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cmd/link: work around arm64 linker bugs with GOT relocations against local symbols

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Change-Id: Ie14530c57720f1af1960ab77686b860e906058c6
Reviewed-on: https://go-review.googlesource.com/16582
Reviewed-by: Russ Cox <rsc@golang.org>
This commit is contained in:
Michael Hudson-Doyle 2015-11-03 10:23:56 +13:00
parent 3534e2bef4
commit 4bae454d68
1 changed files with 32 additions and 2 deletions
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34
src/cmd/link/internal/arm64/asm.go
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@ -241,8 +241,38 @@ func archreloc(r *ld.Reloc, s *ld.LSym, val *int64) int {
default:
return -1
case obj.R_ADDRARM64,
obj.R_ARM64_GOTPCREL:
case obj.R_ARM64_GOTPCREL:
var o1, o2 uint32
if ld.Ctxt.Arch.ByteOrder == binary.BigEndian {
o1 = uint32(*val >> 32)
o2 = uint32(*val)
} else {
o1 = uint32(*val)
o2 = uint32(*val >> 32)
}
// Any relocation against a function symbol is redirected to
// be against a local symbol instead (see putelfsym in
// symtab.go) but unfortunately the system linker was buggy
// when confronted with a R_AARCH64_ADR_GOT_PAGE relocation
// against a local symbol until May 2015
// (https://sourceware.org/bugzilla/show_bug.cgi?id=18270). So
// we convert the adrp; ld64 + R_ARM64_GOTPCREL into adrp;
// add + R_ADDRARM64.
if !(r.Sym.Version != 0 || (r.Sym.Type&obj.SHIDDEN != 0) || r.Sym.Local) && r.Sym.Type == obj.STEXT && ld.DynlinkingGo() {
if o2&0xffc00000 != 0xf9400000 {
ld.Ctxt.Diag("R_ARM64_GOTPCREL against unexpected instruction %x", o2)
}
o2 = 0x91000000 | (o2 & 0x000003ff)
r.Type = obj.R_ADDRARM64
}
if ld.Ctxt.Arch.ByteOrder == binary.BigEndian {
*val = int64(o1)<<32 | int64(o2)
} else {
*val = int64(o2)<<32 | int64(o1)
}
fallthrough
case obj.R_ADDRARM64:
r.Done = 0
// set up addend for eventual relocation via outer symbol.