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[PATCH] ARM: Fix R_ARM_IRELATIVE RELA relocations


Hi,

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.
OK to apply?

(Strangely, this appears to be my first glibc patch, so I'm not
entirely certain if I have write access!)

Thanks,

Julian

ChangeLog

    * sysdeps/arm/dl-machine.h (elf_machine_rela): Fix R_ARM_IRELATIVE
    handling.
diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h
index 02d1a5e..899b256 100644
--- 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;

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