From 23ec1e32b1ab714649a7c25e49b5d721fe3bd3db Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Mon, 24 Apr 2017 20:15:31 +0100 Subject: [PATCH] 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_dynamic_sections): Also call `_bfd_elf_link_renumber_dynsyms' if the backend has requested it. (bfd_elf_size_dynsym_hash_dynstr): Likewise. ld/ PR ld/21334 * testsuite/ld-mips-elf/pr21334.dd: New test. * testsuite/ld-mips-elf/pr21334.gd: New test. * testsuite/ld-mips-elf/pr21334.ld: New test linker script. * testsuite/ld-mips-elf/pr21334.s: New test source. * testsuite/ld-mips-elf/mips-elf.exp: Run the new tests. --- bfd/ChangeLog | 14 ++++++++++++++ bfd/elf-bfd.h | 4 ++++ bfd/elflink.c | 34 +++++++++++++++++++++++----------- bfd/elfxx-mips.h | 1 + bfd/elfxx-target.h | 6 +++++- ld/ChangeLog | 9 +++++++++ ld/testsuite/ld-mips-elf/mips-elf.exp | 10 ++++++++++ ld/testsuite/ld-mips-elf/pr21334.dd | 10 ++++++++++ ld/testsuite/ld-mips-elf/pr21334.gd | 11 +++++++++++ ld/testsuite/ld-mips-elf/pr21334.ld | 9 +++++++++ ld/testsuite/ld-mips-elf/pr21334.s | 20 ++++++++++++++++++++ 11 files changed, 116 insertions(+), 12 deletions(-) create mode 100644 ld/testsuite/ld-mips-elf/pr21334.dd create mode 100644 ld/testsuite/ld-mips-elf/pr21334.gd create mode 100644 ld/testsuite/ld-mips-elf/pr21334.ld create mode 100644 ld/testsuite/ld-mips-elf/pr21334.s diff --git a/bfd/ChangeLog b/bfd/ChangeLog index 0e6ac1b..c75897c 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_dynamic_sections): Also call + `_bfd_elf_link_renumber_dynsyms' if the backend has requested + it. + (bfd_elf_size_dynsym_hash_dynstr): Likewise. + +2017-04-26 Maciej W. Rozycki + * elflink.c (bfd_elf_size_dynamic_sections): Only call `_bfd_elf_link_renumber_dynsyms' after section GC if dynamic sections have been created. diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h index 4c0c9e8..2649939 100644 --- a/bfd/elf-bfd.h +++ b/bfd/elf-bfd.h @@ -1531,6 +1531,10 @@ 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 05b1211..73af763 100644 --- a/bfd/elflink.c +++ b/bfd/elflink.c @@ -6460,7 +6460,11 @@ bfd_elf_size_dynamic_sections (bfd *output_bfd, 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 (output_bfd, info, §ion_sym_count); } @@ -6828,6 +6832,8 @@ 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; @@ -6835,24 +6841,30 @@ 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); diff --git a/bfd/elfxx-mips.h b/bfd/elfxx-mips.h index 32d8e91..45eb74f 100644 --- a/bfd/elfxx-mips.h +++ b/bfd/elfxx-mips.h @@ -194,3 +194,4 @@ 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 2551267..2e24e11 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 @@ -878,7 +881,8 @@ 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. */ diff --git a/ld/ChangeLog b/ld/ChangeLog index ed3797e..93165f2 100644 --- a/ld/ChangeLog +++ b/ld/ChangeLog @@ -1,3 +1,12 @@ +2017-04-26 Maciej W. Rozycki + + PR ld/21334 + * testsuite/ld-mips-elf/pr21334.dd: New test. + * testsuite/ld-mips-elf/pr21334.gd: New test. + * testsuite/ld-mips-elf/pr21334.ld: New test linker script. + * testsuite/ld-mips-elf/pr21334.s: New test source. + * testsuite/ld-mips-elf/mips-elf.exp: Run the new tests. + 2017-04-24 H.J. Lu * testsuite/ld-x86-64/no-plt.exp: Also check no-plt-1e.nd. diff --git a/ld/testsuite/ld-mips-elf/mips-elf.exp b/ld/testsuite/ld-mips-elf/mips-elf.exp index 3ef9963..f824e7c 100644 --- a/ld/testsuite/ld-mips-elf/mips-elf.exp +++ b/ld/testsuite/ld-mips-elf/mips-elf.exp @@ -1129,3 +1129,13 @@ if { $linux_gnu } { "export-$class-ref"]] } } + +# PR ld/21334 GOT relocation in static binary test. +run_ld_link_tests [list \ + [list \ + "PR ld/21233 MIPS GOT16 relocation in static binary" \ + "$abi_ldflags(o32) -e foo -T pr21334.ld" "" "$abi_asflags(o32)" \ + {pr21334.s} \ + {{objdump {-d --prefix-addresses} pr21334.dd} \ + {readelf -A pr21334.gd}} \ + "pr21334"]] diff --git a/ld/testsuite/ld-mips-elf/pr21334.dd b/ld/testsuite/ld-mips-elf/pr21334.dd new file mode 100644 index 0000000..01c3718 --- /dev/null +++ b/ld/testsuite/ld-mips-elf/pr21334.dd @@ -0,0 +1,10 @@ +.*: +file format .*mips.* + +Disassembly of section \.text: +[0-9a-f]+ <[^>]*> lui gp,0x1 +[0-9a-f]+ <[^>]*> addiu gp,gp,-32736 +[0-9a-f]+ <[^>]*> addu gp,gp,t9 +[0-9a-f]+ <[^>]*> lw v0,-32744\(gp\) +[0-9a-f]+ <[^>]*> jr ra +[0-9a-f]+ <[^>]*> addiu v0,v0,4 + \.\.\. diff --git a/ld/testsuite/ld-mips-elf/pr21334.gd b/ld/testsuite/ld-mips-elf/pr21334.gd new file mode 100644 index 0000000..c8467ee --- /dev/null +++ b/ld/testsuite/ld-mips-elf/pr21334.gd @@ -0,0 +1,11 @@ +Static GOT: + Canonical gp value: 00008020 + + Reserved entries: + Address Access Value + 00000030 -32752\(gp\) 00000000 + 00000034 -32748\(gp\) 80000000 + + Local entries: + Address Access Value + 00000038 -32744\(gp\) 00000000 diff --git a/ld/testsuite/ld-mips-elf/pr21334.ld b/ld/testsuite/ld-mips-elf/pr21334.ld new file mode 100644 index 0000000..5fb94bd --- /dev/null +++ b/ld/testsuite/ld-mips-elf/pr21334.ld @@ -0,0 +1,9 @@ +SECTIONS +{ + .text : { *(.text) } + HIDDEN (_gp = ALIGN (16) + 0x7ff0); + .got : { *(.got) } + .symtab : { *(.symtab) } + .strtab : { *(.strtab) } + /DISCARD/ : { *(*) } +} diff --git a/ld/testsuite/ld-mips-elf/pr21334.s b/ld/testsuite/ld-mips-elf/pr21334.s new file mode 100644 index 0000000..d62c18c --- /dev/null +++ b/ld/testsuite/ld-mips-elf/pr21334.s @@ -0,0 +1,20 @@ + .abicalls + .text + .set noreorder + .globl foo + .ent foo +foo: + .frame $sp, 0, $31 + .mask 0x00000000, 0 + .fmask 0x00000000, 0 + .cpload $25 + lw $2, %got(bar)($28) + jr $31 + addiu $2, $2, 4 + .end foo + .weak bar + .hidden bar + +# Force some (non-delay-slot) zero bytes, to make 'objdump' print ... + .align 4, 0 + .space 16 -- 2.7.4