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Re: [Xen-devel] [PATCH] xen: arm: arm64: Fix memory cloberring issues during VFP save restore.



Hi Julieng,

On 7 February 2014 17:24, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> Hello,
>
> Thanks for sending the patch quickly.
>
>
> On 07/02/14 10:38, Pranavkumar Sawargaonkar wrote:
>>
>> This patch addresses memory cloberring issue mentioed by Julien Grall
>
>
> clobbering mentioned.
>
>
>> with my earlier patch -
>> Ref:
>> http://www.gossamer-threads.com/lists/xen/devel/316247
>
>
> Can you add the commit id?
Sure.
>
>
>>
>> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@xxxxxxxxxx>
>> Signed-off-by: Anup Patel <anup.patel@xxxxxxxxxx>
>> ---
>>   xen/arch/arm/arm64/vfp.c |   70
>> ++++++++++++++++++++++++----------------------
>>   1 file changed, 36 insertions(+), 34 deletions(-)
>>
>> diff --git a/xen/arch/arm/arm64/vfp.c b/xen/arch/arm/arm64/vfp.c
>> index c09cf0c..62f56a3 100644
>> --- a/xen/arch/arm/arm64/vfp.c
>> +++ b/xen/arch/arm/arm64/vfp.c
>> @@ -8,23 +8,24 @@ void vfp_save_state(struct vcpu *v)
>>       if ( !cpu_has_fp )
>>           return;
>>
>> -    asm volatile("stp q0, q1, [%0, #16 * 0]\n\t"
>> -                 "stp q2, q3, [%0, #16 * 2]\n\t"
>> -                 "stp q4, q5, [%0, #16 * 4]\n\t"
>> -                 "stp q6, q7, [%0, #16 * 6]\n\t"
>> -                 "stp q8, q9, [%0, #16 * 8]\n\t"
>> -                 "stp q10, q11, [%0, #16 * 10]\n\t"
>> -                 "stp q12, q13, [%0, #16 * 12]\n\t"
>> -                 "stp q14, q15, [%0, #16 * 14]\n\t"
>> -                 "stp q16, q17, [%0, #16 * 16]\n\t"
>> -                 "stp q18, q19, [%0, #16 * 18]\n\t"
>> -                 "stp q20, q21, [%0, #16 * 20]\n\t"
>> -                 "stp q22, q23, [%0, #16 * 22]\n\t"
>> -                 "stp q24, q25, [%0, #16 * 24]\n\t"
>> -                 "stp q26, q27, [%0, #16 * 26]\n\t"
>> -                 "stp q28, q29, [%0, #16 * 28]\n\t"
>> -                 "stp q30, q31, [%0, #16 * 30]\n\t"
>> -                 :: "r" ((char *)(&v->arch.vfp.fpregs)): "memory");
>> +    asm volatile("stp q0, q1, [%1, #16 * 0]\n\t"
>> +                 "stp q2, q3, [%1, #16 * 2]\n\t"
>> +                 "stp q4, q5, [%1, #16 * 4]\n\t"
>> +                 "stp q6, q7, [%1, #16 * 6]\n\t"
>> +                 "stp q8, q9, [%1, #16 * 8]\n\t"
>> +                 "stp q10, q11, [%1, #16 * 10]\n\t"
>> +                 "stp q12, q13, [%1, #16 * 12]\n\t"
>> +                 "stp q14, q15, [%1, #16 * 14]\n\t"
>> +                 "stp q16, q17, [%1, #16 * 16]\n\t"
>> +                 "stp q18, q19, [%1, #16 * 18]\n\t"
>> +                 "stp q20, q21, [%1, #16 * 20]\n\t"
>> +                 "stp q22, q23, [%1, #16 * 22]\n\t"
>> +                 "stp q24, q25, [%1, #16 * 24]\n\t"
>> +                 "stp q26, q27, [%1, #16 * 26]\n\t"
>> +                 "stp q28, q29, [%1, #16 * 28]\n\t"
>> +                 "stp q30, q31, [%1, #16 * 30]\n\t"
>> +                 :"=Q" (*v->arch.vfp.fpregs): "r" (v->arch.vfp.fpregs)
>> +                 : "memory");
>
>
> You don't need anymore to clobber the whole memory. "memory" can be removed.
Ok I will remove it in V2.
>
>
>>
>>       v->arch.vfp.fpsr = READ_SYSREG32(FPSR);
>>       v->arch.vfp.fpcr = READ_SYSREG32(FPCR);
>> @@ -36,23 +37,24 @@ void vfp_restore_state(struct vcpu *v)
>>       if ( !cpu_has_fp )
>>           return;
>>
>> -    asm volatile("ldp q0, q1, [%0, #16 * 0]\n\t"
>> -                 "ldp q2, q3, [%0, #16 * 2]\n\t"
>> -                 "ldp q4, q5, [%0, #16 * 4]\n\t"
>> -                 "ldp q6, q7, [%0, #16 * 6]\n\t"
>> -                 "ldp q8, q9, [%0, #16 * 8]\n\t"
>> -                 "ldp q10, q11, [%0, #16 * 10]\n\t"
>> -                 "ldp q12, q13, [%0, #16 * 12]\n\t"
>> -                 "ldp q14, q15, [%0, #16 * 14]\n\t"
>> -                 "ldp q16, q17, [%0, #16 * 16]\n\t"
>> -                 "ldp q18, q19, [%0, #16 * 18]\n\t"
>> -                 "ldp q20, q21, [%0, #16 * 20]\n\t"
>> -                 "ldp q22, q23, [%0, #16 * 22]\n\t"
>> -                 "ldp q24, q25, [%0, #16 * 24]\n\t"
>> -                 "ldp q26, q27, [%0, #16 * 26]\n\t"
>> -                 "ldp q28, q29, [%0, #16 * 28]\n\t"
>> -                 "ldp q30, q31, [%0, #16 * 30]\n\t"
>> -                 :: "r" ((char *)(&v->arch.vfp.fpregs)): "memory");
>> +    asm volatile("ldp q0, q1, [%1, #16 * 0]\n\t"
>> +                 "ldp q2, q3, [%1, #16 * 2]\n\t"
>> +                 "ldp q4, q5, [%1, #16 * 4]\n\t"
>> +                 "ldp q6, q7, [%1, #16 * 6]\n\t"
>> +                 "ldp q8, q9, [%1, #16 * 8]\n\t"
>> +                 "ldp q10, q11, [%1, #16 * 10]\n\t"
>> +                 "ldp q12, q13, [%1, #16 * 12]\n\t"
>> +                 "ldp q14, q15, [%1, #16 * 14]\n\t"
>> +                 "ldp q16, q17, [%1, #16 * 16]\n\t"
>> +                 "ldp q18, q19, [%1, #16 * 18]\n\t"
>> +                 "ldp q20, q21, [%1, #16 * 20]\n\t"
>> +                 "ldp q22, q23, [%1, #16 * 22]\n\t"
>> +                 "ldp q24, q25, [%1, #16 * 24]\n\t"
>> +                 "ldp q26, q27, [%1, #16 * 26]\n\t"
>> +                 "ldp q28, q29, [%1, #16 * 28]\n\t"
>> +                 "ldp q30, q31, [%1, #16 * 30]\n\t"
>> +                 :: "Q" (*v->arch.vfp.fpregs), "r" (v->arch.vfp.fpregs)
>> +                 : "memory");
>
>
> Same here.
>
> Cheers,
>
> --
> Julien Grall

-
Pranav

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