MIPS: asm: asmmacro: Replace "add" instructions with "addu"

commit 98a833c1 upstream.

The "add" instruction is actually a macro in binutils and depending on
the size of the immediate it can expand to an "addi" instruction.
However, the "addi" instruction traps on overflows which is not
something we want on address calculation.

Link: http://www.linux-mips.org/archives/linux-mips/2015-01/msg00121.html
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

arch/mips/include/asm/asmmacro.h

@@ -293,7 +293,7 @@
 	.macro	ld_d	wd, off, base
 	.set	push
 	.set	noat
-	add	$1, \base, \off
+	addu	$1, \base, \off
 	.word	LDD_MSA_INSN | (\wd << 6)
 	.set	pop
 	.endm
@@ -301,7 +301,7 @@
 	.macro	st_d	wd, off, base
 	.set	push
 	.set	noat
-	add	$1, \base, \off
+	addu	$1, \base, \off
 	.word	STD_MSA_INSN | (\wd << 6)
 	.set	pop
 	.endm