Re: [Minios-devel] [UNIKRAFT PATCHv3 12/25] arch/include: Add a _regs member to save origial stack pointer

[Sharan Santhanam <sharan.santhanam@xxxxxxxxx>]

Hello,

This patch seems fine.


Reviewed-by: Sharan Santhanam <sharan.santhanam@xxxxxxxxx>

Thanks & Regards
Sharan

On 12/13/18 10:15 AM, Wei Chen wrote:
> There is a issue about stack alignment check in url[1]. There
> might be case where the stack pointer is not aligned at EL1
> exception. We will force align the stack for EL1 exceptions,
> so we add a sp to save original stack pointer in this patch.
>
> [1] https://www.spinics.net/lists/arm-kernel/msg678761.html
>
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> ---
>   arch/arm/arm64/include/uk/asm/lcpu.h | 16 +++++++++++++---
>   1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/arm64/include/uk/asm/lcpu.h 
> b/arch/arm/arm64/include/uk/asm/lcpu.h
> index 2719313..9eea746 100644
> --- a/arch/arm/arm64/include/uk/asm/lcpu.h
> +++ b/arch/arm/arm64/include/uk/asm/lcpu.h
> @@ -35,13 +35,20 @@
>    * Stack size to save general purpose registers and essential system
>    * registers. 8 * (30 + lr + elr_el1 + spsr_el1 + esr_el1) = 272.
>    * From exceptions come from EL0, we have to save sp_el0. So the
> - * TRAP_STACK_SIZE should be 272 + 8 = 280
> + * TRAP_STACK_SIZE should be 272 + 8 = 280. But we enable the stack
> + * alignment check, we will force align the stack for EL1 exceptions,
> + * so we add a sp to save original stack pointer: 280 + 8 = 288
>    *
>    * TODO: We'd better to calculate this size automatically later.
>    */
> -#define __TRAP_STACK_SIZE 280
> +#define __TRAP_STACK_SIZE      288
> +#define __SP_OFFSET            272
> +#define __SP_EL0_OFFSET                280
>   #else
> -/* Change this structure must update TRAP_STACK_SIZE at the same time */
> +/*
> + * Change this structure must update TRAP_STACK_SIZE at the same time.
> + * This data structure must be 16-byte alignment.
> + */
>   struct __regs {
>         /* Generic Purpose registers, from x0 ~ x29 */
>         unsigned long x[30];
> @@ -60,6 +67,9 @@ struct __regs {
>   
>   	/* Stack Pointer */
>         unsigned long sp;
> +
> +       /* Stack Pointer from el0 */
> +       unsigned long sp_el0;
>   };
>   
>   /*
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