[PATCH V5 08/11] riscv: Support HAVE_IRQ_EXIT_ON_IRQ_STACK

[Chen Zhongjin]

Hi,

On 2022/9/18 23:52, guoren at kernel.org wrote:
> diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
> index 5f49517cd3a2..426529b84db0 100644
> --- a/arch/riscv/kernel/entry.S
> +++ b/arch/riscv/kernel/entry.S
> @@ -332,6 +332,33 @@ ENTRY(ret_from_kernel_thread)
>   	tail syscall_exit_to_user_mode
>   ENDPROC(ret_from_kernel_thread)
>   
> +#ifdef CONFIG_IRQ_STACKS
> +ENTRY(call_on_stack)
> +	/* Create a frame record to save our ra and fp */
> +	addi	sp, sp, -RISCV_SZPTR
> +	REG_S	ra, (sp)
> +	addi	sp, sp, -RISCV_SZPTR
> +	REG_S	fp, (sp)
> +
> +	/* Save sp in fp */
> +	move	fp, sp
> +
> +	/* Move to the new stack and call the function there */
> +	li	a3, IRQ_STACK_SIZE
> +	add	sp, a1, a3
> +	jalr	a2
> +
> +	/*
> +	 * Restore sp from prev fp, and fp, ra from the frame
> +	 */
> +	move	sp, fp
> +	REG_L	fp, (sp)
> +	addi	sp, sp, RISCV_SZPTR
> +	REG_L	ra, (sp)
> +	addi	sp, sp, RISCV_SZPTR
> +	ret
> +ENDPROC(call_on_stack)
> +#endif

Seems my compiler (riscv64-linux-gnu-gcc 8.4.0, cross compiling from 
x86) cannot recognize the register `fp`.

After I changed it to `s0` this can pass compiling.


Seems there is nowhere else using `fp`, can this just using `s0` instead?

Best,

Chen