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SubjectRe: [PATCH 087/100] powerpc: Restore registers on error exit from csum_partial_copy_generic()
Date
Luis Henriques <luis.henriques@canonical.com> writes:

> 3.5.7.23 -stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
>
> commit 8f21bd0090052e740944f9397e2be5ac7957ded7 upstream.

I'm dropping this patch as it is causing some build failures on
powerpc configs.

Cheers,
--
Luis


>
> The csum_partial_copy_generic() function saves the PowerPC
>non-volatile
> r14, r15, and r16 registers for the main checksum-and-copy loop.
> Unfortunately, it fails to restore them upon error exit from this loop,
> which results in silent corruption of these registers in the presumably
> rare event of an access exception within that loop.
>
> This commit therefore restores these register on error exit from the loop.
>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Signed-off-by: Anton Blanchard <anton@samba.org>
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
> ---
> arch/powerpc/lib/checksum_64.S | 54 +++++++++++++++++++++++++++++++-----------
> 1 file changed, 40 insertions(+), 14 deletions(-)
>
> diff --git a/arch/powerpc/lib/checksum_64.S b/arch/powerpc/lib/checksum_64.S
> index afa2eba..d0e8390 100644
> --- a/arch/powerpc/lib/checksum_64.S
> +++ b/arch/powerpc/lib/checksum_64.S
> @@ -229,19 +229,35 @@ _GLOBAL(csum_partial)
> blr
>
>
> - .macro source
> + .macro srcnr
> 100:
> .section __ex_table,"a"
> .align 3
> - .llong 100b,.Lsrc_error
> + .llong 100b,.Lsrc_error_nr
> .previous
> .endm
>
> - .macro dest
> + .macro source
> +150:
> + .section __ex_table,"a"
> + .align 3
> + .llong 150b,.Lsrc_error
> + .previous
> + .endm
> +
> + .macro dstnr
> 200:
> .section __ex_table,"a"
> .align 3
> - .llong 200b,.Ldest_error
> + .llong 200b,.Ldest_error_nr
> + .previous
> + .endm
> +
> + .macro dest
> +250:
> + .section __ex_table,"a"
> + .align 3
> + .llong 250b,.Ldest_error
> .previous
> .endm
>
> @@ -277,11 +293,11 @@ _GLOBAL(csum_partial_copy_generic)
> mtctr r6
>
> 1:
> -source; lhz r6,0(r3) /* align to doubleword */
> +srcnr; lhz r6,0(r3) /* align to doubleword */
> subi r5,r5,2
> addi r3,r3,2
> adde r0,r0,r6
> -dest; sth r6,0(r4)
> +dstnr; sth r6,0(r4)
> addi r4,r4,2
> bdnz 1b
>
> @@ -395,10 +411,10 @@ dest; std r16,56(r4)
>
> mtctr r6
> 3:
> -source; ld r6,0(r3)
> +srcnr; ld r6,0(r3)
> addi r3,r3,8
> adde r0,r0,r6
> -dest; std r6,0(r4)
> +dstnr; std r6,0(r4)
> addi r4,r4,8
> bdnz 3b
>
> @@ -408,10 +424,10 @@ dest; std r6,0(r4)
> srdi. r6,r5,2
> beq .Lcopy_tail_halfword
>
> -source; lwz r6,0(r3)
> +srcnr; lwz r6,0(r3)
> addi r3,r3,4
> adde r0,r0,r6
> -dest; stw r6,0(r4)
> +dstnr; stw r6,0(r4)
> addi r4,r4,4
> subi r5,r5,4
>
> @@ -419,10 +435,10 @@ dest; stw r6,0(r4)
> srdi. r6,r5,1
> beq .Lcopy_tail_byte
>
> -source; lhz r6,0(r3)
> +srcnr; lhz r6,0(r3)
> addi r3,r3,2
> adde r0,r0,r6
> -dest; sth r6,0(r4)
> +dstnr; sth r6,0(r4)
> addi r4,r4,2
> subi r5,r5,2
>
> @@ -430,10 +446,10 @@ dest; sth r6,0(r4)
> andi. r6,r5,1
> beq .Lcopy_finish
>
> -source; lbz r6,0(r3)
> +srcnr; lbz r6,0(r3)
> sldi r9,r6,8 /* Pad the byte out to 16 bits */
> adde r0,r0,r9
> -dest; stb r6,0(r4)
> +dstnr; stb r6,0(r4)
>
> .Lcopy_finish:
> addze r0,r0 /* add in final carry */
> @@ -443,6 +459,11 @@ dest; stb r6,0(r4)
> blr
>
> .Lsrc_error:
> + ld r14,STK_REG(R14)(r1)
> + ld r15,STK_REG(R15)(r1)
> + ld r16,STK_REG(R16)(r1)
> + addi r1,r1,STACKFRAMESIZE
> +.Lsrc_error_nr:
> cmpdi 0,r7,0
> beqlr
> li r6,-EFAULT
> @@ -450,6 +471,11 @@ dest; stb r6,0(r4)
> blr
>
> .Ldest_error:
> + ld r14,STK_REG(R14)(r1)
> + ld r15,STK_REG(R15)(r1)
> + ld r16,STK_REG(R16)(r1)
> + addi r1,r1,STACKFRAMESIZE
> +.Ldest_error_nr:
> cmpdi 0,r8,0
> beqlr
> li r6,-EFAULT


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