From: H.J. Lu <hjl.tools@gmail.com>
Date: Wed, 22 Apr 2015 12:24:54 +0000 (-0700)
Subject: i386: Allow copy relocs for building PIE
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=d5597ebccca6761fb641b7fc99b6e8b56fbac6e2;p=binutils-gdb.git

i386: Allow copy relocs for building PIE

This patch allows copy relocs for R_386_GOTOFF relocations in PIE.  For

extern int glob_a;
int foo ()
{
  return glob_a;
}

compiler now can optimize it from

	call	__x86.get_pc_thunk.ax
	addl	$_GLOBAL_OFFSET_TABLE_, %eax
	movl	glob_a@GOT(%eax), %eax
	movl	(%eax), %eax
	ret

to

	call	__x86.get_pc_thunk.ax
	addl	$_GLOBAL_OFFSET_TABLE_, %eax
	movl	glob_a@GOTOFF(%eax), %eax
	ret

bfd/

	PR ld/18289
	* elf32-i386.c (elf_i386_link_hash_entry): Add gotoff_ref.
	(elf_i386_link_hash_newfunc): Initialize gotoff_ref to 0.
	(elf_i386_create_dynamic_sections): Always allow copy relocs for
	building executables.
	(elf_i386_copy_indirect_symbol): Also copy gotoff_ref.
	(elf_i386_check_relocs): Set gotoff_ref for R_386_GOTOFF.
	(elf_i386_adjust_dynamic_symbol): Also allocate copy relocs for
	PIE and R_386_GOTOFF.
	(elf_i386_relocate_section): Allow R_386_GOTOFF in executable.

ld/testsuite/

	PR ld/18289
	* ld-i386/copyreloc-lib.c: New file.
	* ld-i386/copyreloc-main.S: Likewise.
	* ld-i386/copyreloc-main.out: Likewise.
	* ld-i386/copyreloc-main1.rd: Likewise.
	* ld-i386/copyreloc-main2.rd: Likewise.
	* ld-i386/dummy.c: Likewise.
	* ld-i386/pr17689.out: Likewise.
	* ld-i386/pr17689.rd: Likewise.
	* ld-i386/pr17689a.c: Likewise.
	* ld-i386/pr17689b.S: Likewise.
	* ld-i386/pr17827.rd: Likewise.
	* ld-i386/pr17827ver.rd: Likewise.
	* ld-i386/i386.exp: Run copyreloc tests.
---

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 1f95fd54c33..94aca528246 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,16 @@
+2015-04-22  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/18289
+	* elf32-i386.c (elf_i386_link_hash_entry): Add gotoff_ref.
+	(elf_i386_link_hash_newfunc): Initialize gotoff_ref to 0.
+	(elf_i386_create_dynamic_sections): Always allow copy relocs for
+	building executables.
+	(elf_i386_copy_indirect_symbol): Also copy gotoff_ref.
+	(elf_i386_check_relocs): Set gotoff_ref for R_386_GOTOFF.
+	(elf_i386_adjust_dynamic_symbol): Also allocate copy relocs for
+	PIE and R_386_GOTOFF.
+	(elf_i386_relocate_section): Allow R_386_GOTOFF in executable.
+
 2015-04-20  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* elf.c (assign_section_numbers): Always set up sh_name.
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index f71bce12243..d76addbeb32 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -756,6 +756,9 @@ struct elf_i386_link_hash_entry
   (GOT_TLS_GD_P (type) || GOT_TLS_GDESC_P (type))
   unsigned char tls_type;
 
+  /* Symbol is referenced by R_386_GOTOFF relocation.  */
+  unsigned int gotoff_ref : 1;
+
   /* Information about the GOT PLT entry. Filled when there are both
      GOT and PLT relocations against the same function.  */
   union gotplt_union plt_got;
@@ -879,6 +882,7 @@ elf_i386_link_hash_newfunc (struct bfd_hash_entry *entry,
       eh = (struct elf_i386_link_hash_entry *) entry;
       eh->dyn_relocs = NULL;
       eh->tls_type = GOT_UNKNOWN;
+      eh->gotoff_ref = 0;
       eh->plt_got.offset = (bfd_vma) -1;
       eh->tlsdesc_got = (bfd_vma) -1;
     }
@@ -1022,13 +1026,28 @@ elf_i386_create_dynamic_sections (bfd *dynobj, struct bfd_link_info *info)
     return FALSE;
 
   htab->sdynbss = bfd_get_linker_section (dynobj, ".dynbss");
-  if (!info->shared)
-    htab->srelbss = bfd_get_linker_section (dynobj, ".rel.bss");
-
-  if (!htab->sdynbss
-      || (!info->shared && !htab->srelbss))
+  if (!htab->sdynbss)
     abort ();
 
+  if (info->executable)
+    {
+      /* Always allow copy relocs for building executables.  */
+      asection *s = bfd_get_linker_section (dynobj, ".rel.bss");
+      if (s == NULL)
+	{
+	  const struct elf_backend_data *bed = get_elf_backend_data (dynobj);
+	  s = bfd_make_section_anyway_with_flags (dynobj,
+						  ".rel.bss",
+						  (bed->dynamic_sec_flags
+						   | SEC_READONLY));
+	  if (s == NULL
+	      || ! bfd_set_section_alignment (dynobj, s,
+					      bed->s->log_file_align))
+	    return FALSE;
+	}
+      htab->srelbss = s;
+    }
+
   if (get_elf_i386_backend_data (dynobj)->is_vxworks
       && !elf_vxworks_create_dynamic_sections (dynobj, info,
 					       &htab->srelplt2))
@@ -1101,6 +1120,10 @@ elf_i386_copy_indirect_symbol (struct bfd_link_info *info,
       eind->tls_type = GOT_UNKNOWN;
     }
 
+  /* Copy gotoff_ref so that elf_i386_adjust_dynamic_symbol will
+     generate a R_386_COPY reloc.  */
+  edir->gotoff_ref |= eind->gotoff_ref;
+
   if (ELIMINATE_COPY_RELOCS
       && ind->root.type != bfd_link_hash_indirect
       && dir->dynamic_adjusted)
@@ -1475,6 +1498,7 @@ elf_i386_check_relocs (bfd *abfd,
       unsigned int r_type;
       unsigned long r_symndx;
       struct elf_link_hash_entry *h;
+      struct elf_i386_link_hash_entry *eh;
       Elf_Internal_Sym *isym;
       const char *name;
       bfd_boolean size_reloc;
@@ -1524,6 +1548,7 @@ elf_i386_check_relocs (bfd *abfd,
 	    h = (struct elf_link_hash_entry *) h->root.u.i.link;
 	}
 
+      eh = (struct elf_i386_link_hash_entry *) h;
       if (h != NULL)
 	{
 	  /* Create the ifunc sections for static executables.  If we
@@ -1535,11 +1560,12 @@ elf_i386_check_relocs (bfd *abfd,
 	    default:
 	      break;
 
+	    case R_386_GOTOFF:
+	      eh->gotoff_ref = 1;
 	    case R_386_32:
 	    case R_386_PC32:
 	    case R_386_PLT32:
 	    case R_386_GOT32:
-	    case R_386_GOTOFF:
 	      if (htab->elf.dynobj == NULL)
 		htab->elf.dynobj = abfd;
 	      if (!_bfd_elf_create_ifunc_sections (htab->elf.dynobj, info))
@@ -1791,7 +1817,7 @@ do_size:
 		 relocations we need for this symbol.  */
 	      if (h != NULL)
 		{
-		  head = &((struct elf_i386_link_hash_entry *) h)->dyn_relocs;
+		  head = &eh->dyn_relocs;
 		}
 	      else
 		{
@@ -2175,12 +2201,14 @@ elf_i386_adjust_dynamic_symbol (struct bfd_link_info *info,
      only references to the symbol are via the global offset table.
      For such cases we need not do anything here; the relocations will
      be handled correctly by relocate_section.  */
-  if (info->shared)
+  if (!info->executable)
     return TRUE;
 
   /* If there are no references to this symbol that do not use the
-     GOT, we don't need to generate a copy reloc.  */
-  if (!h->non_got_ref)
+     GOT nor R_386_GOTOFF relocation, we don't need to generate a copy
+     reloc.  */
+  eh = (struct elf_i386_link_hash_entry *) h;
+  if (!h->non_got_ref && !eh->gotoff_ref)
     return TRUE;
 
   /* If -z nocopyreloc was given, we won't generate them either.  */
@@ -2194,14 +2222,15 @@ elf_i386_adjust_dynamic_symbol (struct bfd_link_info *info,
   if (htab == NULL)
     return FALSE;
 
-  /* If there aren't any dynamic relocs in read-only sections, then
-     we can keep the dynamic relocs and avoid the copy reloc.  This
-     doesn't work on VxWorks, where we can not have dynamic relocations
-     (other than copy and jump slot relocations) in an executable.  */
+  /* If there aren't any dynamic relocs in read-only sections nor
+     R_386_GOTOFF relocation, then we can keep the dynamic relocs and
+     avoid the copy reloc.  This doesn't work on VxWorks, where we can
+     not have dynamic relocations (other than copy and jump slot
+     relocations) in an executable.  */
   if (ELIMINATE_COPY_RELOCS
+      && !eh->gotoff_ref
       && !get_elf_i386_backend_data (info->output_bfd)->is_vxworks)
     {
-      eh = (struct elf_i386_link_hash_entry *) h;
       for (p = eh->dyn_relocs; p != NULL; p = p->next)
 	{
 	  s = p->sec->output_section;
@@ -3718,7 +3747,7 @@ elf_i386_relocate_section (bfd *output_bfd,
 	     symbol for shared library since it may not be local when
 	     used as function address or with copy relocation.  We also
 	     need to make sure that a symbol is referenced locally.  */
-	  if (info->shared && h)
+	  if (!info->executable && h)
 	    {
 	      if (!h->def_regular)
 		{
@@ -3746,8 +3775,7 @@ elf_i386_relocate_section (bfd *output_bfd,
 		  bfd_set_error (bfd_error_bad_value);
 		  return FALSE;
 		}
-	      else if (!info->executable
-		       && !SYMBOL_REFERENCES_LOCAL (info, h)
+	      else if (!SYMBOL_REFERENCES_LOCAL (info, h)
 		       && (h->type == STT_FUNC
 			   || h->type == STT_OBJECT)
 		       && ELF_ST_VISIBILITY (h->other) == STV_PROTECTED)
diff --git a/ld/testsuite/ChangeLog b/ld/testsuite/ChangeLog
index 240a4444195..ea6a86326be 100644
--- a/ld/testsuite/ChangeLog
+++ b/ld/testsuite/ChangeLog
@@ -1,3 +1,20 @@
+2015-04-22  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/18289
+	* ld-i386/copyreloc-lib.c: New file.
+	* ld-i386/copyreloc-main.S: Likewise.
+	* ld-i386/copyreloc-main.out: Likewise.
+	* ld-i386/copyreloc-main1.rd: Likewise.
+	* ld-i386/copyreloc-main2.rd: Likewise.
+	* ld-i386/dummy.c: Likewise.
+	* ld-i386/pr17689.out: Likewise.
+	* ld-i386/pr17689.rd: Likewise.
+	* ld-i386/pr17689a.c: Likewise.
+	* ld-i386/pr17689b.S: Likewise.
+	* ld-i386/pr17827.rd: Likewise.
+	* ld-i386/pr17827ver.rd: Likewise.
+	* ld-i386/i386.exp: Run copyreloc tests.
+
 2015-04-20  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* ld-mmix/bspec1.d: Don't hardcode offset of .shstrtab section.
diff --git a/ld/testsuite/ld-i386/copyreloc-lib.c b/ld/testsuite/ld-i386/copyreloc-lib.c
new file mode 100644
index 00000000000..cbbc5e245eb
--- /dev/null
+++ b/ld/testsuite/ld-i386/copyreloc-lib.c
@@ -0,0 +1 @@
+int a_glob = 2;
diff --git a/ld/testsuite/ld-i386/copyreloc-main.S b/ld/testsuite/ld-i386/copyreloc-main.S
new file mode 100644
index 00000000000..98aef839e07
--- /dev/null
+++ b/ld/testsuite/ld-i386/copyreloc-main.S
@@ -0,0 +1,24 @@
+	.section	.text.startup,"ax",@progbits
+	.p2align 4,,15
+	.globl	main
+	.type	main, @function
+main:
+	.cfi_startproc
+	call	__x86.get_pc_thunk.ax
+	addl	$_GLOBAL_OFFSET_TABLE_, %eax
+	cmpl	$2, a_glob@GOTOFF(%eax)
+	setne	%al
+	movzbl	%al, %eax
+	ret
+	.cfi_endproc
+	.size	main, .-main
+	.section	.text.__x86.get_pc_thunk.ax,"axG",@progbits,__x86.get_pc_thunk.ax,comdat
+	.globl	__x86.get_pc_thunk.ax
+	.hidden	__x86.get_pc_thunk.ax
+	.type	__x86.get_pc_thunk.ax, @function
+__x86.get_pc_thunk.ax:
+	.cfi_startproc
+	movl	(%esp), %eax
+	ret
+	.cfi_endproc
+	.section	.note.GNU-stack,"",@progbits
diff --git a/ld/testsuite/ld-i386/copyreloc-main.out b/ld/testsuite/ld-i386/copyreloc-main.out
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/ld/testsuite/ld-i386/copyreloc-main1.rd b/ld/testsuite/ld-i386/copyreloc-main1.rd
new file mode 100644
index 00000000000..a6bd67c7442
--- /dev/null
+++ b/ld/testsuite/ld-i386/copyreloc-main1.rd
@@ -0,0 +1,3 @@
+#...
+[0-9a-f ]+R_386_COPY+[0-9a-f ]+ +a_glob
+#...
diff --git a/ld/testsuite/ld-i386/copyreloc-main2.rd b/ld/testsuite/ld-i386/copyreloc-main2.rd
new file mode 100644
index 00000000000..ed61aa1927f
--- /dev/null
+++ b/ld/testsuite/ld-i386/copyreloc-main2.rd
@@ -0,0 +1,4 @@
+#failif
+#...
+[0-9a-f ]+R_386_NONE.*
+#...
diff --git a/ld/testsuite/ld-i386/dummy.c b/ld/testsuite/ld-i386/dummy.c
new file mode 100644
index 00000000000..5c0328739c6
--- /dev/null
+++ b/ld/testsuite/ld-i386/dummy.c
@@ -0,0 +1 @@
+/* An empty file.  */
diff --git a/ld/testsuite/ld-i386/i386.exp b/ld/testsuite/ld-i386/i386.exp
index f214d896ecc..8399cbcdde1 100644
--- a/ld/testsuite/ld-i386/i386.exp
+++ b/ld/testsuite/ld-i386/i386.exp
@@ -335,6 +335,78 @@ if { [isnative]
 	    {{readelf {-Wr} plt-main.rd}} \
 	    "plt-main" \
 	] \
+	[list \
+	    "Build copyreloc-lib.so" \
+	    "-shared" \
+	    "-fPIC" \
+	    { copyreloc-lib.c } \
+	    {} \
+	    "copyreloc-lib.so" \
+	] \
+	[list \
+	    "Build copyreloc-main with PIE and GOTOFF (1)" \
+	    "tmpdir/copyreloc-lib.so -pie" \
+	    "" \
+	    { copyreloc-main.S } \
+	    {{readelf {-Wr} copyreloc-main1.rd}} \
+	    "copyreloc-main" \
+	] \
+	[list \
+	    "Build copyreloc-main with PIE and GOTOFF (2)" \
+	    "tmpdir/copyreloc-lib.so -pie" \
+	    "" \
+	    { copyreloc-main.S } \
+	    {{readelf {-Wr} copyreloc-main2.rd}} \
+	    "copyreloc-main" \
+	] \
+	[list \
+	    "Build pr17689.so" \
+	    "-shared" \
+	    "-fPIC" \
+	    { pr17689a.c } \
+	    {} \
+	    "pr17689.so" \
+	] \
+	[list \
+	    "Build pr17689ver.so" \
+	    "-shared -Wl,--version-script,pr17689a.t" \
+	    "-fPIC" \
+	    { pr17689a.c } \
+	    {} \
+	    "pr17689ver.so" \
+	] \
+	[list \
+	    "Build pr17689.a" \
+	    "" \
+	    "" \
+	    { pr17689b.S } \
+	    {} \
+	    "pr17689.a" \
+	] \
+	[list \
+	    "Build pr17689 with PIE and GOTOFF" \
+	    "tmpdir/pr17689b.o tmpdir/pr17689.so -pie" \
+	    "" \
+	    { dummy.c } \
+	    {{readelf {-Wr} pr17689.rd}} \
+	    "pr17689" \
+	] \
+	[list \
+	    "Build pr17689ver with PIE and GOTOFF" \
+	    "tmpdir/pr17689b.o tmpdir/pr17689ver.so -pie" \
+	    "" \
+	    { dummy.c } \
+	    {{readelf {-Wr} pr17689ver.rd}} \
+	    "pr17689ver" \
+	] \
+	[list \
+	    "Build pr17827 with PIE and GOTOFF" \
+	    "tmpdir/pr17689b.o tmpdir/pr17689.so -pie" \
+	    "" \
+	    { dummy.c } \
+	    {{readelf {-Wr} pr17827.rd}} \
+	    "pr17827" \
+	] \
     ]
 
     run_ld_link_exec_tests [] [list \
@@ -357,5 +429,29 @@ if { [isnative]
 	    "plt-main.out" \
 	    "-fPIC" \
 	] \
+	[list \
+	    "Run copyreloc-main with PIE and GOTOFF" \
+	    "tmpdir/copyreloc-lib.so -pie" \
+	    "" \
+	    { copyreloc-main.S } \
+	    "copyreloc-main" \
+	    "copyreloc-main.out" \
+	] \
+	[list \
+	    "Run pr17689 with PIE and GOTOFF" \
+	    "tmpdir/pr17689b.o tmpdir/pr17689.so -pie" \
+	    "" \
+	    { dummy.c } \
+	    "pr17689" \
+	    "pr17689.out" \
+	] \
+	[list \
+	    "Run pr17689ver with PIE and GOTOFF" \
+	    "tmpdir/pr17689b.o tmpdir/pr17689ver.so -pie" \
+	    "" \
+	    { dummy.c } \
+	    "pr17689ver" \
+	    "pr17689.out" \
+	] \
     ]
 }
diff --git a/ld/testsuite/ld-i386/pr17689.out b/ld/testsuite/ld-i386/pr17689.out
new file mode 100644
index 00000000000..38e03525155
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr17689.out
@@ -0,0 +1,2 @@
+PASS
+PASS
diff --git a/ld/testsuite/ld-i386/pr17689.rd b/ld/testsuite/ld-i386/pr17689.rd
new file mode 100644
index 00000000000..dda18509c0b
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr17689.rd
@@ -0,0 +1,3 @@
+#...
+[0-9a-f ]+R_386_COPY+[0-9a-f ]+ +bar
+#...
diff --git a/ld/testsuite/ld-i386/pr17689a.c b/ld/testsuite/ld-i386/pr17689a.c
new file mode 100644
index 00000000000..5317668876e
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr17689a.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+
+char *bar = "PASS";
+extern char *bar_alias __attribute__ ((weak, alias ("bar")));
+
+void
+foo (char *x)
+{
+  printf ("%s\n", x);
+}
diff --git a/ld/testsuite/ld-i386/pr17689a.t b/ld/testsuite/ld-i386/pr17689a.t
new file mode 100644
index 00000000000..7f0efef7b42
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr17689a.t
@@ -0,0 +1,6 @@
+VERSION {
+  global:
+    bar_alias; bar; foo;
+  local:
+    *;
+};
diff --git a/ld/testsuite/ld-i386/pr17689b.S b/ld/testsuite/ld-i386/pr17689b.S
new file mode 100644
index 00000000000..24daf36308d
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr17689b.S
@@ -0,0 +1,44 @@
+	.text
+	.globl	main
+	.type	main, @function
+main:
+	leal	4(%esp), %ecx
+	andl	$-16, %esp
+	pushl	-4(%ecx)
+	pushl	%ebp
+	movl	%esp, %ebp
+	pushl	%ebx
+	pushl	%ecx
+	call	__x86.get_pc_thunk.bx
+	addl	$_GLOBAL_OFFSET_TABLE_, %ebx
+	subl	$12, %esp
+	pushl	bar_alias@GOTOFF(%ebx)
+	call	foo@PLT
+	popl	%eax
+	movl	ptr@GOTOFF(%ebx), %eax
+	pushl	(%eax)
+	call	foo@PLT
+	addl	$16, %esp
+	leal	-8(%ebp), %esp
+	xorl	%eax, %eax
+	popl	%ecx
+	popl	%ebx
+	popl	%ebp
+	leal	-4(%ecx), %esp
+	ret
+	.size	main, .-main
+	.globl	ptr
+	.section	.data.rel.local,"aw",@progbits
+	.align 4
+	.type	ptr, @object
+	.size	ptr, 4
+ptr:
+	.long	bar_alias
+	.section	.text.__x86.get_pc_thunk.bx,"axG",@progbits,__x86.get_pc_thunk.bx,comdat
+	.globl	__x86.get_pc_thunk.bx
+	.hidden	__x86.get_pc_thunk.bx
+	.type	__x86.get_pc_thunk.bx, @function
+__x86.get_pc_thunk.bx:
+	movl	(%esp), %ebx
+	ret
+	.section	.note.GNU-stack,"",@progbits
diff --git a/ld/testsuite/ld-i386/pr17689ver.rd b/ld/testsuite/ld-i386/pr17689ver.rd
new file mode 100644
index 00000000000..6cebe73e29d
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr17689ver.rd
@@ -0,0 +1,3 @@
+#...
+[0-9a-f ]+R_386_COPY+[0-9a-f ]+ +bar@VERSION
+#...
diff --git a/ld/testsuite/ld-i386/pr17827.rd b/ld/testsuite/ld-i386/pr17827.rd
new file mode 100644
index 00000000000..ed61aa1927f
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr17827.rd
@@ -0,0 +1,4 @@
+#failif
+#...
+[0-9a-f ]+R_386_NONE.*
+#...