[Bug gold/14091] New: Gold doesn't handle R_X86_64_RELATIVE properly for x32

[hjl.tools at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14091

             Bug #: 14091
           Summary: Gold doesn't handle R_X86_64_RELATIVE properly for x32
           Product: binutils
           Version: 2.23 (HEAD)
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gold
        AssignedTo: address@hidden
        ReportedBy: address@hidden
                CC: address@hidden
    Classification: Unclassified


address@hidden gold]$ cat main.c 
extern void foo (void);

int
main (void)
{
  foo ();
  return 0;
}
address@hidden gold]$ cat tst-quadmod2.S
#define BIAS 0x7fff0000

    .section    .data.rel.local,"aw",@progbits
    .align 8
.Ljmp:
    .quad    func + BIAS
    .text
    .type    func, @function
func:
    .cfi_startproc
    xorl    %edi, %edi
    jmp    address@hidden
    .cfi_endproc
    .size    func, .-func
    .globl    foo
    .type    foo, @function
foo:
    .cfi_startproc
    .cfi_def_cfa_register 6
    movq    .Ljmp(%rip), %rax
    subq    $BIAS, %rax
    jmp    *%rax
    .cfi_endproc
    .size    foo, .-foo
address@hidden gold]$ make
gcc -B./ -mx32 -g   -c -o main.o main.c
gcc -B./ -mx32 -c -g -o tst-quadmod2.o tst-quadmod2.S
./ld -shared -m elf32_x86_64 -o libtst-quadmod2.so tst-quadmod2.o
gcc -B./ -mx32 -g -o x2 main.o libtst-quadmod2.so -Wl,-rpath,.
./readelf -r --wide libtst-quadmod2.so

Relocation section '.rela.dyn' at offset 0x164 contains 1 entries:
 Offset     Info    Type                Sym. Value  Symbol's Name + Addend
000012f0  00000008 R_X86_64_RELATIVE                  7fff01a0

Relocation section '.rela.plt' at offset 0x170 contains 1 entries:
 Offset     Info    Type                Sym. Value  Symbol's Name + Addend
000012e8  00000107 R_X86_64_JUMP_SLOT     00000000   exit + 0
./x2
make: *** [all] Segmentation fault
address@hidden gold]$ 

The problem is

address@hidden gold]$ readelf -rW tst-quadmod2.o
...
 Offset     Info    Type                Sym. Value  Symbol's Name + Addend
00000000  00000101 R_X86_64_64            00000000   .text + 7fff0000

Symbol value + addend > 32bits at run-time.  BFD linker generates:

address@hidden gold]$ make LD=ld
gcc -B./ -mx32 -g   -c -o main.o main.c
gcc -B./ -mx32 -c -g -o tst-quadmod2.o tst-quadmod2.S
ld -shared -m elf32_x86_64 -o libtst-quadmod2.so tst-quadmod2.o
gcc -B./ -mx32 -g -o x2 main.o libtst-quadmod2.so -Wl,-rpath,.
./readelf -r --wide libtst-quadmod2.so

Relocation section '.rela.dyn' at offset 0x158 contains 1 entries:
 Offset     Info    Type                Sym. Value  Symbol's Name + Addend
002002b0  00000026 R_X86_64_RELATIVE64                 7fff0190

Relocation section '.rela.plt' at offset 0x164 contains 1 entries:
 Offset     Info    Type                Sym. Value  Symbol's Name + Addend
address@hidden gold]$ 

The difference is R_X86_64_RELATIVE64 vs R_X86_64_RELATIVE.  For
R_X86_64_64, we need to generate R_X86_64_RELATIVE64.

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