IFUNC: Update IFUNC resolver check with DT_TEXTREL

Add ifunc_resolvers to elf_link_hash_table and use it for both x86 and
ppc64.  Before glibc commit b5c45e837, DT_TEXTREL is incompatible with
IFUNC resolvers.  Set ifunc_resolvers if there are IFUNC resolvers and
issue a warning for IFUNC resolvers with DT_TEXTREL.

bfd/

	PR ld/18801
	* elf-bfd.h (elf_link_hash_table): Add ifunc_resolvers.
	(_bfd_elf_allocate_ifunc_dyn_relocs): Remove the
	bfd_boolean * argument.  Set ifunc_resolvers if there are IFUNC
	resolvers.
	* elf-ifunc.c (_bfd_elf_allocate_ifunc_dyn_relocs): Updated.
	Set ifunc_resolvers if there are FUNC resolvers.
	* elf64-ppc.c (ppc_link_hash_table): Remove local_ifunc_resolver.
	(build_global_entry_stubs_and_plt): Replace local_ifunc_resolver
	with elf.ifunc_resolvers.
	(write_plt_relocs_for_local_syms): Likewise.
	(ppc64_elf_relocate_section): Likewise.
	(ppc64_elf_finish_dynamic_sections): Likewise.
	* elfnn-aarch64.c (elfNN_aarch64_allocate_ifunc_dynrelocs):
	Updated.
	* elfxx-x86.c (elf_x86_allocate_dynrelocs): Likewise.
	(_bfd_x86_elf_size_dynamic_sections): Check elf.ifunc_resolvers
	instead of readonly_dynrelocs_against_ifunc.
	* elfxx-x86.h (elf_x86_link_hash_table): Remove
	readonly_dynrelocs_against_ifunc.

ld/

	PR ld/18801
	* testsuite/ld-i386/i386.exp: Run ifunc-textrel-1a,
	ifunc-textrel-1b, ifunc-textrel-2a and ifunc-textrel-2b.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
	* testsuite/ld-i386/ifunc-textrel-1a.d: Likewise.
	* testsuite/ld-i386/ifunc-textrel-1b.d: Likewise.
	* testsuite/ld-i386/ifunc-textrel-2a.d: Likewise.
	* testsuite/ld-i386/ifunc-textrel-2b.d: Likewise.
	* testsuite/ld-x86-64/ifunc-textrel-1.s: Likewise.
	* testsuite/ld-x86-64/ifunc-textrel-1a.d: Likewise.
	* testsuite/ld-x86-64/ifunc-textrel-1b.d: Likewise.
	* testsuite/ld-x86-64/ifunc-textrel-2.s: Likewise.
	* testsuite/ld-x86-64/ifunc-textrel-2a.d: Likewise.
	* testsuite/ld-x86-64/ifunc-textrel-2b.d: Likewise.
	* testsuite/ld-i386/pr18801a.d: Expect warning for IFUNC
	resolvers.
	* testsuite/ld-i386/pr18801b.d: Likewise.
	* estsuite/ld-x86-64/pr18801a.d: Likewise.
	* estsuite/ld-x86-64/pr18801b.d: Likewise.

bfd/ChangeLog

@@ -1,3 +1,26 @@
+2020-06-09  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/18801
+	* elf-bfd.h (elf_link_hash_table): Add ifunc_resolvers.
+	(_bfd_elf_allocate_ifunc_dyn_relocs): Remove the
+	bfd_boolean * argument.  Set ifunc_resolvers if there are IFUNC
+	resolvers.
+	* elf-ifunc.c (_bfd_elf_allocate_ifunc_dyn_relocs): Updated.
+	Set ifunc_resolvers if there are FUNC resolvers.
+	* elf64-ppc.c (ppc_link_hash_table): Remove local_ifunc_resolver.
+	(build_global_entry_stubs_and_plt): Replace local_ifunc_resolver
+	with elf.ifunc_resolvers.
+	(write_plt_relocs_for_local_syms): Likewise.
+	(ppc64_elf_relocate_section): Likewise.
+	(ppc64_elf_finish_dynamic_sections): Likewise.
+	* elfnn-aarch64.c (elfNN_aarch64_allocate_ifunc_dynrelocs):
+	Updated.
+	* elfxx-x86.c (elf_x86_allocate_dynrelocs): Likewise.
+	(_bfd_x86_elf_size_dynamic_sections): Check elf.ifunc_resolvers
+	instead of readonly_dynrelocs_against_ifunc.
+	* elfxx-x86.h (elf_x86_link_hash_table): Remove
+	readonly_dynrelocs_against_ifunc.
+
 2020-06-09  Alan Modra  <amodra@gmail.com>
 
 	* elf64-ppc.c (struct ppc_link_hash_table): Delete

bfd/elf-bfd.h

@@ -570,6 +570,9 @@ struct elf_link_hash_table
      section symbols.  */
   bfd_boolean is_relocatable_executable;
 
+  /* TRUE if there are IFUNC resolvers.  */
+  bfd_boolean ifunc_resolvers;
+
   /* The BFD used to hold special sections created by the linker.
      This will be the first BFD found which requires these sections to
      be created.  */
@@ -2875,8 +2878,8 @@ extern bfd_boolean _bfd_elf_create_ifunc_sections
   (bfd *, struct bfd_link_info *);
 extern bfd_boolean _bfd_elf_allocate_ifunc_dyn_relocs
   (struct bfd_link_info *, struct elf_link_hash_entry *,
-   struct elf_dyn_relocs **, bfd_boolean *, unsigned int,
+   struct elf_dyn_relocs **, unsigned int, unsigned int,
-   unsigned int, unsigned int, bfd_boolean);
+   unsigned int, bfd_boolean);
 
 extern void elf_append_rela (bfd *, asection *, Elf_Internal_Rela *);
 extern void elf_append_rel (bfd *, asection *, Elf_Internal_Rela *);

bfd/elf-ifunc.c

@@ -107,7 +107,6 @@ bfd_boolean
 _bfd_elf_allocate_ifunc_dyn_relocs (struct bfd_link_info *info,
 				    struct elf_link_hash_entry *h,
 				    struct elf_dyn_relocs **head,
-				    bfd_boolean *readonly_dynrelocs_against_ifunc_p,
 				    unsigned int plt_entry_size,
 				    unsigned int plt_header_size,
 				    unsigned int got_entry_size,
@@ -118,7 +117,6 @@ _bfd_elf_allocate_ifunc_dyn_relocs (struct bfd_link_info *info,
   unsigned int sizeof_reloc;
   const struct elf_backend_data *bed;
   struct elf_link_hash_table *htab;
-  bfd_boolean readonly_dynrelocs_against_ifunc;
   /* If AVOID_PLT is TRUE, don't use PLT if possible.  */
   bfd_boolean use_plt = !avoid_plt || h->plt.refcount > 0;
   bfd_boolean need_dynreloc = !use_plt || bfd_link_pic (info);
@@ -255,8 +253,6 @@ _bfd_elf_allocate_ifunc_dyn_relocs (struct bfd_link_info *info,
   if (!need_dynreloc || !h->non_got_ref)
     *head = NULL;
 
-  readonly_dynrelocs_against_ifunc = FALSE;
-
   /* Finally, allocate space.  */
   p = *head;
   if (p != NULL)
@@ -264,17 +260,13 @@ _bfd_elf_allocate_ifunc_dyn_relocs (struct bfd_link_info *info,
       bfd_size_type count = 0;
       do
 	{
-	  if (!readonly_dynrelocs_against_ifunc)
-	    {
-	      asection *s = p->sec->output_section;
-	      if (s != NULL && (s->flags & SEC_READONLY) != 0)
-		readonly_dynrelocs_against_ifunc = TRUE;
-	    }
 	  count += p->count;
 	  p = p->next;
 	}
       while (p != NULL);
 
+      htab->ifunc_resolvers = count != 0;
+
       /* Dynamic relocations are stored in
 	 1. .rel[a].ifunc section in PIC object.
 	 2. .rel[a].got section in dynamic executable.
@@ -290,9 +282,6 @@ _bfd_elf_allocate_ifunc_dyn_relocs (struct bfd_link_info *info,
 	}
     }
 
-  if (readonly_dynrelocs_against_ifunc_p)
-    *readonly_dynrelocs_against_ifunc_p = readonly_dynrelocs_against_ifunc;
-
   /* For STT_GNU_IFUNC symbol, .got.plt has the real function address
      and .got has the PLT entry adddress.  We will load the GOT entry
      with the PLT entry in finish_dynamic_symbol if it is used.  For

bfd/elf64-ppc.c

@@ -3239,10 +3239,6 @@ struct ppc_link_hash_table
   /* Whether func_desc_adjust needs to be run over symbols.  */
   unsigned int need_func_desc_adj:1;
 
-  /* Whether there exist local gnu indirect function resolvers,
-     referenced by dynamic relocations.  */
-  unsigned int local_ifunc_resolver:1;
-
   /* Whether plt calls for ELFv2 localentry:0 funcs have been optimized.  */
   unsigned int has_plt_localentry0:1;
 
@@ -13880,7 +13876,7 @@ build_global_entry_stubs_and_plt (struct elf_link_hash_entry *h, void *inf)
 	      {
 		plt = htab->elf.iplt;
 		relplt = htab->elf.irelplt;
-		htab->local_ifunc_resolver = 1;
+		htab->elf.ifunc_resolvers = TRUE;
 		if (htab->opd_abi)
 		  rela.r_info = ELF64_R_INFO (0, R_PPC64_JMP_IREL);
 		else
@@ -13934,7 +13930,7 @@ build_global_entry_stubs_and_plt (struct elf_link_hash_entry *h, void *inf)
 		   + ((ent->plt.offset - PLT_INITIAL_ENTRY_SIZE (htab))
 		      / PLT_ENTRY_SIZE (htab) * sizeof (Elf64_External_Rela)));
 	    if (h->type == STT_GNU_IFUNC && is_static_defined (h))
-	      htab->local_ifunc_resolver = 1;
+	      htab->elf.ifunc_resolvers = TRUE;
 	    bfd_elf64_swap_reloca_out (info->output_bfd, &rela, loc);
 	  }
       }
@@ -14076,7 +14072,7 @@ write_plt_relocs_for_local_syms (struct bfd_link_info *info)
 
 	      if (ELF_ST_TYPE (sym->st_info) == STT_GNU_IFUNC)
 		{
-		  htab->local_ifunc_resolver = 1;
+		  htab->elf.ifunc_resolvers = TRUE;
 		  plt = htab->elf.iplt;
 		  relplt = htab->elf.irelplt;
 		}
@@ -16103,7 +16099,7 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 		  {
 		    relgot = htab->elf.irelplt;
 		    if (indx == 0 || is_static_defined (&h->elf))
-		      htab->local_ifunc_resolver = 1;
+		      htab->elf.ifunc_resolvers = TRUE;
 		  }
 		else if (indx != 0
 			 || (bfd_link_pic (info)
@@ -16633,7 +16629,7 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 		{
 		  sreloc = htab->elf.irelplt;
 		  if (indx == 0 || is_static_defined (&h->elf))
-		    htab->local_ifunc_resolver = 1;
+		    htab->elf.ifunc_resolvers = TRUE;
 		}
 	      if (sreloc == NULL)
 		abort ();
@@ -17397,7 +17393,7 @@ ppc64_elf_finish_dynamic_sections (bfd *output_bfd,
 	      break;
 
 	    case DT_TEXTREL:
-	      if (htab->local_ifunc_resolver)
+	      if (htab->elf.ifunc_resolvers)
 		info->callbacks->einfo
 		  (_("%P: warning: text relocations and GNU indirect "
 		     "functions may result in a segfault at runtime\n"));

bfd/elfnn-aarch64.c

@@ -8818,7 +8818,6 @@ elfNN_aarch64_allocate_ifunc_dynrelocs (struct elf_link_hash_entry *h,
       && h->def_regular)
     return _bfd_elf_allocate_ifunc_dyn_relocs (info, h,
 					       &h->dyn_relocs,
-					       NULL,
 					       htab->plt_entry_size,
 					       htab->plt_header_size,
 					       GOT_ENTRY_SIZE,

bfd/elfxx-x86.c

@@ -132,7 +132,6 @@ elf_x86_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
       && h->def_regular)
     {
       if (_bfd_elf_allocate_ifunc_dyn_relocs (info, h, &h->dyn_relocs,
-					      &htab->readonly_dynrelocs_against_ifunc,
 					      plt_entry_size,
 					      (htab->plt.has_plt0
 					       * plt_entry_size),
@@ -1416,15 +1415,11 @@ _bfd_x86_elf_size_dynamic_sections (bfd *output_bfd,
 
 	  if ((info->flags & DF_TEXTREL) != 0)
 	    {
-	      if (htab->readonly_dynrelocs_against_ifunc)
+	      if (htab->elf.ifunc_resolvers)
-		{
+		info->callbacks->einfo
-		  info->callbacks->einfo
+		  (_("%P: warning: GNU indirect functions with DT_TEXTREL "
-		    (_("%P%X: read-only segment has dynamic IFUNC relocations;"
+		     "may result in a segfault at runtime; recompile with %s\n"),
-		       " recompile with %s\n"),
+		   bfd_link_dll (info) ? "-fPIC" : "-fPIE");
-		     bfd_link_dll (info) ? "-fPIC" : "-fPIE");
-		  bfd_set_error (bfd_error_bad_value);
-		  return FALSE;
-		}
 
 	      if (!add_dynamic_entry (DT_TEXTREL, 0))
 		return FALSE;

bfd/elfxx-x86.h

@@ -483,10 +483,6 @@ struct elf_x86_link_hash_table
   /* The index of the next R_X86_64_IRELATIVE entry in .rela.plt.  */
   bfd_vma next_irelative_index;
 
-  /* TRUE if there are dynamic relocs against IFUNC symbols that apply
-     to read-only sections.  */
-  bfd_boolean readonly_dynrelocs_against_ifunc;
-
   /* The (unloaded but important) .rel.plt.unloaded section on VxWorks.
      This is used for i386 only.  */
   asection *srelplt2;

ld/ChangeLog

@@ -1,3 +1,25 @@
+2020-06-09  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/18801
+	* testsuite/ld-i386/i386.exp: Run ifunc-textrel-1a,
+	ifunc-textrel-1b, ifunc-textrel-2a and ifunc-textrel-2b.
+	* testsuite/ld-x86-64/x86-64.exp: Likewise.
+	* testsuite/ld-i386/ifunc-textrel-1a.d: Likewise.
+	* testsuite/ld-i386/ifunc-textrel-1b.d: Likewise.
+	* testsuite/ld-i386/ifunc-textrel-2a.d: Likewise.
+	* testsuite/ld-i386/ifunc-textrel-2b.d: Likewise.
+	* testsuite/ld-x86-64/ifunc-textrel-1.s: Likewise.
+	* testsuite/ld-x86-64/ifunc-textrel-1a.d: Likewise.
+	* testsuite/ld-x86-64/ifunc-textrel-1b.d: Likewise.
+	* testsuite/ld-x86-64/ifunc-textrel-2.s: Likewise.
+	* testsuite/ld-x86-64/ifunc-textrel-2a.d: Likewise.
+	* testsuite/ld-x86-64/ifunc-textrel-2b.d: Likewise.
+	* testsuite/ld-i386/pr18801a.d: Expect warning for IFUNC
+	resolvers.
+	* testsuite/ld-i386/pr18801b.d: Likewise.
+	* estsuite/ld-x86-64/pr18801a.d: Likewise.
+	* estsuite/ld-x86-64/pr18801b.d: Likewise.
+
 2020-06-09  Alan Modra  <amodra@gmail.com>
 
 	PR 26065

ld/testsuite/ld-i386/i386.exp

@@ -519,6 +519,10 @@ run_dump_test "pr17935-1"
 run_dump_test "pr17935-2"
 run_dump_test "pr18801a"
 run_dump_test "pr18801b"
+run_dump_test "ifunc-textrel-1a"
+run_dump_test "ifunc-textrel-1b"
+run_dump_test "ifunc-textrel-2a"
+run_dump_test "ifunc-textrel-2b"
 run_dump_test "pr18815"
 run_dump_test "pr19939a"
 run_dump_test "pr19939b"

ld/testsuite/ld-i386/ifunc-textrel-1a.d

@@ -0,0 +1,4 @@
+#source: ../ld-x86-64/ifunc-textrel-1.s
+#as: --32
+#ld: -m elf_i386 -pie
+#warning: GNU indirect functions with DT_TEXTREL may result in a segfault at runtime; recompile with -fPIE

ld/testsuite/ld-i386/ifunc-textrel-1b.d

@@ -0,0 +1,4 @@
+#source: ../ld-x86-64/ifunc-textrel-1.s
+#as: --32
+#ld: -m elf_i386 -shared
+#warning: GNU indirect functions with DT_TEXTREL may result in a segfault at runtime; recompile with -fPIC

ld/testsuite/ld-i386/ifunc-textrel-2a.d

@@ -0,0 +1,8 @@
+#source: ../ld-x86-64/ifunc-textrel-2.s
+#as: --32
+#ld: -m elf_i386 -pie -z notext
+#readelf: -r --wide
+
+#failif
+[0-9a-f]+ +[0-9a-f]+ +R_386_IRELATIVE +
+#..

ld/testsuite/ld-i386/ifunc-textrel-2b.d

@@ -0,0 +1,8 @@
+#source: ../ld-x86-64/ifunc-textrel-2.s
+#as: --32
+#ld: -m elf_i386 -shared -z notext
+#readelf: -r --wide
+
+#failif
+[0-9a-f]+ +[0-9a-f]+ +R_386_IRELATIVE +
+#..

ld/testsuite/ld-i386/pr18801a.d

@@ -1,4 +1,4 @@
 #source: pr18801.s
 #as: --32
 #ld: -m elf_i386 -pie
-#error: read-only segment has dynamic IFUNC relocations; recompile with -fPIE
+#warning: GNU indirect functions with DT_TEXTREL may result in a segfault at runtime; recompile with -fPIE

ld/testsuite/ld-i386/pr18801b.d

@@ -1,4 +1,4 @@
 #source: pr18801.s
 #as: --32
 #ld: -m elf_i386 -shared
-#error: read-only segment has dynamic IFUNC relocations; recompile with -fPIC
+#warning: GNU indirect functions with DT_TEXTREL may result in a segfault at runtime; recompile with -fPIC

ld/testsuite/ld-x86-64/ifunc-textrel-1.s

@@ -0,0 +1,28 @@
+	.text
+	.type   selector, %function
+foo:
+	movl	$0, %eax
+	ret
+selector:
+.ifdef __x86_64__
+	leaq	foo(%rip), %rax
+.else
+	leal	foo@GOTOFF(%eax), %eax
+.endif
+	ret
+	.type   selector, %gnu_indirect_function
+	.globl	_start
+_start:
+.ifdef __x86_64__
+	movabs	ptr, %rax
+	call	*%rax
+.else
+	mov	ptr, %eax
+	call	*%eax
+.endif
+	ret
+	.data
+	.type	ptr, @object
+ptr:
+	.dc.a	selector
+	.section	.note.GNU-stack,"",@progbits

ld/testsuite/ld-x86-64/ifunc-textrel-1a.d

@@ -0,0 +1,4 @@
+#source: ifunc-textrel-1.s
+#as: --64 -defsym __x86_64__=1
+#ld: -m elf_x86_64 -pie
+#warning: GNU indirect functions with DT_TEXTREL may result in a segfault at runtime; recompile with -fPIE

ld/testsuite/ld-x86-64/ifunc-textrel-1b.d

@@ -0,0 +1,4 @@
+#source: ifunc-textrel-1.s
+#as: --64 -defsym __x86_64__=1
+#ld: -m elf_x86_64 -shared
+#warning: GNU indirect functions with DT_TEXTREL may result in a segfault at runtime; recompile with -fPIC

ld/testsuite/ld-x86-64/ifunc-textrel-2.s

@@ -0,0 +1,28 @@
+	.text
+	.type   selector, %function
+foo:
+	movl	$0, %eax
+	ret
+selector:
+.ifdef __x86_64__
+	leaq	foo(%rip), %rax
+.else
+	leal	foo@GOTOFF(%eax), %eax
+.endif
+	ret
+	.type   selector, %gnu_indirect_function
+	.globl	_start
+_start:
+.ifdef __x86_64__
+	movabs	ptr, %rax
+	call	*%rax
+.else
+	mov	ptr, %eax
+	call	*%eax
+.endif
+	ret
+	.data
+	.type	ptr, @object
+ptr:
+	.dc.a	foo
+	.section	.note.GNU-stack,"",@progbits

ld/testsuite/ld-x86-64/ifunc-textrel-2a.d

@@ -0,0 +1,8 @@
+#source: ifunc-textrel-2.s
+#as: --64 -defsym __x86_64__=1
+#ld: -m elf_x86_64 -pie -z notext
+#readelf: -r --wide
+
+#failif
+[0-9a-f]+ +[0-9a-f]+ +R_X86_64_IRELATIVE +[0-9a-f]+
+#..

ld/testsuite/ld-x86-64/ifunc-textrel-2b.d

@@ -0,0 +1,8 @@
+#source: ifunc-textrel-2.s
+#as: --64 -defsym __x86_64__=1
+#ld: -m elf_x86_64 -shared -z notext
+#readelf: -r --wide
+
+#failif
+[0-9a-f]+ +[0-9a-f]+ +R_X86_64_IRELATIVE +[0-9a-f]+
+#..

ld/testsuite/ld-x86-64/pr18801a.d

@@ -1,4 +1,4 @@
 #source: pr18801.s
 #as: --64
 #ld: -melf_x86_64 -pie
-#error: read-only segment has dynamic IFUNC relocations; recompile with -fPIE
+#warning: GNU indirect functions with DT_TEXTREL may result in a segfault at runtime; recompile with -fPIE

ld/testsuite/ld-x86-64/pr18801b.d

@@ -1,4 +1,4 @@
 #source: pr18801.s
 #as: --64
 #ld: -melf_x86_64 -shared
-#error: read-only segment has dynamic IFUNC relocations; recompile with -fPIC
+#warning: GNU indirect functions with DT_TEXTREL may result in a segfault at runtime; recompile with -fPIC

ld/testsuite/ld-x86-64/x86-64.exp

@@ -581,6 +581,10 @@ run_dump_test "pr18160"
 run_dump_test "pr18176"
 run_dump_test "pr18801a"
 run_dump_test "pr18801b"
+run_dump_test "ifunc-textrel-1a"
+run_dump_test "ifunc-textrel-1b"
+run_dump_test "ifunc-textrel-2a"
+run_dump_test "ifunc-textrel-2b"
 run_dump_test "pr18815"
 run_dump_test "pr19013"
 run_dump_test "pr19013-x32"