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.

diff --git a/ChangeLog b/ChangeLog
index 0aedae84ff5749ce86f41aa29f3bee40a3797ec7..9ccb1a34ccfb653de1217ce8c1861bb3b48e5c27 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-03-12  Alexey Neyman <stilor@att.net>
+
+       * 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
+
 2016-03-12  Marko Myllynen  <myllynen@redhat.com>
 
        * sysdeps/unix/sysv/linux/alpha/kernel-features.h

diff --git a/sysdeps/sh/dl-machine.h b/sysdeps/sh/dl-machine.h
index 449deea6fe2b3779270422dd69d9c6a9b2d98242..2b468af6fa1f44b3610797e282c45d5702ea74e3 100644 (file)
--- 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