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 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
