buildroot

From 98cadd4b9fa8e32d1d0dea8e46b5ba829af4e8a2 Mon Sep 17 00:00:00 2001

From: Alexey Neyman <stilor@att.net>

Date: Wed, 8 Feb 2017 16:00:57 -0200

Subject: [PATCH] sh: Fix building with gcc5/6

​

Build glibc for sh4-unknown-linux-gnu currently fails if one's

using GCC5/6: in dl-conflict.c, the elf_machine_rela() function

is called with NULL as its 3rd argument, sym. The implementation

of that function in sysdeps/sh/dl-machine.h dereferences that pointer:

​

const Elf32_Sym *const refsym = sym;

...

if (map == &GL(dl_rtld_map))

  value -= map->l_addr + refsym->st_value + reloc->r_addend;

​

GCC discovers a null pointer dereference, and in accordance with

-fdelete-null-pointer-checks (which is enabled in -O2) replaces this

code with a trap - which, as SH does not implement a trap pattern in

GCC, evaluates to an abort() call. This abort() call pulls many more

objects from libc_nonshared.a, eventually resulting in link failure

due to multiple definitions for a number of symbols.

​

As far as I see, the conditional before this code is always false in

rtld: _dl_resolve_conflicts() is called with main_map as the first

argument, not GL(_dl_rtld_map), but since that call is in yet another

compilation unit, GCC does not know about it. Patch that wraps this

conditional into !defined RESOLVE_CONFLICT_FIND_MAP attached.

​

    * sysdeps/sh/dl-machine.h (elf_machine_rela): The condition

    in R_SH_DIR32 case is always false when inlined from

    dl-conflict.c. Ifdef out to prevent GCC from insertin an

    abort() call.

​

[Waldemar: backport of

https://sourceware.org/git/?p=glibc.git;a=commit;h=d40dbe722f004f999b589de776f7e57e564dda01.]

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>

---

 sysdeps/sh/dl-machine.h | 2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

​

diff --git a/sysdeps/sh/dl-machine.h b/sysdeps/sh/dl-machine.h

index 5bb37d0..6509055 100644

--- a/sysdeps/sh/dl-machine.h

+++ b/sysdeps/sh/dl-machine.h

@@ -389,7 +389,7 @@ elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,

      break;

    case R_SH_DIR32:

      {

-#ifndef RTLD_BOOTSTRAP

+#if !defined RTLD_BOOTSTRAP && !defined RESOLVE_CONFLICT_FIND_MAP

       /* This is defined in rtld.c, but nowhere in the static

          libc.a; make the reference weak so static programs can

          still link.  This declaration cannot be done when

-- 

2.7.4

​