From 51ffcfc2c67b4c4aa1620fb4c9834c38d150e1c5 Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Wed, 26 Apr 2017 22:23:44 +0100 Subject: PR ld/21334: Always call `_bfd_elf_link_renumber_dynsyms' if required Complement commit e17b0c351f0b ("MIPS/BFD: Respect the ELF gABI dynamic symbol table sort requirement") and correct an inconsistency in dynamic symbol accounting data causing an assertion failure in the MIPS backend: ld: BFD (GNU Binutils) 2.28.51.20170330 assertion fail ../../binutils-gdb/bfd/elfxx-mips.c:3860 in the course of making a GOT entry in a static binary to satisfy a GOT relocation present in input, due to the local dynamic symbol count not having been established. To do so let backends request `_bfd_elf_link_renumber_dynsyms' to be always called, rather than where a dynamic binary is linked only, and then make this request in the MIPS backend. bfd/ PR ld/21334 * elf-bfd.h (elf_backend_data): Add `always_renumber_dynsyms' member. * elfxx-target.h [!elf_backend_always_renumber_dynsyms] (elf_backend_always_renumber_dynsyms): Define. (elfNN_bed): Initialize `always_renumber_dynsyms' member. * elfxx-mips.h (elf_backend_always_renumber_dynsyms): Define. * elflink.c (bfd_elf_size_dynsym_hash_dynstr): Also call `_bfd_elf_link_renumber_dynsyms' if the backend has requested it. (elf_gc_sweep): Likewise. (backported from commit 23ec1e32b1ab714649a7c25e49b5d721fe3bd3db) --- bfd/ChangeLog | 14 ++++++++++++++ bfd/elf-bfd.h | 4 ++++ bfd/elflink.c | 34 +++++++++++++++++++++++----------- bfd/elfxx-mips.h | 1 + bfd/elfxx-target.h | 6 +++++- 5 files changed, 47 insertions(+), 12 deletions(-) diff --git a/bfd/ChangeLog b/bfd/ChangeLog index 537ebb5e2c..3f10bc55f2 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,5 +1,19 @@ 2017-04-26 Maciej W. Rozycki + PR ld/21334 + * elf-bfd.h (elf_backend_data): Add `always_renumber_dynsyms' + member. + * elfxx-target.h [!elf_backend_always_renumber_dynsyms] + (elf_backend_always_renumber_dynsyms): Define. + (elfNN_bed): Initialize `always_renumber_dynsyms' member. + * elfxx-mips.h (elf_backend_always_renumber_dynsyms): Define. + * elflink.c (bfd_elf_size_dynsym_hash_dynstr): Also call + `_bfd_elf_link_renumber_dynsyms' if the backend has requested + it. + (elf_gc_sweep): Likewise. + +2017-04-26 Maciej W. Rozycki + * elflink.c (elf_gc_sweep): Only call `_bfd_elf_link_renumber_dynsyms' if dynamic sections have been created. diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h index 5de9ab6ca6..dc4bd87f89 100644 --- a/bfd/elf-bfd.h +++ b/bfd/elf-bfd.h @@ -1478,6 +1478,10 @@ struct elf_backend_data /* Address of protected data defined in the shared library may be external, i.e., due to copy relocation. */ unsigned extern_protected_data : 1; + + /* True if `_bfd_elf_link_renumber_dynsyms' must be called even for + static binaries. */ + unsigned always_renumber_dynsyms : 1; }; /* Information about reloc sections associated with a bfd_elf_section_data diff --git a/bfd/elflink.c b/bfd/elflink.c index 75d6543dcc..507f2b6259 100644 --- a/bfd/elflink.c +++ b/bfd/elflink.c @@ -6710,6 +6710,8 @@ bfd_boolean bfd_elf_size_dynsym_hash_dynstr (bfd *output_bfd, struct bfd_link_info *info) { const struct elf_backend_data *bed; + unsigned long section_sym_count; + bfd_size_type dynsymcount; if (!is_elf_hash_table (info->hash)) return TRUE; @@ -6717,24 +6719,30 @@ bfd_elf_size_dynsym_hash_dynstr (bfd *output_bfd, struct bfd_link_info *info) bed = get_elf_backend_data (output_bfd); (*bed->elf_backend_init_index_section) (output_bfd, info); + /* Assign dynsym indices. In a shared library we generate a section + symbol for each output section, which come first. Next come all + of the back-end allocated local dynamic syms, followed by the rest + of the global symbols. + + This is usually not needed for static binaries, however backends + can request to always do it, e.g. the MIPS backend uses dynamic + symbol counts to lay out GOT, which will be produced in the + presence of GOT relocations even in static binaries (holding fixed + data in that case, to satisfy those relocations). */ + + if (elf_hash_table (info)->dynamic_sections_created + || bed->always_renumber_dynsyms) + dynsymcount = _bfd_elf_link_renumber_dynsyms (output_bfd, info, + §ion_sym_count); + if (elf_hash_table (info)->dynamic_sections_created) { bfd *dynobj; asection *s; - bfd_size_type dynsymcount; - unsigned long section_sym_count; unsigned int dtagcount; dynobj = elf_hash_table (info)->dynobj; - /* Assign dynsym indicies. In a shared library we generate a - section symbol for each output section, which come first. - Next come all of the back-end allocated local dynamic syms, - followed by the rest of the global symbols. */ - - dynsymcount = _bfd_elf_link_renumber_dynsyms (output_bfd, info, - §ion_sym_count); - /* Work out the size of the symbol version section. */ s = bfd_get_linker_section (dynobj, ".gnu.version"); BFD_ASSERT (s != NULL); @@ -12986,7 +12994,11 @@ elf_gc_sweep (bfd *abfd, struct bfd_link_info *info) elf_link_hash_traverse (elf_hash_table (info), elf_gc_sweep_symbol, &sweep_info); - if (elf_hash_table (info)->dynamic_sections_created) + /* We need to reassign dynsym indices now that symbols may have + been removed. See the call in `bfd_elf_size_dynsym_hash_dynstr' + for the details of the conditions used here. */ + if (elf_hash_table (info)->dynamic_sections_created + || bed->always_renumber_dynsyms) _bfd_elf_link_renumber_dynsyms (abfd, info, §ion_sym_count); return TRUE; } diff --git a/bfd/elfxx-mips.h b/bfd/elfxx-mips.h index fa5b5d2de9..274129b2e5 100644 --- a/bfd/elfxx-mips.h +++ b/bfd/elfxx-mips.h @@ -196,3 +196,4 @@ literal_reloc_p (int r_type) #define elf_backend_post_process_headers _bfd_mips_post_process_headers #define elf_backend_compact_eh_encoding _bfd_mips_elf_compact_eh_encoding #define elf_backend_cant_unwind_opcode _bfd_mips_elf_cant_unwind_opcode +#define elf_backend_always_renumber_dynsyms TRUE diff --git a/bfd/elfxx-target.h b/bfd/elfxx-target.h index d063fb7f1b..d07600c15d 100644 --- a/bfd/elfxx-target.h +++ b/bfd/elfxx-target.h @@ -126,6 +126,9 @@ #ifndef elf_backend_extern_protected_data #define elf_backend_extern_protected_data 0 #endif +#ifndef elf_backend_always_renumber_dynsyms +#define elf_backend_always_renumber_dynsyms FALSE +#endif #ifndef elf_backend_stack_align #define elf_backend_stack_align 16 #endif @@ -866,7 +869,8 @@ static struct elf_backend_data elfNN_bed = elf_backend_no_page_alias, elf_backend_default_execstack, elf_backend_caches_rawsize, - elf_backend_extern_protected_data + elf_backend_extern_protected_data, + elf_backend_always_renumber_dynsyms }; /* Forward declaration for use when initialising alternative_target field. */ -- 2.11.0