz = rel->length;
rp->type = 512 + (rel->type<<1) + rel->pcrel;
rp->off = rel->addr;
rp->add = e->e32(s->p+rp->off);
// Handle X86_64_RELOC_SIGNED referencing a section (rel->extrn == 0).
if (thechar == '6' && rel->extrn == 0 && rel->type == 1) {
// Calculate the addend as the offset into the section.
//
// The rip-relative offset stored in the object file is encoded
// as follows:
//
// movsd 0x00000360(%rip),%xmm0
//
// To get the absolute address of the value this rip-relative address is pointing
// to, we must add the address of the next instruction to it. This is done by
// taking the address of the relocation and adding 4 to it (since the rip-relative
// offset can at most be 32 bits long). To calculate the offset into the section the
// relocation is referencing, we subtract the vaddr of the start of the referenced
// section found in the original object file.
//
// [For future reference, see Darwin's /usr/include/mach-o/x86_64/reloc.h]
secaddr = c->seg.sect[rel->symnum-1].addr;
rp->add = e->e32(s->p+rp->off) + rp->off + 4 - secaddr;
} else
rp->add = e->e32(s->p+rp->off);
// For i386 Mach-O PC-relative, the addend is written such that
// it *is* the PC being subtracted. Use that to make
// it match our version of PC-relative.