ich777/linux_media
1
0
Fork 0
mirror of https://github.com/tbsdtv/linux_media.git synced 2025-07-23 20:51:03 +02:00
Code Issues Packages Projects Releases Wiki Activity

bpf: Introduce bpf_per_cpu_ptr()

Browse Source 
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
This commit is contained in:
Hao Luo
2020-09-29 16:50:47 -07:00
committed by Alexei Starovoitov
parent 2c2f6abeff
commit eaa6bcb71e
8 changed files with 132 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
include/uapi/linux/bpf.h
View File

@@ -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