Subtract GOT base only with a base register

When relocating R_386_GOT32 in "op $0, bar@GOT", we shouldn't subtract
GOT base without a base register and we should disallow it without a
base register for PIC.

bfd/

	PR ld/20244
	* elf32-i386.c (elf_i386_relocate_section): When relocating
	R_386_GOT32, return error without a base register for PIC and
	subtract the .got.plt section address only with a base register.

ld/

	PR ld/20244
	* testsuite/ld-i386/i386.exp: Run pr20244-1a and pr20244-1b.
	* testsuite/ld-i386/pr20244-1.s: New file.
	* testsuite/ld-i386/pr20244-1a.d: Likewise.
	* testsuite/ld-i386/pr20244-1b.d: Likewise.
	* testsuite/ld-i386/pr20244-1c.d: Likewise.

8 files changed, 109 insertions, 4 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 67b9778..b9c3a73 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,10 @@
+2016-06-11  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/20244
+	* elf32-i386.c (elf_i386_relocate_section): When relocating
+	R_386_GOT32, return error without a base register for PIC and
+	subtract the .got.plt section address only with a base register.
+
 2016-06-10  Alan Modra  <amodra@gmail.com>
 
 	* elf-strtab.c (struct strtab_save): Use size_t for "size".
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index 38c0520..7e2b2cb 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -4208,10 +4208,38 @@ r_386_got32:
 	  if (off >= (bfd_vma) -2)
 	    abort ();
 
-	  relocation = htab->elf.sgot->output_section->vma
-		       + htab->elf.sgot->output_offset + off
-		       - htab->elf.sgotplt->output_section->vma
-		       - htab->elf.sgotplt->output_offset;
+	  relocation = (htab->elf.sgot->output_section->vma
+			+ htab->elf.sgot->output_offset + off);
+	  if ((*(contents + rel->r_offset - 1) & 0xc7) == 0x5)
+	    {
+	      if (bfd_link_pic (info))
+		{
+		  /* For PIC, disallow R_386_GOT32 without a base
+		     register since we don't know what the GOT base
+		     is.  */
+		  const char *name;
+
+		  if (h == NULL)
+		    name = bfd_elf_sym_name (input_bfd, symtab_hdr, sym,
+					     NULL);
+		  else
+		    name = h->root.root.string;
+
+		  (*_bfd_error_handler)
+		    (_("%B: direct GOT relocation R_386_GOT32 against `%s' without base register can not be used when making a shared object"),
+		     input_bfd, name);
+		  bfd_set_error (bfd_error_bad_value);
+		  return FALSE;
+		}
+	    }
+	  else
+	    {
+	      /* Subtract the .got.plt section address only with a base
+		 register.  */
+	      relocation -= (htab->elf.sgotplt->output_section->vma
+			     + htab->elf.sgotplt->output_offset);
+	    }
+
 	  break;
 
 	case R_386_GOTOFF:
diff --git a/ld/ChangeLog b/ld/ChangeLog
index 234bf05..4a74c8f 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,12 @@
+2016-06-11  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/20244
+	* testsuite/ld-i386/i386.exp: Run pr20244-1a and pr20244-1b.
+	* testsuite/ld-i386/pr20244-1.s: New file.
+	* testsuite/ld-i386/pr20244-1a.d: Likewise.
+	* testsuite/ld-i386/pr20244-1b.d: Likewise.
+	* testsuite/ld-i386/pr20244-1c.d: Likewise.
+
 2016-06-08  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
 
 	PR ld/20221
diff --git a/ld/testsuite/ld-i386/i386.exp b/ld/testsuite/ld-i386/i386.exp
index f6cbe43..a6efa53 100644
--- a/ld/testsuite/ld-i386/i386.exp
+++ b/ld/testsuite/ld-i386/i386.exp
@@ -400,6 +400,9 @@ run_dump_test "undefweaka"
 run_dump_test "undefweakb"
 run_dump_test "pr19539"
 run_dump_test "pr20117"
+run_dump_test "pr20244-1a"
+run_dump_test "pr20244-1b"
+run_dump_test "pr20244-1c"
 
 if { !([istarget "i?86-*-linux*"]
        || [istarget "i?86-*-gnu*"]
diff --git a/ld/testsuite/ld-i386/pr20244-1.s b/ld/testsuite/ld-i386/pr20244-1.s
new file mode 100644
index 0000000..f22ce62
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr20244-1.s
@@ -0,0 +1,17 @@
+	.data
+	.type	bar, @object
+bar:
+	.byte	1
+	.size	bar, .-bar
+	.globl	foo
+	.type	foo, @object
+foo:
+	.byte	1
+	.size	foo, .-foo
+	.text
+	.globl	_start
+	.type	_start, @function
+_start:
+	movl	$0, bar@GOT
+	cmpl	$0, foo@GOT
+	movl	$bar@GOT, %ecx
diff --git a/ld/testsuite/ld-i386/pr20244-1a.d b/ld/testsuite/ld-i386/pr20244-1a.d
new file mode 100644
index 0000000..46ae4be
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr20244-1a.d
@@ -0,0 +1,26 @@
+#source: pr20244-1.s
+#as: --32
+#ld: -m elf_i386
+#objdump: --sym -dw
+#notarget: i?86-*-nacl* x86_64-*-nacl*
+
+.*: +file format .*
+
+SYMBOL TABLE:
+#...
+0+80490a0 l     O .data	00000001 bar
+#...
+0+8048074 g     F .text	00000000 _start
+#...
+0+80490a1 g     O .data	00000001 foo
+#...
+
+
+
+Disassembly of section .text:
+
+0+8048074 <_start>:
+ +[a-f0-9]+:	c7 05 8c 90 04 08 00 00 00 00 	movl   \$0x0,0x804908c
+ +[a-f0-9]+:	83 3d 90 90 04 08 00 	cmpl   \$0x0,0x8049090
+ +[a-f0-9]+:	b9 f8 ff ff ff       	mov    \$0xfffffff8,%ecx
+#pass
diff --git a/ld/testsuite/ld-i386/pr20244-1b.d b/ld/testsuite/ld-i386/pr20244-1b.d
new file mode 100644
index 0000000..d8ac4aa
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr20244-1b.d
@@ -0,0 +1,11 @@
+#source: pr20244-1.s
+#as: --32
+#ld: -m elf_i386
+#objdump: -s -j .got
+#notarget: i?86-*-nacl* x86_64-*-nacl*
+
+.*: +file format .*
+
+Contents of section .got:
+ 804908c a0900408 a1900408 +........ +
+#pass
diff --git a/ld/testsuite/ld-i386/pr20244-1c.d b/ld/testsuite/ld-i386/pr20244-1c.d
new file mode 100644
index 0000000..c670507
--- /dev/null
+++ b/ld/testsuite/ld-i386/pr20244-1c.d
@@ -0,0 +1,4 @@
+#source: pr20244-1.s
+#as: --32
+#ld: -pie -m elf_i386
+#error: direct GOT relocation R_386_GOT32 against `bar' without base register can not be used when making a shared object