From: Feng Yang <yangfeng@kylinos.cn>

All BPF programs either disable CPU preemption or CPU migration,
so the bpf_get_smp_processor_id_proto can be safely removed,
and the bpf_get_raw_smp_processor_id_proto in bpf_base_func_proto works perfectly.

Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
---
 include/linux/bpf.h      |  1 -
 kernel/bpf/core.c        |  1 -
 kernel/bpf/helpers.c     | 12 ------------
 kernel/trace/bpf_trace.c |  2 --
 net/core/filter.c        |  6 ------
 5 files changed, 22 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3f0cc89c0622..36e525141556 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -3316,7 +3316,6 @@ extern const struct bpf_func_proto bpf_map_peek_elem_proto;
 extern const struct bpf_func_proto bpf_map_lookup_percpu_elem_proto;
 
 extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
-extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
 extern const struct bpf_func_proto bpf_get_numa_node_id_proto;
 extern const struct bpf_func_proto bpf_tail_call_proto;
 extern const struct bpf_func_proto bpf_ktime_get_ns_proto;
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index ba6b6118cf50..1ad41a16b86e 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2943,7 +2943,6 @@ const struct bpf_func_proto bpf_spin_unlock_proto __weak;
 const struct bpf_func_proto bpf_jiffies64_proto __weak;
 
 const struct bpf_func_proto bpf_get_prandom_u32_proto __weak;
-const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak;
 const struct bpf_func_proto bpf_get_numa_node_id_proto __weak;
 const struct bpf_func_proto bpf_ktime_get_ns_proto __weak;
 const struct bpf_func_proto bpf_ktime_get_boot_ns_proto __weak;
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index e3a2662f4e33..2d2bfb2911f8 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -149,18 +149,6 @@ const struct bpf_func_proto bpf_get_prandom_u32_proto = {
 	.ret_type	= RET_INTEGER,
 };
 
-BPF_CALL_0(bpf_get_smp_processor_id)
-{
-	return smp_processor_id();
-}
-
-const struct bpf_func_proto bpf_get_smp_processor_id_proto = {
-	.func		= bpf_get_smp_processor_id,
-	.gpl_only	= false,
-	.ret_type	= RET_INTEGER,
-	.allow_fastcall	= true,
-};
-
 BPF_CALL_0(bpf_get_numa_node_id)
 {
 	return numa_node_id();
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 0f5906f43d7c..39360cd6baf1 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1462,8 +1462,6 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_get_current_comm_proto;
 	case BPF_FUNC_trace_printk:
 		return bpf_get_trace_printk_proto();
-	case BPF_FUNC_get_smp_processor_id:
-		return &bpf_get_smp_processor_id_proto;
 	case BPF_FUNC_get_numa_node_id:
 		return &bpf_get_numa_node_id_proto;
 	case BPF_FUNC_perf_event_read:
diff --git a/net/core/filter.c b/net/core/filter.c
index bc6828761a47..7f7ec913ddbc 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -8264,8 +8264,6 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_set_hash_proto;
 	case BPF_FUNC_perf_event_output:
 		return &bpf_skb_event_output_proto;
-	case BPF_FUNC_get_smp_processor_id:
-		return &bpf_get_smp_processor_id_proto;
 	case BPF_FUNC_skb_under_cgroup:
 		return &bpf_skb_under_cgroup_proto;
 	case BPF_FUNC_get_socket_cookie:
@@ -8343,8 +8341,6 @@ xdp_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	switch (func_id) {
 	case BPF_FUNC_perf_event_output:
 		return &bpf_xdp_event_output_proto;
-	case BPF_FUNC_get_smp_processor_id:
-		return &bpf_get_smp_processor_id_proto;
 	case BPF_FUNC_csum_diff:
 		return &bpf_csum_diff_proto;
 	case BPF_FUNC_xdp_adjust_head:
@@ -8570,8 +8566,6 @@ lwt_out_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_get_hash_recalc_proto;
 	case BPF_FUNC_perf_event_output:
 		return &bpf_skb_event_output_proto;
-	case BPF_FUNC_get_smp_processor_id:
-		return &bpf_get_smp_processor_id_proto;
 	case BPF_FUNC_skb_under_cgroup:
 		return &bpf_skb_under_cgroup_proto;
 	default:
-- 
2.39.0.windows.2

On Thu, Apr 17, 2025 at 8:41 PM Feng Yang <yangfeng59949@163.com> wrote:
>
> From: Feng Yang <yangfeng@kylinos.cn>
>
> All BPF programs either disable CPU preemption or CPU migration,
> so the bpf_get_smp_processor_id_proto can be safely removed,
> and the bpf_get_raw_smp_processor_id_proto in bpf_base_func_proto works perfectly.
>
> Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
> ---
>  include/linux/bpf.h      |  1 -
>  kernel/bpf/core.c        |  1 -
>  kernel/bpf/helpers.c     | 12 ------------
>  kernel/trace/bpf_trace.c |  2 --
>  net/core/filter.c        |  6 ------
>  5 files changed, 22 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 3f0cc89c0622..36e525141556 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -3316,7 +3316,6 @@ extern const struct bpf_func_proto bpf_map_peek_elem_proto;
>  extern const struct bpf_func_proto bpf_map_lookup_percpu_elem_proto;
>
>  extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
> -extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
>  extern const struct bpf_func_proto bpf_get_numa_node_id_proto;
>  extern const struct bpf_func_proto bpf_tail_call_proto;
>  extern const struct bpf_func_proto bpf_ktime_get_ns_proto;
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index ba6b6118cf50..1ad41a16b86e 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -2943,7 +2943,6 @@ const struct bpf_func_proto bpf_spin_unlock_proto __weak;
>  const struct bpf_func_proto bpf_jiffies64_proto __weak;
>
>  const struct bpf_func_proto bpf_get_prandom_u32_proto __weak;
> -const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak;
>  const struct bpf_func_proto bpf_get_numa_node_id_proto __weak;
>  const struct bpf_func_proto bpf_ktime_get_ns_proto __weak;
>  const struct bpf_func_proto bpf_ktime_get_boot_ns_proto __weak;
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index e3a2662f4e33..2d2bfb2911f8 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -149,18 +149,6 @@ const struct bpf_func_proto bpf_get_prandom_u32_proto = {
>         .ret_type       = RET_INTEGER,
>  };
>
> -BPF_CALL_0(bpf_get_smp_processor_id)
> -{
> -       return smp_processor_id();
> -}
> -
> -const struct bpf_func_proto bpf_get_smp_processor_id_proto = {
> -       .func           = bpf_get_smp_processor_id,
> -       .gpl_only       = false,
> -       .ret_type       = RET_INTEGER,
> -       .allow_fastcall = true,
> -};
> -

bpf_get_raw_smp_processor_id_proto doesn't have
allow_fastcall = true

so this breaks tests.

Instead of removing BPF_CALL_0(bpf_get_smp_processor_id)
we should probably remove BPF_CALL_0(bpf_get_raw_cpu_id)
and adjust SKF_AD_OFF + SKF_AD_CPU case.
I don't recall why raw_ version was used back in 2014.

pw-bot: cr