[PATCH 1/2] powerpc/memcpy: Fix stack corruption for smaller sizes

[Christophe Leroy]

Hi,

The subjet is misleading. This isn't powerpc but only powerpc/64, and 
this is not memcpy() but memcpy_mcsafe()

Christophe

Le 03/09/2019 à 23:43, Santosh Sivaraj a écrit :
> For sizes lesser than 128 bytes, the code branches out early without saving
> the stack frame, which when restored later drops frame of the caller.
> 
> Tested-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> Signed-off-by: Santosh Sivaraj <santosh at fossix.org>
> ---
>   arch/powerpc/lib/memcpy_mcsafe_64.S | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/lib/memcpy_mcsafe_64.S b/arch/powerpc/lib/memcpy_mcsafe_64.S
> index 949976dc115d..cb882d9a6d8a 100644
> --- a/arch/powerpc/lib/memcpy_mcsafe_64.S
> +++ b/arch/powerpc/lib/memcpy_mcsafe_64.S
> @@ -84,7 +84,6 @@ err1;	stw	r0,0(r3)
>   
>   3:	sub	r5,r5,r6
>   	cmpldi	r5,128
> -	blt	5f
>   
>   	mflr	r0
>   	stdu	r1,-STACKFRAMESIZE(r1)
> @@ -99,6 +98,7 @@ err1;	stw	r0,0(r3)
>   	std	r22,STK_REG(R22)(r1)
>   	std	r0,STACKFRAMESIZE+16(r1)
>   
> +	blt	5f
>   	srdi	r6,r5,7
>   	mtctr	r6
>   
>