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![Ian Rogers](/assets/img/avatar_default.png)
If bperf (perf tools that use BPF skels) sets evsel->leader_skel or evsel->follower_skel then it appears that evsel->bpf_skel is set and can trigger the following use-after-free: ==13575==ERROR: AddressSanitizer: heap-use-after-free on address 0x60c000014080 at pc 0x55684b939880 bp 0x7ffdfcf30d70 sp 0x7ffdfcf30d68 READ of size 8 at 0x60c000014080 thread T0 #0 0x55684b93987f in sample_filter_bpf__destroy tools/perf/bpf_skel/sample_filter.skel.h:44:11 #1 0x55684b93987f in perf_bpf_filter__destroy tools/perf/util/bpf-filter.c:155:2 #2 0x55684b98f71e in evsel__exit tools/perf/util/evsel.c:1521:2 #3 0x55684b98a352 in evsel__delete tools/perf/util/evsel.c:1547:2 #4 0x55684b981918 in evlist__purge tools/perf/util/evlist.c:148:3 #5 0x55684b981918 in evlist__delete tools/perf/util/evlist.c:169:2 #6 0x55684b887d60 in cmd_stat tools/perf/builtin-stat.c:2598:2 .. 0x60c000014080 is located 0 bytes inside of 128-byte region [0x60c000014080,0x60c000014100) freed by thread T0 here: #0 0x55684b780e86 in free compiler-rt/lib/asan/asan_malloc_linux.cpp:52:3 #1 0x55684b9462da in bperf_cgroup_bpf__destroy tools/perf/bpf_skel/bperf_cgroup.skel.h:61:2 #2 0x55684b9462da in bperf_cgrp__destroy tools/perf/util/bpf_counter_cgroup.c:282:2 #3 0x55684b944c75 in bpf_counter__destroy tools/perf/util/bpf_counter.c:819:2 #4 0x55684b98f716 in evsel__exit tools/perf/util/evsel.c:1520:2 #5 0x55684b98a352 in evsel__delete tools/perf/util/evsel.c:1547:2 #6 0x55684b981918 in evlist__purge tools/perf/util/evlist.c:148:3 #7 0x55684b981918 in evlist__delete tools/perf/util/evlist.c:169:2 #8 0x55684b887d60 in cmd_stat tools/perf/builtin-stat.c:2598:2 ... previously allocated by thread T0 here: #0 0x55684b781338 in calloc compiler-rt/lib/asan/asan_malloc_linux.cpp:77:3 #1 0x55684b944e25 in bperf_cgroup_bpf__open_opts tools/perf/bpf_skel/bperf_cgroup.skel.h:73:35 #2 0x55684b944e25 in bperf_cgroup_bpf__open tools/perf/bpf_skel/bperf_cgroup.skel.h:97:9 #3 0x55684b944e25 in bperf_load_program tools/perf/util/bpf_counter_cgroup.c:55:9 #4 0x55684b944e25 in bperf_cgrp__load tools/perf/util/bpf_counter_cgroup.c:178:23 #5 0x55684b889289 in __run_perf_stat tools/perf/builtin-stat.c:713:7 #6 0x55684b889289 in run_perf_stat tools/perf/builtin-stat.c:949:8 #7 0x55684b888029 in cmd_stat tools/perf/builtin-stat.c:2537:12 Resolve by clearing 'evsel->bpf_skel' as part of bpf_counter__destroy(). Suggested-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: bpf@vger.kernel.org Link: http://lore.kernel.org/lkml/20230411051718.267228-1-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
819 lines
22 KiB
C
819 lines
22 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2019 Facebook */
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#include <assert.h>
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#include <limits.h>
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#include <unistd.h>
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#include <sys/file.h>
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#include <sys/time.h>
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#include <linux/err.h>
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#include <linux/zalloc.h>
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#include <api/fs/fs.h>
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#include <perf/bpf_perf.h>
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#include "bpf_counter.h"
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#include "bpf-utils.h"
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#include "counts.h"
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#include "debug.h"
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#include "evsel.h"
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#include "evlist.h"
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#include "target.h"
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#include "cgroup.h"
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#include "cpumap.h"
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#include "thread_map.h"
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#include "bpf_skel/bpf_prog_profiler.skel.h"
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#include "bpf_skel/bperf_u.h"
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#include "bpf_skel/bperf_leader.skel.h"
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#include "bpf_skel/bperf_follower.skel.h"
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#define ATTR_MAP_SIZE 16
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static inline void *u64_to_ptr(__u64 ptr)
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{
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return (void *)(unsigned long)ptr;
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}
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static struct bpf_counter *bpf_counter_alloc(void)
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{
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struct bpf_counter *counter;
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counter = zalloc(sizeof(*counter));
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if (counter)
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INIT_LIST_HEAD(&counter->list);
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return counter;
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}
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static int bpf_program_profiler__destroy(struct evsel *evsel)
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{
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struct bpf_counter *counter, *tmp;
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list_for_each_entry_safe(counter, tmp,
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&evsel->bpf_counter_list, list) {
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list_del_init(&counter->list);
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bpf_prog_profiler_bpf__destroy(counter->skel);
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free(counter);
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}
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assert(list_empty(&evsel->bpf_counter_list));
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return 0;
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}
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static char *bpf_target_prog_name(int tgt_fd)
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{
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struct bpf_func_info *func_info;
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struct perf_bpil *info_linear;
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const struct btf_type *t;
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struct btf *btf = NULL;
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char *name = NULL;
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info_linear = get_bpf_prog_info_linear(tgt_fd, 1UL << PERF_BPIL_FUNC_INFO);
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if (IS_ERR_OR_NULL(info_linear)) {
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pr_debug("failed to get info_linear for prog FD %d\n", tgt_fd);
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return NULL;
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}
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if (info_linear->info.btf_id == 0) {
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pr_debug("prog FD %d doesn't have valid btf\n", tgt_fd);
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goto out;
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}
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btf = btf__load_from_kernel_by_id(info_linear->info.btf_id);
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if (libbpf_get_error(btf)) {
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pr_debug("failed to load btf for prog FD %d\n", tgt_fd);
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goto out;
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}
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func_info = u64_to_ptr(info_linear->info.func_info);
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t = btf__type_by_id(btf, func_info[0].type_id);
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if (!t) {
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pr_debug("btf %d doesn't have type %d\n",
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info_linear->info.btf_id, func_info[0].type_id);
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goto out;
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}
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name = strdup(btf__name_by_offset(btf, t->name_off));
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out:
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btf__free(btf);
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free(info_linear);
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return name;
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}
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static int bpf_program_profiler_load_one(struct evsel *evsel, u32 prog_id)
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{
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struct bpf_prog_profiler_bpf *skel;
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struct bpf_counter *counter;
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struct bpf_program *prog;
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char *prog_name;
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int prog_fd;
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int err;
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prog_fd = bpf_prog_get_fd_by_id(prog_id);
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if (prog_fd < 0) {
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pr_err("Failed to open fd for bpf prog %u\n", prog_id);
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return -1;
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}
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counter = bpf_counter_alloc();
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if (!counter) {
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close(prog_fd);
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return -1;
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}
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skel = bpf_prog_profiler_bpf__open();
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if (!skel) {
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pr_err("Failed to open bpf skeleton\n");
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goto err_out;
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}
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skel->rodata->num_cpu = evsel__nr_cpus(evsel);
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bpf_map__set_max_entries(skel->maps.events, evsel__nr_cpus(evsel));
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bpf_map__set_max_entries(skel->maps.fentry_readings, 1);
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bpf_map__set_max_entries(skel->maps.accum_readings, 1);
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prog_name = bpf_target_prog_name(prog_fd);
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if (!prog_name) {
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pr_err("Failed to get program name for bpf prog %u. Does it have BTF?\n", prog_id);
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goto err_out;
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}
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bpf_object__for_each_program(prog, skel->obj) {
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err = bpf_program__set_attach_target(prog, prog_fd, prog_name);
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if (err) {
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pr_err("bpf_program__set_attach_target failed.\n"
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"Does bpf prog %u have BTF?\n", prog_id);
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goto err_out;
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}
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}
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set_max_rlimit();
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err = bpf_prog_profiler_bpf__load(skel);
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if (err) {
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pr_err("bpf_prog_profiler_bpf__load failed\n");
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goto err_out;
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}
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assert(skel != NULL);
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counter->skel = skel;
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list_add(&counter->list, &evsel->bpf_counter_list);
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close(prog_fd);
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return 0;
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err_out:
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bpf_prog_profiler_bpf__destroy(skel);
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free(counter);
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close(prog_fd);
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return -1;
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}
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static int bpf_program_profiler__load(struct evsel *evsel, struct target *target)
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{
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char *bpf_str, *bpf_str_, *tok, *saveptr = NULL, *p;
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u32 prog_id;
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int ret;
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bpf_str_ = bpf_str = strdup(target->bpf_str);
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if (!bpf_str)
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return -1;
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while ((tok = strtok_r(bpf_str, ",", &saveptr)) != NULL) {
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prog_id = strtoul(tok, &p, 10);
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if (prog_id == 0 || prog_id == UINT_MAX ||
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(*p != '\0' && *p != ',')) {
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pr_err("Failed to parse bpf prog ids %s\n",
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target->bpf_str);
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return -1;
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}
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ret = bpf_program_profiler_load_one(evsel, prog_id);
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if (ret) {
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bpf_program_profiler__destroy(evsel);
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free(bpf_str_);
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return -1;
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}
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bpf_str = NULL;
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}
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free(bpf_str_);
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return 0;
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}
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static int bpf_program_profiler__enable(struct evsel *evsel)
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{
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struct bpf_counter *counter;
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int ret;
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list_for_each_entry(counter, &evsel->bpf_counter_list, list) {
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assert(counter->skel != NULL);
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ret = bpf_prog_profiler_bpf__attach(counter->skel);
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if (ret) {
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bpf_program_profiler__destroy(evsel);
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return ret;
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}
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}
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return 0;
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}
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static int bpf_program_profiler__disable(struct evsel *evsel)
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{
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struct bpf_counter *counter;
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list_for_each_entry(counter, &evsel->bpf_counter_list, list) {
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assert(counter->skel != NULL);
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bpf_prog_profiler_bpf__detach(counter->skel);
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}
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return 0;
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}
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static int bpf_program_profiler__read(struct evsel *evsel)
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{
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// BPF_MAP_TYPE_PERCPU_ARRAY uses /sys/devices/system/cpu/possible
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// Sometimes possible > online, like on a Ryzen 3900X that has 24
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// threads but its possible showed 0-31 -acme
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int num_cpu_bpf = libbpf_num_possible_cpus();
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struct bpf_perf_event_value values[num_cpu_bpf];
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struct bpf_counter *counter;
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struct perf_counts_values *counts;
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int reading_map_fd;
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__u32 key = 0;
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int err, idx, bpf_cpu;
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if (list_empty(&evsel->bpf_counter_list))
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return -EAGAIN;
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perf_cpu_map__for_each_idx(idx, evsel__cpus(evsel)) {
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counts = perf_counts(evsel->counts, idx, 0);
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counts->val = 0;
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counts->ena = 0;
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counts->run = 0;
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}
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list_for_each_entry(counter, &evsel->bpf_counter_list, list) {
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struct bpf_prog_profiler_bpf *skel = counter->skel;
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assert(skel != NULL);
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reading_map_fd = bpf_map__fd(skel->maps.accum_readings);
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err = bpf_map_lookup_elem(reading_map_fd, &key, values);
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if (err) {
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pr_err("failed to read value\n");
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return err;
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}
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for (bpf_cpu = 0; bpf_cpu < num_cpu_bpf; bpf_cpu++) {
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idx = perf_cpu_map__idx(evsel__cpus(evsel),
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(struct perf_cpu){.cpu = bpf_cpu});
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if (idx == -1)
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continue;
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counts = perf_counts(evsel->counts, idx, 0);
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counts->val += values[bpf_cpu].counter;
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counts->ena += values[bpf_cpu].enabled;
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counts->run += values[bpf_cpu].running;
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}
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}
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return 0;
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}
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static int bpf_program_profiler__install_pe(struct evsel *evsel, int cpu_map_idx,
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int fd)
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{
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struct bpf_prog_profiler_bpf *skel;
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struct bpf_counter *counter;
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int ret;
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list_for_each_entry(counter, &evsel->bpf_counter_list, list) {
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skel = counter->skel;
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assert(skel != NULL);
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ret = bpf_map_update_elem(bpf_map__fd(skel->maps.events),
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&cpu_map_idx, &fd, BPF_ANY);
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if (ret)
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return ret;
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}
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return 0;
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}
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struct bpf_counter_ops bpf_program_profiler_ops = {
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.load = bpf_program_profiler__load,
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.enable = bpf_program_profiler__enable,
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.disable = bpf_program_profiler__disable,
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.read = bpf_program_profiler__read,
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.destroy = bpf_program_profiler__destroy,
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.install_pe = bpf_program_profiler__install_pe,
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};
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static bool bperf_attr_map_compatible(int attr_map_fd)
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{
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struct bpf_map_info map_info = {0};
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__u32 map_info_len = sizeof(map_info);
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int err;
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err = bpf_obj_get_info_by_fd(attr_map_fd, &map_info, &map_info_len);
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if (err)
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return false;
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return (map_info.key_size == sizeof(struct perf_event_attr)) &&
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(map_info.value_size == sizeof(struct perf_event_attr_map_entry));
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}
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static int bperf_lock_attr_map(struct target *target)
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{
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char path[PATH_MAX];
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int map_fd, err;
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if (target->attr_map) {
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scnprintf(path, PATH_MAX, "%s", target->attr_map);
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} else {
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scnprintf(path, PATH_MAX, "%s/fs/bpf/%s", sysfs__mountpoint(),
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BPF_PERF_DEFAULT_ATTR_MAP_PATH);
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}
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if (access(path, F_OK)) {
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map_fd = bpf_map_create(BPF_MAP_TYPE_HASH, NULL,
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sizeof(struct perf_event_attr),
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sizeof(struct perf_event_attr_map_entry),
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ATTR_MAP_SIZE, NULL);
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if (map_fd < 0)
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return -1;
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err = bpf_obj_pin(map_fd, path);
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if (err) {
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/* someone pinned the map in parallel? */
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close(map_fd);
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map_fd = bpf_obj_get(path);
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if (map_fd < 0)
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return -1;
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}
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} else {
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map_fd = bpf_obj_get(path);
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if (map_fd < 0)
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return -1;
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}
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if (!bperf_attr_map_compatible(map_fd)) {
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close(map_fd);
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return -1;
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}
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err = flock(map_fd, LOCK_EX);
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if (err) {
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close(map_fd);
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return -1;
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}
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return map_fd;
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}
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static int bperf_check_target(struct evsel *evsel,
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struct target *target,
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enum bperf_filter_type *filter_type,
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__u32 *filter_entry_cnt)
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{
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if (evsel->core.leader->nr_members > 1) {
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pr_err("bpf managed perf events do not yet support groups.\n");
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return -1;
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}
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/* determine filter type based on target */
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if (target->system_wide) {
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*filter_type = BPERF_FILTER_GLOBAL;
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*filter_entry_cnt = 1;
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} else if (target->cpu_list) {
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*filter_type = BPERF_FILTER_CPU;
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*filter_entry_cnt = perf_cpu_map__nr(evsel__cpus(evsel));
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} else if (target->tid) {
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*filter_type = BPERF_FILTER_PID;
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*filter_entry_cnt = perf_thread_map__nr(evsel->core.threads);
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} else if (target->pid || evsel->evlist->workload.pid != -1) {
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*filter_type = BPERF_FILTER_TGID;
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*filter_entry_cnt = perf_thread_map__nr(evsel->core.threads);
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} else {
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pr_err("bpf managed perf events do not yet support these targets.\n");
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return -1;
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}
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return 0;
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}
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static struct perf_cpu_map *all_cpu_map;
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static int bperf_reload_leader_program(struct evsel *evsel, int attr_map_fd,
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struct perf_event_attr_map_entry *entry)
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{
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struct bperf_leader_bpf *skel = bperf_leader_bpf__open();
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int link_fd, diff_map_fd, err;
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struct bpf_link *link = NULL;
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if (!skel) {
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pr_err("Failed to open leader skeleton\n");
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return -1;
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}
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bpf_map__set_max_entries(skel->maps.events, libbpf_num_possible_cpus());
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err = bperf_leader_bpf__load(skel);
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if (err) {
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pr_err("Failed to load leader skeleton\n");
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goto out;
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}
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link = bpf_program__attach(skel->progs.on_switch);
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if (IS_ERR(link)) {
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pr_err("Failed to attach leader program\n");
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err = PTR_ERR(link);
|
|
goto out;
|
|
}
|
|
|
|
link_fd = bpf_link__fd(link);
|
|
diff_map_fd = bpf_map__fd(skel->maps.diff_readings);
|
|
entry->link_id = bpf_link_get_id(link_fd);
|
|
entry->diff_map_id = bpf_map_get_id(diff_map_fd);
|
|
err = bpf_map_update_elem(attr_map_fd, &evsel->core.attr, entry, BPF_ANY);
|
|
assert(err == 0);
|
|
|
|
evsel->bperf_leader_link_fd = bpf_link_get_fd_by_id(entry->link_id);
|
|
assert(evsel->bperf_leader_link_fd >= 0);
|
|
|
|
/*
|
|
* save leader_skel for install_pe, which is called within
|
|
* following evsel__open_per_cpu call
|
|
*/
|
|
evsel->leader_skel = skel;
|
|
evsel__open_per_cpu(evsel, all_cpu_map, -1);
|
|
|
|
out:
|
|
bperf_leader_bpf__destroy(skel);
|
|
bpf_link__destroy(link);
|
|
return err;
|
|
}
|
|
|
|
static int bperf__load(struct evsel *evsel, struct target *target)
|
|
{
|
|
struct perf_event_attr_map_entry entry = {0xffffffff, 0xffffffff};
|
|
int attr_map_fd, diff_map_fd = -1, err;
|
|
enum bperf_filter_type filter_type;
|
|
__u32 filter_entry_cnt, i;
|
|
|
|
if (bperf_check_target(evsel, target, &filter_type, &filter_entry_cnt))
|
|
return -1;
|
|
|
|
if (!all_cpu_map) {
|
|
all_cpu_map = perf_cpu_map__new(NULL);
|
|
if (!all_cpu_map)
|
|
return -1;
|
|
}
|
|
|
|
evsel->bperf_leader_prog_fd = -1;
|
|
evsel->bperf_leader_link_fd = -1;
|
|
|
|
/*
|
|
* Step 1: hold a fd on the leader program and the bpf_link, if
|
|
* the program is not already gone, reload the program.
|
|
* Use flock() to ensure exclusive access to the perf_event_attr
|
|
* map.
|
|
*/
|
|
attr_map_fd = bperf_lock_attr_map(target);
|
|
if (attr_map_fd < 0) {
|
|
pr_err("Failed to lock perf_event_attr map\n");
|
|
return -1;
|
|
}
|
|
|
|
err = bpf_map_lookup_elem(attr_map_fd, &evsel->core.attr, &entry);
|
|
if (err) {
|
|
err = bpf_map_update_elem(attr_map_fd, &evsel->core.attr, &entry, BPF_ANY);
|
|
if (err)
|
|
goto out;
|
|
}
|
|
|
|
evsel->bperf_leader_link_fd = bpf_link_get_fd_by_id(entry.link_id);
|
|
if (evsel->bperf_leader_link_fd < 0 &&
|
|
bperf_reload_leader_program(evsel, attr_map_fd, &entry)) {
|
|
err = -1;
|
|
goto out;
|
|
}
|
|
/*
|
|
* The bpf_link holds reference to the leader program, and the
|
|
* leader program holds reference to the maps. Therefore, if
|
|
* link_id is valid, diff_map_id should also be valid.
|
|
*/
|
|
evsel->bperf_leader_prog_fd = bpf_prog_get_fd_by_id(
|
|
bpf_link_get_prog_id(evsel->bperf_leader_link_fd));
|
|
assert(evsel->bperf_leader_prog_fd >= 0);
|
|
|
|
diff_map_fd = bpf_map_get_fd_by_id(entry.diff_map_id);
|
|
assert(diff_map_fd >= 0);
|
|
|
|
/*
|
|
* bperf uses BPF_PROG_TEST_RUN to get accurate reading. Check
|
|
* whether the kernel support it
|
|
*/
|
|
err = bperf_trigger_reading(evsel->bperf_leader_prog_fd, 0);
|
|
if (err) {
|
|
pr_err("The kernel does not support test_run for raw_tp BPF programs.\n"
|
|
"Therefore, --use-bpf might show inaccurate readings\n");
|
|
goto out;
|
|
}
|
|
|
|
/* Step 2: load the follower skeleton */
|
|
evsel->follower_skel = bperf_follower_bpf__open();
|
|
if (!evsel->follower_skel) {
|
|
err = -1;
|
|
pr_err("Failed to open follower skeleton\n");
|
|
goto out;
|
|
}
|
|
|
|
/* attach fexit program to the leader program */
|
|
bpf_program__set_attach_target(evsel->follower_skel->progs.fexit_XXX,
|
|
evsel->bperf_leader_prog_fd, "on_switch");
|
|
|
|
/* connect to leader diff_reading map */
|
|
bpf_map__reuse_fd(evsel->follower_skel->maps.diff_readings, diff_map_fd);
|
|
|
|
/* set up reading map */
|
|
bpf_map__set_max_entries(evsel->follower_skel->maps.accum_readings,
|
|
filter_entry_cnt);
|
|
/* set up follower filter based on target */
|
|
bpf_map__set_max_entries(evsel->follower_skel->maps.filter,
|
|
filter_entry_cnt);
|
|
err = bperf_follower_bpf__load(evsel->follower_skel);
|
|
if (err) {
|
|
pr_err("Failed to load follower skeleton\n");
|
|
bperf_follower_bpf__destroy(evsel->follower_skel);
|
|
evsel->follower_skel = NULL;
|
|
goto out;
|
|
}
|
|
|
|
for (i = 0; i < filter_entry_cnt; i++) {
|
|
int filter_map_fd;
|
|
__u32 key;
|
|
|
|
if (filter_type == BPERF_FILTER_PID ||
|
|
filter_type == BPERF_FILTER_TGID)
|
|
key = perf_thread_map__pid(evsel->core.threads, i);
|
|
else if (filter_type == BPERF_FILTER_CPU)
|
|
key = perf_cpu_map__cpu(evsel->core.cpus, i).cpu;
|
|
else
|
|
break;
|
|
|
|
filter_map_fd = bpf_map__fd(evsel->follower_skel->maps.filter);
|
|
bpf_map_update_elem(filter_map_fd, &key, &i, BPF_ANY);
|
|
}
|
|
|
|
evsel->follower_skel->bss->type = filter_type;
|
|
|
|
err = bperf_follower_bpf__attach(evsel->follower_skel);
|
|
|
|
out:
|
|
if (err && evsel->bperf_leader_link_fd >= 0)
|
|
close(evsel->bperf_leader_link_fd);
|
|
if (err && evsel->bperf_leader_prog_fd >= 0)
|
|
close(evsel->bperf_leader_prog_fd);
|
|
if (diff_map_fd >= 0)
|
|
close(diff_map_fd);
|
|
|
|
flock(attr_map_fd, LOCK_UN);
|
|
close(attr_map_fd);
|
|
|
|
return err;
|
|
}
|
|
|
|
static int bperf__install_pe(struct evsel *evsel, int cpu_map_idx, int fd)
|
|
{
|
|
struct bperf_leader_bpf *skel = evsel->leader_skel;
|
|
|
|
return bpf_map_update_elem(bpf_map__fd(skel->maps.events),
|
|
&cpu_map_idx, &fd, BPF_ANY);
|
|
}
|
|
|
|
/*
|
|
* trigger the leader prog on each cpu, so the accum_reading map could get
|
|
* the latest readings.
|
|
*/
|
|
static int bperf_sync_counters(struct evsel *evsel)
|
|
{
|
|
int num_cpu, i, cpu;
|
|
|
|
num_cpu = perf_cpu_map__nr(all_cpu_map);
|
|
for (i = 0; i < num_cpu; i++) {
|
|
cpu = perf_cpu_map__cpu(all_cpu_map, i).cpu;
|
|
bperf_trigger_reading(evsel->bperf_leader_prog_fd, cpu);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int bperf__enable(struct evsel *evsel)
|
|
{
|
|
evsel->follower_skel->bss->enabled = 1;
|
|
return 0;
|
|
}
|
|
|
|
static int bperf__disable(struct evsel *evsel)
|
|
{
|
|
evsel->follower_skel->bss->enabled = 0;
|
|
return 0;
|
|
}
|
|
|
|
static int bperf__read(struct evsel *evsel)
|
|
{
|
|
struct bperf_follower_bpf *skel = evsel->follower_skel;
|
|
__u32 num_cpu_bpf = cpu__max_cpu().cpu;
|
|
struct bpf_perf_event_value values[num_cpu_bpf];
|
|
struct perf_counts_values *counts;
|
|
int reading_map_fd, err = 0;
|
|
__u32 i;
|
|
int j;
|
|
|
|
bperf_sync_counters(evsel);
|
|
reading_map_fd = bpf_map__fd(skel->maps.accum_readings);
|
|
|
|
for (i = 0; i < bpf_map__max_entries(skel->maps.accum_readings); i++) {
|
|
struct perf_cpu entry;
|
|
__u32 cpu;
|
|
|
|
err = bpf_map_lookup_elem(reading_map_fd, &i, values);
|
|
if (err)
|
|
goto out;
|
|
switch (evsel->follower_skel->bss->type) {
|
|
case BPERF_FILTER_GLOBAL:
|
|
assert(i == 0);
|
|
|
|
perf_cpu_map__for_each_cpu(entry, j, evsel__cpus(evsel)) {
|
|
counts = perf_counts(evsel->counts, j, 0);
|
|
counts->val = values[entry.cpu].counter;
|
|
counts->ena = values[entry.cpu].enabled;
|
|
counts->run = values[entry.cpu].running;
|
|
}
|
|
break;
|
|
case BPERF_FILTER_CPU:
|
|
cpu = perf_cpu_map__cpu(evsel__cpus(evsel), i).cpu;
|
|
assert(cpu >= 0);
|
|
counts = perf_counts(evsel->counts, i, 0);
|
|
counts->val = values[cpu].counter;
|
|
counts->ena = values[cpu].enabled;
|
|
counts->run = values[cpu].running;
|
|
break;
|
|
case BPERF_FILTER_PID:
|
|
case BPERF_FILTER_TGID:
|
|
counts = perf_counts(evsel->counts, 0, i);
|
|
counts->val = 0;
|
|
counts->ena = 0;
|
|
counts->run = 0;
|
|
|
|
for (cpu = 0; cpu < num_cpu_bpf; cpu++) {
|
|
counts->val += values[cpu].counter;
|
|
counts->ena += values[cpu].enabled;
|
|
counts->run += values[cpu].running;
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
static int bperf__destroy(struct evsel *evsel)
|
|
{
|
|
bperf_follower_bpf__destroy(evsel->follower_skel);
|
|
close(evsel->bperf_leader_prog_fd);
|
|
close(evsel->bperf_leader_link_fd);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* bperf: share hardware PMCs with BPF
|
|
*
|
|
* perf uses performance monitoring counters (PMC) to monitor system
|
|
* performance. The PMCs are limited hardware resources. For example,
|
|
* Intel CPUs have 3x fixed PMCs and 4x programmable PMCs per cpu.
|
|
*
|
|
* Modern data center systems use these PMCs in many different ways:
|
|
* system level monitoring, (maybe nested) container level monitoring, per
|
|
* process monitoring, profiling (in sample mode), etc. In some cases,
|
|
* there are more active perf_events than available hardware PMCs. To allow
|
|
* all perf_events to have a chance to run, it is necessary to do expensive
|
|
* time multiplexing of events.
|
|
*
|
|
* On the other hand, many monitoring tools count the common metrics
|
|
* (cycles, instructions). It is a waste to have multiple tools create
|
|
* multiple perf_events of "cycles" and occupy multiple PMCs.
|
|
*
|
|
* bperf tries to reduce such wastes by allowing multiple perf_events of
|
|
* "cycles" or "instructions" (at different scopes) to share PMUs. Instead
|
|
* of having each perf-stat session to read its own perf_events, bperf uses
|
|
* BPF programs to read the perf_events and aggregate readings to BPF maps.
|
|
* Then, the perf-stat session(s) reads the values from these BPF maps.
|
|
*
|
|
* ||
|
|
* shared progs and maps <- || -> per session progs and maps
|
|
* ||
|
|
* --------------- ||
|
|
* | perf_events | ||
|
|
* --------------- fexit || -----------------
|
|
* | --------||----> | follower prog |
|
|
* --------------- / || --- -----------------
|
|
* cs -> | leader prog |/ ||/ | |
|
|
* --> --------------- /|| -------------- ------------------
|
|
* / | | / || | filter map | | accum_readings |
|
|
* / ------------ ------------ || -------------- ------------------
|
|
* | | prev map | | diff map | || |
|
|
* | ------------ ------------ || |
|
|
* \ || |
|
|
* = \ ==================================================== | ============
|
|
* \ / user space
|
|
* \ /
|
|
* \ /
|
|
* BPF_PROG_TEST_RUN BPF_MAP_LOOKUP_ELEM
|
|
* \ /
|
|
* \ /
|
|
* \------ perf-stat ----------------------/
|
|
*
|
|
* The figure above shows the architecture of bperf. Note that the figure
|
|
* is divided into 3 regions: shared progs and maps (top left), per session
|
|
* progs and maps (top right), and user space (bottom).
|
|
*
|
|
* The leader prog is triggered on each context switch (cs). The leader
|
|
* prog reads perf_events and stores the difference (current_reading -
|
|
* previous_reading) to the diff map. For the same metric, e.g. "cycles",
|
|
* multiple perf-stat sessions share the same leader prog.
|
|
*
|
|
* Each perf-stat session creates a follower prog as fexit program to the
|
|
* leader prog. It is possible to attach up to BPF_MAX_TRAMP_PROGS (38)
|
|
* follower progs to the same leader prog. The follower prog checks current
|
|
* task and processor ID to decide whether to add the value from the diff
|
|
* map to its accumulated reading map (accum_readings).
|
|
*
|
|
* Finally, perf-stat user space reads the value from accum_reading map.
|
|
*
|
|
* Besides context switch, it is also necessary to trigger the leader prog
|
|
* before perf-stat reads the value. Otherwise, the accum_reading map may
|
|
* not have the latest reading from the perf_events. This is achieved by
|
|
* triggering the event via sys_bpf(BPF_PROG_TEST_RUN) to each CPU.
|
|
*
|
|
* Comment before the definition of struct perf_event_attr_map_entry
|
|
* describes how different sessions of perf-stat share information about
|
|
* the leader prog.
|
|
*/
|
|
|
|
struct bpf_counter_ops bperf_ops = {
|
|
.load = bperf__load,
|
|
.enable = bperf__enable,
|
|
.disable = bperf__disable,
|
|
.read = bperf__read,
|
|
.install_pe = bperf__install_pe,
|
|
.destroy = bperf__destroy,
|
|
};
|
|
|
|
extern struct bpf_counter_ops bperf_cgrp_ops;
|
|
|
|
static inline bool bpf_counter_skip(struct evsel *evsel)
|
|
{
|
|
return evsel->bpf_counter_ops == NULL;
|
|
}
|
|
|
|
int bpf_counter__install_pe(struct evsel *evsel, int cpu_map_idx, int fd)
|
|
{
|
|
if (bpf_counter_skip(evsel))
|
|
return 0;
|
|
return evsel->bpf_counter_ops->install_pe(evsel, cpu_map_idx, fd);
|
|
}
|
|
|
|
int bpf_counter__load(struct evsel *evsel, struct target *target)
|
|
{
|
|
if (target->bpf_str)
|
|
evsel->bpf_counter_ops = &bpf_program_profiler_ops;
|
|
else if (cgrp_event_expanded && target->use_bpf)
|
|
evsel->bpf_counter_ops = &bperf_cgrp_ops;
|
|
else if (target->use_bpf || evsel->bpf_counter ||
|
|
evsel__match_bpf_counter_events(evsel->name))
|
|
evsel->bpf_counter_ops = &bperf_ops;
|
|
|
|
if (evsel->bpf_counter_ops)
|
|
return evsel->bpf_counter_ops->load(evsel, target);
|
|
return 0;
|
|
}
|
|
|
|
int bpf_counter__enable(struct evsel *evsel)
|
|
{
|
|
if (bpf_counter_skip(evsel))
|
|
return 0;
|
|
return evsel->bpf_counter_ops->enable(evsel);
|
|
}
|
|
|
|
int bpf_counter__disable(struct evsel *evsel)
|
|
{
|
|
if (bpf_counter_skip(evsel))
|
|
return 0;
|
|
return evsel->bpf_counter_ops->disable(evsel);
|
|
}
|
|
|
|
int bpf_counter__read(struct evsel *evsel)
|
|
{
|
|
if (bpf_counter_skip(evsel))
|
|
return -EAGAIN;
|
|
return evsel->bpf_counter_ops->read(evsel);
|
|
}
|
|
|
|
void bpf_counter__destroy(struct evsel *evsel)
|
|
{
|
|
if (bpf_counter_skip(evsel))
|
|
return;
|
|
evsel->bpf_counter_ops->destroy(evsel);
|
|
evsel->bpf_counter_ops = NULL;
|
|
evsel->bpf_skel = NULL;
|
|
}
|