[PATCH v2] arm: handle unaligned ABS relocs

[Mike Frysinger <vapier@gentoo.org>]

When relocating a misaligned R_ARM_ABS32, glibc currently crashes.

URL: https://bugs.gentoo.org/394237
URL: http://gcc.gnu.org/PR51456
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

2012-08-12  Mike Frysinger  <vapier@gentoo.org>

	* sysdeps/arm/dl-machine.h (elf_machine_rel) [R_ARM_ABS32]: Declare
	a new unaligned struct.  Cast reloc_addr to that when updating the
	value it points to.
---
 ports/sysdeps/arm/dl-machine.h |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/ports/sysdeps/arm/dl-machine.h b/ports/sysdeps/arm/dl-machine.h
index fe39a5e..ca66e83 100644
--- a/ports/sysdeps/arm/dl-machine.h
+++ b/ports/sysdeps/arm/dl-machine.h
@@ -413,6 +413,10 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc,
 	  break;
 	case R_ARM_ABS32:
 	  {
+	    struct unaligned
+	      {
+		Elf32_Addr x;
+	      } __attribute__((packed, may_alias));
 # ifndef RTLD_BOOTSTRAP
 	   /* This is defined in rtld.c, but nowhere in the static
 	      libc.a; make the reference weak so static programs can
@@ -431,7 +435,8 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc,
 		 used while loading those libraries.  */
 	      value -= map->l_addr + refsym->st_value;
 # endif
-	    *reloc_addr += value;
+	    /* Support relocations on mis-aligned offsets.  */
+	    ((struct unaligned *) reloc_addr)->x += value;
 	    break;
 	  }
 	case R_ARM_TLS_DESC:
-- 
1.7.9.7