[x86] Resolve non-PIC undefweak symbols in executable

For i386 and x86-64, non-PIC references to undefined weak symbols are
resolved without dynamic relocation when creating executable.  Resolved
undefined weak symbols are removed from the dynamic symbol table in
executable.  One exception is on i386, we need resolved undefined weak
symbols in the dynamic symbol table in PIE if input relocatable files
contain branchs without PLT so that we can branch to 0 with dynamic
relocation in text section.

This makes behaviors of dynamic executable and position independent
executable predictable with mixed PIC and non-PIC references to undefined
weak symbols.  If all references to undefined weak symbols are PIC,
dynamic relocations against undefined weak symbols will be generated
in executable unless -z nodynamic-undefined-weak is passed to linker.

bfd/

	PR ld/19636
	PR ld/19704
	PR ld/19719
	* elf32-i386.c (UNDEFINED_WEAK_RESOLVED_TO_ZERO): New.
	(elf_i386_link_hash_entry): Add has_got_reloc and
	has_non_got_reloc.
	(elf_i386_link_hash_table): Add interp.
	(elf_i386_link_hash_newfunc): Initialize has_got_reloc and
	has_non_got_reloc.
	(elf_i386_copy_indirect_symbol): Copy has_got_reloc and
	has_non_got_reloc.
	(elf_i386_check_relocs): Set has_got_reloc and has_non_got_reloc.
	(elf_i386_fixup_symbol): New function.
	(elf_i386_pie_finish_undefweak_symbol): Likewise.
	(elf_i386_allocate_dynrelocs): Don't allocate space for dynamic
	relocations and discard relocations against resolved undefined
	weak symbols in executable.  Don't make resolved undefined weak
	symbols in executable dynamic.  Keep dynamic non-GOT/non-PLT
	relocation against undefined weak symbols in PIE.
	(elf_i386_size_dynamic_sections): Set interp to .interp section.
	(elf_i386_relocate_section): Don't generate dynamic relocations
	against resolved undefined weak symbols in PIE, except for
	R_386_PC32.
	(elf_i386_finish_dynamic_symbol): Keep PLT/GOT entries without
	dynamic PLT/GOT relocations for resolved undefined weak symbols.
	Don't generate dynamic relocation against resolved undefined weak
	symbol in executable.
	(elf_i386_finish_dynamic_sections): Call
	elf_i386_pie_finish_undefweak_symbol on all symbols in PIE.
	(elf_backend_fixup_symbol): New.
	* elf64-x86-64.c (UNDEFINED_WEAK_RESOLVED_TO_ZERO): New.
	(elf_x86_64_link_hash_entry): Add has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_link_hash_table): Add interp.
	(elf_x86_64_link_hash_newfunc): Initialize has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_copy_indirect_symbol): Copy has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_check_relocs): Set has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_fixup_symbol): New function.
	(elf_x86_64_pie_finish_undefweak_symbol): Likewise.
	(elf_x86_64_allocate_dynrelocs): Don't allocate space for dynamic
	relocations and discard relocations against resolved undefined
	weak symbols in executable.  Don't make resolved undefined weak
	symbols in executable dynamic.
	(elf_x86_64_size_dynamic_sections): Set interp to .interp section.
	(elf_x86_64_relocate_section): Check relocation overflow for
	dynamic relocations against unresolved weak undefined symbols.
	Don't generate dynamic relocations against resolved weak
	undefined symbols in PIE.
	(elf_x86_64_finish_dynamic_symbol): Keep PLT/GOT entries without
	dynamic PLT/GOT relocations for resolved undefined weak symbols.
	Don't generate dynamic relocation against resolved undefined weak
	symbol in executable.
	(elf_x86_64_finish_dynamic_sections): Call
	elf_x86_64_pie_finish_undefweak_symbol on all symbols in PIE.
	(elf_backend_fixup_symbol): New.

include/

	PR ld/19636
	PR ld/19704
	PR ld/19719
	* bfdlink.h (bfd_link_info): Add dynamic_undefined_weak.

ld/

	PR ld/19636
	PR ld/19704
	PR ld/19719
	* Makefile.am (ELF_X86_DEPS): Add dynamic_undefined_weak.sh.
	* Makefile.in: Regenerated.
	* NEWS: Mention -z nodynamic-undefined-weak.
	* ld.texinfo: Document -z nodynamic-undefined-weak.
	* ldmain.c (main): Initialize dynamic_undefined_weak to -1.
	* emulparams/dynamic_undefined_weak.sh: New file.
	* emulparams/elf32_x86_64.sh: Source dynamic_undefined_weak.sh.
	* emulparams/elf_i386.sh: Likewise.
	* emulparams/elf_i386_be.sh: Likewise.
	* emulparams/elf_i386_chaos.sh: Likewise.
	* emulparams/elf_i386_ldso.sh: Likewise.
	* emulparams/elf_i386_vxworks.sh: Likewise.
	* emulparams/elf_iamcu.sh: Likewise.
	* emulparams/elf_k1om.sh: Likewise.
	* emulparams/elf_l1om.sh: Likewise.
	* emulparams/elf_x86_64.sh: Likewise.
	* emulparams/extern_protected_data.sh (PARSE_AND_LIST_OPTIONS):
	Append.
	(PARSE_AND_LIST_ARGS_CASE_Z): Likewise.
	* testsuite/ld-elf/pr19719a.c: New file.
	* testsuite/ld-elf/pr19719b.c: Likewise.
	* testsuite/ld-elf/pr19719c.c: Likewise.
	* testsuite/ld-elf/pr19719d.c: Likewise.
	* testsuite/ld-i386/pr19636-1.s: Likewise.
	* testsuite/ld-i386/pr19636-1a.d: Likewise.
	* testsuite/ld-i386/pr19636-1b.d: Likewise.
	* testsuite/ld-i386/pr19636-1c.d: Likewise.
	* testsuite/ld-i386/pr19636-1d-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-1d.d: Likewise.
	* testsuite/ld-i386/pr19636-1e.d: Likewise.
	* testsuite/ld-i386/pr19636-1f.d: Likewise.
	* testsuite/ld-i386/pr19636-1g.d: Likewise.
	* testsuite/ld-i386/pr19636-1h.d: Likewise.
	* testsuite/ld-i386/pr19636-1i.d: Likewise.
	* testsuite/ld-i386/pr19636-2.s: Likewise.
	* testsuite/ld-i386/pr19636-2a.d: Likewise.
	* testsuite/ld-i386/pr19636-2b.d: Likewise.
	* testsuite/ld-i386/pr19636-2c-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-2c.d: Likewise.
	* testsuite/ld-i386/pr19636-2d-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-2d.d: Likewise.
	* testsuite/ld-i386/pr19636-2e-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-2e.d: Likewise.
	* testsuite/ld-i386/pr19636-3.s: Likewise.
	* testsuite/ld-i386/pr19636-3a.d: Likewise.
	* testsuite/ld-i386/pr19636-3b.d: Likewise.
	* testsuite/ld-i386/pr19636-3c.d: Likewise.
	* testsuite/ld-i386/pr19636-3d.d: Likewise.
	* testsuite/ld-i386/pr19636-3e.d: Likewise.
	* testsuite/ld-i386/pr19636-3f.d: Likewise.
	* testsuite/ld-i386/pr19636-3g.d: Likewise.
	* testsuite/ld-i386/pr19636-4.s: Likewise.
	* testsuite/ld-i386/pr19636-4a.d: Likewise.
	* testsuite/ld-i386/pr19636-4b.d: Likewise.
	* testsuite/ld-i386/pr19636-4c.d: Likewise.
	* testsuite/ld-i386/pr19636-4d.d: Likewise.
	* testsuite/ld-i386/pr19704.out: Likewise.
	* testsuite/ld-i386/pr19704a.c: Likewise.
	* testsuite/ld-i386/pr19704b.c: Likewise.
	* testsuite/ld-x86-64/pr19636-1.s: Likewise.
	* testsuite/ld-x86-64/pr19636-1a.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1b.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1c.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1d.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1e.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1f.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1g.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2.s: Likewise.
	* testsuite/ld-x86-64/pr19636-2a.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2b.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2c.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2d-nacl.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2d.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2e.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2f.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2g.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2h.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2i.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3.s: Likewise.
	* testsuite/ld-x86-64/pr19636-3a.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3b.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3c.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3d.d: Likewise.
	* testsuite/ld-x86-64/pr19704.out: Likewise.
	* testsuite/ld-x86-64/pr19704a.c: Likewise.
	* testsuite/ld-x86-64/pr19704b.c: Likewise.
	* testsuite/ld-elf/shared.exp (mix_pic_and_non_pic): New.
	Run mix_pic_and_non_pic.
	* testsuite/ld-i386/i386.exp (undefined_weak): New.
	Run undefined_weak and PR ld/19636 tests.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
	* testsuite/ld-x86-64/pr13082-3b.d: Updated.
	* testsuite/ld-x86-64/pr13082-4b.d: Likewise.

1 files changed, 221 insertions, 66 deletions

diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index f6c9c65..2ae5e44 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -737,6 +737,20 @@ static const struct elf_i386_backend_data elf_i386_arch_bed =
 
 #define	elf_backend_arch_data	&elf_i386_arch_bed
 
+/* Is a undefined weak symbol which is resolved to 0.  Reference to an
+   undefined weak symbol is resolved to 0 when building executable if
+   it isn't dynamic and
+   1. Has non-GOT/non-PLT relocations in text section.  Or
+   2. Has no GOT/PLT relocation.
+ */
+#define UNDEFINED_WEAK_RESOLVED_TO_ZERO(INFO, EH) \
+  ((EH)->elf.root.type == bfd_link_hash_undefweak		\
+   && bfd_link_executable (INFO)				\
+   && (elf_i386_hash_table (INFO)->interp == NULL	 	\
+       || !(EH)->has_got_reloc					\
+       || (EH)->has_non_got_reloc				\
+       || !(INFO)->dynamic_undefined_weak))
+
 /* i386 ELF linker hash entry.  */
 
 struct elf_i386_link_hash_entry
@@ -767,6 +781,12 @@ struct elf_i386_link_hash_entry
   /* Symbol is referenced by R_386_GOTOFF relocation.  */
   unsigned int gotoff_ref : 1;
 
+  /* Symbol has GOT or PLT relocations.  */
+  unsigned int has_got_reloc : 1;
+
+  /* Symbol has non-GOT/non-PLT relocations in text sections.  */
+  unsigned int has_non_got_reloc : 1;
+
   /* Reference count of C/C++ function pointer relocations in read-write
      section which can be resolved at run-time.  */
   bfd_signed_vma func_pointer_refcount;
@@ -821,6 +841,7 @@ struct elf_i386_link_hash_table
   struct elf_link_hash_table elf;
 
   /* Short-cuts to get to dynamic linker sections.  */
+  asection *interp;
   asection *sdynbss;
   asection *srelbss;
   asection *plt_eh_frame;
@@ -895,6 +916,8 @@ elf_i386_link_hash_newfunc (struct bfd_hash_entry *entry,
       eh->dyn_relocs = NULL;
       eh->tls_type = GOT_UNKNOWN;
       eh->gotoff_ref = 0;
+      eh->has_got_reloc = 0;
+      eh->has_non_got_reloc = 0;
       eh->func_pointer_refcount = 0;
       eh->plt_got.offset = (bfd_vma) -1;
       eh->tlsdesc_got = (bfd_vma) -1;
@@ -1138,6 +1161,9 @@ elf_i386_copy_indirect_symbol (struct bfd_link_info *info,
      generate a R_386_COPY reloc.  */
   edir->gotoff_ref |= eind->gotoff_ref;
 
+  edir->has_got_reloc |= eind->has_got_reloc;
+  edir->has_non_got_reloc |= eind->has_non_got_reloc;
+
   if (ELIMINATE_COPY_RELOCS
       && ind->root.type != bfd_link_hash_indirect
       && dir->dynamic_adjusted)
@@ -1630,6 +1656,7 @@ elf_i386_check_relocs (bfd *abfd,
 	  if (h == NULL)
 	    continue;
 
+	  eh->has_got_reloc = 1;
 	  h->needs_plt = 1;
 	  h->plt.refcount += 1;
 	  break;
@@ -1760,18 +1787,27 @@ elf_i386_check_relocs (bfd *abfd,
 		return FALSE;
 	    }
 	  if (r_type != R_386_TLS_IE)
-	    break;
+	    {
+	      if (eh != NULL)
+		eh->has_got_reloc = 1;
+	      break;
+	    }
 	  /* Fall through */
 
 	case R_386_TLS_LE_32:
 	case R_386_TLS_LE:
+	  if (eh != NULL)
+	    eh->has_got_reloc = 1;
 	  if (bfd_link_executable (info))
 	    break;
 	  info->flags |= DF_STATIC_TLS;
-	  /* Fall through */
+	  goto do_relocation;
 
 	case R_386_32:
 	case R_386_PC32:
+	  if (eh != NULL && (sec->flags & SEC_CODE) != 0)
+	    eh->has_non_got_reloc = 1;
+do_relocation:
 	  if (h != NULL && bfd_link_executable (info))
 	    {
 	      /* If this reloc is in a read-only section, we might
@@ -2147,6 +2183,24 @@ elf_i386_gc_sweep_hook (bfd *abfd,
   return TRUE;
 }
 
+/* Remove undefined weak symbol from the dynamic symbol table if it
+   is resolved to 0.   */
+
+static bfd_boolean
+elf_i386_fixup_symbol (struct bfd_link_info *info,
+		       struct elf_link_hash_entry *h)
+{
+  if (h->dynindx != -1
+      && UNDEFINED_WEAK_RESOLVED_TO_ZERO (info,
+					  elf_i386_hash_entry (h)))
+    {
+      h->dynindx = -1;
+      _bfd_elf_strtab_delref (elf_hash_table (info)->dynstr,
+			      h->dynstr_index);
+    }
+  return TRUE;
+}
+
 /* Adjust a symbol defined by a dynamic object and referenced by a
    regular object.  The current definition is in some section of the
    dynamic object, but we're not including those sections.  We have to
@@ -2335,6 +2389,7 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
   struct elf_i386_link_hash_entry *eh;
   struct elf_dyn_relocs *p;
   unsigned plt_entry_size;
+  bfd_boolean resolved_to_zero;
 
   if (h->root.type == bfd_link_hash_indirect)
     return TRUE;
@@ -2348,6 +2403,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 
   plt_entry_size = GET_PLT_ENTRY_SIZE (info->output_bfd);
 
+  resolved_to_zero = UNDEFINED_WEAK_RESOLVED_TO_ZERO (info, eh);
+
   /* Clear the reference count of function pointer relocations if
      symbol isn't a normal function.  */
   if (h->type != STT_FUNC)
@@ -2405,7 +2462,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
       /* Make sure this symbol is output as a dynamic symbol.
 	 Undefined weak syms won't yet be marked as dynamic.  */
       if (h->dynindx == -1
-	  && !h->forced_local)
+	  && !h->forced_local
+	  && !resolved_to_zero)
 	{
 	  if (! bfd_elf_link_record_dynamic_symbol (info, h))
 	    return FALSE;
@@ -2462,9 +2520,15 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 		 script.  */
 	      htab->elf.sgotplt->size += 4;
 
-	      /* We also need to make an entry in the .rel.plt section.  */
-	      htab->elf.srelplt->size += sizeof (Elf32_External_Rel);
-	      htab->elf.srelplt->reloc_count++;
+	      /* There should be no PLT relocation against resolved
+		 undefined weak symbol in executable.  */
+	      if (!resolved_to_zero)
+		{
+		  /* We also need to make an entry in the .rel.plt
+		     section.  */
+		  htab->elf.srelplt->size += sizeof (Elf32_External_Rel);
+		  htab->elf.srelplt->reloc_count++;
+		}
 	    }
 
 	  if (get_elf_i386_backend_data (info->output_bfd)->is_vxworks
@@ -2520,7 +2584,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
       /* Make sure this symbol is output as a dynamic symbol.
 	 Undefined weak syms won't yet be marked as dynamic.  */
       if (h->dynindx == -1
-	  && !h->forced_local)
+	  && !h->forced_local
+	  && !resolved_to_zero)
 	{
 	  if (! bfd_elf_link_record_dynamic_symbol (info, h))
 	    return FALSE;
@@ -2548,7 +2613,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 	 R_386_TLS_IE resp. R_386_TLS_GOTIE needs one dynamic relocation,
 	 (but if both R_386_TLS_IE_32 and R_386_TLS_IE is present, we
 	 need two), R_386_TLS_GD needs one if local symbol and two if
-	 global.  */
+	 global.  No dynamic relocation against resolved undefined weak
+	 symbol in executable.  */
       if (tls_type == GOT_TLS_IE_BOTH)
 	htab->elf.srelgot->size += 2 * sizeof (Elf32_External_Rel);
       else if ((GOT_TLS_GD_P (tls_type) && h->dynindx == -1)
@@ -2557,7 +2623,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
       else if (GOT_TLS_GD_P (tls_type))
 	htab->elf.srelgot->size += 2 * sizeof (Elf32_External_Rel);
       else if (! GOT_TLS_GDESC_P (tls_type)
-	       && (ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
+	       && ((ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
+		    && !resolved_to_zero)
 		   || h->root.type != bfd_link_hash_undefweak)
 	       && (bfd_link_pic (info)
 		   || WILL_CALL_FINISH_DYNAMIC_SYMBOL (dyn, 0, h)))
@@ -2613,15 +2680,43 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 	}
 
       /* Also discard relocs on undefined weak syms with non-default
-    	 visibility.  */
+	 visibility or in PIE.  */
       if (eh->dyn_relocs != NULL
 	  && h->root.type == bfd_link_hash_undefweak)
 	{
-	  if (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
-	    eh->dyn_relocs = NULL;
+	  /* Undefined weak symbol is never bound locally in shared
+	     library.  */
+	  if (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT
+	      || resolved_to_zero)
+	    {
+	      if (h->non_got_ref)
+		{
+		  /* Keep dynamic non-GOT/non-PLT relocation so that we
+		     can branch to 0 without PLT.  */
+		  struct elf_dyn_relocs **pp;
+
+		  for (pp = &eh->dyn_relocs; (p = *pp) != NULL; )
+		    if (p->pc_count == 0)
+		      *pp = p->next;
+		    else
+		      {
+			/* Remove non-R_386_PC32 relocation.  */
+			p->count = p->pc_count;
+			pp = &p->next;
+		      }
 
-	  /* Make sure undefined weak symbols are output as a dynamic
-	     symbol in PIEs.  */
+		  if (eh->dyn_relocs != NULL)
+		    {
+		      /* Make sure undefined weak symbols are output
+			 as dynamic symbols in PIEs for dynamic non-GOT
+			 non-PLT reloations.  */
+		      if (! bfd_elf_link_record_dynamic_symbol (info, h))
+			return FALSE;
+		    }
+		}
+	      else
+		eh->dyn_relocs = NULL;
+	    }
 	  else if (h->dynindx == -1
 		   && !h->forced_local)
 	    {
@@ -2637,7 +2732,10 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 	 dynamic.  Keep dynamic relocations for run-time function
 	 pointer initialization.  */
 
-      if ((!h->non_got_ref || eh->func_pointer_refcount > 0)
+      if ((!h->non_got_ref
+	   || eh->func_pointer_refcount > 0
+	   || (h->root.type == bfd_link_hash_undefweak
+	       && !resolved_to_zero))
 	  && ((h->def_dynamic
 	       && !h->def_regular)
 	      || (htab->elf.dynamic_sections_created
@@ -2647,7 +2745,8 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
 	  /* Make sure this symbol is output as a dynamic symbol.
 	     Undefined weak syms won't yet be marked as dynamic.  */
 	  if (h->dynindx == -1
-	      && !h->forced_local)
+	      && !h->forced_local
+	      && !resolved_to_zero)
 	    {
 	      if (! bfd_elf_link_record_dynamic_symbol (info, h))
 		return FALSE;
@@ -3110,6 +3209,7 @@ elf_i386_size_dynamic_sections (bfd *output_bfd, struct bfd_link_info *info)
 	    abort ();
 	  s->size = sizeof ELF_DYNAMIC_INTERPRETER;
 	  s->contents = (unsigned char *) ELF_DYNAMIC_INTERPRETER;
+	  htab->interp = s;
 	}
     }
 
@@ -3640,6 +3740,7 @@ elf_i386_relocate_section (bfd *output_bfd,
       int tls_type;
       bfd_vma st_size;
       asection *resolved_plt;
+      bfd_boolean resolved_to_zero;
 
       r_type = ELF32_R_TYPE (rel->r_info);
       if (r_type == R_386_GNU_VTINHERIT
@@ -3981,6 +4082,9 @@ elf_i386_relocate_section (bfd *output_bfd,
 	}
 
       eh = (struct elf_i386_link_hash_entry *) h;
+      resolved_to_zero = (eh != NULL
+			  && UNDEFINED_WEAK_RESOLVED_TO_ZERO (info, eh));
+
       switch (r_type)
 	{
 	case R_386_GOT32X:
@@ -4246,18 +4350,25 @@ r_386_got32:
 	      || is_vxworks_tls)
 	    break;
 
-	  /* Copy dynamic function pointer relocations.  */
+	  /* Copy dynamic function pointer relocations.  Don't generate
+	     dynamic relocations against resolved undefined weak symbols
+	     in PIE, except for R_386_PC32.  */
 	  if ((bfd_link_pic (info)
 	       && (h == NULL
-		   || ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
-		   || h->root.type != bfd_link_hash_undefweak)
+		   || ((ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
+			&& (!resolved_to_zero
+			    || r_type == R_386_PC32))
+		       || h->root.type != bfd_link_hash_undefweak))
 	       && ((r_type != R_386_PC32 && r_type != R_386_SIZE32)
 		   || !SYMBOL_CALLS_LOCAL (info, h)))
 	      || (ELIMINATE_COPY_RELOCS
 		  && !bfd_link_pic (info)
 		  && h != NULL
 		  && h->dynindx != -1
-		  && (!h->non_got_ref || eh->func_pointer_refcount > 0)
+		  && (!h->non_got_ref
+		      || eh->func_pointer_refcount > 0
+		      || (h->root.type == bfd_link_hash_undefweak
+			  && !resolved_to_zero))
 		  && ((h->def_dynamic
 		       && !h->def_regular)
 		      || h->root.type == bfd_link_hash_undefweak
@@ -5011,6 +5122,7 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
   unsigned plt_entry_size;
   const struct elf_i386_backend_data *abed;
   struct elf_i386_link_hash_entry *eh;
+  bfd_boolean local_undefweak;
 
   htab = elf_i386_hash_table (info);
   if (htab == NULL)
@@ -5021,6 +5133,11 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
 
   eh = (struct elf_i386_link_hash_entry *) h;
 
+  /* We keep PLT/GOT entries without dynamic PLT/GOT relocations for
+     resolved undefined weak symbols in executable so that their
+     references have value 0 at run-time.  */
+  local_undefweak = UNDEFINED_WEAK_RESOLVED_TO_ZERO (info, eh);
+
   if (h->plt.offset != (bfd_vma) -1)
     {
       bfd_vma plt_index;
@@ -5048,6 +5165,7 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
 	 it up.  */
 
       if ((h->dynindx == -1
+	   && !local_undefweak
 	   && !((h->forced_local || bfd_link_executable (info))
 		&& h->def_regular
 		&& h->type == STT_GNU_IFUNC))
@@ -5136,54 +5254,61 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
                       + abed->plt->plt_got_offset);
 	}
 
-      /* Fill in the entry in the global offset table.  */
-      bfd_put_32 (output_bfd,
-		  (plt->output_section->vma
-		   + plt->output_offset
-		   + h->plt.offset
-		   + abed->plt->plt_lazy_offset),
-		  gotplt->contents + got_offset);
-
-      /* Fill in the entry in the .rel.plt section.  */
-      rel.r_offset = (gotplt->output_section->vma
-		      + gotplt->output_offset
-		      + got_offset);
-      if (h->dynindx == -1
-	  || ((bfd_link_executable (info)
-	       || ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
-	      && h->def_regular
-	       && h->type == STT_GNU_IFUNC))
+      /* Fill in the entry in the global offset table.  Leave the entry
+	 as zero for undefined weak symbol in PIE.  No PLT relocation
+	 against undefined weak symbol in PIE.  */
+      if (!local_undefweak)
 	{
-	  /* If an STT_GNU_IFUNC symbol is locally defined, generate
-	     R_386_IRELATIVE instead of R_386_JUMP_SLOT.  Store addend
-	     in the .got.plt section.  */
 	  bfd_put_32 (output_bfd,
-		      (h->root.u.def.value
-		       + h->root.u.def.section->output_section->vma
-		       + h->root.u.def.section->output_offset),
+		      (plt->output_section->vma
+		       + plt->output_offset
+		       + h->plt.offset
+		       + abed->plt->plt_lazy_offset),
 		      gotplt->contents + got_offset);
-	  rel.r_info = ELF32_R_INFO (0, R_386_IRELATIVE);
-	  /* R_386_IRELATIVE comes last.  */
-	  plt_index = htab->next_irelative_index--;
-	}
-      else
-	{
-	  rel.r_info = ELF32_R_INFO (h->dynindx, R_386_JUMP_SLOT);
-	  plt_index = htab->next_jump_slot_index++;
-	}
-      loc = relplt->contents + plt_index * sizeof (Elf32_External_Rel);
-      bfd_elf32_swap_reloc_out (output_bfd, &rel, loc);
 
-      /* Don't fill PLT entry for static executables.  */
-      if (plt == htab->elf.splt)
-	{
-	  bfd_put_32 (output_bfd, plt_index * sizeof (Elf32_External_Rel),
-		      plt->contents + h->plt.offset
-                      + abed->plt->plt_reloc_offset);
-	  bfd_put_32 (output_bfd, - (h->plt.offset
-                                     + abed->plt->plt_plt_offset + 4),
-		      plt->contents + h->plt.offset
-                      + abed->plt->plt_plt_offset);
+	  /* Fill in the entry in the .rel.plt section.  */
+	  rel.r_offset = (gotplt->output_section->vma
+			  + gotplt->output_offset
+			  + got_offset);
+	  if (h->dynindx == -1
+	      || ((bfd_link_executable (info)
+		   || ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
+		  && h->def_regular
+		  && h->type == STT_GNU_IFUNC))
+	    {
+	      /* If an STT_GNU_IFUNC symbol is locally defined, generate
+		 R_386_IRELATIVE instead of R_386_JUMP_SLOT.  Store addend
+		 in the .got.plt section.  */
+	      bfd_put_32 (output_bfd,
+			  (h->root.u.def.value
+			   + h->root.u.def.section->output_section->vma
+			   + h->root.u.def.section->output_offset),
+			  gotplt->contents + got_offset);
+	      rel.r_info = ELF32_R_INFO (0, R_386_IRELATIVE);
+	      /* R_386_IRELATIVE comes last.  */
+	      plt_index = htab->next_irelative_index--;
+	    }
+	  else
+	    {
+	      rel.r_info = ELF32_R_INFO (h->dynindx, R_386_JUMP_SLOT);
+	      plt_index = htab->next_jump_slot_index++;
+	    }
+
+	  loc = relplt->contents + plt_index * sizeof (Elf32_External_Rel);
+	  bfd_elf32_swap_reloc_out (output_bfd, &rel, loc);
+
+	  /* Don't fill PLT entry for static executables.  */
+	  if (plt == htab->elf.splt)
+	    {
+	      bfd_put_32 (output_bfd,
+			  plt_index * sizeof (Elf32_External_Rel),
+			  plt->contents + h->plt.offset
+			  + abed->plt->plt_reloc_offset);
+	      bfd_put_32 (output_bfd, - (h->plt.offset
+					 + abed->plt->plt_plt_offset + 4),
+			  plt->contents + h->plt.offset
+			  + abed->plt->plt_plt_offset);
+	    }
 	}
     }
   else if (eh->plt_got.offset != (bfd_vma) -1)
@@ -5229,7 +5354,8 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
 		  plt->contents + plt_offset + plt_got_offset);
     }
 
-  if (!h->def_regular
+  if (!local_undefweak
+      && !h->def_regular
       && (h->plt.offset != (bfd_vma) -1
 	  || eh->plt_got.offset != (bfd_vma) -1))
     {
@@ -5246,9 +5372,12 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
 	sym->st_value = 0;
     }
 
+  /* Don't generate dynamic GOT relocation against undefined weak
+     symbol in executable.  */
   if (h->got.offset != (bfd_vma) -1
       && ! GOT_TLS_GD_ANY_P (elf_i386_hash_entry(h)->tls_type)
-      && (elf_i386_hash_entry(h)->tls_type & GOT_TLS_IE) == 0)
+      && (elf_i386_hash_entry(h)->tls_type & GOT_TLS_IE) == 0
+      && !local_undefweak)
     {
       Elf_Internal_Rela rel;
 
@@ -5348,6 +5477,25 @@ elf_i386_finish_local_dynamic_symbol (void **slot, void *inf)
 					 h, NULL);
 }
 
+/* Finish up undefined weak symbol handling in PIE.  Fill its PLT entry
+   here since undefined weak symbol may not be dynamic and may not be
+   called for elf_i386_finish_dynamic_symbol.  */
+
+static bfd_boolean
+elf_i386_pie_finish_undefweak_symbol (struct bfd_hash_entry *bh,
+				      void *inf)
+{
+  struct elf_link_hash_entry *h = (struct elf_link_hash_entry *) bh;
+  struct bfd_link_info *info = (struct bfd_link_info *) inf;
+
+  if (h->root.type != bfd_link_hash_undefweak
+      || h->dynindx != -1)
+    return TRUE;
+
+  return elf_i386_finish_dynamic_symbol (info->output_bfd,
+					     info, h, NULL);
+}
+
 /* Used to decide how to sort relocs in an optimal manner for the
    dynamic linker, before writing them out.  */
 
@@ -5626,6 +5774,12 @@ elf_i386_finish_dynamic_sections (bfd *output_bfd,
 		 elf_i386_finish_local_dynamic_symbol,
 		 info);
 
+  /* Fill PLT entries for undefined weak symbols in PIE.  */
+  if (bfd_link_pie (info))
+    bfd_hash_traverse (&info->hash->table,
+		       elf_i386_pie_finish_undefweak_symbol,
+		       info);
+
   return TRUE;
 }
 
@@ -5803,6 +5957,7 @@ elf_i386_add_symbol_hook (bfd * abfd,
   ((bfd_boolean (*) (bfd *, struct bfd_link_info *, asection *)) bfd_true)
 #define elf_backend_hash_symbol		      elf_i386_hash_symbol
 #define elf_backend_add_symbol_hook           elf_i386_add_symbol_hook
+#define elf_backend_fixup_symbol	      elf_i386_fixup_symbol
 
 #include "elf32-target.h"