[v3 5/7] powerpc/memcpy_mcsafe: return remaining bytes

Sat Jul 6 16:16:33 AEST 2019

Le 05/07/2019 à 23:26, Santosh Sivaraj a écrit :
> 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.

AFAIU, this behaviour is the expected behaviour for memcpy_mcsafe(). Why 
implement a different behaviour in patch 3 and then change it here. 
Can't memcpy_mcsafe() return remaining bytes as expected from patch 3 ?

Christophe

> 
> Signed-off-by: Santosh Sivaraj <santosh at fossix.org>
> ---
>   arch/powerpc/lib/memcpy_mcsafe_64.S | 142 ++++++++++++++++------------
>   1 file changed, 83 insertions(+), 59 deletions(-)
> 
> diff --git a/arch/powerpc/lib/memcpy_mcsafe_64.S b/arch/powerpc/lib/memcpy_mcsafe_64.S
> index 50f865db0338..4d8a3d315992 100644
> --- a/arch/powerpc/lib/memcpy_mcsafe_64.S
> +++ b/arch/powerpc/lib/memcpy_mcsafe_64.S
> @@ -30,11 +30,25 @@
>   	ld	r14,STK_REG(R14)(r1)
>   	addi	r1,r1,STACKFRAMESIZE
>   .Ldo_err1:
> -	li	r3,-EFAULT
> +	/* Do a byte by byte copy to get the exact remaining size */
> +	mtctr	r7
> +100:	EX_TABLE(100b, .Ldone)
> +46:
> +err1;	lbz	r0,0(r4)
> +	addi	r4,r4,1
> +err1;	stb	r0,0(r3)
> +	addi	r3,r3,1
> +	bdnz	46b
> +	li	r3,0
> +	blr
> +
> +.Ldone:
> +	mfctr	r3
>   	blr
>   
>   
>   _GLOBAL(memcpy_mcsafe)
> +	mr	r7,r5
>   	cmpldi	r5,16
>   	blt	.Lshort_copy
>   
> @@ -49,18 +63,21 @@ 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 +104,69 @@ 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 +177,19 @@ 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 +199,7 @@ 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 +213,21 @@ 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)
> 