ld/x86: Add -z report-relative-reloc

Linker generated relative relocations don't have symbol info:

[hjl@gnu-cfl-2 tmpdir]$ readelf -rW dump

Relocation section '.rela.dyn' at offset 0x180 contains 2 entries:
 Offset     Info    Type                Sym. Value  Symbol's Name + Addend
00002f70  00000008 R_X86_64_RELATIVE                 1000
00002f68  00000025 R_X86_64_IRELATIVE                1007
[hjl@gnu-cfl-2 tmpdir]$

Add -z report-relative-reloc to x86 ELF linker to report dynamic relative
relocations:

[hjl@gnu-cfl-2 tmpdir]$ ../ld-new -pie -melf32_x86_64 -z report-relative-reloc -o dump report-reloc-1.o
dump: R_X86_64_IRELATIVE (offset: 0x00002f68, info: 0x00000025, addend: 0x00001007) against 'ifunc' for section '.data.rel.ro.local' in report-reloc-1.o
dump: R_X86_64_RELATIVE (offset: 0x00002f70, info: 0x00000008, addend: 0x00001000) against '_start' for section '.data.rel.ro.local' in report-reloc-1.o
[hjl@gnu-cfl-2 tmpdir]$

It can be used to map relative relocations to corresponding symbols.

bfd/

	* elf-linker-x86.h (elf_linker_x86_params): Add
	report_relative_reloc.
	* elf32-i386.c (elf_i386_relocate_section): Call
	_bfd_x86_elf_link_report_relative_reloc to report relative
	relocations for -z report-relative-reloc.
	(elf_i386_finish_dynamic_symbol): Likewse.
	* elf64-x86-64.c (elf_x86_64_relocate_section): Likewse.
	(elf_x86_64_finish_dynamic_symbol): Likewse.
	* elfxx-x86.c (_bfd_x86_elf_link_report_relative_reloc): New
	function.
	* elfxx-x86.h (_bfd_x86_elf_link_report_relative_reloc): New
	prototype.

ld/

	* NEWS: Mention -z report-relative-reloc.
	* ld.texi: Document -z report-relative-reloc.
	* emulparams/elf32_x86_64.sh: Source x86-report-relative.sh.
	* emulparams/elf_i386.sh: Likewse.
	* emulparams/elf_x86_64.sh: Likewse.
	* emulparams/x86-report-relative.sh: New file.
	* testsuite/ld-i386/report-reloc-1.d: Likewse.
	* testsuite/ld-i386/report-reloc-1.l: Likewse.
	* testsuite/ld-i386/report-reloc-1.s: Likewse.
	* testsuite/ld-x86-64/report-reloc-1-x32.d: Likewse.
	* testsuite/ld-x86-64/report-reloc-1.d: Likewse.
	* testsuite/ld-x86-64/report-reloc-1.l: Likewse.
	* testsuite/ld-x86-64/report-reloc-1.s: Likewse.
	* testsuite/ld-i386/i386.exp: Run report-reloc-1.
	* testsuite/ld-x86-64/x86-64.exp: Run report-reloc-1 and
	report-reloc-1-x32.

6 files changed, 138 insertions, 0 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 40534b8..ac18a85 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,18 @@
+2021-01-15  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* elf-linker-x86.h (elf_linker_x86_params): Add
+	report_relative_reloc.
+	* elf32-i386.c (elf_i386_relocate_section): Call
+	_bfd_x86_elf_link_report_relative_reloc to report relative
+	relocations for -z report-relative-reloc.
+	(elf_i386_finish_dynamic_symbol): Likewse.
+	* elf64-x86-64.c (elf_x86_64_relocate_section): Likewse.
+	(elf_x86_64_finish_dynamic_symbol): Likewse.
+	* elfxx-x86.c (_bfd_x86_elf_link_report_relative_reloc): New
+	function.
+	* elfxx-x86.h (_bfd_x86_elf_link_report_relative_reloc): New
+	prototype.
+
 2021-01-16  Alan Modra  <amodra@gmail.com>
 
 	* compress.c (decompress_contents): Tidy inflateEnd result test.
diff --git a/bfd/elf-linker-x86.h b/bfd/elf-linker-x86.h
index e17ba5d..acce1bb 100644
--- a/bfd/elf-linker-x86.h
+++ b/bfd/elf-linker-x86.h
@@ -61,6 +61,9 @@ struct elf_linker_x86_params
   /* TRUE if --dynamic-linker is passed at command-line.  */
   unsigned int has_dynamic_linker : 1;
 
+  /* Report relative relocations.  */
+  unsigned int report_relative_reloc : 1;
+
   /* X86-64 ISA level needed.  */
   unsigned int isa_level;
 
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index db7dd10..04ea7d0 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -2409,6 +2409,12 @@ elf_i386_relocate_section (bfd *output_bfd,
 
 		      /* This symbol is resolved locally.  */
 		      outrel.r_info = ELF32_R_INFO (0, R_386_IRELATIVE);
+
+		      if (htab->params->report_relative_reloc)
+			_bfd_x86_elf_link_report_relative_reloc
+			  (info, input_section, h, sym,
+			   "R_386_IRELATIVE", &outrel);
+
 		      bfd_put_32 (output_bfd,
 				  (h->root.u.def.value
 				   + h->root.u.def.section->output_section->vma
@@ -2532,6 +2538,12 @@ elf_i386_relocate_section (bfd *output_bfd,
 				 + htab->elf.sgot->output_offset
 				 + off);
 	      outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
+
+	      if (htab->params->report_relative_reloc)
+		_bfd_x86_elf_link_report_relative_reloc
+		  (info, input_section, h, sym, "R_386_RELATIVE",
+		   &outrel);
+
 	      elf_append_rel (output_bfd, s, &outrel);
 	    }
 
@@ -2738,6 +2750,11 @@ elf_i386_relocate_section (bfd *output_bfd,
 		  /* This symbol is local, or marked to become local.  */
 		  relocate = TRUE;
 		  outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
+
+		  if (htab->params->report_relative_reloc)
+		    _bfd_x86_elf_link_report_relative_reloc
+		      (info, input_section, h, sym, "R_386_RELATIVE",
+		       &outrel);
 		}
 
 	      sreloc = elf_section_data (input_section)->sreloc;
@@ -2769,6 +2786,12 @@ elf_i386_relocate_section (bfd *output_bfd,
 				+ input_section->output_section->vma
 				+ input_section->output_offset;
 	      outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
+
+	      if (htab->params->report_relative_reloc)
+		_bfd_x86_elf_link_report_relative_reloc
+		  (info, input_section, h, sym, "R_386_RELATIVE",
+		   &outrel);
+
 	      sreloc = elf_section_data (input_section)->sreloc;
 	      if (sreloc == NULL)
 		abort ();
@@ -3664,6 +3687,11 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
 			   + h->root.u.def.section->output_offset),
 			  gotplt->contents + got_offset);
 	      rel.r_info = ELF32_R_INFO (0, R_386_IRELATIVE);
+
+	      if (htab->params->report_relative_reloc)
+		_bfd_x86_elf_link_report_relative_reloc
+		  (info, relplt, h, sym, "R_386_IRELATIVE", &rel);
+
 	      /* R_386_IRELATIVE comes last.  */
 	      plt_index = htab->next_irelative_index--;
 	    }
@@ -3762,6 +3790,7 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
     {
       Elf_Internal_Rela rel;
       asection *relgot = htab->elf.srelgot;
+      const char *relative_reloc_name = NULL;
 
       /* This symbol has an entry in the global offset table.  Set it
 	 up.  */
@@ -3802,6 +3831,7 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
 			       + h->root.u.def.section->output_offset),
 			      htab->elf.sgot->contents + h->got.offset);
 		  rel.r_info = ELF32_R_INFO (0, R_386_IRELATIVE);
+		  relative_reloc_name = "R_386_IRELATIVE";
 		}
 	      else
 		goto do_glob_dat;
@@ -3844,6 +3874,7 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
 	{
 	  BFD_ASSERT((h->got.offset & 1) != 0);
 	  rel.r_info = ELF32_R_INFO (0, R_386_RELATIVE);
+	  relative_reloc_name = "R_386_RELATIVE";
 	}
       else
 	{
@@ -3854,6 +3885,11 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
 	  rel.r_info = ELF32_R_INFO (h->dynindx, R_386_GLOB_DAT);
 	}
 
+      if (relative_reloc_name != NULL
+	  && htab->params->report_relative_reloc)
+	_bfd_x86_elf_link_report_relative_reloc
+	  (info, relgot, h, sym, relative_reloc_name, &rel);
+
       elf_append_rel (output_bfd, relgot, &rel);
     }
 
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index daae52b..500f8bf 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -2784,6 +2784,11 @@ elf_x86_64_relocate_section (bfd *output_bfd,
 		      outrel.r_addend = (h->root.u.def.value
 					 + h->root.u.def.section->output_section->vma
 					 + h->root.u.def.section->output_offset);
+
+		      if (htab->params->report_relative_reloc)
+			_bfd_x86_elf_link_report_relative_reloc
+			  (info, input_section, h, sym,
+			   "R_X86_64_IRELATIVE", &outrel);
 		    }
 		  else
 		    {
@@ -2940,6 +2945,12 @@ elf_x86_64_relocate_section (bfd *output_bfd,
 				 + off);
 	      outrel.r_info = htab->r_info (0, R_X86_64_RELATIVE);
 	      outrel.r_addend = relocation;
+
+	      if (htab->params->report_relative_reloc)
+		_bfd_x86_elf_link_report_relative_reloc
+		  (info, input_section, h, sym, "R_X86_64_RELATIVE",
+		   &outrel);
+
 	      elf_append_rela (output_bfd, s, &outrel);
 	    }
 
@@ -3221,6 +3232,7 @@ elf_x86_64_relocate_section (bfd *output_bfd,
 	      Elf_Internal_Rela outrel;
 	      bfd_boolean skip, relocate;
 	      asection *sreloc;
+	      const char *relative_reloc_name = NULL;
 
 	      /* When generating a shared object, these relocations
 		 are copied into the output file to be resolved at run
@@ -3259,6 +3271,7 @@ elf_x86_64_relocate_section (bfd *output_bfd,
 		      relocate = TRUE;
 		      outrel.r_info = htab->r_info (0, R_X86_64_RELATIVE);
 		      outrel.r_addend = relocation + rel->r_addend;
+		      relative_reloc_name = "R_X86_64_RELATIVE";
 		    }
 		  else if (r_type == R_X86_64_64
 			   && !ABI_64_P (output_bfd))
@@ -3267,6 +3280,7 @@ elf_x86_64_relocate_section (bfd *output_bfd,
 		      outrel.r_info = htab->r_info (0,
 						    R_X86_64_RELATIVE64);
 		      outrel.r_addend = relocation + rel->r_addend;
+		      relative_reloc_name = "R_X86_64_RELATIVE64";
 		      /* Check addend overflow.  */
 		      if ((outrel.r_addend & 0x80000000)
 			  != (rel->r_addend & 0x80000000))
@@ -3333,6 +3347,12 @@ elf_x86_64_relocate_section (bfd *output_bfd,
 		  goto check_relocation_error;
 		}
 
+	      if (relative_reloc_name
+		  && htab->params->report_relative_reloc)
+		_bfd_x86_elf_link_report_relative_reloc
+		  (info, input_section, h, sym, relative_reloc_name,
+		   &outrel);
+
 	      elf_append_rela (output_bfd, sreloc, &outrel);
 
 	      /* If this reloc is against an external symbol, we do
@@ -4292,6 +4312,11 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
 	      rela.r_addend = (h->root.u.def.value
 			       + h->root.u.def.section->output_section->vma
 			       + h->root.u.def.section->output_offset);
+
+	      if (htab->params->report_relative_reloc)
+		_bfd_x86_elf_link_report_relative_reloc
+		  (info, relplt, h, sym, "R_X86_64_IRELATIVE", &rela);
+
 	      /* R_X86_64_IRELATIVE comes last.  */
 	      plt_index = htab->next_irelative_index--;
 	    }
@@ -4409,6 +4434,7 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
     {
       Elf_Internal_Rela rela;
       asection *relgot = htab->elf.srelgot;
+      const char *relative_reloc_name = NULL;
 
       /* This symbol has an entry in the global offset table.  Set it
 	 up.  */
@@ -4447,6 +4473,7 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
 		  rela.r_addend = (h->root.u.def.value
 				   + h->root.u.def.section->output_section->vma
 				   + h->root.u.def.section->output_offset);
+		  relative_reloc_name = "R_X86_64_IRELATIVE";
 		}
 	      else
 		goto do_glob_dat;
@@ -4494,6 +4521,7 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
 	  rela.r_addend = (h->root.u.def.value
 			   + h->root.u.def.section->output_section->vma
 			   + h->root.u.def.section->output_offset);
+	  relative_reloc_name = "R_X86_64_RELATIVE";
 	}
       else
 	{
@@ -4505,6 +4533,11 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
 	  rela.r_addend = 0;
 	}
 
+      if (relative_reloc_name != NULL
+	  && htab->params->report_relative_reloc)
+	_bfd_x86_elf_link_report_relative_reloc
+	  (info, relgot, h, sym, relative_reloc_name, &rela);
+
       elf_append_rela (output_bfd, relgot, &rela);
     }
 
diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
index 3a0dffc..8cda8d2 100644
--- a/bfd/elfxx-x86.c
+++ b/bfd/elfxx-x86.c
@@ -1742,6 +1742,53 @@ _bfd_x86_elf_link_fixup_ifunc_symbol (struct bfd_link_info *info,
     }
 }
 
+/* Report relative relocation.  */
+
+void
+_bfd_x86_elf_link_report_relative_reloc
+  (struct bfd_link_info *info, asection *asect,
+   struct elf_link_hash_entry *h, Elf_Internal_Sym *sym,
+   const char *reloc_name, const void *reloc)
+{
+  const char *name;
+  bfd *abfd;
+  const Elf_Internal_Rela *rel = (const Elf_Internal_Rela *) reloc;
+  char r_offset[30], r_info[30];
+
+  /* Use the output BFD for linker created sections.  */
+  if ((asect->flags & SEC_LINKER_CREATED) != 0)
+    abfd = info->output_bfd;
+  else
+    abfd = asect->owner;
+
+  if (h != NULL && h->root.root.string != NULL)
+    name = h->root.root.string;
+  else
+    name = bfd_elf_sym_name (abfd, &elf_symtab_hdr (abfd), sym, NULL);
+
+  bfd_sprintf_vma (abfd, r_offset, rel->r_offset);
+  bfd_sprintf_vma (abfd, r_info, rel->r_info);
+
+  if (asect->use_rela_p)
+    {
+      char r_addend[30];
+
+      bfd_sprintf_vma (abfd, r_addend, rel->r_addend);
+
+      info->callbacks->einfo
+	(_("%pB: %s (offset: 0x%s, info: 0x%s, addend: 0x%s) against "
+	   "'%s' " "for section '%pA' in %pB\n"),
+	 info->output_bfd, reloc_name, r_offset, r_info, r_addend,
+	 name, asect, abfd);
+    }
+  else
+    info->callbacks->einfo
+      (_("%pB: %s (offset: 0x%s, info: 0x%s) against '%s' for section "
+	 "'%pA' in %pB\n"),
+       info->output_bfd, reloc_name, r_offset, r_info, name,
+       asect, abfd);
+}
+
 /* Return TRUE if symbol should be hashed in the `.gnu.hash' section.  */
 
 bfd_boolean
diff --git a/bfd/elfxx-x86.h b/bfd/elfxx-x86.h
index e11e06b..7a5b9e0 100644
--- a/bfd/elfxx-x86.h
+++ b/bfd/elfxx-x86.h
@@ -686,6 +686,10 @@ extern void _bfd_x86_elf_link_fixup_ifunc_symbol
   (struct bfd_link_info *, struct elf_x86_link_hash_table *,
    struct elf_link_hash_entry *, Elf_Internal_Sym *sym);
 
+extern void _bfd_x86_elf_link_report_relative_reloc
+  (struct bfd_link_info *, asection *, struct elf_link_hash_entry *,
+   Elf_Internal_Sym *, const char *, const void *);
+
 #define bfd_elf64_mkobject \
   _bfd_x86_elf_mkobject
 #define bfd_elf32_mkobject \