ld: Extract _bfd_elf_link_iterate_on_relocs

DT_RELR encodes consecutive R_*_RELATIVE relocations in GOT (the global
offset table) and data sections in a compact format:

https://groups.google.com/g/generic-abi/c/bX460iggiKg

On some targets, R_*_RELATIVE relocations are counted and the GOT offsets
are allocated when setting the dynamic section sizes after seeing all
relocations.  R_*_RELATIVE relocations are generated while relocating
sections after section layout has been finalized.

To prepare for DT_RELR implementation on these targets, extract
_bfd_elf_link_iterate_on_relocs from _bfd_elf_link_check_relocs so
that a backend can scan relocations in elf_backend_always_size_sections

For x86 targets, the old check_relocs is renamed to scan_relocs and a
new check_relocs is added to chek input sections and create dynamic
relocation sections so that they will be mapped to output sections.
scan_relocs is now called from elf_backend_always_size_sections.

Since relocations are scanned after __start, __stop, .startof. and
.sizeof. symbols have been finalized on x86, __[start|stop]_SECNAME for
--gc-sections -z start-stop-gc are now zero when all SECNAME sections
been garbage collected.  This is no need for elf_x86_start_stop_gc_p.

bfd/

	* elf-bfd.h (_bfd_elf_link_iterate_on_relocs): New.
	* elf32-i386.c (elf_i386_convert_load_reloc): Don't call
	elf_x86_start_stop_gc_p.
	(elf_i386_check_relocs): Renamed to ...
	(elf_i386_scan_relocs): This.  Don't call
	_bfd_elf_make_dynamic_reloc_section.
	(elf_i386_always_size_sections): New.
	(elf_backend_check_relocs): Removed.
	(elf_backend_always_size_sections): New.
	* elf64-x86-64.c (elf_x86_64_convert_load_reloc): Don't call
	elf_x86_start_stop_gc_p.
	(elf_x86_64_check_relocs): Renamed to ...
	(elf_x86_64_scan_relocs): This.  Don't call
	_bfd_elf_make_dynamic_reloc_section.
	(elf_x86_64_always_size_sections): New.
	(elf_backend_check_relocs): Removed.
	(elf_backend_always_size_sections): New.
	* elflink.c (elf_link_check_or_scan_relocs):
	New.  Extracted from _bfd_elf_link_check_relocs.
	(_bfd_elf_link_check_relocs): Call elf_link_check_or_scan_relocs.
	* elfxx-x86.c (_bfd_x86_elf_check_relocs): New.
	* elfxx-x86.h (X86_64_NEED_DYNAMIC_RELOC_TYPE_P): New.
	(I386_NEED_DYNAMIC_RELOC_TYPE_P): Likewise.
	(X86_NEED_DYNAMIC_RELOC_TYPE_P): Likewise.
	(_bfd_x86_elf_check_relocs): Likewise.
	(elf_backend_check_relocs): Likewise.
	(elf_backend_always_size_sections): Removed.
	(elf_x86_start_stop_gc_p): Likewise.

ld/

	* testsuite/ld-i386/pr27491-1a.d: Updated.
	* testsuite/ld-x86-64/pr27491-1a.d: Likewise.

1 files changed, 26 insertions, 29 deletions

diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 22aa3ee3b68..ad885f89e11 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -1309,7 +1309,7 @@ elf_x86_64_tls_transition (struct bfd_link_info *info, bfd *abfd,
 	    }
 
 	  /* We checked the transition before when we were called from
-	     elf_x86_64_check_relocs.  We only want to check the new
+	     elf_x86_64_scan_relocs.  We only want to check the new
 	     transition which hasn't been checked before.  */
 	  check = new_to_type != to_type && from_type == to_type;
 	  to_type = new_to_type;
@@ -1628,11 +1628,6 @@ elf_x86_64_convert_load_reloc (bfd *abfd,
 			   || h->root.type == bfd_link_hash_defweak)
 			  && h->root.u.def.section == bfd_und_section_ptr))))
 	    {
-	      /* Skip __start_SECNAME/__stop_SECNAME when --gc-sections
-	         -z start-stop-gc are used.  */
-	      if (elf_x86_start_stop_gc_p (link_info, h))
-		return true;
-
 	      /* Skip since R_X86_64_32/R_X86_64_32S may overflow.  */
 	      if (no_overflow)
 		return true;
@@ -1823,20 +1818,19 @@ elf_x86_64_convert_load_reloc (bfd *abfd,
 }
 
 /* Look through the relocs for a section during the first phase, and
-   calculate needed space in the global offset table, procedure
-   linkage table, and dynamic reloc sections.  */
+   calculate needed space in the global offset table, and procedure
+   linkage table.  */
 
 static bool
-elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
-			 asection *sec,
-			 const Elf_Internal_Rela *relocs)
+elf_x86_64_scan_relocs (bfd *abfd, struct bfd_link_info *info,
+			asection *sec,
+			const Elf_Internal_Rela *relocs)
 {
   struct elf_x86_link_hash_table *htab;
   Elf_Internal_Shdr *symtab_hdr;
   struct elf_link_hash_entry **sym_hashes;
   const Elf_Internal_Rela *rel;
   const Elf_Internal_Rela *rel_end;
-  asection *sreloc;
   bfd_byte *contents;
   bool converted;
 
@@ -1866,8 +1860,6 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
 
   converted = false;
 
-  sreloc = NULL;
-
   rel_end = relocs + sec->reloc_count;
   for (rel = relocs; rel < rel_end; rel++)
     {
@@ -2263,19 +2255,6 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
 	      struct elf_dyn_relocs *p;
 	      struct elf_dyn_relocs **head;
 
-	      /* We must copy these reloc types into the output file.
-		 Create a reloc section in dynobj and make room for
-		 this reloc.  */
-	      if (sreloc == NULL)
-		{
-		  sreloc = _bfd_elf_make_dynamic_reloc_section
-		    (sec, htab->elf.dynobj, ABI_64_P (abfd) ? 3 : 2,
-		     abfd, /*rela?*/ true);
-
-		  if (sreloc == NULL)
-		    goto error_return;
-		}
-
 	      /* If this is a global symbol, we count the number of
 		 relocations we need for this symbol.  */
 	      if (h != NULL)
@@ -2371,6 +2350,24 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
   return false;
 }
 
+static bool
+elf_x86_64_always_size_sections (bfd *output_bfd,
+				 struct bfd_link_info *info)
+{
+  bfd *abfd;
+
+  /* Scan relocations after rel_from_abs has been set on __ehdr_start.  */
+  for (abfd = info->input_bfds;
+       abfd != (bfd *) NULL;
+       abfd = abfd->link.next)
+    if (bfd_get_flavour (abfd) == bfd_target_elf_flavour
+	&& !_bfd_elf_link_iterate_on_relocs (abfd, info,
+					     elf_x86_64_scan_relocs))
+      return false;
+
+  return _bfd_x86_elf_always_size_sections (output_bfd, info);
+}
+
 /* Return the relocation value for @tpoff relocation
    if STT_TLS virtual address is ADDRESS.  */
 
@@ -2413,7 +2410,7 @@ elf_x86_64_relocate_section (bfd *output_bfd,
   unsigned int plt_entry_size;
   bool status;
 
-  /* Skip if check_relocs failed.  */
+  /* Skip if check_relocs or scan_relocs failed.  */
   if (input_section->check_relocs_failed)
     return false;
 
@@ -5238,7 +5235,7 @@ elf_x86_64_special_sections[]=
   elf_x86_64_reloc_name_lookup
 
 #define elf_backend_relocs_compatible	    elf_x86_64_relocs_compatible
-#define elf_backend_check_relocs	    elf_x86_64_check_relocs
+#define elf_backend_always_size_sections    elf_x86_64_always_size_sections
 #define elf_backend_create_dynamic_sections _bfd_elf_create_dynamic_sections
 #define elf_backend_finish_dynamic_sections elf_x86_64_finish_dynamic_sections
 #define elf_backend_finish_dynamic_symbol   elf_x86_64_finish_dynamic_symbol