ppc476 linker workaround shared lib fixes

When building a shared lib from non-PIC objects, we'll get dynamic
text relocations.  These need to move with any insns we move.
Otherwise the dynamic reloc will modify the branch, resulting in
crashes and other unpleasant behaviour.

Also, ld -r --ppc476-workaround used with sufficiently aligned PIC
objects needs a fix for emitted REL16 relocs.

bfd/
	* elf64-ppc.c (ppc_elf_relocate_section): Move dynamic text
	relocs with insns moved by --ppc476-workaround.  Correct
	output of REL16 relocs.
ld/testsuite/
	* ld-powerpc/ppc476-shared.s,
	* ld-powerpc/ppc476-shared.lnk,
	* ld-powerpc/ppc476-shared.d,
	* ld-powerpc/ppc476-shared2.d: New tests.
	* ld-powerpc/powerpc.exp: Run them.

8 files changed, 130 insertions, 0 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 4001dce..d7ba09b 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,9 @@
+2015-06-05  Alan Modra  <amodra@gmail.com>
+
+	* elf64-ppc.c (ppc_elf_relocate_section): Move dynamic text
+	relocs with insns moved by --ppc476-workaround.  Correct
+	output of REL16 relocs.
+
 2015-06-01  Jiong Wang  <jiong.wang@arm.com>
 
 	* elfnn-aarch64.c (aarch64_reloc_got_type): Support
diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index 663a871..a947e8e 100644
--- a/bfd/elf32-ppc.c
+++ b/bfd/elf32-ppc.c
@@ -9608,6 +9608,8 @@ ppc_elf_relocate_section (bfd *output_bfd,
 	      && rel->r_offset >= offset
 	      && rel->r_offset < offset + 4)
 	    {
+	      asection *sreloc;
+
 	      /* If the insn we are patching had a reloc, adjust the
 		 reloc r_offset so that the reloc applies to the moved
 		 location.  This matters for -r and --emit-relocs.  */
@@ -9620,6 +9622,56 @@ ppc_elf_relocate_section (bfd *output_bfd,
 		  relend[-1] = tmp;
 		}
 	      relend[-1].r_offset += patch_off - offset;
+
+	      /* Adjust REL16 addends too.  */
+	      switch (ELF32_R_TYPE (relend[-1].r_info))
+		{
+		case R_PPC_REL16:
+		case R_PPC_REL16_LO:
+		case R_PPC_REL16_HI:
+		case R_PPC_REL16_HA:
+		  relend[-1].r_addend += patch_off - offset;
+		  break;
+		default:
+		  break;
+		}
+
+	      /* If we are building a PIE or shared library with
+		 non-PIC objects, perhaps we had a dynamic reloc too?
+		 If so, the dynamic reloc must move with the insn.  */
+	      sreloc = elf_section_data (input_section)->sreloc;
+	      if (sreloc != NULL)
+		{
+		  bfd_byte *slo, *shi, *srelend;
+		  bfd_vma soffset;
+
+		  slo = sreloc->contents;
+		  shi = srelend
+		    = slo + sreloc->reloc_count * sizeof (Elf32_External_Rela);
+		  soffset = (offset + input_section->output_section->vma
+			     + input_section->output_offset);
+		  while (slo < shi)
+		    {
+		      bfd_byte *srel = slo + (shi - slo) / 2;
+		      bfd_elf32_swap_reloca_in (output_bfd, srel, &outrel);
+		      if (outrel.r_offset < soffset)
+			slo = srel + 1;
+		      else if (outrel.r_offset > soffset + 3)
+			shi = srel;
+		      else
+			{
+			  bfd_byte *nextr = srel + sizeof (Elf32_External_Rela);
+			  if (nextr != srelend)
+			    {
+			      memmove (srel, nextr, srelend - nextr);
+			      srel = srelend - sizeof (Elf32_External_Rela);
+			    }
+			  outrel.r_offset += patch_off - offset;
+			  bfd_elf32_swap_reloca_out (output_bfd, &outrel, srel);
+			  break;
+			}
+		    }
+		}
 	    }
 	  else
 	    rel = NULL;
diff --git a/ld/testsuite/ChangeLog b/ld/testsuite/ChangeLog
index fe62990..e51f16b 100644
--- a/ld/testsuite/ChangeLog
+++ b/ld/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2015-06-05  Alan Modra  <amodra@gmail.com>
+
+	* ld-powerpc/ppc476-shared.s,
+	* ld-powerpc/ppc476-shared.lnk,
+	* ld-powerpc/ppc476-shared.d,
+	* ld-powerpc/ppc476-shared2.d: New tests.
+	* ld-powerpc/powerpc.exp: Run them.
+
 2015-06-02  Jiong Wang  <jiong.wang@arm.com>
 
 	* ld-aarch64/emit-relocs-313.s: Use gotpage_lo15.
diff --git a/ld/testsuite/ld-powerpc/powerpc.exp b/ld/testsuite/ld-powerpc/powerpc.exp
index 48aec4a..976e89b 100644
--- a/ld/testsuite/ld-powerpc/powerpc.exp
+++ b/ld/testsuite/ld-powerpc/powerpc.exp
@@ -325,3 +325,6 @@ run_dump_test "attr-gnu-12-11"
 run_dump_test "attr-gnu-12-21"
 
 run_dump_test "vle-multiseg-6"
+
+run_dump_test "ppc476-shared"
+run_dump_test "ppc476-shared2"
diff --git a/ld/testsuite/ld-powerpc/ppc476-shared.d b/ld/testsuite/ld-powerpc/ppc476-shared.d
new file mode 100644
index 0000000..8fda847
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/ppc476-shared.d
@@ -0,0 +1,30 @@
+#source: ppc476-shared.s
+#as: -a32
+#ld: -melf32ppc -q -shared --ppc476-workaround -T ppc476-shared.lnk
+#objdump: -dr
+#target: powerpc*-*-*
+
+.*:     file format .*
+
+Disassembly of section \.text:
+
+0+fffc <\.text>:
+    fffc:	(48 01 00 04|04 00 01 48) 	b       20000 .*
+   10000:	(38 63 00 00|00 00 63 38) 	addi    r3,r3,0
+			1000[02]: R_PPC_ADDR16_LO	.bss
+	\.\.\.
+   1fff0:	(42 9f 00 05|05 00 9f 42) 	bcl     .*
+   1fff4:	(7d 28 02 a6|a6 02 28 7d) 	mflr    r9
+   1fff8:	(3d 29 00 00|00 00 29 3d) 	addis   r9,r9,0
+			1fff[8a]: R_PPC_REL16_HA	.bss\+0x[46]
+   1fffc:	(48 00 00 14|14 00 00 48) 	b       20010 .*
+   20000:	(3c 60 00 00|00 00 60 3c) 	lis     r3,0
+			2000[02]: R_PPC_ADDR16_HA	.bss
+   20004:	(4b fe ff fc|fc ff fe 4b) 	b       10000 .*
+   20008:	(48 00 00 02|02 00 00 48) 	ba      0 .*
+   2000c:	(48 00 00 02|02 00 00 48) 	ba      0 .*
+   20010:	(39 29 01 00|00 01 29 39) 	addi    r9,r9,256
+			2001[02]: R_PPC_REL16_LO	.bss\+0x1[ce]
+   20014:	(4b ff ff ec|ec ff ff 4b) 	b       20000 .*
+   20018:	(48 00 00 02|02 00 00 48) 	ba      0 .*
+   2001c:	(48 00 00 02|02 00 00 48) 	ba      0 .*
diff --git a/ld/testsuite/ld-powerpc/ppc476-shared.lnk b/ld/testsuite/ld-powerpc/ppc476-shared.lnk
new file mode 100644
index 0000000..5339358
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/ppc476-shared.lnk
@@ -0,0 +1,6 @@
+SECTIONS
+{
+  . = 0xfffc;
+  .text : { *(.text) }
+  .bss : { *(.bss) }
+}
diff --git a/ld/testsuite/ld-powerpc/ppc476-shared.s b/ld/testsuite/ld-powerpc/ppc476-shared.s
new file mode 100644
index 0000000..6774bad
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/ppc476-shared.s
@@ -0,0 +1,13 @@
+ .text
+ lis 3,x@ha
+ addi 3,3,x@l
+
+ .org 0xfff4
+ bcl 20,31,.+4
+0:
+ mflr 9
+ addis 9,9,x-0b@ha
+ addi 9,9,x-0b@l
+
+ .section .bss,"aw",@nobits
+x: .space 4
diff --git a/ld/testsuite/ld-powerpc/ppc476-shared2.d b/ld/testsuite/ld-powerpc/ppc476-shared2.d
new file mode 100644
index 0000000..ebb8bf1
--- /dev/null
+++ b/ld/testsuite/ld-powerpc/ppc476-shared2.d
@@ -0,0 +1,12 @@
+#source: ppc476-shared.s
+#as: -a32
+#ld: -melf32ppc -shared --ppc476-workaround -T ppc476-shared.lnk
+#objdump: -R
+#target: powerpc*-*-*
+
+.*:     file format .*
+
+DYNAMIC RELOCATION RECORDS
+OFFSET   TYPE              VALUE 
+0001000[02] R_PPC_ADDR16_LO   \.text\+0x000200f4
+0002000[02] R_PPC_ADDR16_HA   \.text\+0x000200f4