diff options
| author | Hao Luo <haoluo@google.com> | 2020-09-29 16:50:47 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-10-02 15:00:49 -0700 |
| commit | eaa6bcb71ef6ed3dc18fc525ee7e293b06b4882b (patch) | |
| tree | f942e4cd04a29b8f50ec5a57db535da79fcdd068 /tools/include | |
| parent | 2c2f6abeff1322a61f5ad7ce0ecccabf53e4fad5 (diff) | |
bpf: Introduce bpf_per_cpu_ptr()
Add bpf_per_cpu_ptr() to help bpf programs access percpu vars.
bpf_per_cpu_ptr() has the same semantic as per_cpu_ptr() in the kernel
except that it may return NULL. This happens when the cpu parameter is
out of range. So the caller must check the returned value.
Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200929235049.2533242-5-haoluo@google.com
Diffstat (limited to 'tools/include')
| -rw-r--r-- | tools/include/uapi/linux/bpf.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 2aa156af24d6..f3c1b637ab39 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3686,6 +3686,23 @@ union bpf_attr { * Return * The helper returns **TC_ACT_REDIRECT** on success or * **TC_ACT_SHOT** on error. + * + * void *bpf_per_cpu_ptr(const void *percpu_ptr, u32 cpu) + * Description + * Take a pointer to a percpu ksym, *percpu_ptr*, and return a + * pointer to the percpu kernel variable on *cpu*. A ksym is an + * extern variable decorated with '__ksym'. For ksym, there is a + * global var (either static or global) defined of the same name + * in the kernel. The ksym is percpu if the global var is percpu. + * The returned pointer points to the global percpu var on *cpu*. + * + * bpf_per_cpu_ptr() has the same semantic as per_cpu_ptr() in the + * kernel, except that bpf_per_cpu_ptr() may return NULL. This + * happens if *cpu* is larger than nr_cpu_ids. The caller of + * bpf_per_cpu_ptr() must check the returned value. + * Return + * A pointer pointing to the kernel percpu variable on *cpu*, or + * NULL, if *cpu* is invalid. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3841,6 +3858,7 @@ union bpf_attr { FN(seq_printf_btf), \ FN(skb_cgroup_classid), \ FN(redirect_neigh), \ + FN(bpf_per_cpu_ptr), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper |