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![Namhyung Kim](/assets/img/avatar_default.png)
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 <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: James Clark <james.clark@arm.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Leo Yan <leo.yan@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Bangoria <ravi.bangoria@amd.com> Cc: Song Liu <song@kernel.org> Cc: Stephane Eranian <eranian@google.com> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230314234237.3008956-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
197 lines
4.8 KiB
C
197 lines
4.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#include <stdlib.h>
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#include <bpf/bpf.h>
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#include <linux/err.h>
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#include <internal/xyarray.h>
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#include "util/debug.h"
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#include "util/evsel.h"
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#include "util/bpf-filter.h"
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#include "util/bpf-filter-flex.h"
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#include "util/bpf-filter-bison.h"
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#include "bpf_skel/sample-filter.h"
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#include "bpf_skel/sample_filter.skel.h"
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#define FD(e, x, y) (*(int *)xyarray__entry(e->core.fd, x, y))
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#define __PERF_SAMPLE_TYPE(st, opt) { st, #st, opt }
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#define PERF_SAMPLE_TYPE(_st, opt) __PERF_SAMPLE_TYPE(PERF_SAMPLE_##_st, opt)
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static const struct perf_sample_info {
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u64 type;
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const char *name;
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const char *option;
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} sample_table[] = {
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/* default sample flags */
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PERF_SAMPLE_TYPE(IP, NULL),
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PERF_SAMPLE_TYPE(TID, NULL),
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PERF_SAMPLE_TYPE(PERIOD, NULL),
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/* flags mostly set by default, but still have options */
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PERF_SAMPLE_TYPE(ID, "--sample-identifier"),
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PERF_SAMPLE_TYPE(CPU, "--sample-cpu"),
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PERF_SAMPLE_TYPE(TIME, "-T"),
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/* optional sample flags */
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PERF_SAMPLE_TYPE(ADDR, "-d"),
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PERF_SAMPLE_TYPE(DATA_SRC, "-d"),
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PERF_SAMPLE_TYPE(PHYS_ADDR, "--phys-data"),
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PERF_SAMPLE_TYPE(WEIGHT, "-W"),
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PERF_SAMPLE_TYPE(WEIGHT_STRUCT, "-W"),
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PERF_SAMPLE_TYPE(TRANSACTION, "--transaction"),
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PERF_SAMPLE_TYPE(CODE_PAGE_SIZE, "--code-page-size"),
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PERF_SAMPLE_TYPE(DATA_PAGE_SIZE, "--data-page-size"),
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};
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static const struct perf_sample_info *get_sample_info(u64 flags)
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{
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size_t i;
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for (i = 0; i < ARRAY_SIZE(sample_table); i++) {
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if (sample_table[i].type == flags)
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return &sample_table[i];
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}
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return NULL;
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}
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static int check_sample_flags(struct evsel *evsel, struct perf_bpf_filter_expr *expr)
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{
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const struct perf_sample_info *info;
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if (evsel->core.attr.sample_type & expr->sample_flags)
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return 0;
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info = get_sample_info(expr->sample_flags);
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if (info == NULL) {
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pr_err("Error: %s event does not have sample flags %lx\n",
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evsel__name(evsel), expr->sample_flags);
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return -1;
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}
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pr_err("Error: %s event does not have %s\n", evsel__name(evsel), info->name);
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if (info->option)
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pr_err(" Hint: please add %s option to perf record\n", info->option);
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return -1;
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}
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int perf_bpf_filter__prepare(struct evsel *evsel)
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{
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int i, x, y, fd;
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struct sample_filter_bpf *skel;
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struct bpf_program *prog;
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struct bpf_link *link;
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struct perf_bpf_filter_expr *expr;
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skel = sample_filter_bpf__open_and_load();
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if (!skel) {
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pr_err("Failed to load perf sample-filter BPF skeleton\n");
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return -1;
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}
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i = 0;
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fd = bpf_map__fd(skel->maps.filters);
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list_for_each_entry(expr, &evsel->bpf_filters, list) {
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struct perf_bpf_filter_entry entry = {
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.op = expr->op,
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.part = expr->part,
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.flags = expr->sample_flags,
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.value = expr->val,
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};
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if (check_sample_flags(evsel, expr) < 0)
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return -1;
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bpf_map_update_elem(fd, &i, &entry, BPF_ANY);
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i++;
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if (expr->op == PBF_OP_GROUP_BEGIN) {
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struct perf_bpf_filter_expr *group;
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list_for_each_entry(group, &expr->groups, list) {
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struct perf_bpf_filter_entry group_entry = {
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.op = group->op,
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.part = group->part,
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.flags = group->sample_flags,
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.value = group->val,
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};
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bpf_map_update_elem(fd, &i, &group_entry, BPF_ANY);
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i++;
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}
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memset(&entry, 0, sizeof(entry));
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entry.op = PBF_OP_GROUP_END;
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bpf_map_update_elem(fd, &i, &entry, BPF_ANY);
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i++;
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}
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}
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if (i > MAX_FILTERS) {
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pr_err("Too many filters: %d (max = %d)\n", i, MAX_FILTERS);
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return -1;
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}
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prog = skel->progs.perf_sample_filter;
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for (x = 0; x < xyarray__max_x(evsel->core.fd); x++) {
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for (y = 0; y < xyarray__max_y(evsel->core.fd); y++) {
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link = bpf_program__attach_perf_event(prog, FD(evsel, x, y));
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if (IS_ERR(link)) {
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pr_err("Failed to attach perf sample-filter program\n");
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return PTR_ERR(link);
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}
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}
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}
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evsel->bpf_skel = skel;
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return 0;
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}
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int perf_bpf_filter__destroy(struct evsel *evsel)
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{
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struct perf_bpf_filter_expr *expr, *tmp;
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list_for_each_entry_safe(expr, tmp, &evsel->bpf_filters, list) {
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list_del(&expr->list);
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free(expr);
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}
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sample_filter_bpf__destroy(evsel->bpf_skel);
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return 0;
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}
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u64 perf_bpf_filter__lost_count(struct evsel *evsel)
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{
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struct sample_filter_bpf *skel = evsel->bpf_skel;
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return skel ? skel->bss->dropped : 0;
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}
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struct perf_bpf_filter_expr *perf_bpf_filter_expr__new(unsigned long sample_flags, int part,
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enum perf_bpf_filter_op op,
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unsigned long val)
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{
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struct perf_bpf_filter_expr *expr;
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expr = malloc(sizeof(*expr));
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if (expr != NULL) {
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expr->sample_flags = sample_flags;
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expr->part = part;
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expr->op = op;
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expr->val = val;
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INIT_LIST_HEAD(&expr->groups);
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}
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return expr;
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}
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int perf_bpf_filter__parse(struct list_head *expr_head, const char *str)
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{
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YY_BUFFER_STATE buffer;
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int ret;
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buffer = perf_bpf_filter__scan_string(str);
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ret = perf_bpf_filter_parse(expr_head);
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perf_bpf_filter__flush_buffer(buffer);
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perf_bpf_filter__delete_buffer(buffer);
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perf_bpf_filter_lex_destroy();
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return ret;
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}
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