This series extends Perf for fine-grained tracing by using BPF program
to pause and resume AUX tracing. The BPF program can be attached to
tracepoints (including ftrace tracepoints and dynamic tracepoints, like
kprobe, kretprobe, uprobe and uretprobe).
The first two patches are changes in kernel - it adds a bpf kfunc which
can be invoked from BPF program.
The Perf tool implements BPF skeleton program, hooks BPF program into a
perf record session. This is finished by patches 03 ~ 05.
The patch 06 updates documentation for usage of the new introduced
option '--bpf-aux-pause'.
This series has been tested on Hikey960 platform with commands:
perf record -e cs_etm/aux-action=start-paused/ \
--bpf-aux-pause="kretprobe:p:__arm64_sys_openat,kprobe:r:__arm64_sys_openat,tp:r:sched:sched_switch"
\
-a -- ls
perf record -e cs_etm/aux-action=start-paused/ \
--bpf-aux-pause="kretprobe:p:__arm64_sys_openat,kprobe:r:__arm64_sys_openat,tp:r:sched:sched_switch"
\
-i -- ls
perf record -e cs_etm/aux-action=start-paused/ \
--bpf-aux-pause="uretprobe:p:/mnt/sort:bubble_sort,uprobe:r:/mnt/sort:bubble_sort"
\
--per-thread -- /mnt/sort
Note, as the AUX pause operation cannot be inherited by child tasks, it
requires to specify the '-i' option for default mode. Otherwise, the
tool reports an error to remind user to disable inherited mode:
Failed to update BPF map for auxtrace: Operation not supported.
Try to disable inherit mode with option '-i'.
Changes in v3:
- Added check "map->type" (Eduard)
- Fixed kfunc with guard(irqsave).
- Link to v2:
https://lore.kernel.org/r/20250718-perf_aux_pause_resume_bpf_rebase-v2-0-992557b8f...@arm.com
Changes in v2:
- Changed to use BPF kfunc and dropped uAPI (Yonghong).
- Added support uprobe/uretprobe.
- Refined the syntax for trigger points (mainly for trigger action {p:r}).
- Fixed a bug in the BPF program with passing wrong flag.
- Rebased on bpf-next branch.
- Link to v1:
https://lore.kernel.org/linux-perf-users/20241215193436.275278-1-leo....@arm.com/T/#m10ea3e66bca7418db07c141a14217934f36e3bc8
---
Leo Yan (6):
perf/core: Make perf_event_aux_pause() as external function
bpf: Add bpf_perf_event_aux_pause kfunc
perf: auxtrace: Control AUX pause and resume with BPF
perf: auxtrace: Add BPF userspace program for AUX pause and resume
perf record: Support AUX pause and resume with BPF
perf docs: Document AUX pause and resume with BPF
include/linux/perf_event.h | 1 +
kernel/events/core.c | 2 +-
kernel/trace/bpf_trace.c | 55 ++++
tools/perf/Documentation/perf-record.txt | 51 ++++
tools/perf/Makefile.perf | 1 +
tools/perf/builtin-record.c | 20 +-
tools/perf/util/Build | 4 +
tools/perf/util/auxtrace.h | 43 +++
tools/perf/util/bpf_auxtrace_pause.c | 408 ++++++++++++++++++++++++++
tools/perf/util/bpf_skel/auxtrace_pause.bpf.c | 156 ++++++++++
tools/perf/util/evsel.c | 6 +
tools/perf/util/record.h | 1 +
12 files changed, 746 insertions(+), 2 deletions(-)
---
base-commit: 95993dc3039e29dabb9a50d074145d4cb757b08b
change-id: 20250717-perf_aux_pause_resume_bpf_rebase-174c79b0bab5
Best regards,
--
Leo Yan <leo....@arm.com>
