[committed 1/4] MIPS/BFD: Set the ISA bit in microMIPS LA25 stub references

["Maciej W. Rozycki" <macro at imgtec dot com>]

Fix a linker regression introduced with commit 9d862524f6ae ("MIPS: 
Verify the ISA mode and alignment of branch and jump targets") causing a 
build failure in microMIPS glibc where the `zdump' tool fails to link:

.../timezone/zdump.o: In function `yeartot':
.../timezone/zdump.c:758:(.text+0x62): Jump to a non-instruction-aligned address
.../timezone/zdump.c:758:(.text+0x76): Jump to a non-instruction-aligned address
.../timezone/zdump.c:768:(.text+0x112): Jump to a non-instruction-aligned address
.../timezone/zdump.c:774:(.text+0x1b8): Jump to a non-instruction-aligned address
.../timezone/zdump.c:774:(.text+0x1cc): Jump to a non-instruction-aligned address
collect2: error: ld returned 1 exit status
make[2]: *** [.../timezone/zdump] Error 1

The cause of the failure is the stricter check introduced with the said 
change for jump and branch targets tripping on the address of microMIPS 
LA25 stubs.  Despite being microMIPS code these stubs do not have the 
ISA bit set throughout the relocation calculation process, because they 
have their address set to the memory offset into the stub section they 
are placed in.

The `mips_elf_la25_stub' structure does not carry ISA mode information, 
but there is no need to extend it, because the ISA mode can be inferred 
from the original symbol, which will have STO_MICROMIPS annotation, so 
use that instead to set the ISA bit appropriately.  Also only LA25 stubs 
associated with microMIPS symbols need to have the ISA bit set, because 
other LA25 stubs are made with regular MIPS code, even if associated 
with a MIPS16 symbol (in which case they are needed by a call thunk only 
rather than the MIPS16 function proper).

	bfd/
	* elfxx-mips.c (mips_elf_calculate_relocation): Set the ISA bit 
	in microMIPS LA25 stub references.
---
binutils-umips-bfd-la25-isa-bit.diff
Index: binutils/bfd/elfxx-mips.c
===================================================================
--- binutils.orig/bfd/elfxx-mips.c	2016-08-08 16:50:32.668787260 +0100
+++ binutils/bfd/elfxx-mips.c	2016-08-08 17:31:58.912513411 +0100
@@ -5577,9 +5580,13 @@ mips_elf_calculate_relocation (bfd *abfd
   else if (h != NULL && h->la25_stub
 	   && mips_elf_relocation_needs_la25_stub (input_bfd, r_type,
 						   target_is_16_bit_code_p))
-    symbol = (h->la25_stub->stub_section->output_section->vma
-	      + h->la25_stub->stub_section->output_offset
-	      + h->la25_stub->offset);
+    {
+	symbol = (h->la25_stub->stub_section->output_section->vma
+		  + h->la25_stub->stub_section->output_offset
+		  + h->la25_stub->offset);
+	if (ELF_ST_IS_MICROMIPS (h->root.other))
+	  symbol |= 1;
+    }
   /* For direct MIPS16 and microMIPS calls make sure the compressed PLT
      entry is used if a standard PLT entry has also been made.  In this
      case the symbol will have been set by mips_elf_set_plt_sym_value