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[PATCH] PR ld/19939: Incorrect error message for undefined symbols

From: "H.J. Lu" <hongjiu dot lu at intel dot com>
To: binutils at sourceware dot org
Date: Mon, 11 Apr 2016 10:27:15 -0700
Subject: [PATCH] PR ld/19939: Incorrect error message for undefined symbols
Authentication-results: sourceware.org; auth=none
Reply-to: "H.J. Lu" <hjl dot tools at gmail dot com>

We shouldn't issue an error for read-only segment with dynamic IFUNC
relocations when dynamic relocations are against normal symbols.

Any comments, feedbacks?

H.J.
---
bfd/

	PR ld/19939
	* elf-ifunc.c (_bfd_elf_allocate_ifunc_dyn_relocs): Set
	readonly_dynrelocs_against_ifunc to TRUE if dynamic reloc applies
	to read-only section.
	* elf32-i386.c (elf_i386_size_dynamic_sections): Issue an error
	for read-only segment with dynamic IFUNC relocations only if
	readonly_dynrelocs_against_ifunc is TRUE.
	* elf64-x86-64.c (elf_x86_64_size_dynamic_sections): Likewise.

include/

	PR ld/19939
	* bfdlink.h (bfd_link_info): Add readonly_dynrelocs_against_ifunc.

ld/

	PR ld/19939
	* testsuite/ld-i386/i386.exp: Run PR ld/19939 tests.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
	* testsuite/ld-i386/pr19939.s: New file.
	* testsuite/ld-i386/pr19939a.d: Likewise.
	* testsuite/ld-i386/pr19939b.d: Likewise.
	* testsuite/ld-x86-64/pr19939.s: Likewise.
	* testsuite/ld-x86-64/pr19939a.d: Likewise.
	* testsuite/ld-x86-64/pr19939b.d: Likewise.
---
 bfd/elf-ifunc.c                   | 3 +++
 bfd/elf32-i386.c                  | 3 +--
 bfd/elf64-x86-64.c                | 3 +--
 include/bfdlink.h                 | 4 ++++
 ld/testsuite/ld-i386/i386.exp     | 2 ++
 ld/testsuite/ld-i386/pr19939.s    | 9 +++++++++
 ld/testsuite/ld-i386/pr19939a.d   | 4 ++++
 ld/testsuite/ld-i386/pr19939b.d   | 8 ++++++++
 ld/testsuite/ld-x86-64/pr19939.s  | 9 +++++++++
 ld/testsuite/ld-x86-64/pr19939a.d | 4 ++++
 ld/testsuite/ld-x86-64/pr19939b.d | 8 ++++++++
 ld/testsuite/ld-x86-64/x86-64.exp | 2 ++
 12 files changed, 55 insertions(+), 4 deletions(-)
 create mode 100644 ld/testsuite/ld-i386/pr19939.s
 create mode 100644 ld/testsuite/ld-i386/pr19939a.d
 create mode 100644 ld/testsuite/ld-i386/pr19939b.d
 create mode 100644 ld/testsuite/ld-x86-64/pr19939.s
 create mode 100644 ld/testsuite/ld-x86-64/pr19939a.d
 create mode 100644 ld/testsuite/ld-x86-64/pr19939b.d

diff --git a/bfd/elf-ifunc.c b/bfd/elf-ifunc.c
index 1368a8e..23ae3c4 100644
--- a/bfd/elf-ifunc.c
+++ b/bfd/elf-ifunc.c
@@ -231,6 +231,9 @@ keep:
       bfd_size_type count = 0;
       do
 	{
+	  asection *s = p->sec->output_section;
+	  if (s != NULL && (s->flags & SEC_READONLY) != 0)
+	    info->readonly_dynrelocs_against_ifunc = TRUE;
 	  count += p->count;
 	  p = p->next;
 	}
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index 1ebb615..c00f4d9 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -3553,8 +3553,7 @@ elf_i386_size_dynamic_sections (bfd *output_bfd, struct bfd_link_info *info)
 
 	  if ((info->flags & DF_TEXTREL) != 0)
 	    {
-	      if ((elf_tdata (output_bfd)->has_gnu_symbols
-		   & elf_gnu_symbol_ifunc) == elf_gnu_symbol_ifunc)
+	      if (info->readonly_dynrelocs_against_ifunc)
 		{
 		  info->callbacks->einfo
 		    (_("%P%X: read-only segment has dynamic IFUNC relocations; recompile with -fPIC\n"));
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index dc7738a..b083265 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -3899,8 +3899,7 @@ elf_x86_64_size_dynamic_sections (bfd *output_bfd,
 
 	  if ((info->flags & DF_TEXTREL) != 0)
 	    {
-	      if ((elf_tdata (output_bfd)->has_gnu_symbols
-		   & elf_gnu_symbol_ifunc) == elf_gnu_symbol_ifunc)
+	      if (info->readonly_dynrelocs_against_ifunc)
 		{
 		  info->callbacks->einfo
 		    (_("%P%X: read-only segment has dynamic IFUNC relocations; recompile with -fPIC\n"));
diff --git a/include/bfdlink.h b/include/bfdlink.h
index a285f6d..5cd3bbe 100644
--- a/include/bfdlink.h
+++ b/include/bfdlink.h
@@ -452,6 +452,10 @@ struct bfd_link_info
   /* TRUE if generate a 1-byte NOP as suffix for x86 call instruction.  */
   unsigned int call_nop_as_suffix : 1;
 
+  /* TRUE if there are dynamic relocs against IFUNC symbols that apply
+     to read-only sections.  */
+  unsigned int readonly_dynrelocs_against_ifunc: 1;
+
   /* The 1-byte NOP for x86 call instruction.  */
   char call_nop_byte;
 
diff --git a/ld/testsuite/ld-i386/i386.exp b/ld/testsuite/ld-i386/i386.exp
index 2b7a09e..c6708ca 100644
--- a/ld/testsuite/ld-i386/i386.exp
+++ b/ld/testsuite/ld-i386/i386.exp
@@ -390,6 +390,8 @@ run_dump_test "pr17935-1"
 run_dump_test "pr17935-2"
 run_dump_test "pr18801"
 run_dump_test "pr18815"
+run_dump_test "pr19939a"
+run_dump_test "pr19939b"
 
 proc undefined_weak {cflags ldflags} {
     set testname "Undefined weak symbol"
diff --git a/ld/testsuite/ld-i386/pr19939.s b/ld/testsuite/ld-i386/pr19939.s
new file mode 100644
index 0000000..fdd1c04
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr19939.s
@@ -0,0 +1,9 @@
+	.text
+selector:
+	movl	foo@GOT(%eax), %eax
+	mov	$bar, %ebx
+	ret
+	.type   selector, %gnu_indirect_function
+	.globl	bar
+bar:
+	jmp	selector@PLT
diff --git a/ld/testsuite/ld-i386/pr19939a.d b/ld/testsuite/ld-i386/pr19939a.d
new file mode 100644
index 0000000..5883cae
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr19939a.d
@@ -0,0 +1,4 @@
+#source: pr19939.s
+#as: --32
+#ld: -melf_i386 -shared -z defs
+#error: undefined reference to `foo'
diff --git a/ld/testsuite/ld-i386/pr19939b.d b/ld/testsuite/ld-i386/pr19939b.d
new file mode 100644
index 0000000..5124ae1
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr19939b.d
@@ -0,0 +1,8 @@
+#source: pr19939.s
+#as: --32
+#ld: -melf_i386 -shared
+#readelf: -d --wide
+
+#...
+.*\(TEXTREL\).*
+#pass
diff --git a/ld/testsuite/ld-x86-64/pr19939.s b/ld/testsuite/ld-x86-64/pr19939.s
new file mode 100644
index 0000000..7eadaaa
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr19939.s
@@ -0,0 +1,9 @@
+	.text
+selector:
+	movq	foo@GOTPCREL(%rip), %rax
+	movabs	$bar, %rbx
+	ret
+	.type   selector, %gnu_indirect_function
+	.globl	bar
+bar:
+	jmp	selector@PLT
diff --git a/ld/testsuite/ld-x86-64/pr19939a.d b/ld/testsuite/ld-x86-64/pr19939a.d
new file mode 100644
index 0000000..af5b976
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr19939a.d
@@ -0,0 +1,4 @@
+#source: pr19939.s
+#as: --64
+#ld: -melf_x86_64 -shared -z defs
+#error: undefined reference to `foo'
diff --git a/ld/testsuite/ld-x86-64/pr19939b.d b/ld/testsuite/ld-x86-64/pr19939b.d
new file mode 100644
index 0000000..2616151
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/pr19939b.d
@@ -0,0 +1,8 @@
+#source: pr19939.s
+#as: --64
+#ld: -melf_x86_64 -shared
+#readelf: -d --wide
+
+#...
+.*\(TEXTREL\).*
+#pass
diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index 603ef37..8abccd4 100644
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -438,6 +438,8 @@ run_dump_test "pr19609-7a"
 run_dump_test "pr19609-7b"
 run_dump_test "pr19609-7c"
 run_dump_test "pr19609-7d"
+run_dump_test "pr19939a"
+run_dump_test "pr19939b"
 
 proc undefined_weak {cflags ldflags} {
     set testname "Undefined weak symbol"
-- 
2.5.5

Follow-Ups:
- Re: [PATCH] PR ld/19939: Incorrect error message for undefined symbols
  - From: Alan Modra

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