On 12/15/24 11:34 AM, Leo Yan wrote:
The bpf_perf_event_aux_pause kfunc will be used to control the Perf AUX
area to pause or resume.
An example use-case is attaching eBPF to Ftrace tracepoints. When a
tracepoint is hit, the associated eBPF program will be executed. The
eBPF program can invoke bpf_perf_event_aux_pause() to pause or resume
AUX trace. This is useful for fine-grained tracing by combining
Perf and eBPF.
This commit implements the bpf_perf_event_aux_pause kfunc, and make it
pass the eBPF verifier.
The subject and commit message mentions to implement a kfunc,
but actually you implemented a uapi helper. Please implement a kfunc
instead (searching __bpf_kfunc in kernel/bpf directory).
Signed-off-by: Leo Yan <leo.yan@xxxxxxx>
---
include/uapi/linux/bpf.h | 21 ++++++++++++++++
kernel/bpf/verifier.c | 2 ++
kernel/trace/bpf_trace.c | 52 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 75 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 4162afc6b5d0..678278c91ce2 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5795,6 +5795,26 @@ union bpf_attr {
* 0 on success.
*
* **-ENOENT** if the bpf_local_storage cannot be found.
+ *
+ * long bpf_perf_event_aux_pause(struct bpf_map *map, u64 flags, u32 pause)
+ * Description
+ * Pause or resume an AUX area trace associated to the perf event.
+ *
+ * The *flags* argument is specified as the key value for
+ * retrieving event pointer from the passed *map*.
+ *
+ * The *pause* argument controls AUX trace pause or resume.
+ * Non-zero values (true) are to pause the AUX trace and the zero
+ * value (false) is for re-enabling the AUX trace.
+ * Return
+ * 0 on success.
+ *
+ * **-ENOENT** if not found event in the events map.
+ *
+ * **-E2BIG** if the event index passed in the *flags* parameter
+ * is out-of-range of the map.
+ *
+ * **-EINVAL** if the flags passed is an invalid value.
*/
#define ___BPF_FUNC_MAPPER(FN, ctx...) \
FN(unspec, 0, ##ctx) \
@@ -6009,6 +6029,7 @@ union bpf_attr {
FN(user_ringbuf_drain, 209, ##ctx) \
FN(cgrp_storage_get, 210, ##ctx) \
FN(cgrp_storage_delete, 211, ##ctx) \
+ FN(perf_event_aux_pause, 212, ##ctx) \
/* */
/* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
[...]