On 14/9/23 00:36, Leon Hwang wrote:
> It's unnecessary to check imm32 in both 'if' and 'else'.
>
> It's better to check it first.
>
> Meanwhile, refactor the code for 'offs' calculation.
>
> Signed-off-by: Leon Hwang <hffilwlqm@xxxxxxxxx>
> ---
> arch/x86/net/bpf_jit_comp.c | 16 +++++++---------
> 1 file changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
> index 2846c21d75bfa..f06e9a48afe52 100644
> --- a/arch/x86/net/bpf_jit_comp.c
> +++ b/arch/x86/net/bpf_jit_comp.c
> @@ -1629,17 +1629,15 @@ st: if (is_imm8(insn->off))
> case BPF_JMP | BPF_CALL: {
> int offs;
>
> + if (!imm32)
> + return -EINVAL;
> +
> func = (u8 *) __bpf_call_base + imm32;
> - if (tail_call_reachable) {
> + if (tail_call_reachable)
> RESTORE_TAIL_CALL_CNT(bpf_prog->aux->stack_depth);
> - if (!imm32)
> - return -EINVAL;
> - offs = 7 + x86_call_depth_emit_accounting(&prog, func);
> - } else {
> - if (!imm32)
> - return -EINVAL;
> - offs = x86_call_depth_emit_accounting(&prog, func);
> - }
> +
> + offs = (tail_call_reachable ? 7 : 0);
This 7 is the byte count of RESTORE_TAIL_CALL_CNT instructions.
I'll update it to RESTORE_TAIL_CALL_CNT_INSN_SIZE in v2 patch.
Thanks,
Leon
> + offs += x86_call_depth_emit_accounting(&prog, func);
> if (emit_call(&prog, func, image + addrs[i - 1] + offs))
> return -EINVAL;
> break;
>
> base-commit: e4f30c666b4933dcd140d5110073aa01a69d2b39
