PR21167, relocation sections not included in groups

This fixes a wart I've known about for years, but haven't done
anything about because BFD treats relocation sections as an adjunct to
the section they relocate.  SHF_GROUP on the section thus implicitly
applies to its relocation section(s), but it is an error that the
reloc sections aren't part of the group.

Like many patches to gas, this wasn't as straightforward as it could
be due to a number of backends, i386, cr16 and others, removing relocs
in tc_get_reloc rather than marking them as "done" earlier in
md_apply_reloc.  So it isn't possible for the group support to
reliably detect the presence of relocs by looking at fixups earlier
than write_relocs.  However the group support needs to create
signature symbols, and that must be done before the symbol table is
frozen, before write_relocs.  So split off the group sizing from
elf_adjust_symtab and put it in elf_frob_file_after_relocs.

bfd/
	PR 21167
	* elf.c (_bfd_elf_setup_sections): Don't trim reloc sections from
	groups.
	(_bfd_elf_init_reloc_shdr): Pass sec_hdr, use it to copy SHF_GROUP
	flag from section.
	(elf_fake_sections): Adjust calls.  Exit immediately on failure.
	(bfd_elf_set_group_contents): Add associated reloc section indices
	to group contents
gas/
	PR 21167
	* config/obj-elf.c (struct group_list): Delete elt_count.
	(groups): New static.
	(build_group_lists): Don't count elements.
	(elf_adjust_symtab): Use groups rather than auto list.  Set up
	pointer from group member to SHT_GROUP section.  Don't size
	SHT_GROUP section or clean up here..
	(elf_frob_file_after_relocs): ..do so here instead.
	* testsuite/gas/arc/jli-1.d,
	* testsuite/gas/elf/groupautob.d,
	* testsuite/gas/mips/compact-eh-eb-2.d,
	* testsuite/gas/mips/compact-eh-eb-5.d,
	* testsuite/gas/mips/compact-eh-el-2.d,
	* testsuite/gas/mips/compact-eh-el-5.d: Adjust.
ld/
	PR 21167
	* testsuite/ld-elf/group9b.d: Adjust for relocs included in group.

2 files changed, 39 insertions, 18 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index cffa777..9b377f5 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,14 @@
+2017-10-05  Alan Modra  <amodra@gmail.com>
+
+	PR 21167
+	* elf.c (_bfd_elf_setup_sections): Don't trim reloc sections from
+	groups.
+	(_bfd_elf_init_reloc_shdr): Pass sec_hdr, use it to copy SHF_GROUP
+	flag from section.
+	(elf_fake_sections): Adjust calls.  Exit immediately on failure.
+	(bfd_elf_set_group_contents): Add associated reloc section indices
+	to group contents.
+
 2017-10-04  Alan Modra  <amodra@gmail.com>
 
 	* elf64-ppc.c (ppc64_elf_get_synthetic_symtab): Don't sort or
diff --git a/bfd/elf.c b/bfd/elf.c
index 38dba48..fd7f773 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -913,15 +913,8 @@ _bfd_elf_setup_sections (bfd *abfd)
 	    continue;
 	  else if (idx->shdr->bfd_section)
 	    elf_sec_group (idx->shdr->bfd_section) = shdr->bfd_section;
-	  else if (idx->shdr->sh_type == SHT_RELA
-		   || idx->shdr->sh_type == SHT_REL)
-	    /* We won't include relocation sections in section groups in
-	       output object files. We adjust the group section size here
-	       so that relocatable link will work correctly when
-	       relocation sections are in section group in input object
-	       files.  */
-	    shdr->bfd_section->size -= 4;
-	  else
+	  else if (idx->shdr->sh_type != SHT_RELA
+		   && idx->shdr->sh_type != SHT_REL)
 	    {
 	      /* There are some unknown sections in the group.  */
 	      _bfd_error_handler
@@ -3068,6 +3061,7 @@ _bfd_elf_set_reloc_sh_name (bfd *abfd,
 static bfd_boolean
 _bfd_elf_init_reloc_shdr (bfd *abfd,
 			  struct bfd_elf_section_reloc_data *reldata,
+			  const Elf_Internal_Shdr *sec_hdr,
 			  const char *sec_name,
 			  bfd_boolean use_rela_p,
 			  bfd_boolean delay_st_name_p)
@@ -3089,7 +3083,7 @@ _bfd_elf_init_reloc_shdr (bfd *abfd,
 			 ? bed->s->sizeof_rela
 			 : bed->s->sizeof_rel);
   rel_hdr->sh_addralign = (bfd_vma) 1 << bed->s->log_file_align;
-  rel_hdr->sh_flags = 0;
+  rel_hdr->sh_flags = sec_hdr->sh_flags & SHF_GROUP;
   rel_hdr->sh_addr = 0;
   rel_hdr->sh_size = 0;
   rel_hdr->sh_offset = 0;
@@ -3380,15 +3374,15 @@ elf_fake_sections (bfd *abfd, asection *asect, void *fsarg)
 	      || arg->link_info->emitrelocations))
 	{
 	  if (esd->rel.count && esd->rel.hdr == NULL
-	      && !_bfd_elf_init_reloc_shdr (abfd, &esd->rel, name, FALSE,
-					    delay_st_name_p))
+	      && !_bfd_elf_init_reloc_shdr (abfd, &esd->rel, this_hdr, name,
+					    FALSE, delay_st_name_p))
 	    {
 	      arg->failed = TRUE;
 	      return;
 	    }
 	  if (esd->rela.count && esd->rela.hdr == NULL
-	      && !_bfd_elf_init_reloc_shdr (abfd, &esd->rela, name, TRUE,
-					    delay_st_name_p))
+	      && !_bfd_elf_init_reloc_shdr (abfd, &esd->rela, this_hdr, name,
+					    TRUE, delay_st_name_p))
 	    {
 	      arg->failed = TRUE;
 	      return;
@@ -3397,17 +3391,24 @@ elf_fake_sections (bfd *abfd, asection *asect, void *fsarg)
       else if (!_bfd_elf_init_reloc_shdr (abfd,
 					  (asect->use_rela_p
 					   ? &esd->rela : &esd->rel),
+					  this_hdr,
 					  name,
 					  asect->use_rela_p,
 					  delay_st_name_p))
+	{
 	  arg->failed = TRUE;
+	  return;
+	}
     }
 
   /* Check for processor-specific section types.  */
   sh_type = this_hdr->sh_type;
   if (bed->elf_backend_fake_sections
       && !(*bed->elf_backend_fake_sections) (abfd, this_hdr, asect))
-    arg->failed = TRUE;
+    {
+      arg->failed = TRUE;
+      return;
+    }
 
   if (sh_type == SHT_NOBITS && asect->size != 0)
     {
@@ -3524,10 +3525,19 @@ bfd_elf_set_group_contents (bfd *abfd, asection *sec, void *failedptrarg)
       if (s != NULL
 	  && !bfd_is_abs_section (s))
 	{
-	  unsigned int idx = elf_section_data (s)->this_idx;
-
+	  struct bfd_elf_section_data *elf_sec = elf_section_data (s);
+	  if (elf_sec->rel.hdr != NULL)
+	    {
+	      loc -= 4;
+	      H_PUT_32 (abfd, elf_sec->rel.idx, loc);
+	    }
+	  if (elf_sec->rela.hdr != NULL)
+	    {
+	      loc -= 4;
+	      H_PUT_32 (abfd, elf_sec->rela.idx, loc);
+	    }
 	  loc -= 4;
-	  H_PUT_32 (abfd, idx, loc);
+	  H_PUT_32 (abfd, elf_sec->this_idx, loc);
 	}
       elt = elf_next_in_group (elt);
       if (elt == first)