tile: fix strncpy_from_user bug

In strncpy_from_user_asm, when the destination buffer length was the
same as the actual string length, we were returning the size of the
destination buffer.  But since it's a NUL terminated string, we should
return the length of the string instead.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/lib/usercopy_32.S

@@ -50,10 +50,11 @@ STD_ENTRY(strncpy_from_user_asm)
 	{ bz r2, 2f; move r3, r0 }
 1:	{ lb_u r4, r1; addi r1, r1, 1; addi r2, r2, -1 }
 	{ sb r0, r4; addi r0, r0, 1 }
-	bz r2, 2f
-	bnzt r4, 1b
-	addi r0, r0, -1   /* don't count the trailing NUL */
-2:      { sub r0, r0, r3; jrp lr }
+	bz r4, 2f
+	bnzt r2, 1b
+	{ sub r0, r0, r3; jrp lr }
+2:	addi r0, r0, -1   /* don't count the trailing NUL */
+	{ sub r0, r0, r3; jrp lr }
 	STD_ENDPROC(strncpy_from_user_asm)
 	.pushsection .fixup,"ax"
 strncpy_from_user_fault:

arch/tile/lib/usercopy_64.S

@@ -50,10 +50,11 @@ STD_ENTRY(strncpy_from_user_asm)
 	{ beqz r2, 2f; move r3, r0 }
 1:	{ ld1u r4, r1; addi r1, r1, 1; addi r2, r2, -1 }
 	{ st1 r0, r4; addi r0, r0, 1 }
-	beqz r2, 2f
-	bnezt r4, 1b
-	addi r0, r0, -1   /* don't count the trailing NUL */
-2:      { sub r0, r0, r3; jrp lr }
+	beqz r4, 2f
+	bnezt r2, 1b
+	{ sub r0, r0, r3; jrp lr }
+2:	addi r0, r0, -1   /* don't count the trailing NUL */
+	{ sub r0, r0, r3; jrp lr }
 	STD_ENDPROC(strncpy_from_user_asm)
 	.pushsection .fixup,"ax"
 strncpy_from_user_fault: