Compact EH Support

The specification for the Compact EH format is available at:
https://github.com/MentorEmbedded/cxx-abi/blob/master/MIPSCompactEH.pdf

2015-05-28  Catherine Moore  <clm@codesourcery.com>
	    Bernd Schmidt <bernds@codesourcery.com>
	    Paul Brook <paul@codesourcery.com>

	bfd/
	* bfd-in2.h: Regenerated.
	* elf-bfd.h (DWARF2_EH_HDR, COMPACT_EH_HDR): Define.
	(COMPACT_EH_CANT_UNWIND_OPCODE): Define.
	(dwarf_eh_frame_hdr_info): Move dwarf-specific fields from
	eh_frame_hdr_info.
	(compact_eh_frame_hdr_info): Declare.
	(eh_frame_hdr_info):  Redeclare with union for dwarf-specific
	fields and compact-eh fields.
	(elf_backend_data): Add cant_unwind_opcode and compact_eh_encoding.
	(bfd_elf_section_data): Add eh_frame_entry_field.
	(elf_section_eh_frame_entry): Define.
	(bfd_elf_parse_eh_frame_entries): Declare.
	(_bfd_elf_parse_eh_frame_entry): Declare.
	(_bfd_elf_end_eh_frame_parsing): Declare.
	(_bfd_elf_write_section_eh_frame_entry): Declare.
	(_bfd_elf_eh_frame_entry_present): Declare.
	(_bfd_elf_section_for_symbol): Declare.
	* elf-eh-frame.c (bfd_elf_discard_eh_frame_entry): New function.
	(bfd_elf_record_eh_frame_entry): New function.
	(_bfd_elf_parse_eh_frame_entry): New function.
	(_bfd_elf_parse_eh_frame): Update hdr_info field references.
	(cmp_eh_frame_hdr): New function.
	(add_eh_frame_hdr_terminator): New function.
	(_bfd_elf_end_eh_frame_parsing): New function.
	(find_merged_cie): Update hdr_info field references.
	(_bfd_elf_discard_section_eh_frame): Likewise.
	(_bfd_elf_discard_section_eh_frame_hdr): Add Compact EH support.
	(_bfd_elf_eh_frame_entry_present): New function.
	(_bfd_elf_maybe_strip_eh_frame_hdr): Add Compact EH support.
	(_bfd_elf_write_section_eh_frame_entry): New function.
	(_bfd_elf_write_section_eh_frame): Update hdr_info field references.
	(_bfd_elf_fixup_eh_frame_hdr): New function.
	(write_compact_eh_frame_hdr): New function.
	(write_dwarf_eh_frame_hdr): New function.
	(_bfd_elf_write_section_eh_frame_hdr): Add Compact EH support.
	* elflink.c (_bfd_elf_section_for_symbol): New function.
	(elf_section_ignore_discarded_relocs): Add Compact EH support.
	(elf_link_input_bfd): Likewise.
	(bfd_elf_final_link): Likewise.
	(_bfd_elf_gc_mark): Likewise.
	(bfd_elf_parse_eh_frame_entries): New function.
	(bfd_elf_gc_sections): Add Compact EH support.
	(bfd_elf_discard_info): Likewise.
	* elfxx-mips.c: Include dwarf2.h.
	(_bfd_mips_elf_compact_eh_encoding): New function.
	(_bfd_mips_elf_cant_unwind_opcode): New function.
	* elfxx-mips.h (_bfd_mips_elf_compact_eh_encoding): Declare.
	(_bfd_mips_elf_cant_unwind_opcode): Declare.
	(elf_backend_compact_eh_encoding): Define.
	(elf_backend_cant_unwind_opcode): Define.
	* elfxx-target.h (elf_backend_compact_eh_encoding): Provide default.
	(elf_backend_cant_unwind_opcode): Provide default.
	(elf_backend_data elfNN_bed): Add elf_backend_compact_eh_encoding and
	elf_backend_cant_unwind_opcode.
	* section.c (SEC_INFO_TYPE_EH_FRAME_ENTRY): Add definition.

	gas/
	* config/tc-alpha.c (all_cfi_sections): Declare.
	(s_alpha_ent): Initialize all_cfi_sections.
	(alpha_elf_md_end): Invoke cfi_set_sections.
	* config/tc-mips.c (md_apply_fix):  Handle BFD_RELOC_NONE.
	(s_ehword): Use BFD_RELOC_32_PCREL.
	(mips_fix_adjustable): Handle BFD_RELOC_32_PCREL.
	(mips_cfi_reloc_for_encoding): New function.
	* tc-mips.h (DWARF2_FDE_RELOC_SIZE): Redefine.
	(DWARF2_FDE_RELOC_ENCODING): Define.
	(tc_cfi_reloc_for_encoding): Define.
	(mips_cfi_reloc_for_encoding): Define.
	(tc_compact_eh_opcode_stop): Define.
	(tc_compact_eh_opcode_pad): Define.
	* doc/as.texinfo: Document Compact EH extensions.
	* doc/internals.texi: Likewise.
	* dw2gencfi.c (EH_FRAME_LINKONCE): Redefine.
	(tc_cfi_reloc_for_encoding): Provide default.
	(compact_eh): Declare.
	(emit_expr_encoded): New function.
	(get_debugseg_name): Add Compact EH support.
	(alloc_debugseg_item): Likewise.
	(cfi_set_sections): New function.
	(dot_cfi_fde_data): New function.
	(dot_cfi_personality_id): New function.
	(dot_cfi_inline_lsda): New function.
	(cfi_pseudo_table): Add cfi_fde_data, cfi_personality_id,
	and cfi_inline_lsda.
	(dot_cfi_personality): Add Compact EH support.
	(dot_cfi_lsda): Likewise.
	(dot_cfi_sections): Likewise.
	(dot_cfi_startproc): Likewise.
	(get_cfi_seg): Likewise.
	(output_compact_unwind_data): New function.
	(output_cfi_insn): Add Compact EH support.
	(output_cie): Likewise.
	(output_fde): Likewise.
	(cfi_finish): Likewise.
	(cfi_emit_eh_header): New function.
	(output_eh_header): New function.
	* dw2gencfi.h (cfi_set_sections): Declare.
	(SUPPORT_COMPACT_EH): Define.
	(MULTIPLE_FRAME_SECTIONS): Define.
	New enumeration to describe the Compact EH header format.
	(fde_entry): Add new fields personality_id, eh_header_type, eh_data_size,
	eh_data, eh_loc and sections.
	(CFI_EMIT_eh_frame, CFI_EMIT_debug_frame, CFI_EMIT_target,
	CFI_EMIT_eh_frame_compact): Define.

2015-05-22  Catherine Moore  <clm@codesourcery.com>
	    Bernd Schmidt <bernds@codesourcery.com>

	gas/testsuite/
	* gas/mips/mips.exp: Run new tests.

	* gas/mips/compact-eh-1.s: New file.
	* gas/mips/compact-eh-2.s: New file.
	* gas/mips/compact-eh-3.s: New file.
	* gas/mips/compact-eh-4.s: New file.
	* gas/mips/compact-eh-5.s: New file.
	* gas/mips/compact-eh-6.s: New file.
	* gas/mips/compact-eh-7.s: New file.
	* gas/mips/compact-eh-eb-1.d: New file.
	* gas/mips/compact-eh-eb-2.d: New file.
	* gas/mips/compact-eh-eb-3.d: New file.
	* gas/mips/compact-eh-eb-4.d: New file.
	* gas/mips/compact-eh-eb-5.d: New file.
	* gas/mips/compact-eh-eb-6.d: New file.
	* gas/mips/compact-eh-eb-7.d: New file.
	* gas/mips/compact-eh-el-1.d: New file.
	* gas/mips/compact-eh-el-2.d: New file.
	* gas/mips/compact-eh-el-3.d: New file.
	* gas/mips/compact-eh-el-4.d: New file.
	* gas/mips/compact-eh-el-5.d: New file.
	* gas/mips/compact-eh-el-6.d: New file.
	* gas/mips/compact-eh-el-7.d: New file.
	* gas/mips/compact-eh-err1.l: New file.
	* gas/mips/compact-eh-err1.s: New file.
	* gas/mips/compact-eh-err2.l: New file.
	* gas/mips/compact-eh-err2.s: New file.

2015-05-22  Catherine Moore  <clm@codesourcery.com>

	include/
	* bfdlink.h: Rename eh_frame_hdr to eh_frame_hdr_type.

2015-05-22  Catherine Moore  <clm@codesourcery.com>
	    Paul Brook <paul@codesourcery.com>

	ld/
	* emultempl/elf32.em (gld${EMULATION_NAME}_after_open):
	Add Compact EH support.
	* scripttempl/elf.sc: Handle .eh_frame_entry and .gnu_extab
	sections.

2015-05-22  Catherine Moore  <clm@codesourcery.com>

	ld/testsuite/
	* ld-mips-elf/compact-eh.ld: New linker script.
	* ld-mips-elf/compact-eh1.d: New.
	* ld-mips-elf/compact-eh1.s: New.
	* ld-mips-elf/compact-eh1a.s: New.
	* ld-mips-elf/compact-eh1b.s: New.
	* ld-mips-elf/compact-eh2.d: New.
	* ld-mips-elf/compact-eh2.s: New.
	* ld-mips-elf/compact-eh3.d: New.
	* ld-mips-elf/compact-eh3.s: New.
	* ld-mips-elf/compact-eh3a.s: New.
	* ld-mips-elf/compact-eh4.d: New.
	* ld-mips-elf/compact-eh5.d: New.
	* ld-mips-elf/compact-eh6.d: New.
	* ld-mips-elf/mips-elf.exp: Run new tests.

1 files changed, 98 insertions, 3 deletions

diff --git a/bfd/elflink.c b/bfd/elflink.c
index 6efe1e4..9520906 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -54,6 +54,47 @@ struct elf_find_verdep_info
 static bfd_boolean _bfd_elf_fix_symbol_flags
   (struct elf_link_hash_entry *, struct elf_info_failed *);
 
+asection *
+_bfd_elf_section_for_symbol (struct elf_reloc_cookie *cookie,
+			     unsigned long r_symndx,
+			     bfd_boolean discard)
+{
+  if (r_symndx >= cookie->locsymcount
+      || ELF_ST_BIND (cookie->locsyms[r_symndx].st_info) != STB_LOCAL)
+    {
+      struct elf_link_hash_entry *h;
+
+      h = cookie->sym_hashes[r_symndx - cookie->extsymoff];
+
+      while (h->root.type == bfd_link_hash_indirect
+	     || h->root.type == bfd_link_hash_warning)
+	h = (struct elf_link_hash_entry *) h->root.u.i.link;
+
+      if ((h->root.type == bfd_link_hash_defined
+	   || h->root.type == bfd_link_hash_defweak)
+	   && discarded_section (h->root.u.def.section))
+        return h->root.u.def.section;
+      else
+	return NULL;
+    }
+  else
+    {
+      /* It's not a relocation against a global symbol,
+	 but it could be a relocation against a local
+	 symbol for a discarded section.  */
+      asection *isec;
+      Elf_Internal_Sym *isym;
+
+      /* Need to: get the symbol; get the section.  */
+      isym = &cookie->locsyms[r_symndx];
+      isec = bfd_section_from_elf_index (cookie->abfd, isym->st_shndx);
+      if (isec != NULL
+	  && discard ? discarded_section (isec) : 1)
+	return isec;
+     }
+  return NULL;
+}
+
 /* Define a symbol in a dynamic linkage section.  */
 
 struct elf_link_hash_entry *
@@ -9284,6 +9325,7 @@ elf_section_ignore_discarded_relocs (asection *sec)
     {
     case SEC_INFO_TYPE_STABS:
     case SEC_INFO_TYPE_EH_FRAME:
+    case SEC_INFO_TYPE_EH_FRAME_ENTRY:
       return TRUE;
     default:
       break;
@@ -10215,6 +10257,14 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
 	      return FALSE;
 	  }
 	  break;
+	case SEC_INFO_TYPE_EH_FRAME_ENTRY:
+	  {
+	    if (! _bfd_elf_write_section_eh_frame_entry (output_bfd,
+							 flinfo->info,
+							 o, contents))
+	      return FALSE;
+	  }
+	  break;
 	default:
 	  {
 	    /* FIXME: octets_per_byte.  */
@@ -11085,6 +11135,9 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 	return FALSE;
     }
 
+  if (!_bfd_elf_fixup_eh_frame_hdr (info))
+    return FALSE;
+
   /* Since ELF permits relocations to be against local symbols, we
      must have the local symbols available when we do the relocations.
      Since we would rather only read the local symbols once, and we
@@ -11994,6 +12047,11 @@ _bfd_elf_gc_mark (struct bfd_link_info *info,
 	}
     }
 
+  eh_frame = elf_section_eh_frame_entry (sec);
+  if (ret && eh_frame && !eh_frame->gc_mark)
+    if (!_bfd_elf_gc_mark (info, eh_frame, gc_mark_hook))
+      ret = FALSE;
+
   return ret;
 }
 
@@ -12409,6 +12467,36 @@ _bfd_elf_gc_keep (struct bfd_link_info *info)
     }
 }
 
+bfd_boolean
+bfd_elf_parse_eh_frame_entries (bfd *abfd ATTRIBUTE_UNUSED,
+				struct bfd_link_info *info)
+{
+  bfd *ibfd = info->input_bfds;
+
+  for (ibfd = info->input_bfds; ibfd != NULL; ibfd = ibfd->link.next)
+    {
+      asection *sec;
+      struct elf_reloc_cookie cookie;
+
+      if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour)
+	continue;
+
+      if (!init_reloc_cookie (&cookie, info, ibfd))
+	return FALSE;
+
+      for (sec = ibfd->sections; sec; sec = sec->next)
+	{
+	  if (CONST_STRNEQ (bfd_section_name (ibfd, sec), ".eh_frame_entry")
+	      && init_reloc_cookie_rels (&cookie, info, ibfd, sec))
+	    {
+	      _bfd_elf_parse_eh_frame_entry (info, sec, &cookie);
+	      fini_reloc_cookie_rels (&cookie, sec);
+	    }
+	}
+    }
+  return TRUE;
+}
+
 /* Do mark and sweep of unused sections.  */
 
 bfd_boolean
@@ -12432,7 +12520,9 @@ bfd_elf_gc_sections (bfd *abfd, struct bfd_link_info *info)
 
   /* Try to parse each bfd's .eh_frame section.  Point elf_eh_frame_section
      at the .eh_frame section if we can mark the FDEs individually.  */
-  for (sub = info->input_bfds; sub != NULL; sub = sub->link.next)
+  for (sub = info->input_bfds;
+       info->eh_frame_hdr_type != COMPACT_EH_HDR && sub != NULL;
+       sub = sub->link.next)
     {
       asection *sec;
       struct elf_reloc_cookie cookie;
@@ -12936,7 +13026,9 @@ bfd_elf_discard_info (bfd *output_bfd, struct bfd_link_info *info)
 	}
     }
 
-  o = bfd_get_section_by_name (output_bfd, ".eh_frame");
+  o = NULL;
+  if (info->eh_frame_hdr_type != COMPACT_EH_HDR)
+    o = bfd_get_section_by_name (output_bfd, ".eh_frame");
   if (o != NULL)
     {
       asection *i;
@@ -12984,7 +13076,10 @@ bfd_elf_discard_info (bfd *output_bfd, struct bfd_link_info *info)
 	}
     }
 
-  if (info->eh_frame_hdr
+  if (info->eh_frame_hdr_type == COMPACT_EH_HDR)
+    _bfd_elf_end_eh_frame_parsing (info);
+
+  if (info->eh_frame_hdr_type
       && !info->relocatable
       && _bfd_elf_discard_section_eh_frame_hdr (output_bfd, info))
     changed = 1;