[PATCH bpf-next] riscv, bpf: Optimize stack usage of trampoline

[Pu Lehui]

On 2024/7/8 19:47, Puranjay Mohan wrote:
> When BPF_TRAMP_F_CALL_ORIG is not set, stack space for passing arguments
> on stack doesn't need to be reserved because the original function is
> not called.
> 
> Only reserve space for stacked arguments when BPF_TRAMP_F_CALL_ORIG is
> set.
> 
> Signed-off-by: Puranjay Mohan <puranjay at kernel.org>
> ---
>   arch/riscv/net/bpf_jit_comp64.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
> index 685c7389ae7e..0795efdd3519 100644
> --- a/arch/riscv/net/bpf_jit_comp64.c
> +++ b/arch/riscv/net/bpf_jit_comp64.c
> @@ -892,7 +892,7 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
>   	stack_size += 8;
>   	sreg_off = stack_size;
>   
> -	if (nr_arg_slots - RV_MAX_REG_ARGS > 0)
> +	if ((flags & BPF_TRAMP_F_CALL_ORIG) && (nr_arg_slots - RV_MAX_REG_ARGS > 0))
>   		stack_size += (nr_arg_slots - RV_MAX_REG_ARGS) * 8;
>   
>   	stack_size = round_up(stack_size, STACK_ALIGN);

Thanks!

Acked-by: Pu Lehui <pulehui at huawei.com>