Re: [PATCH v2 2/6] riscv: Deduplicate IRQ stack switching

[Sami Tolvanen]

Hi Clément,

On Thu, Aug 24, 2023 at 1:12 AM Clément Léger <cleger@xxxxxxxxxxxx> wrote:
>
> Some defines for stack frame offsets could be added in asm-offsets for
> the offsets:
>
>         DEFINE(STACKFRAME_SIZE_ON_STACK, ALIGN(sizeof(struct stackframe),
> STACK_ALIGN));
>         OFFSET(STACKFRAME_FP, stackframe, fp);
>         OFFSET(STACKFRAME_RA, stackframe, ra);
>
> And you can probably increment the stack at once (saving two addi in
> prologue/epilogue) for both RA and FP and reuse the asm-offsets defines:
>
>         addi    sp, sp, -STACKFRAME_SIZE_ON_STACK
>         REG_S   ra, STACKFRAME_RA(sp)
>         REG_S   s0, STACKFRAME_FP(sp)
>         addi    s0, sp, STACKFRAME_SIZE_ON_STACK

Thanks for taking a look!

I just copied the existing inline assembly here, but I do agree that
defining stack frame offsets and avoiding the extra addis is a cleaner
approach. I'll change this in v3.

Sami