arm: handle unaligned ABS relocs

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>

diff --git a/ports/ChangeLog.arm b/ports/ChangeLog.arm
index 34d606d..6775af4 100644 (file)
--- a/ports/ChangeLog.arm
+++ b/ports/ChangeLog.arm
@@ -1,3 +1,9 @@
+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.
+
 2012-08-09  Roland McGrath  <roland@hack.frob.com>
 
        * sysdeps/arm/arm-features.h: Document ARM_ASSUME_NO_IWMMXT.

diff --git a/ports/sysdeps/arm/dl-machine.h b/ports/sysdeps/arm/dl-machine.h
index fe39a5e..ca66e83 100644 (file)
--- 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: