powerpc/memcpy_mcsafe: return remaining bytes

memcpy_mcsafe currently return -EFAULT on a machine check exception, change
it to return the remaining bytes that needs to be copied, so that machine
check safe copy_to_user can maintain the same behavior as copy_to_user.

Signed-off-by: Santosh Sivaraj <santosh@fossix.org>

arch/powerpc/lib/memcpy_mcsafe_64.S

@@ -30,11 +30,12 @@
 	ld	r14,STK_REG(R14)(r1)
 	addi	r1,r1,STACKFRAMESIZE
 .Ldo_err1:
-	li	r3,-EFAULT
+	mr	r3,r7
 	blr
 
 
 _GLOBAL(memcpy_mcsafe)
+	mr	r7,r5
 	cmpldi	r5,16
 	blt	.Lshort_copy
 
@@ -49,18 +50,21 @@ err1;	lbz	r0,0(r4)
 	addi	r4,r4,1
 err1;	stb	r0,0(r3)
 	addi	r3,r3,1
+	subi	r7,r7,1
 
 1:	bf	cr7*4+2,2f
 err1;	lhz	r0,0(r4)
 	addi	r4,r4,2
 err1;	sth	r0,0(r3)
 	addi	r3,r3,2
+	subi	r7,r7,2
 
 2:	bf	cr7*4+1,3f
 err1;	lwz	r0,0(r4)
 	addi	r4,r4,4
 err1;	stw	r0,0(r3)
 	addi	r3,r3,4
+	subi	r7,r7,4
 
 3:	sub	r5,r5,r6
 	cmpldi	r5,128
@@ -87,43 +91,69 @@ err1;	stw	r0,0(r3)
 4:
 err2;	ld	r0,0(r4)
 err2;	ld	r6,8(r4)
-err2;	ld	r7,16(r4)
-err2;	ld	r8,24(r4)
-err2;	ld	r9,32(r4)
-err2;	ld	r10,40(r4)
-err2;	ld	r11,48(r4)
-err2;	ld	r12,56(r4)
-err2;	ld	r14,64(r4)
-err2;	ld	r15,72(r4)
-err2;	ld	r16,80(r4)
-err2;	ld	r17,88(r4)
-err2;	ld	r18,96(r4)
-err2;	ld	r19,104(r4)
-err2;	ld	r20,112(r4)
-err2;	ld	r21,120(r4)
+err2;	ld	r8,16(r4)
+err2;	ld	r9,24(r4)
+err2;	ld	r10,32(r4)
+err2;	ld	r11,40(r4)
+err2;	ld	r12,48(r4)
+err2;	ld	r14,56(r4)
+err2;	ld	r15,64(r4)
+err2;	ld	r16,72(r4)
+err2;	ld	r17,80(r4)
+err2;	ld	r18,88(r4)
+err2;	ld	r19,96(r4)
+err2;	ld	r20,104(r4)
+err2;	ld	r21,112(r4)
+err2;	ld	r22,120(r4)
 	addi	r4,r4,128
 err2;	std	r0,0(r3)
 err2;	std	r6,8(r3)
-err2;	std	r7,16(r3)
-err2;	std	r8,24(r3)
-err2;	std	r9,32(r3)
-err2;	std	r10,40(r3)
-err2;	std	r11,48(r3)
-err2;	std	r12,56(r3)
-err2;	std	r14,64(r3)
-err2;	std	r15,72(r3)
-err2;	std	r16,80(r3)
-err2;	std	r17,88(r3)
-err2;	std	r18,96(r3)
-err2;	std	r19,104(r3)
-err2;	std	r20,112(r3)
-err2;	std	r21,120(r3)
+err2;	std	r8,16(r3)
+err2;	std	r9,24(r3)
+err2;	std	r10,32(r3)
+err2;	std	r11,40(r3)
+err2;	std	r12,48(r3)
+err2;	std	r14,56(r3)
+err2;	std	r15,64(r3)
+err2;	std	r16,72(r3)
+err2;	std	r17,80(r3)
+err2;	std	r18,88(r3)
+err2;	std	r19,96(r3)
+err2;	std	r20,104(r3)
+err2;	std	r21,112(r3)
+err2;	std	r22,120(r3)
 	addi	r3,r3,128
+	subi	r7,r7,128
 	bdnz	4b
 
 	clrldi	r5,r5,(64-7)
 
-	ld	r14,STK_REG(R14)(r1)
+	/* Up to 127B to go */
+5:	srdi	r6,r5,4
+	mtocrf	0x01,r6
+
+6:	bf	cr7*4+1,7f
+err2;	ld	r0,0(r4)
+err2;	ld	r6,8(r4)
+err2;	ld	r8,16(r4)
+err2;	ld	r9,24(r4)
+err2;	ld	r10,32(r4)
+err2;	ld	r11,40(r4)
+err2;	ld	r12,48(r4)
+err2;	ld	r14,56(r4)
+	addi	r4,r4,64
+err2;	std	r0,0(r3)
+err2;	std	r6,8(r3)
+err2;	std	r8,16(r3)
+err2;	std	r9,24(r3)
+err2;	std	r10,32(r3)
+err2;	std	r11,40(r3)
+err2;	std	r12,48(r3)
+err2;	std	r14,56(r3)
+	addi	r3,r3,64
+	subi	r7,r7,64
+
+7:	ld	r14,STK_REG(R14)(r1)
 	ld	r15,STK_REG(R15)(r1)
 	ld	r16,STK_REG(R16)(r1)
 	ld	r17,STK_REG(R17)(r1)
@@ -134,42 +164,19 @@ err2;	std	r21,120(r3)
 	ld	r22,STK_REG(R22)(r1)
 	addi	r1,r1,STACKFRAMESIZE
 
-	/* Up to 127B to go */
-5:	srdi	r6,r5,4
-	mtocrf	0x01,r6
-
-6:	bf	cr7*4+1,7f
-err1;	ld	r0,0(r4)
-err1;	ld	r6,8(r4)
-err1;	ld	r7,16(r4)
-err1;	ld	r8,24(r4)
-err1;	ld	r9,32(r4)
-err1;	ld	r10,40(r4)
-err1;	ld	r11,48(r4)
-err1;	ld	r12,56(r4)
-	addi	r4,r4,64
-err1;	std	r0,0(r3)
-err1;	std	r6,8(r3)
-err1;	std	r7,16(r3)
-err1;	std	r8,24(r3)
-err1;	std	r9,32(r3)
-err1;	std	r10,40(r3)
-err1;	std	r11,48(r3)
-err1;	std	r12,56(r3)
-	addi	r3,r3,64
-
 	/* Up to 63B to go */
-7:	bf	cr7*4+2,8f
+	bf	cr7*4+2,8f
 err1;	ld	r0,0(r4)
 err1;	ld	r6,8(r4)
-err1;	ld	r7,16(r4)
-err1;	ld	r8,24(r4)
+err1;	ld	r8,16(r4)
+err1;	ld	r9,24(r4)
 	addi	r4,r4,32
 err1;	std	r0,0(r3)
 err1;	std	r6,8(r3)
-err1;	std	r7,16(r3)
-err1;	std	r8,24(r3)
+err1;	std	r8,16(r3)
+err1;	std	r9,24(r3)
 	addi	r3,r3,32
+	subi	r7,r7,32
 
 	/* Up to 31B to go */
 8:	bf	cr7*4+3,9f
@@ -179,6 +186,7 @@ err1;	ld	r6,8(r4)
 err1;	std	r0,0(r3)
 err1;	std	r6,8(r3)
 	addi	r3,r3,16
+	subi	r7,r7,16
 
 9:	clrldi	r5,r5,(64-4)
 
@@ -192,18 +200,21 @@ err1;	lwz	r6,4(r4)
 err1;	stw	r0,0(r3)
 err1;	stw	r6,4(r3)
 	addi	r3,r3,8
+	subi	r7,r7,8
 
 12:	bf	cr7*4+1,13f
 err1;	lwz	r0,0(r4)
 	addi	r4,r4,4
 err1;	stw	r0,0(r3)
 	addi	r3,r3,4
+	subi	r7,r7,4
 
 13:	bf	cr7*4+2,14f
 err1;	lhz	r0,0(r4)
 	addi	r4,r4,2
 err1;	sth	r0,0(r3)
 	addi	r3,r3,2
+	subi	r7,r7,2
 
 14:	bf	cr7*4+3,15f
 err1;	lbz	r0,0(r4)