Andrii Nakryiko wrote:
> If BPF JIT supports per-CPU MOV instruction, inline bpf_get_smp_processor_id()
> to eliminate unnecessary function calls.
>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> ---
> kernel/bpf/verifier.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index edb650667f44..af0274b090bb 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -20072,6 +20072,30 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> goto next_insn;
> }
>
> +#ifdef CONFIG_X86_64
> + /* Implement bpf_get_smp_processor_id() inline. */
> + if (insn->imm == BPF_FUNC_get_smp_processor_id &&
> + prog->jit_requested && bpf_jit_supports_percpu_insn()) {
> + /* BPF_FUNC_get_smp_processor_id inlining is an
> + * optimization, so if pcpu_hot.cpu_number is ever
> + * changed in some incompatible and hard to support
> + * way, it's fine to back out this inlining logic
> + */
> + insn_buf[0] = BPF_MOV32_IMM(BPF_REG_0, (u32)(unsigned long)&pcpu_hot.cpu_number);
> + insn_buf[1] = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0);
> + insn_buf[2] = BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0);
> + cnt = 3;
> +
> + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
> + if (!new_prog)
> + return -ENOMEM;
> +
> + delta += cnt - 1;
> + env->prog = prog = new_prog;
> + insn = new_prog->insnsi + i + delta;
> + goto next_insn;
> + }
> +#endif
> /* Implement bpf_get_func_arg inline. */
> if (prog_type == BPF_PROG_TYPE_TRACING &&
> insn->imm == BPF_FUNC_get_func_arg) {
> --
> 2.43.0
>
>
Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
