R_MICROMIPS_GPREL7_S2

This reloc is meant for the 16-bit LWGP instruction, 0x6400/0xfc00
match/mask encoding in `micromips_opcodes'.  It is correctly specified
to operate on a half-word by the howtos in elf32-mips.c, elfn32-mips.c
and elf64-mips.c, but is incorrectly subject to shuffle/unshuffle in
code like _bfd_mips_elf32_gprel16_reloc.

Current behaviour when applying the reloc to .byte 0x11,0x22,0x33,0x44
is to apply the reloc to byte 0x22 when big-endian, and to byte 0x33
when little-endian.  Big-endian behaviour is unchanged after this
patch and little-endian correctly applies the reloc to byte 0x11.

The patch also corrects REL addend extraction from section contents,
and overflow checking.  gold had all of the bfd problems with this
reloc and additionally did not apply the rightshift by two.

bfd/
	* elfxx-mips.c (micromips_reloc_shuffle_p): Return false for
	R_MICROMIPS_GPREL7_S2.
	(mips_elf_calculate_relocation): Correct sign extension and
	overflow calculation for R_MICROMIPS_GPREL7_S2.
	(_bfd_mips_elf_relocate_section): Update small-data overflow
	message.
gold/
	* mips.cc (Mips_relocate_functions::should_shuffle_micromips_reloc):
	Return false for R_MICROMIPS_GPREL7_S2.
	(Mips_relocate_functions::mips_reloc_unshuffle): Update comment.
	(Mips_relocate_functions::relgprel): Remove R_MICROMIPS_GPREL7_S2
	handling.
	(Mips_relocate_functions::relgprel7): New function.
	(Target_mips::Relocate::relocate): Adjust to suit.
ld/
	* testsuite/ld-mips-elf/reloc-4.d: Adjust expected error.
	* testsuite/ld-mips-elf/reloc-5.d: Likewise.

1 files changed, 24 insertions, 19 deletions

diff --git a/bfd/elfxx-mips.c b/bfd/elfxx-mips.c
index 4b1ec67..bae8622 100644
--- a/bfd/elfxx-mips.c
+++ b/bfd/elfxx-mips.c
@@ -2223,15 +2223,17 @@ micromips_reloc_p (unsigned int r_type)
 }
 
 /* Similar to MIPS16, the two 16-bit halves in microMIPS must be swapped
-   on a little-endian system.  This does not apply to R_MICROMIPS_PC7_S1
-   and R_MICROMIPS_PC10_S1 relocs that apply to 16-bit instructions.  */
+   on a little-endian system.  This does not apply to R_MICROMIPS_PC7_S1,
+   R_MICROMIPS_PC10_S1 and R_MICROMIPS_GPREL7_S2 relocs that apply to
+   16-bit instructions.  */
 
 static inline bool
 micromips_reloc_shuffle_p (unsigned int r_type)
 {
   return (micromips_reloc_p (r_type)
 	  && r_type != R_MICROMIPS_PC7_S1
-	  && r_type != R_MICROMIPS_PC10_S1);
+	  && r_type != R_MICROMIPS_PC10_S1
+	  && r_type != R_MICROMIPS_GPREL7_S2);
 }
 
 static inline bool
@@ -6255,21 +6257,24 @@ mips_elf_calculate_relocation (bfd *abfd, bfd *input_bfd,
     case R_MIPS_GPREL16:
     case R_MICROMIPS_GPREL7_S2:
     case R_MICROMIPS_GPREL16:
-      /* Only sign-extend the addend if it was extracted from the
-	 instruction.  If the addend was separate, leave it alone,
-	 otherwise we may lose significant bits.  */
-      if (howto->partial_inplace)
-	addend = _bfd_mips_elf_sign_extend (addend, 16);
-      value = symbol + addend - gp;
-      /* If the symbol was local, any earlier relocatable links will
-	 have adjusted its addend with the gp offset, so compensate
-	 for that now.  Don't do it for symbols forced local in this
-	 link, though, since they won't have had the gp offset applied
-	 to them before.  */
-      if (was_local_p)
-	value += gp0;
-      if (was_local_p || h->root.root.type != bfd_link_hash_undefweak)
-	overflowed_p = mips_elf_overflow_p (value, 16);
+      {
+	int bits = howto->bitsize + howto->rightshift;
+	/* Only sign-extend the addend if it was extracted from the
+	   instruction.  If the addend was separate, leave it alone,
+	   otherwise we may lose significant bits.  */
+	if (howto->partial_inplace)
+	  addend = _bfd_mips_elf_sign_extend (addend, bits);
+	value = symbol + addend - gp;
+	/* If the symbol was local, any earlier relocatable links will
+	   have adjusted its addend with the gp offset, so compensate
+	   for that now.  Don't do it for symbols forced local in this
+	   link, though, since they won't have had the gp offset applied
+	   to them before.  */
+	if (was_local_p)
+	  value += gp0;
+	if (was_local_p || h->root.root.type != bfd_link_hash_undefweak)
+	  overflowed_p = mips_elf_overflow_p (value, bits);
+      }
       break;
 
     case R_MIPS16_GOT16:
@@ -10671,7 +10676,7 @@ _bfd_mips_elf_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
 		  && (gprel16_reloc_p (howto->type)
 		      || literal_reloc_p (howto->type)))
 		{
-		  msg = _("small-data section exceeds 64KB;"
+		  msg = _("small-data section too large;"
 			  " lower small-data size limit (see option -G)");
 
 		  htab->small_data_overflow_reported = true;