[PATCH v5] MIPS: Reject branch absolute relocs for PIC for linking

[YunQiang Su <syq@gcc.gnu.org>]

The asm code like:
	b	(8)
will emit absolute relocs like:
	R_MIPS_PC16	*ABS*

If they are included into PIC shared objects or PIE executables,
the branch target will be like 0x12340000, which will make the
programs crash.
---
 bfd/elfxx-mips.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/bfd/elfxx-mips.c b/bfd/elfxx-mips.c
index 69dd71419ff..9542250dec4 100644
--- a/bfd/elfxx-mips.c
+++ b/bfd/elfxx-mips.c
@@ -9258,6 +9258,15 @@ _bfd_mips_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
 		   (h) ? h->root.root.string : "a local symbol");
 	      break;
 	    default:
+	      if (branch_reloc_p (r_type) && r_symndx == STN_UNDEF)
+		{
+		  howto = MIPS_ELF_RTYPE_TO_HOWTO (abfd, r_type, NEWABI_P (abfd));
+		  info->callbacks->einfo
+		    /* xgettext:c-format */
+		    (_("%X%H: relocation %s against `*ABS*' cannot be used"
+		       " when making a PIC/PIE object\n"),
+		     abfd, sec, rel->r_offset, howto->name);
+		}
 	      break;
 	    }
 	}
-- 
2.39.2