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.

1 files changed, 52 insertions, 0 deletions

diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index 663a8713a7..a947e8ef41 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;