ARM: Fix R_ARM_IRELATIVE RELA relocations.

This patch fixes what I believe to be a bug in the handling of
R_ARM_IRELATIVE RELA relocations. At present, these are handled the
same as REL relocations: i.e. the addend is loaded from the relocation
address. Most of the time this isn't a problem because RELA relocations
aren't used on ARM (GNU/Linux at least) anyway, but it causes problems
with prelink, which uses RELA on all targets for its conflict table.
(Support for ifunc prelinking requires a prelink patch, not yet posted.)

Anyway, this patch works, though I'm not 100% sure if it is correct: I
notice that this code path received attention last year:

https://sourceware.org/ml/libc-ports/2013-07/msg00000.html

I'm not sure under what circumstances that patch would have had an
effect, nor if my patch conflicts with that case.

No regressions using Mentor's usual glibc cross-testing infrastructure.

	[BZ #16888]
	* sysdeps/arm/dl-machine.h (elf_machine_rela): Fix R_ARM_IRELATIVE
	handling.

diff --git a/ChangeLog b/ChangeLog
index e0d131d..1e6dda8 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2014-04-30  Julian Brown  <julian@codesourcery.com>
+
+       [BZ #16888]
+       * sysdeps/arm/dl-machine.h (elf_machine_rela): Fix R_ARM_IRELATIVE
+       handling.
+
 2014-04-30  Joseph Myers  <joseph@codesourcery.com>
 
        [BZ #9894]

diff --git a/NEWS b/NEWS
index 9d4db05..445acab 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -15,7 +15,7 @@ Version 2.20
   16632, 16634, 16639, 16642, 16648, 16649, 16670, 16674, 16677, 16680,
   16683, 16689, 16695, 16701, 16706, 16707, 16712, 16713, 16714, 16731,
   16739, 16740, 16743, 16754, 16758, 16759, 16760, 16770, 16786, 16789,
-  16791, 16799, 16800, 16815, 16823, 16824, 16831, 16838, 16854.
+  16791, 16799, 16800, 16815, 16823, 16824, 16831, 16838, 16854, 16888.
 
 * The minimum Linux kernel version that this version of the GNU C Library
   can be used with is 2.6.32.

diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h
index 02d1a5e..899b256 100644 (file)
--- a/sysdeps/arm/dl-machine.h
+++ b/sysdeps/arm/dl-machine.h
@@ -594,7 +594,7 @@ elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
            }
          break;
        case R_ARM_IRELATIVE:
-         value = map->l_addr + *reloc_addr;
+         value = map->l_addr + reloc->r_addend;
          value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
          *reloc_addr = value;
          break;