From c7e17e05b647f6233c2062d038e5421686217816 Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Mon, 13 Jan 2014 13:51:16 +1030 Subject: [PATCH] Error on shared lib call to @local ifunc On powerpc32, making ifuncs have non-default visibility in shared libraries or pies can result in runtime failures. The problem is that if gcc is told that a given function has non-default visibility, then calls to that function are assumed to be local (which is true) and thus need not go via a plt call stub (which is false for ifunc). If the caller has no other reason to set up the got pointer (r30), code won't be emitted to do so. However, a pic plt call stub makes use of r30 to load the plt entry. So a call to an ifunc, which always needs a plt entry, will fail. This patch makes ld emit an error for the problem case, and allows calls to non-default visibility ifuncs to work in normal executables. I also fix some cases where ifuncs fail when using the old bss-plt. * elf32-ppc.c (ppc_elf_check_relocs): For @local call to ifunc, error when shared and force a plt call otherwise. (ppc_elf_size_dynamic_sections): Don't emit DT_PPC_GOT unless plt_type == PLT_NEW. (ppc_elf_relocate_section): Add missing test to resolve ifuncs to the appropriate call stub. --- bfd/elf32-ppc.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c index b601f05eee6..61c45d8437a 100644 --- a/bfd/elf32-ppc.c +++ b/bfd/elf32-ppc.c @@ -4283,6 +4283,20 @@ ppc_elf_check_relocs (bfd *abfd, htab->plt_type = PLT_OLD; htab->old_bfd = abfd; } + if (h != NULL && h->type == STT_GNU_IFUNC) + { + if (info->shared) + { + info->callbacks->einfo (_("%P: %H: @local call to ifunc %s\n"), + abfd, sec, rel->r_offset, + h->root.root.string); + bfd_set_error (bfd_error_bad_value); + return FALSE; + } + h->needs_plt = 1; + if (!update_plt_info (abfd, &h->plt.plist, NULL, 0)) + return FALSE; + } break; /* This relocation describes the C++ object vtable hierarchy. @@ -6481,7 +6495,9 @@ ppc_elf_size_dynamic_sections (bfd *output_bfd ATTRIBUTE_UNUSED, return FALSE; } - if (htab->glink != NULL && htab->glink->size != 0) + if (htab->plt_type == PLT_NEW + && htab->glink != NULL + && htab->glink->size != 0) { if (!add_dynamic_entry (DT_PPC_GOT, 0)) return FALSE; @@ -7863,7 +7879,8 @@ ppc_elf_relocate_section (bfd *output_bfd, unresolved_reloc = FALSE; if (htab->plt_type == PLT_NEW || !htab->elf.dynamic_sections_created - || h == NULL) + || h == NULL + || h->dynindx == -1) relocation = (htab->glink->output_section->vma + htab->glink->output_offset + (ent->glink_offset & ~1)); -- 2.30.2