From patchwork Wed May 22 21:56:13 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namhyung Kim X-Patchwork-Id: 13671127 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 29E981474C0; Wed, 22 May 2024 21:56:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716414980; cv=none; b=bgkrr3HfTdTLT/LuYUEssQepiL4pJ2xnG4X0OXrqoYvMuWT0t8EX7k2RQFYATMrWTuQsGycNMJYUufdYmyzygtC5TeTfjTfLlOmbkv6+RKvF9Z0Xe6FOYzRP+NNVDCWJjvaffXxArEJk7j1eDuCD0hWzrat8rIzDK4LrTDz6Cms= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716414980; c=relaxed/simple; bh=yAYFbGmjGhvJIkcoRRf+aOEVh50XwtRzoVVUOUa9xeM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=T4aI2BL2XmcCGN2aLFNw8gfh3396Se3Gyd4YlcObsBaiol5V0tczfVJ2UCC/wP6IbrADPGtDJnMa6aqDQWrb9TYUdSDVrcVvIsOPKc3Asdbu7xnt5XMB2N9ocBXoBQ+JibPDMc9U7CDe/KvhN7MKwlpGIAbeKaxJNrPc45WLt6A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dWael7eS; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dWael7eS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48802C4AF17; Wed, 22 May 2024 21:56:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1716414979; bh=yAYFbGmjGhvJIkcoRRf+aOEVh50XwtRzoVVUOUa9xeM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dWael7eSgdCAGNUrNkqy7ZTtZUGQ1TzEfKCfNd3FRqQgXm5g/FioZrGyPJskQISXx VgRU8ptZuCFinHWGoydK6Nmo41sY7s0fOFxHY/SATq0h7YuDE+o8HGYqea76JviO3k DA94w0HBYlD3oQFFIST+pWKt/O5qA7kutjLl7QKYitInBGo1CM50W3XbIZOEAkzhW2 RWjg/9yx2hH1f5Jj2X1L7gZXvNB9Nzor3qeH3Z6Q5k/0sjKRk3eI7XJ74bQRODirPH 4HpoowlrElAlHIDFEw1CG+xy3lozWoO+yoTOEbqvjT05LNmDUpYsYhvwmtWKbQJmAj GudycpABegpHw== From: Namhyung Kim To: Arnaldo Carvalho de Melo , Ian Rogers , Kan Liang Cc: Jiri Olsa , Adrian Hunter , Peter Zijlstra , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org, KP Singh , Stephane Eranian , Song Liu , bpf@vger.kernel.org Subject: [PATCH 3/6] perf bpf-filter: Split per-task filter use case Date: Wed, 22 May 2024 14:56:13 -0700 Message-ID: <20240522215616.762195-4-namhyung@kernel.org> X-Mailer: git-send-email 2.45.1.288.g0e0cd299f1-goog In-Reply-To: <20240522215616.762195-1-namhyung@kernel.org> References: <20240522215616.762195-1-namhyung@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 If the target is a list of tasks, it can use a shared hash map for filter expressions. The key of the filter map is an integer index like in an array. A separate pid_hash map is added to get the index for the filter map using the tgid. For system-wide mode including per-cpu or per-user targets are handled by the single entry map like before. Signed-off-by: Namhyung Kim --- tools/perf/util/bpf-filter.c | 186 +++++++++++++++---- tools/perf/util/bpf_skel/sample-filter.h | 1 + tools/perf/util/bpf_skel/sample_filter.bpf.c | 23 ++- 3 files changed, 168 insertions(+), 42 deletions(-) diff --git a/tools/perf/util/bpf-filter.c b/tools/perf/util/bpf-filter.c index f43b9e61bf42..2187975189c9 100644 --- a/tools/perf/util/bpf-filter.c +++ b/tools/perf/util/bpf-filter.c @@ -3,10 +3,13 @@ #include #include +#include #include +#include #include "util/debug.h" #include "util/evsel.h" +#include "util/target.h" #include "util/bpf-filter.h" #include @@ -85,38 +88,17 @@ static int check_sample_flags(struct evsel *evsel, struct perf_bpf_filter_expr * return -1; } -int perf_bpf_filter__prepare(struct evsel *evsel, struct target *target __maybe_unused) +static int get_filter_entries(struct evsel *evsel, struct perf_bpf_filter_entry *entry) { - int i, x, y, fd, ret; - struct sample_filter_bpf *skel; - struct bpf_program *prog; - struct bpf_link *link; + int i = 0; struct perf_bpf_filter_expr *expr; - struct perf_bpf_filter_entry *entry; - - entry = calloc(MAX_FILTERS, sizeof(*entry)); - if (entry == NULL) - return -1; - - skel = sample_filter_bpf__open_and_load(); - if (!skel) { - pr_err("Failed to load perf sample-filter BPF skeleton\n"); - ret = -EPERM; - goto err; - } - i = 0; - fd = bpf_map__fd(skel->maps.filters); list_for_each_entry(expr, &evsel->bpf_filters, list) { - if (check_sample_flags(evsel, expr) < 0) { - ret = -EINVAL; - goto err; - } + if (check_sample_flags(evsel, expr) < 0) + return -EINVAL; - if (i == MAX_FILTERS) { - ret = -E2BIG; - goto err; - } + if (i == MAX_FILTERS) + return -E2BIG; entry[i].op = expr->op; entry[i].part = expr->part; @@ -128,10 +110,8 @@ int perf_bpf_filter__prepare(struct evsel *evsel, struct target *target __maybe_ struct perf_bpf_filter_expr *group; list_for_each_entry(group, &expr->groups, list) { - if (i == MAX_FILTERS) { - ret = -E2BIG; - goto err; - } + if (i == MAX_FILTERS) + return -E2BIG; entry[i].op = group->op; entry[i].part = group->part; @@ -140,10 +120,8 @@ int perf_bpf_filter__prepare(struct evsel *evsel, struct target *target __maybe_ i++; } - if (i == MAX_FILTERS) { - ret = -E2BIG; - goto err; - } + if (i == MAX_FILTERS) + return -E2BIG; entry[i].op = PBF_OP_GROUP_END; i++; @@ -155,15 +133,143 @@ int perf_bpf_filter__prepare(struct evsel *evsel, struct target *target __maybe_ entry[i].op = PBF_OP_DONE; i++; } + return 0; +} + +static int convert_to_tgid(int tid) +{ + char path[128]; + char *buf, *p, *q; + int tgid; + size_t len; + + scnprintf(path, sizeof(path), "%d/status", tid); + if (procfs__read_str(path, &buf, &len) < 0) + return -1; - /* The filters map has only one entry for now */ - i = 0; - if (bpf_map_update_elem(fd, &i, entry, BPF_ANY) < 0) { - ret = -errno; - pr_err("Failed to update the filter map\n"); + p = strstr(buf, "Tgid:"); + if (p == NULL) { + free(buf); + return -1; + } + + tgid = strtol(p + 6, &q, 0); + free(buf); + if (*q != '\n') + return -1; + + return tgid; +} + +static int update_pid_hash(struct sample_filter_bpf *skel, struct evsel *evsel, + struct perf_bpf_filter_entry *entry) +{ + int filter_idx; + int nr, last; + int fd = bpf_map__fd(skel->maps.filters); + struct perf_thread_map *threads; + + /* Find the first available entry in the filters map */ + for (filter_idx = 0; filter_idx < MAX_FILTERS; filter_idx++) { + if (bpf_map_update_elem(fd, &filter_idx, entry, BPF_NOEXIST) == 0) + break; + } + + if (filter_idx == MAX_FILTERS) { + pr_err("Too many users for the filter map\n"); + return -EBUSY; + } + + threads = perf_evsel__threads(&evsel->core); + if (threads == NULL) { + pr_err("Cannot get the thread list of the event\n"); + return -EINVAL; + } + + /* save the index to a hash map */ + fd = bpf_map__fd(skel->maps.pid_hash); + + last = -1; + nr = perf_thread_map__nr(threads); + for (int i = 0; i < nr; i++) { + int pid = perf_thread_map__pid(threads, i); + int tgid; + + /* it actually needs tgid, let's get tgid from /proc. */ + tgid = convert_to_tgid(pid); + if (tgid < 0) { + /* the thread may be dead, ignore. */ + continue; + } + + if (tgid == last) + continue; + last = tgid; + + if (bpf_map_update_elem(fd, &tgid, &filter_idx, BPF_ANY) < 0) { + pr_err("Failed to update the pid hash\n"); + return -errno; + } + pr_debug("pid hash: %d -> %d\n", tgid, filter_idx); + } + return 0; +} + +int perf_bpf_filter__prepare(struct evsel *evsel, struct target *target) +{ + int i, x, y, fd, ret; + struct sample_filter_bpf *skel = NULL; + struct bpf_program *prog; + struct bpf_link *link; + struct perf_bpf_filter_entry *entry; + bool needs_pid_hash = !target__has_cpu(target) && !target->uid_str; + + entry = calloc(MAX_FILTERS, sizeof(*entry)); + if (entry == NULL) + return -1; + + ret = get_filter_entries(evsel, entry); + if (ret < 0) { + pr_err("Failed to process filter entries\n"); + goto err; + } + + skel = sample_filter_bpf__open(); + if (!skel) { + pr_err("Failed to open perf sample-filter BPF skeleton\n"); + ret = -EPERM; goto err; } + if (needs_pid_hash) { + bpf_map__set_max_entries(skel->maps.filters, MAX_FILTERS); + bpf_map__set_max_entries(skel->maps.pid_hash, MAX_PIDS); + skel->rodata->use_pid_hash = 1; + } + + if (sample_filter_bpf__load(skel) < 0) { + pr_err("Failed to load perf sample-filter BPF skeleton\n"); + ret = -EPERM; + goto err; + } + + if (needs_pid_hash) { + /* The filters map is shared among other processes */ + ret = update_pid_hash(skel, evsel, entry); + if (ret < 0) + goto err; + } else { + i = 0; + fd = bpf_map__fd(skel->maps.filters); + + /* The filters map has only one entry in this case */ + if (bpf_map_update_elem(fd, &i, entry, BPF_ANY) < 0) { + ret = -errno; + pr_err("Failed to update the filter map\n"); + goto err; + } + } + prog = skel->progs.perf_sample_filter; for (x = 0; x < xyarray__max_x(evsel->core.fd); x++) { for (y = 0; y < xyarray__max_y(evsel->core.fd); y++) { diff --git a/tools/perf/util/bpf_skel/sample-filter.h b/tools/perf/util/bpf_skel/sample-filter.h index cf18f570eef4..375e27206640 100644 --- a/tools/perf/util/bpf_skel/sample-filter.h +++ b/tools/perf/util/bpf_skel/sample-filter.h @@ -2,6 +2,7 @@ #define PERF_UTIL_BPF_SKEL_SAMPLE_FILTER_H #define MAX_FILTERS 64 +#define MAX_PIDS (16 * 1024) /* supported filter operations */ enum perf_bpf_filter_op { diff --git a/tools/perf/util/bpf_skel/sample_filter.bpf.c b/tools/perf/util/bpf_skel/sample_filter.bpf.c index 5f17cd6458b7..1ccb0e8be73b 100644 --- a/tools/perf/util/bpf_skel/sample_filter.bpf.c +++ b/tools/perf/util/bpf_skel/sample_filter.bpf.c @@ -15,7 +15,16 @@ struct filters { __uint(max_entries, 1); } filters SEC(".maps"); +/* tgid to filter index */ +struct pid_hash { + __uint(type, BPF_MAP_TYPE_HASH); + __type(key, int); + __type(value, int); + __uint(max_entries, 1); +} pid_hash SEC(".maps"); + int dropped; +volatile const int use_pid_hash; void *bpf_cast_to_kern_ctx(void *) __ksym; @@ -140,11 +149,21 @@ int perf_sample_filter(void *ctx) __u64 sample_data; int in_group = 0; int group_result = 0; - int i; + int i = 0; kctx = bpf_cast_to_kern_ctx(ctx); - i = 0; + if (use_pid_hash) { + int tgid = bpf_get_current_pid_tgid() >> 32; + int *idx; + + idx = bpf_map_lookup_elem(&pid_hash, &tgid); + if (idx) + i = *idx; + else + goto drop; + } + entry = bpf_map_lookup_elem(&filters, &i); if (entry == NULL) goto drop;