On Thu, Jan 12, 2023 at 01:40:07PM -0800, Namhyung Kim wrote: > Hello, > > The perf_prepare_sample() is to fill the perf sample data and update the > header info before sending it to the ring buffer. But we want to use it > for BPF overflow handler so that it can access the sample data to filter > relevant ones. > > Changes in v2) > * the layout change is merged > * reduce branches using __cond_set (PeterZ) > * add helpers to set dynamic sample data (PeterZ) > * introduce perf_prepare_header() (PeterZ) > * call perf_prepare_sample() before bpf_overflow_handler unconditionally > > This means the perf_prepare_handler() can be called more than once. To > avoid duplicate work, use the data->sample_flags and save the data size. > > I also added a few of helpers to set those information accordingly. > But it looks some fields like REGS_USER, STACK_USER and AUX are saved in > the perf_prepare_sample() so I didn't add the helpers for them. > > After than we can just check the filtered_sample_type flags begin zero > to determine if it has more work. In that case, it needs to update the > data->type since it's possible to miss when PMU driver sets all required > sample flags before calling perf_prepare_sample(). > > The code is also available at 'perf/prepare-sample-v2' branch in > > git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git > > Thanks, > Namhyung > > > Cc: Song Liu <song@xxxxxxxxxx> > Cc: bpf@xxxxxxxxxxxxxxx > > > Namhyung Kim (8): > perf/core: Save the dynamic parts of sample data size > perf/core: Add perf_sample_save_callchain() helper > perf/core: Add perf_sample_save_raw_data() helper > perf/core: Add perf_sample_save_brstack() helper > perf/core: Set data->sample_flags in perf_prepare_sample() > perf/core: Do not pass header for sample id init > perf/core: Introduce perf_prepare_header() > perf/core: Call perf_prepare_sample() before running BPF lgtm, I ran the bpf selftests on top of that and it's ok jirka > > arch/powerpc/perf/core-book3s.c | 3 +- > arch/s390/kernel/perf_cpum_cf.c | 4 +- > arch/s390/kernel/perf_cpum_sf.c | 3 +- > arch/s390/kernel/perf_pai_crypto.c | 4 +- > arch/s390/kernel/perf_pai_ext.c | 4 +- > arch/x86/events/amd/core.c | 6 +- > arch/x86/events/amd/ibs.c | 9 +- > arch/x86/events/intel/core.c | 6 +- > arch/x86/events/intel/ds.c | 24 ++-- > include/linux/perf_event.h | 133 +++++++++++++----- > kernel/events/core.c | 207 ++++++++++++++++------------- > kernel/trace/bpf_trace.c | 6 +- > 12 files changed, 236 insertions(+), 173 deletions(-) > > > base-commit: 9fcad995c6c52cc9791f7ee9f1386a5684055f9c > -- > 2.39.0.314.g84b9a713c41-goog >
