hi,
at the moment we can't retrieve the number of missed kprobe
executions and subsequent execution of BPF programs.
This patchset adds:
- counting of missed execution on attach layer for:
. kprobes attached through perf link (kprobe/ftrace)
. kprobes attached through kprobe.multi link (fprobe)
- counting of recursion_misses for BPF kprobe programs
It's still technically possible to create kprobe without perf link (using
SET_BPF perf ioctl) in which case we don't have a way to retrieve the kprobe's
'missed' count. However both libbpf and cilium/ebpf libraries use perf link
if it's available, and for old kernels without perf link support we can use
BPF program to retrieve the kprobe missed count.
v2 changes:
- rename bpf_prog_missed_array to bpf_prog_inc_misses_counters [Alexei]
- add missing space to 'missed' output [Quentin]
- drop runtime stats changes [Hou Tao]
- add common helper for kprobe missed stats [Hou Tao]
- add test for tracepoint recursion missed counts [Hou Tao]
Also available at:
https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
bpf/missed_stats
thanks,
jirka
---
Jiri Olsa (9):
bpf: Count stats for kprobe_multi programs
bpf: Add missed value to kprobe_multi link info
bpf: Add missed value to kprobe perf link info
bpf: Count missed stats in trace_call_bpf
bpftool: Display missed count for kprobe_multi link
bpftool: Display missed count for kprobe perf link
selftests/bpf: Add test for missed counts of perf event link kprobe
selftests/bpf: Add test for recursion counts of perf event link kprobe
selftests/bpf: Add test for recursion counts of perf event link tracepoint
include/linux/bpf.h | 16 ++++++++++++++++
include/linux/trace_events.h | 6 ++++--
include/uapi/linux/bpf.h | 2 ++
kernel/bpf/syscall.c | 14 ++++++++------
kernel/trace/bpf_trace.c | 10 ++++++++--
kernel/trace/trace_kprobe.c | 14 +++++++++++---
tools/bpf/bpftool/link.c | 6 ++++++
tools/include/uapi/linux/bpf.h | 2 ++
tools/testing/selftests/bpf/DENYLIST.aarch64 | 1 +
tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c | 5 +++++
tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h | 2 ++
tools/testing/selftests/bpf/prog_tests/missed.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/progs/missed_kprobe.c | 30 ++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/progs/missed_tp_recursion.c | 41 +++++++++++++++++++++++++++++++++++++++++
15 files changed, 322 insertions(+), 13 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/missed.c
create mode 100644 tools/testing/selftests/bpf/progs/missed_kprobe.c
create mode 100644 tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c
create mode 100644 tools/testing/selftests/bpf/progs/missed_tp_recursion.c
