From 0df8ad28f0f727fab3a696d6c98b9a8a77ee1024 Mon Sep 17 00:00:00 2001 From: Nick Clifton Date: Thu, 26 Apr 2018 15:12:42 +0100 Subject: Extend the assembler so that it can automatically generate GNU Build attribute notes if none are present in the input files. gas * as.c (flag_generate_build_notes): New variable. (show_usage): Add entry for --generate-missing-build-notes. (parse_args): Parse --generate-missing-build-notes. * as.h: Export flag_generate_build_notes. * symbols.c (save_symbol_name): Ensure that the name parameter is not NULL. * write.c (create_obj_attrs_section): Reformat. (create_note_reloc): New function - creates a relocation for a field in a GNU Build attribute note. (maybe_generate_build_notes): New function - created GNU Build attribute notes if none are present in the output file. (write_object_file): Call maybe_generate_build_notes. * configure.ac (--enable-generate-build-notes): New option. * NEWS: Announce the new feature. * doc/as.textinfo: Document the new option. * config.in: Regenerate. * configure: Regenerate. binutils* readelf.c (is_32bit_abs_reloc): Support R_PARISC_DIR32 as a 32-bit absolute reloc for the HPPA target. * testsuite/binutils-all/note-5.d: New test. * testsuite/binutils-all/note-5.s: Source file for new test. * testsuite/binutils-all/objcopy.exp: Run new test. --- gas/write.c | 213 +++++++++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 197 insertions(+), 16 deletions(-) (limited to 'gas/write.c') diff --git a/gas/write.c b/gas/write.c index 2d0bbe4..b902bf8 100644 --- a/gas/write.c +++ b/gas/write.c @@ -1867,25 +1867,200 @@ create_obj_attrs_section (void) const char *name; size = bfd_elf_obj_attr_size (stdoutput); - if (size) + if (size == 0) + return; + + name = get_elf_backend_data (stdoutput)->obj_attrs_section; + if (!name) + name = ".gnu.attributes"; + s = subseg_new (name, 0); + elf_section_type (s) + = get_elf_backend_data (stdoutput)->obj_attrs_section_type; + bfd_set_section_flags (stdoutput, s, SEC_READONLY | SEC_DATA); + frag_now_fix (); + p = frag_more (size); + bfd_elf_set_obj_attr_contents (stdoutput, (bfd_byte *)p, size); + + subsegs_finish_section (s); + relax_segment (seg_info (s)->frchainP->frch_root, s, 0); + size_seg (stdoutput, s, NULL); +} + +#include "struc-symbol.h" + +/* Create a relocation against an entry in a GNU Build attribute section. */ + +static void +create_note_reloc (segT sec, + symbolS * sym, + bfd_size_type offset, + int reloc_type, + bfd_vma addend, + char * note) +{ + struct reloc_list * reloc; + + reloc = XNEW (struct reloc_list); + + /* We create a .b type reloc as resolve_reloc_expr_symbols() has already been called. */ + reloc->u.b.sec = sec; + reloc->u.b.s = sym->bsym; + reloc->u.b.r.sym_ptr_ptr = & reloc->u.b.s; + reloc->u.b.r.address = offset; + reloc->u.b.r.addend = addend; + reloc->u.b.r.howto = bfd_reloc_type_lookup (stdoutput, reloc_type); + + if (reloc->u.b.r.howto == NULL) { - name = get_elf_backend_data (stdoutput)->obj_attrs_section; - if (!name) - name = ".gnu.attributes"; - s = subseg_new (name, 0); - elf_section_type (s) - = get_elf_backend_data (stdoutput)->obj_attrs_section_type; - bfd_set_section_flags (stdoutput, s, SEC_READONLY | SEC_DATA); - frag_now_fix (); - p = frag_more (size); - bfd_elf_set_obj_attr_contents (stdoutput, (bfd_byte *)p, size); - - subsegs_finish_section (s); - relax_segment (seg_info (s)->frchainP->frch_root, s, 0); - size_seg (stdoutput, s, NULL); + as_bad (_("unable to create reloc for build note")); + return; + } + + reloc->file = N_(""); + reloc->line = 0; + + reloc->next = reloc_list; + reloc_list = reloc; + + /* For REL relocs, store the addend in the section. */ + if (! sec->use_rela_p + /* The SH target is a special case that uses RELA relocs + but still stores the addend in the word being relocated. */ + || strstr (bfd_get_target (stdoutput), "-sh") != NULL) + { + if (target_big_endian) + { + if (bfd_arch_bits_per_address (stdoutput) <= 32) + note[offset + 3] = addend; + else + note[offset + 7] = addend; + } + else + note[offset] = addend; } } -#endif + +static void +maybe_generate_build_notes (void) +{ + segT sec; + char * note; + offsetT note_size; + offsetT desc_size; + offsetT desc2_offset; + int desc_reloc; + symbolS * sym; + + if (! flag_generate_build_notes + || bfd_get_section_by_name (stdoutput, + GNU_BUILD_ATTRS_SECTION_NAME) != NULL) + return; + + /* Create a GNU Build Attribute section. */ + sec = subseg_new (GNU_BUILD_ATTRS_SECTION_NAME, FALSE); + elf_section_type (sec) = SHT_NOTE; + bfd_set_section_flags (stdoutput, sec, + SEC_READONLY | SEC_HAS_CONTENTS | SEC_DATA); + bfd_set_section_alignment (stdoutput, sec, 2); + + /* Create a version note. */ + if (bfd_arch_bits_per_address (stdoutput) <= 32) + { + note_size = 28; + desc_size = 8; /* Two 4-byte offsets. */ + desc2_offset = 24; + + /* FIXME: The BFD backend for the CRX target does not support the + BFD_RELOC_32, even though it really should. Likewise for the + CR16 target. So we have special case code here... */ + if (strstr (bfd_get_target (stdoutput), "-crx") != NULL) + desc_reloc = BFD_RELOC_CRX_NUM32; + else if (strstr (bfd_get_target (stdoutput), "-cr16") != NULL) + desc_reloc = BFD_RELOC_CR16_NUM32; + else + desc_reloc = BFD_RELOC_32; + } + else + { + note_size = 36; + desc_size = 16; /* Two 8-byte offsets. */ + desc2_offset = 28; + /* FIXME: The BFD backend for the IA64 target does not support the + BFD_RELOC_64, even though it really should. The HPPA backend + has a similar issue, although it does not support BFD_RELOCs at + all! So we have special case code to handle these targets. */ + if (strstr (bfd_get_target (stdoutput), "-ia64") != NULL) + desc_reloc = target_big_endian ? BFD_RELOC_IA64_DIR32MSB : BFD_RELOC_IA64_DIR32LSB; + else if (strstr (bfd_get_target (stdoutput), "-hppa") != NULL) + desc_reloc = 80; /* R_PARISC_DIR64. */ + else + desc_reloc = BFD_RELOC_64; + } + + frag_now_fix (); + note = frag_more (note_size); + memset (note, 0, note_size); + + if (target_big_endian) + { + note[3] = 8; /* strlen (name) + 1. */ + note[7] = desc_size; /* Two 8-byte offsets. */ + note[10] = NT_GNU_BUILD_ATTRIBUTE_OPEN >> 8; + note[11] = NT_GNU_BUILD_ATTRIBUTE_OPEN & 0xff; + } + else + { + note[0] = 8; /* strlen (name) + 1. */ + note[4] = desc_size; /* Two 8-byte offsets. */ + note[8] = NT_GNU_BUILD_ATTRIBUTE_OPEN & 0xff; + note[9] = NT_GNU_BUILD_ATTRIBUTE_OPEN >> 8; + } + + /* The a1 version number indicates that this note was + generated by the assembler and not the gcc annobin plugin. */ + memcpy (note + 12, "GA$3a1", 8); + + /* Find the first code section symbol. */ + for (sym = symbol_rootP; sym != NULL; sym = sym->sy_next) + if (sym->bsym != NULL + && sym->bsym->flags & BSF_SECTION_SYM + && sym->bsym->section != NULL + && sym->bsym->section->flags & SEC_CODE) + { + /* Found one - now create a relocation against this symbol. */ + create_note_reloc (sec, sym, 20, desc_reloc, 0, note); + break; + } + + /* Find the last code section symbol. */ + if (sym) + { + for (sym = symbol_lastP; sym != NULL; sym = sym->sy_previous) + if (sym->bsym != NULL + && sym->bsym->flags & BSF_SECTION_SYM + && sym->bsym->section != NULL + && sym->bsym->section->flags & SEC_CODE) + { + /* Create a relocation against the end of this symbol. */ + create_note_reloc (sec, sym, desc2_offset, desc_reloc, + bfd_get_section_size (sym->bsym->section), + note); + break; + } + } + /* else - if we were unable to find any code section symbols then + probably there is no code in the output. So leaving the start + and end values as zero in the note is OK. */ + + /* FIXME: Maybe add a note recording the assembler command line and version ? */ + + /* Install the note(s) into the section. */ + bfd_set_section_contents (stdoutput, sec, (bfd_byte *) note, 0, note_size); + subsegs_finish_section (sec); + relax_segment (seg_info (sec)->frchainP->frch_root, sec, 0); + size_seg (stdoutput, sec, NULL); +} +#endif /* OBJ_ELF */ /* Write the object file. */ @@ -2097,6 +2272,11 @@ write_object_file (void) resolve_local_symbol_values (); resolve_reloc_expr_symbols (); +#ifdef OBJ_ELF + if (IS_ELF) + maybe_generate_build_notes (); +#endif + PROGRESS (1); #ifdef tc_frob_file_before_adjust @@ -2273,6 +2453,7 @@ write_object_file (void) #ifdef obj_coff_generate_pdata obj_coff_generate_pdata (); #endif + bfd_map_over_sections (stdoutput, write_relocs, (char *) 0); #ifdef tc_frob_file_after_relocs -- cgit v1.1