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[ELF] - R_386_GOT32 relocation calculation fix. 

R_386_GOT32 has multiple descriptions:

"System V Application Binary Interface Intel386 Architecture Processor Supplement Version 1.1" (https://github.com/hjl-tools/x86-psABI/wiki/intel386-psABI-1.1.pdf), p36 contains next calculation for R_386_GOT32: G + A - GOT.
SYSTEM V APPLICATION BINARY INTERFACE 4 (https://refspecs.linuxfoundation.org/elf/abi386-4.pdf, p78) tolds us its G + A - P.
Oracle docs (https://docs.oracle.com/cd/E19455-01/816-0559/chapter6-26/index.html) says its should be G + A.

gold/bfd calculates it as "G + A - GOT", but GOT means the end of the GOT section.
Patch fixes current calculation to gold/ld behavior.

Differential revision: http://reviews.llvm.org/D15750

llvm-svn: 258115
This commit is contained in:
George Rimar 2016-01-19 11:00:48 +00:00
parent f82d71f025
commit ffb673515e
2 changed files with 24 additions and 8 deletions
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8
lld/ELF/Target.cpp
View File

@ -426,7 +426,13 @@ void X86TargetInfo::relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type,
case R_386_32: case R_386_32:
add32le(Loc, SA); add32le(Loc, SA);
break; break;
case R_386_GOT32: case R_386_GOT32: {
uint64_t V = SA - Out<ELF32LE>::Got->getVA() -
Out<ELF32LE>::Got->getNumEntries() * 4;
checkInt<32>(V, Type);
add32le(Loc, V);
break;
}
case R_386_GOTOFF: case R_386_GOTOFF:
add32le(Loc, SA - Out<ELF32LE>::Got->getVA()); add32le(Loc, SA - Out<ELF32LE>::Got->getVA());
break; break;

24
lld/test/ELF/relocation-i686.s
View File

@ -45,8 +45,8 @@ movl bar@GOT, %eax
// ADDR-NEXT: SHF_ALLOC // ADDR-NEXT: SHF_ALLOC
// ADDR-NEXT: SHF_EXECINSTR // ADDR-NEXT: SHF_EXECINSTR
// ADDR-NEXT: ] // ADDR-NEXT: ]
// ADDR-NEXT: Address: 0x11030 // ADDR-NEXT: Address: 0x11040
// ADDR-NEXT: Offset: 0x1030 // ADDR-NEXT: Offset: 0x1040
// ADDR-NEXT: Size: 32 // ADDR-NEXT: Size: 32
// ADDR: Name: .got // ADDR: Name: .got
@ -69,16 +69,26 @@ R_386_GOTPC:
.section .dynamic_reloc, "ax",@progbits .section .dynamic_reloc, "ax",@progbits
call bar call bar
// 0x11030 - (0x11019 + 5) = 18 // addr(.plt) + 16 - (0x11019 + 5) = 50
// CHECK: Disassembly of section .dynamic_reloc: // CHECK: Disassembly of section .dynamic_reloc:
// CHECK-NEXT: .dynamic_reloc: // CHECK-NEXT: .dynamic_reloc:
// CHECK-NEXT: 11019: e8 22 00 00 00 calll 34 // CHECK-NEXT: 11019: e8 32 00 00 00 calll 50
.section .R_386_GOT32,"ax",@progbits .section .R_386_GOT32,"ax",@progbits
.global R_386_GOT32 .global R_386_GOT32
R_386_GOT32: R_386_GOT32:
movl zed@GOT, %eax movl bar@GOT, %eax
// This is the second symbol in the got, so the offset is 4. movl zed@GOT, %eax
movl bar+8@GOT, %eax
movl zed+4@GOT, %eax
// 4294967288 = 0xFFFFFFF8 = got[0](0x12070) - .got(0x12070) - sizeof(.got)(8)
// 4294967292 = 0xFFFFFFFC = got[1](0x12074) - .got(0x12070) - sizeof(.got)(8)
// 0xFFFFFFF8 + 8 = 0
// 0xFFFFFFFC + 4 = 0
// CHECK: Disassembly of section .R_386_GOT32: // CHECK: Disassembly of section .R_386_GOT32:
// CHECK-NEXT: R_386_GOT32: // CHECK-NEXT: R_386_GOT32:
// CHECK-NEXT: 1101e: {{.*}} movl 4, %eax // CHECK-NEXT: 1101e: a1 f8 ff ff ff movl 4294967288, %eax
// CHECK-NEXT: 11023: a1 fc ff ff ff movl 4294967292, %eax
// CHECK-NEXT: 11028: a1 00 00 00 00 movl 0, %eax
// CHECK-NEXT: 1102d: a1 00 00 00 00 movl 0, %eax