powerpc: Fix string library functions

The powerpc strncmp implementation does not correctly handle a zero
length, despite the claim in 0119536cd314ef95553604208c25bc35581f7f0a
(Add hand-coded assembly strcmp).

Additionally, all the length arguments are size_t, not int, so use
PPC_LCMPI and eq instead of cmpwi and le throughout.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/lib/string.S

@@ -28,7 +28,7 @@ _GLOBAL(strcpy)
 /* This clears out any unused part of the destination buffer,
    just as the libc version does.  -- paulus */
 _GLOBAL(strncpy)
-	cmpwi	0,r5,0
+	PPC_LCMPI 0,r5,0
 	beqlr
 	mtctr	r5
 	addi	r6,r3,-1
@@ -39,7 +39,7 @@ _GLOBAL(strncpy)
 	bdnzf	2,1b		/* dec ctr, branch if ctr != 0 && !cr0.eq */
 	bnelr			/* if we didn't hit a null char, we're done */
 	mfctr	r5
-	cmpwi	0,r5,0		/* any space left in destination buffer? */
+	PPC_LCMPI 0,r5,0	/* any space left in destination buffer? */
 	beqlr			/* we know r0 == 0 here */
 2:	stbu	r0,1(r6)	/* clear it out if so */
 	bdnz	2b
@@ -70,8 +70,8 @@ _GLOBAL(strcmp)
 	blr
 
 _GLOBAL(strncmp)
-	PPC_LCMPI r5,0
-	ble-	2f
+	PPC_LCMPI 0,r5,0
+	beq-	2f
 	mtctr	r5
 	addi	r5,r3,-1
 	addi	r4,r4,-1
@@ -94,8 +94,8 @@ _GLOBAL(strlen)
 	blr
 
 _GLOBAL(memcmp)
-	cmpwi	0,r5,0
-	ble-	2f
+	PPC_LCMPI 0,r5,0
+	beq-	2f
 	mtctr	r5
 	addi	r6,r3,-1
 	addi	r4,r4,-1
@@ -108,8 +108,8 @@ _GLOBAL(memcmp)
 	blr
 
 _GLOBAL(memchr)
-	cmpwi	0,r5,0
-	ble-	2f
+	PPC_LCMPI 0,r5,0
+	beq-	2f
 	mtctr	r5
 	addi	r3,r3,-1
 1:	lbzu	r0,1(r3)