ARM: Fix exidx coverage for relocatable builds.

bfd  * elf-bfd.h: Add callback to count additional relocations.
     * elf32-arm.c (_arm_elf_section_data): Add new counter.
     (insert_cantunwind_after): Increment relocations counter.
     (elf32_arm_fix_exidx_coverage): Remove exidx entries and add
     terminating CANTUNWIND entry only in final builds.
     (elf32_arm_add_relocation): New function.
     (elf32_arm_write_section): Add relocations in relocatable builds.
     (elf32_arm_count_additional_relocs): New function.
     (elf_backend_count_additional_relocs): New define.
     * bfd/elflink.c (bfd_elf_final_link): Use callback and adjust size of
     .rel section.
     * bfd/elfxx-target.h (elf_backend_count_additional_relocs): New define.

ld   * emultempl/armelf.em (gld${EMULATION_NAME}_after_allocation): Call
     elf32_arm_fix_exidx_coverage for relocatable builds.

ld/testsuite
     * ld-arm/arm-elf.exp: New test.
     * ld-arm/unwind-rel.d: New file.
     * ld-arm/unwind-rel1.s: New file.
     * ld-arm/unwind-rel2.s: New file.
     * ld-arm/unwind-rel3.s: New file.

1 files changed, 68 insertions, 2 deletions

diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index 5d31ef2..583db4d 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -2802,6 +2802,7 @@ typedef struct _arm_elf_section_data
   elf32_vfp11_erratum_list *erratumlist;
   unsigned int stm32l4xx_erratumcount;
   elf32_stm32l4xx_erratum_list *stm32l4xx_erratumlist;
+  unsigned int additional_reloc_count;
   /* Information about unwind tables.  */
   union
   {
@@ -11619,6 +11620,8 @@ insert_cantunwind_after(asection *text_sec, asection *exidx_sec)
     &exidx_arm_data->u.exidx.unwind_edit_tail,
     INSERT_EXIDX_CANTUNWIND_AT_END, text_sec, UINT_MAX);
 
+  exidx_arm_data->additional_reloc_count++;
+
   adjust_exidx_size(exidx_sec, 8);
 }
 
@@ -11761,7 +11764,7 @@ elf32_arm_fix_exidx_coverage (asection **text_section_order,
 	  else
 	    unwind_type = 2;
 
-	  if (elide)
+	  if (elide && !bfd_link_relocatable (info))
 	    {
 	      add_unwind_table_edit (&unwind_edit_head, &unwind_edit_tail,
 				     DELETE_EXIDX_ENTRY, NULL, j / 8);
@@ -11788,7 +11791,8 @@ elf32_arm_fix_exidx_coverage (asection **text_section_order,
     }
 
   /* Add terminating CANTUNWIND entry.  */
-  if (last_exidx_sec && last_unwind_type != 0)
+  if (!bfd_link_relocatable (info) && last_exidx_sec
+      && last_unwind_type != 0)
     insert_cantunwind_after(last_text_sec, last_exidx_sec);
 
   return TRUE;
@@ -16984,6 +16988,39 @@ stm32l4xx_create_replacing_stub (struct elf32_arm_link_hash_table * htab,
 /* End of stm32l4xx work-around.  */
 
 
+static void
+elf32_arm_add_relocation (bfd *output_bfd, struct bfd_link_info *info,
+			  asection *output_sec, Elf_Internal_Rela *rel)
+{
+  BFD_ASSERT (output_sec && rel);
+  struct bfd_elf_section_reloc_data *output_reldata;
+  struct elf32_arm_link_hash_table *htab;
+  struct bfd_elf_section_data *oesd = elf_section_data (output_sec);
+  Elf_Internal_Shdr *rel_hdr;
+
+
+  if (oesd->rel.hdr)
+    {
+      rel_hdr = oesd->rel.hdr;
+      output_reldata = &(oesd->rel);
+    }
+  else if (oesd->rela.hdr)
+    {
+      rel_hdr = oesd->rela.hdr;
+      output_reldata = &(oesd->rela);
+    }
+  else
+    {
+      abort ();
+    }
+
+  bfd_byte *erel = rel_hdr->contents;
+  erel += output_reldata->count * rel_hdr->sh_entsize;
+  htab = elf32_arm_hash_table (info);
+  SWAP_RELOC_OUT (htab) (output_bfd, rel, erel);
+  output_reldata->count++;
+}
+
 /* Do code byteswapping.  Return FALSE afterwards so that the section is
    written out as normal.  */
 
@@ -17228,6 +17265,26 @@ elf32_arm_write_section (bfd *output_bfd,
 			   usual BFD method.  */
 			prel31_offset = (text_offset - exidx_offset)
 					& 0x7ffffffful;
+			if (bfd_link_relocatable (link_info))
+			  {
+			    /* Here relocation for new EXIDX_CANTUNWIND is
+			       created, so there is no need to
+			       adjust offset by hand.  */
+			    prel31_offset = text_sec->output_offset
+					    + text_sec->size;
+
+			    /* New relocation entity.  */
+			    asection *text_out = text_sec->output_section;
+			    Elf_Internal_Rela rel;
+			    rel.r_addend = 0;
+			    rel.r_offset = exidx_offset;
+			    rel.r_info = ELF32_R_INFO (text_out->target_index,
+						       R_ARM_PREL31);
+
+			    elf32_arm_add_relocation (output_bfd, link_info,
+						      sec->output_section,
+						      &rel);
+			  }
 
 			/* First address we can't unwind.  */
 			bfd_put_32 (output_bfd, prel31_offset,
@@ -17742,6 +17799,14 @@ elf32_arm_lookup_section_flags (char *flag_name)
   return SEC_NO_FLAGS;
 }
 
+static unsigned int
+elf32_arm_count_additional_relocs (asection *sec)
+{
+  struct _arm_elf_section_data *arm_data;
+  arm_data = get_arm_elf_section_data (sec);
+  return arm_data->additional_reloc_count;
+}
+
 #define ELF_ARCH			bfd_arch_arm
 #define ELF_TARGET_ID			ARM_ELF_DATA
 #define ELF_MACHINE_CODE		EM_ARM
@@ -17796,6 +17861,7 @@ elf32_arm_lookup_section_flags (char *flag_name)
 #define elf_backend_output_arch_local_syms      elf32_arm_output_arch_local_syms
 #define elf_backend_begin_write_processing      elf32_arm_begin_write_processing
 #define elf_backend_add_symbol_hook		elf32_arm_add_symbol_hook
+#define elf_backend_count_additional_relocs	elf32_arm_count_additional_relocs
 
 #define elf_backend_can_refcount       1
 #define elf_backend_can_gc_sections    1