https://sourceware.org/bugzilla/show_bug.cgi?id=16202
Bug ID: 16202
Summary: ABS8 and ABS16 get wrong addend on ARM-ELF (big
endian)
Product: binutils
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: gas
Assignee: unassigned at sourceware dot org
Reporter: ma.jiang at zte dot com.cn
on ARM-ELF , in function elf32_arm_final_link_relocate, addend is get from :
addend = bfd_get_32 (input_bfd, hit_data) & howto->src_mask;
.There is a little problem, becasue howto->scr_mask is a constant that designed
for little endian.
for example , in the testcase in gas testsuit:
.syntax unified
.byte x -128
.byte x +255
.short y -32768
.short y +65535
the first ABS8 reloc for x should get a addend -128.But on big endian ARM,
"bfd_get_32 (input_bfd, hit_data)" get a 0x80ff8000, and with a
howto->src_mask=0xff, the final addend is 0.
in the ABS8 branch, the addend is used directly.
case R_ARM_ABS8:
value += addend;
/* There is no way to tell whether the user intended to use a signed or
unsigned addend. When checking for overflow we accept either,
as specified by the AAELF. */
if ((long) value > 0xff || (long) value < -0x80)
return bfd_reloc_overflow;
bfd_put_8 (input_bfd, value, hit_data);
return bfd_reloc_ok;
Finally, a 0 is put into the object file, which of course is totally wrong.
ABS16 has the same problem.
============================================================================
Fix for this problem is quite strait-forward. IN ABS8/ABS16 branch, we can
fetch addend once more using correct bfd_get_8/bfd_get_16, as following codes :
case R_ARM_ABS8:
addend = bfd_get_8 (input_bfd, hit_data); /*fectch addend again with
bfd_get_8 */
value += addend;
/* There is no way to tell whether the user intended to use a signed or
unsigned addend. When checking for overflow we accept either,
as specified by the AAELF. */
if ((long) value > 0xff || (long) value < -0x80)
return bfd_reloc_overflow;
bfd_put_8 (input_bfd, value, hit_data);
return bfd_reloc_ok;
.
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