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[PATCH] ARM: Fix relocation of EXIDX sections


As reported in PR binutils/20595, BFD has a bug that it doesn't delete
relocations for deleted exidx. This change fixes the behavior.

bfd * elf-bfd.h: Add callback to count relocations in the final output.
    * elf-arm.c (elf32_arm_add_relocation): Deleted.
    (elf32_arm_write_section): Move additional relocation to emit_relocs.
    (elf32_arm_count_output_relocs): New function.
    (emit_relocs): New function.
    (elf32_arm_emit_relocs): New function.
    (elf32_arm_vxworks_emit_relocs): New function.
    (elf_backend_emit_relocs): Updated to use the new functions.
    (elf_backend_count_output_relocs): New define.
    * bfd/elflink.c (bfd_elf_final_link): Do not add additional_reloc_count
    to the relocation count.
    (_bfd_elf_link_size_reloc_section): Use callback to count the
    relocations which will be in output.
    (_bfd_elf_default_count_output_relocs): New function.
    * bfd/elfxx-target.h (elf_backend_count_output_relocs): New define.
---
 bfd/elf-bfd.h      |   8 ++
 bfd/elf32-arm.c    | 262 +++++++++++++++++++++++++++++++++++++++++++----------
 bfd/elflink.c      |  46 +++++++---
 bfd/elfxx-target.h |   4 +
 4 files changed, 259 insertions(+), 61 deletions(-)

diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index 163ef35..2f2b42c 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -1176,6 +1176,11 @@ struct elf_backend_data
   unsigned int (*elf_backend_count_additional_relocs)
     (asection *);
 
+  /* Count relocations to be output. The result may be different if the
+     input relocations are expected to be modified by the backend. */
+  unsigned int (* elf_backend_count_output_relocs)
+    (struct bfd_link_info *info, asection *o, bfd_boolean rela);
+
   /* Say whether to sort relocs output by ld -r and ld --emit-relocs,
      by r_offset.  If NULL, default to true.  */
   bfd_boolean (*sort_relocs_p)
@@ -2143,6 +2148,9 @@ extern bfd_boolean _bfd_elf_link_output_relocs
   (bfd *, asection *, Elf_Internal_Shdr *, Elf_Internal_Rela *,
    struct elf_link_hash_entry **);
 
+extern unsigned int _bfd_elf_default_count_output_relocs
+  (struct bfd_link_info *info ATTRIBUTE_UNUSED, asection *o, bfd_boolean rela);
+
 extern bfd_boolean _bfd_elf_adjust_dynamic_copy
   (struct bfd_link_info *, struct elf_link_hash_entry *, asection *);
 
diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index 3d4a458..28c6fb1 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -17365,39 +17365,6 @@ 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.  */
 
@@ -17649,18 +17616,6 @@ elf32_arm_write_section (bfd *output_bfd,
 			       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.  */
@@ -18175,6 +18130,74 @@ elf32_arm_count_additional_relocs (asection *sec)
   return arm_data->additional_reloc_count;
 }
 
+static unsigned int
+elf32_arm_count_output_relocs (struct bfd_link_info *info, asection *o,
+			       bfd_boolean rela)
+{
+  struct bfd_elf_section_data *esdo;
+  struct bfd_link_order *p;
+  bfd_size_type count;
+
+  esdo = elf_section_data (o->output_section);
+  if (esdo->this_hdr.sh_type != SHT_ARM_EXIDX)
+    return _bfd_elf_default_count_output_relocs (info, o, rela);
+
+  count = 0;
+  for (p = o->map_head.link_order; p != NULL; p = p->next)
+    {
+      struct _arm_elf_section_data *arm_data;
+      arm_unwind_table_edit *edit_list;
+      Elf_Internal_Rela *relocs;
+      asection *sec;
+      bfd_size_type num_rel;
+      bfd_size_type num_rela;
+      unsigned int i;
+
+      if (p->type == bfd_section_reloc_link_order
+	  || p->type == bfd_symbol_reloc_link_order)
+	{
+	  count++;
+	  continue;
+	}
+
+      sec = p->u.indirect.section;
+      arm_data = get_arm_elf_section_data (sec);
+
+      if (arm_data->additional_reloc_count)
+	count += arm_data->additional_reloc_count;
+
+      edit_list = arm_data->u.exidx.unwind_edit_list;
+      if (!edit_list)
+	{
+	  count += sec->reloc_count;
+	  continue;
+	}
+
+      relocs = _bfd_elf_link_read_relocs (sec->owner, sec, NULL, NULL,
+					  info->keep_memory);
+      num_rel = esdo->rel.hdr ? NUM_SHDR_ENTRIES (esdo->rel.hdr) : 0;
+      num_rela = esdo->rela.hdr ? NUM_SHDR_ENTRIES (esdo->rela.hdr) : 0;
+
+      for (i = rela ? num_rel : 0; i < (rela ? num_rela : num_rel); i++)
+	{
+	  arm_unwind_table_edit *edit_node;
+	  unsigned int index;
+
+	  index = (relocs[i].r_offset - sec->vma) / 8;
+
+	  for (edit_node = edit_list;
+	       edit_node->next && edit_node->next->index > index;
+	       edit_node++);
+
+	  if (edit_node->type != DELETE_EXIDX_ENTRY ||
+	      edit_node->index != index)
+	    count++;
+	}
+    }
+
+  return count;
+}
+
 /* Called to set the sh_flags, sh_link and sh_info fields of OSECTION which
    has a type >= SHT_LOOS.  Returns TRUE if these fields were initialised 
    FALSE otherwise.  ISECTION is the best guess matching section from the
@@ -18303,6 +18326,139 @@ elf32_arm_backend_symbol_processing (bfd *abfd, asymbol *sym)
     sym->flags |= BSF_KEEP;
 }
 
+static bfd_boolean
+emit_relocs (bfd *output_bfd,
+	     asection *input_section,
+	     Elf_Internal_Shdr *input_rel_hdr,
+	     Elf_Internal_Rela *internal_relocs,
+	     struct elf_link_hash_entry **rel_hash,
+	     bfd_boolean (*fallback) (bfd *, asection *,
+				      Elf_Internal_Shdr *,
+				      Elf_Internal_Rela *,
+				      struct elf_link_hash_entry **))
+{
+  _arm_elf_section_data *arm_data;
+  struct bfd_elf_section_reloc_data *output_reldata;
+  Elf_Internal_Shdr *output_rel_hdr;
+  Elf_Internal_Rela *irela;
+  Elf_Internal_Rela *irelaend;
+  asection *output_section;
+  const struct elf_backend_data *bed;
+  void (*swap_out) (bfd *, const Elf_Internal_Rela *, bfd_byte *);
+  struct bfd_elf_section_data *esdo;
+  arm_unwind_table_edit *edit_list, *edit_tail;
+  bfd_byte *erel;
+  bfd_vma offset;
+
+  arm_data = get_arm_elf_section_data (input_section);
+
+  if (!arm_data || arm_data->elf.this_hdr.sh_type != SHT_ARM_EXIDX)
+    goto fallback_label;
+
+  edit_list = arm_data->u.exidx.unwind_edit_list;
+  edit_tail = arm_data->u.exidx.unwind_edit_tail;
+
+  if (!edit_list)
+    goto fallback_label;
+
+  output_section = input_section->output_section;
+  offset = output_section->vma + input_section->output_offset;
+
+  bed = get_elf_backend_data (output_bfd);
+  esdo = elf_section_data (output_section);
+  if (esdo->rel.hdr && esdo->rel.hdr->sh_entsize == input_rel_hdr->sh_entsize)
+    {
+      output_reldata = &esdo->rel;
+      swap_out = bed->s->swap_reloc_out;
+    }
+  else if (esdo->rela.hdr &&
+	   esdo->rela.hdr->sh_entsize == input_rel_hdr->sh_entsize)
+    {
+      output_reldata = &esdo->rela;
+      swap_out = bed->s->swap_reloca_out;
+    }
+  else
+    {
+      (*_bfd_error_handler)
+	(_("%B: relocation size mismatch in %B section %A"),
+	 output_bfd, input_section->owner, input_section);
+	 bfd_set_error (bfd_error_wrong_format);
+      return FALSE;
+    }
+
+  output_rel_hdr = output_reldata->hdr;
+  erel = output_rel_hdr->contents;
+  erel += output_reldata->count * input_rel_hdr->sh_entsize;
+
+  irela = internal_relocs;
+  irelaend = irela + (NUM_SHDR_ENTRIES (input_rel_hdr)
+		      * bed->s->int_rels_per_ext_rel);
+  while (irela < irelaend)
+    {
+      arm_unwind_table_edit *edit_node, *edit_next;
+      Elf_Internal_Rela rel;
+      bfd_vma bias;
+      bfd_vma index;
+
+      index = (irela->r_offset - offset) / 8;
+
+      bias = 0;
+      edit_node = edit_list;
+      for (edit_next = edit_list;
+	   edit_next && edit_next->index <= index;
+	   edit_next = edit_node->next)
+	{
+	  bias++;
+	  edit_node = edit_next;
+	}
+
+      if (edit_node->type != DELETE_EXIDX_ENTRY || edit_node->index != index)
+	{
+	  rel.r_offset = irela->r_offset - bias * 8;
+	  rel.r_info = irela->r_info;
+	  rel.r_addend = irela->r_addend;
+
+	  (*swap_out) (output_bfd, &rel, erel);
+	  erel += output_rel_hdr->sh_entsize;
+	  output_reldata->count++;
+	}
+
+      irela += bed->s->int_rels_per_ext_rel;
+    }
+
+  if (edit_tail->type == INSERT_EXIDX_CANTUNWIND_AT_END)
+    {
+      /* New relocation entity.  */
+      asection *text_sec = edit_tail->linked_section;
+      asection *text_out = text_sec->output_section;
+      bfd_vma exidx_offset = offset + input_section->size - 8;
+      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);
+      (*swap_out) (output_bfd, &rel, erel);
+      output_reldata->count++;
+    }
+
+  return TRUE;
+
+fallback_label:
+  return fallback (output_bfd, input_section, input_rel_hdr,
+		   internal_relocs, rel_hash);
+}
+
+static bfd_boolean
+elf32_arm_emit_relocs (bfd *output_bfd,
+			       asection *input_section,
+			       Elf_Internal_Shdr *input_rel_hdr,
+			       Elf_Internal_Rela *internal_relocs,
+			       struct elf_link_hash_entry **rel_hash)
+{
+  return emit_relocs (output_bfd, input_section, input_rel_hdr, internal_relocs,
+		      rel_hash, _bfd_elf_link_output_relocs);
+}
+
 #undef  elf_backend_copy_special_section_fields
 #define elf_backend_copy_special_section_fields elf32_arm_copy_special_section_fields
 
@@ -18333,6 +18489,7 @@ elf32_arm_backend_symbol_processing (bfd *abfd, asymbol *sym)
 #define bfd_elf32_bfd_final_link		elf32_arm_final_link
 #define bfd_elf32_get_synthetic_symtab  elf32_arm_get_synthetic_symtab
 
+#define elf_backend_emit_relocs			elf32_arm_emit_relocs
 #define elf_backend_get_symbol_type             elf32_arm_get_symbol_type
 #define elf_backend_gc_mark_hook                elf32_arm_gc_mark_hook
 #define elf_backend_gc_mark_extra_sections	elf32_arm_gc_mark_extra_sections
@@ -18361,6 +18518,7 @@ elf32_arm_backend_symbol_processing (bfd *abfd, asymbol *sym)
 #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_count_output_relocs		elf32_arm_count_output_relocs
 #define elf_backend_symbol_processing		elf32_arm_backend_symbol_processing
 
 #define elf_backend_can_refcount       1
@@ -18527,6 +18685,17 @@ elf32_arm_vxworks_final_write_processing (bfd *abfd, bfd_boolean linker)
   elf_vxworks_final_write_processing (abfd, linker);
 }
 
+static bfd_boolean
+elf32_arm_vxworks_emit_relocs (bfd *output_bfd,
+			       asection *input_section,
+			       Elf_Internal_Shdr *input_rel_hdr,
+			       Elf_Internal_Rela *internal_relocs,
+			       struct elf_link_hash_entry **rel_hash)
+{
+  return emit_relocs (output_bfd, input_section, input_rel_hdr, internal_relocs,
+		      rel_hash, elf_vxworks_emit_relocs);
+}
+
 #undef  elf32_bed
 #define elf32_bed elf32_arm_vxworks_bed
 
@@ -18535,7 +18704,7 @@ elf32_arm_vxworks_final_write_processing (bfd *abfd, bfd_boolean linker)
 #undef  elf_backend_final_write_processing
 #define elf_backend_final_write_processing	elf32_arm_vxworks_final_write_processing
 #undef  elf_backend_emit_relocs
-#define elf_backend_emit_relocs			elf_vxworks_emit_relocs
+#define elf_backend_emit_relocs			elf32_arm_vxworks_emit_relocs
 
 #undef  elf_backend_may_use_rel_p
 #define elf_backend_may_use_rel_p	0
@@ -18899,6 +19068,7 @@ elf32_arm_symbian_plt_sym_val (bfd_vma i, const asection *plt,
   (SEC_HAS_CONTENTS | SEC_IN_MEMORY | SEC_LINKER_CREATED)
 
 #undef elf_backend_emit_relocs
+#define elf_backend_emit_relocs			elf32_arm_emit_relocs
 
 #undef  bfd_elf32_bfd_link_hash_table_create
 #define bfd_elf32_bfd_link_hash_table_create	elf32_arm_symbian_link_hash_table_create
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 3e24940..20e7086 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -2447,13 +2447,23 @@ _bfd_elf_link_read_relocs (bfd *abfd,
    section header for a section containing relocations for O.  */
 
 static bfd_boolean
-_bfd_elf_link_size_reloc_section (bfd *abfd,
-				  struct bfd_elf_section_reloc_data *reldata)
+_bfd_elf_link_size_reloc_section (bfd *abfd, struct bfd_link_info *info,
+				  asection *o, bfd_boolean rela)
 {
-  Elf_Internal_Shdr *rel_hdr = reldata->hdr;
+  struct bfd_elf_section_data *esdo;
+  const struct elf_backend_data *bed;
+  struct bfd_elf_section_reloc_data *reldata;
+  Elf_Internal_Shdr *rel_hdr;
+  unsigned int count;
+
+  esdo = elf_section_data (o);
+  reldata = rela ? &esdo->rela : &esdo->rel;
+  rel_hdr = reldata->hdr;
 
   /* That allows us to calculate the size of the section.  */
-  rel_hdr->sh_size = rel_hdr->sh_entsize * reldata->count;
+  bed = get_elf_backend_data (abfd);
+  count = (*bed->elf_backend_count_output_relocs) (info, o, rela);
+  rel_hdr->sh_size = count * rel_hdr->sh_entsize;
 
   /* The contents field must last into write_object_contents, so we
      allocate it with bfd_alloc rather than malloc.  Also since we
@@ -2541,6 +2551,19 @@ _bfd_elf_link_output_relocs (bfd *output_bfd,
 
   return TRUE;
 }
+
+unsigned int
+_bfd_elf_default_count_output_relocs (
+  struct bfd_link_info *info ATTRIBUTE_UNUSED, asection *o, bfd_boolean rela)
+{
+  struct bfd_elf_section_data *esdo;
+  struct bfd_elf_section_reloc_data *reldata;
+
+  esdo = elf_section_data (o);
+  reldata = rela ? &esdo->rela : &esdo->rel;
+
+  return reldata->count;
+}
 
 /* Make weak undefined symbols in PIE dynamic.  */
 
@@ -11182,12 +11205,12 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
   for (o = abfd->sections; o != NULL; o = o->next)
     {
       struct bfd_elf_section_data *esdo = elf_section_data (o);
+      unsigned int additional_reloc_count = 0;
       o->reloc_count = 0;
 
       for (p = o->map_head.link_order; p != NULL; p = p->next)
 	{
 	  unsigned int reloc_count = 0;
-	  unsigned int additional_reloc_count = 0;
 	  struct bfd_elf_section_data *esdi = NULL;
 
 	  if (p->type == bfd_section_reloc_link_order
@@ -11273,21 +11296,14 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 	  if (reloc_count == 0)
 	    continue;
 
-	  reloc_count += additional_reloc_count;
 	  o->reloc_count += reloc_count;
 
 	  if (p->type == bfd_indirect_link_order && emit_relocs)
 	    {
 	      if (esdi->rel.hdr)
-		{
 		  esdo->rel.count += NUM_SHDR_ENTRIES (esdi->rel.hdr);
-		  esdo->rel.count += additional_reloc_count;
-		}
 	      if (esdi->rela.hdr)
-		{
 		  esdo->rela.count += NUM_SHDR_ENTRIES (esdi->rela.hdr);
-		  esdo->rela.count += additional_reloc_count;
-		}
 	    }
 	  else
 	    {
@@ -11298,7 +11314,7 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 	    }
 	}
 
-      if (o->reloc_count > 0)
+      if (o->reloc_count > 0 || additional_reloc_count > 0)
 	o->flags |= SEC_RELOC;
       else
 	{
@@ -11336,11 +11352,11 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
       if ((o->flags & SEC_RELOC) != 0)
 	{
 	  if (esdo->rel.hdr
-	      && !(_bfd_elf_link_size_reloc_section (abfd, &esdo->rel)))
+	      && !(_bfd_elf_link_size_reloc_section (abfd, info, o, FALSE)))
 	    goto error_return;
 
 	  if (esdo->rela.hdr
-	      && !(_bfd_elf_link_size_reloc_section (abfd, &esdo->rela)))
+	      && !(_bfd_elf_link_size_reloc_section (abfd, info, o, TRUE)))
 	    goto error_return;
 	}
 
diff --git a/bfd/elfxx-target.h b/bfd/elfxx-target.h
index 97aa5e6..5424cf3 100644
--- a/bfd/elfxx-target.h
+++ b/bfd/elfxx-target.h
@@ -551,6 +551,9 @@
 #ifndef elf_backend_count_additional_relocs
 #define elf_backend_count_additional_relocs	NULL
 #endif
+#ifndef elf_backend_count_output_relocs
+#define elf_backend_count_output_relocs		_bfd_elf_default_count_output_relocs
+#endif
 #ifndef elf_backend_sort_relocs_p
 #define elf_backend_sort_relocs_p		NULL
 #endif
@@ -773,6 +776,7 @@ static struct elf_backend_data elfNN_bed =
   elf_backend_emit_relocs,
   elf_backend_count_relocs,
   elf_backend_count_additional_relocs,
+  elf_backend_count_output_relocs,
   elf_backend_sort_relocs_p,
   elf_backend_grok_prstatus,
   elf_backend_grok_psinfo,
-- 
2.9.3


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