From 4310551b76e0d6762abb78fc23d50dcc3c608c33 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Tue, 14 Mar 2023 16:42:36 -0700 Subject: perf bpf filter: Show warning for missing sample flags For a BPF filter to work properly, users need to provide appropriate options to enable the sample types. Otherwise the BPF program would see an invalid value (i.e. always 0) and filter won't work well. Show a warning message if sample types are missing like below. $ sudo ./perf record -e cycles --filter 'addr < 100' true Error: cycles event does not have PERF_SAMPLE_ADDR Hint: please add -d option to perf record. failed to set filter "BPF" on event cycles with 22 (Invalid argument) Signed-off-by: Namhyung Kim Cc: Adrian Hunter Cc: Andi Kleen Cc: Hao Luo Cc: Ian Rogers Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Leo Yan Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Song Liu Cc: Stephane Eranian Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230314234237.3008956-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-record.c | 2 +- tools/perf/util/bpf-filter.c | 62 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 63 insertions(+), 1 deletion(-) diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 6df8b823859d..7b7e74a56346 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -1353,7 +1353,7 @@ try_again: if (evlist__apply_filters(evlist, &pos)) { pr_err("failed to set filter \"%s\" on event %s with %d (%s)\n", - pos->filter, evsel__name(pos), errno, + pos->filter ?: "BPF", evsel__name(pos), errno, str_error_r(errno, msg, sizeof(msg))); rc = -1; goto out; diff --git a/tools/perf/util/bpf-filter.c b/tools/perf/util/bpf-filter.c index bd638737e12f..0b30688d78a7 100644 --- a/tools/perf/util/bpf-filter.c +++ b/tools/perf/util/bpf-filter.c @@ -17,6 +17,64 @@ #define FD(e, x, y) (*(int *)xyarray__entry(e->core.fd, x, y)) +#define __PERF_SAMPLE_TYPE(st, opt) { st, #st, opt } +#define PERF_SAMPLE_TYPE(_st, opt) __PERF_SAMPLE_TYPE(PERF_SAMPLE_##_st, opt) + +static const struct perf_sample_info { + u64 type; + const char *name; + const char *option; +} sample_table[] = { + /* default sample flags */ + PERF_SAMPLE_TYPE(IP, NULL), + PERF_SAMPLE_TYPE(TID, NULL), + PERF_SAMPLE_TYPE(PERIOD, NULL), + /* flags mostly set by default, but still have options */ + PERF_SAMPLE_TYPE(ID, "--sample-identifier"), + PERF_SAMPLE_TYPE(CPU, "--sample-cpu"), + PERF_SAMPLE_TYPE(TIME, "-T"), + /* optional sample flags */ + PERF_SAMPLE_TYPE(ADDR, "-d"), + PERF_SAMPLE_TYPE(DATA_SRC, "-d"), + PERF_SAMPLE_TYPE(PHYS_ADDR, "--phys-data"), + PERF_SAMPLE_TYPE(WEIGHT, "-W"), + PERF_SAMPLE_TYPE(WEIGHT_STRUCT, "-W"), + PERF_SAMPLE_TYPE(TRANSACTION, "--transaction"), + PERF_SAMPLE_TYPE(CODE_PAGE_SIZE, "--code-page-size"), + PERF_SAMPLE_TYPE(DATA_PAGE_SIZE, "--data-page-size"), +}; + +static const struct perf_sample_info *get_sample_info(u64 flags) +{ + size_t i; + + for (i = 0; i < ARRAY_SIZE(sample_table); i++) { + if (sample_table[i].type == flags) + return &sample_table[i]; + } + return NULL; +} + +static int check_sample_flags(struct evsel *evsel, struct perf_bpf_filter_expr *expr) +{ + const struct perf_sample_info *info; + + if (evsel->core.attr.sample_type & expr->sample_flags) + return 0; + + info = get_sample_info(expr->sample_flags); + if (info == NULL) { + pr_err("Error: %s event does not have sample flags %lx\n", + evsel__name(evsel), expr->sample_flags); + return -1; + } + + pr_err("Error: %s event does not have %s\n", evsel__name(evsel), info->name); + if (info->option) + pr_err(" Hint: please add %s option to perf record\n", info->option); + return -1; +} + int perf_bpf_filter__prepare(struct evsel *evsel) { int i, x, y, fd; @@ -40,6 +98,10 @@ int perf_bpf_filter__prepare(struct evsel *evsel) .flags = expr->sample_flags, .value = expr->val, }; + + if (check_sample_flags(evsel, expr) < 0) + return -1; + bpf_map_update_elem(fd, &i, &entry, BPF_ANY); i++; -- cgit v1.2.3