http://sourceware.org/bugzilla/show_bug.cgi?id=13581
Bug #: 13581
Summary: R_X86_64_PC32 against global symbol can't be used for
PIC on x32
Product: binutils
Version: 2.23 (HEAD)
Status: NEW
Severity: normal
Priority: P2
Component: ld
AssignedTo: unassig...@sourceware.org
ReportedBy: hjl.to...@gmail.com
Classification: Unclassified
[hjl@gnu-6 gold-2]$ cat x.c
#include <stdio.h>
int bar;
extern void foo ();
int
main ()
{
printf ("main: %d\n", bar);
foo ();
printf ("main: %d\n", bar);
bar += 3;
foo ();
printf ("main: %d\n", bar);
return 0;
}
[hjl@gnu-6 gold-2]$ cat y.c
#include <stdio.h>
extern int bar;
void
foo ()
{
printf ("bar: %d\n", bar);
bar += 2;
}
[hjl@gnu-6 gold-2]$ make
/usr/gcc-4.6.3-x32/bin/gcc -mx32 -g -c y.c
/usr/gcc-4.6.3-x32/bin/gcc -shared -mx32 -g -o y.so y.o
/usr/gcc-4.6.3-x32/bin/gcc -mx32 -g -o x x.c y.so -Wl,-rpath,.
./x
main: 0
make: *** [all] Segmentation fault
[hjl@gnu-6 gold-2]$ gdb x
GNU gdb (GDB) 7.3.50.20110914-cvs
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /export/home/hjl/bugs/binutils/x32/gold-2/x...done.
(gdb) r
Starting program: /export/home/hjl/bugs/binutils/x32/gold-2/x
main: 0
Program received signal SIGSEGV, Segmentation fault.
foo () at y.c:8
8 printf ("bar: %d\n", bar);
(gdb) disass
Dump of assembler code for function foo:
0xf7dfb454 <+0>: push %rbp
0xf7dfb455 <+1>: mov %esp,%ebp
=> 0xf7dfb457 <+3>: mov 0x88053c3(%rip),%edx # 0x600820
0xf7dfb45d <+9>: mov $0xf7dfb4d2,%eax
0xf7dfb462 <+14>: mov %eax,%eax
0xf7dfb464 <+16>: mov %edx,%esi
0xf7dfb466 <+18>: mov %rax,%rdi
0xf7dfb469 <+21>: mov $0x0,%eax
0xf7dfb46e <+26>: callq 0xf7a8a1f0 <printf>
0xf7dfb473 <+31>: mov 0x88053a7(%rip),%eax # 0x600820
0xf7dfb479 <+37>: add $0x2,%eax
0xf7dfb47c <+40>: mov %eax,0x880539e(%rip) # 0x600820
0xf7dfb482 <+46>: pop %rbp
0xf7dfb483 <+47>: retq
End of assembler dump.
(gdb) p &bar
$1 = (int *) 0x600820
(gdb) p $rip
$2 = 4158633047
(gdb) p/x $rip
$3 = 0xf7dfb457
(gdb) p/x $rip + 0x88053c3
$4 = 0x10060081a
(gdb) quit
A debugging session is active.
Inferior 1 [process 10205] will be killed.
Quit anyway? (y or n) y
[hjl@gnu-6 gold-2]$ readelf -r y.o
Relocation section '.rela.text' at offset 0x80c contains 5 entries:
Offset Info Type Sym.Value Sym. Name + Addend
00000005 00001002 R_X86_64_PC32 00000000 bar - 4
0000000a 0000050a R_X86_64_32 00000000 .rodata + 0
0000001b 00001102 R_X86_64_PC32 00000000 printf - 4
00000021 00001002 R_X86_64_PC32 00000000 bar - 4
0000002a 00001002 R_X86_64_PC32 00000000 bar - 4
Here 0x88053c3(%rip) overflows 32bit address space.
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