From d40dbe722f004f999b589de776f7e57e564dda01 Mon Sep 17 00:00:00 2001 From: Alexey Neyman 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. --- ChangeLog | 6 ++++++ sysdeps/sh/dl-machine.h | 2 +- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/ChangeLog b/ChangeLog index 0aedae84ff..9ccb1a34cc 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2017-03-12 Alexey Neyman + + * 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 * sysdeps/unix/sysv/linux/alpha/kernel-features.h diff --git a/sysdeps/sh/dl-machine.h b/sysdeps/sh/dl-machine.h index 449deea6fe..2b468af6fa 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