From patchwork Mon Jul 3 01:36:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jackie Liu X-Patchwork-Id: 13299558 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 4BDD2362 for ; Mon, 3 Jul 2023 01:36:33 +0000 (UTC) Received: from out-52.mta0.migadu.com (out-52.mta0.migadu.com [91.218.175.52]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64B4C18F for ; Sun, 2 Jul 2023 18:36:31 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1688348189; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=13N9J5gxTFfgqs14HOsjZrzpqxkCAZ9ktqkserYTFZo=; b=RNTiKDI1SUBK4THCQ4UNH1kwZn08sMCiSA4GBRJPkAEzj1J9tlLHxYyeO8BB9jcSnGMAzA sOU3QDbIK/ZdM6p/s8kFtlXrWmdGpn1yeQSzMK936ZdQKAZyURN7+F/VKMi7tc6eq0X7sV xyfSlbu8XOjQxIw0k81X7z8j71Nk0Ys= From: Jackie Liu To: olsajiri@gmail.com, andrii@kernel.org Cc: martin.lau@linux.dev, song@kernel.org, yhs@fb.com, bpf@vger.kernel.org, liuyun01@kylinos.cn, lkp@intel.com Subject: [PATCH v3 1/2] libbpf: kprobe.multi: cross filter using available_filter_functions and kallsyms Date: Mon, 3 Jul 2023 09:36:17 +0800 Message-Id: <20230703013618.1959621-1-liu.yun@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net From: Jackie Liu When using regular expression matching with "kprobe multi", it scans all the functions under "/proc/kallsyms" that can be matched. However, not all of them can be traced by kprobe.multi. If any one of the functions fails to be traced, it will result in the failure of all functions. The best approach is to filter out the functions that cannot be traced to ensure proper tracking of the functions. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202307030355.TdXOHklM-lkp@intel.com/ Suggested-by: Jiri Olsa Suggested-by: Andrii Nakryiko Signed-off-by: Jackie Liu --- v2->v3: fix 'fscanf' may overflow tools/lib/bpf/libbpf.c | 122 ++++++++++++++++++++++++++++++++++++----- 1 file changed, 109 insertions(+), 13 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 214f828ece6b..232268215bb7 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -10224,6 +10224,12 @@ static const char *tracefs_uprobe_events(void) return use_debugfs() ? DEBUGFS"/uprobe_events" : TRACEFS"/uprobe_events"; } +static const char *tracefs_available_filter_functions(void) +{ + return use_debugfs() ? DEBUGFS"/available_filter_functions" : + TRACEFS"/available_filter_functions"; +} + static void gen_kprobe_legacy_event_name(char *buf, size_t buf_sz, const char *kfunc_name, size_t offset) { @@ -10539,23 +10545,113 @@ struct kprobe_multi_resolve { size_t cnt; }; -static int -resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type, - const char *sym_name, void *ctx) +static int qsort_compare_function(const void *a, const void *b) { - struct kprobe_multi_resolve *res = ctx; - int err; + return strcmp(*(const char **)a, *(const char **)b); +} - if (!glob_match(sym_name, res->pattern)) - return 0; +static int bsearch_compare_function(const void *a, const void *b) +{ + return strcmp((const char *)a, *(const char **)b); +} - err = libbpf_ensure_mem((void **) &res->addrs, &res->cap, sizeof(unsigned long), - res->cnt + 1); - if (err) +static int libbpf_available_kallsyms_parse(struct kprobe_multi_resolve *res) +{ + char sym_name[500]; + const char *available_functions_file = tracefs_available_filter_functions(); + FILE *f; + int err = 0, ret, i; + struct function_info { + const char **syms; + size_t cap; + size_t cnt; + } infos = {}; + + f = fopen(available_functions_file, "r"); + if (!f) { + err = -errno; + pr_warn("failed to open %s\n", available_functions_file); return err; + } - res->addrs[res->cnt++] = (unsigned long) sym_addr; - return 0; + while (true) { + char *name; + + ret = fscanf(f, "%499s%*[^\n]\n", sym_name); + if (ret == EOF && feof(f)) + break; + + if (ret != 1) { + pr_warn("failed to read available function file entry: %d\n", + ret); + err = -EINVAL; + goto cleanup; + } + + if (!glob_match(sym_name, res->pattern)) + continue; + + err = libbpf_ensure_mem((void **)&infos.syms, &infos.cap, + sizeof(void *), infos.cnt + 1); + if (err) + goto cleanup; + + name = strdup(sym_name); + if (!name) { + err = -errno; + goto cleanup; + } + + infos.syms[infos.cnt++] = name; + } + fclose(f); + + /* sort available functions */ + qsort(infos.syms, infos.cnt, sizeof(void *), qsort_compare_function); + + f = fopen("/proc/kallsyms", "r"); + if (!f) { + err = -errno; + pr_warn("failed to open /proc/kallsyms\n"); + goto free_infos; + } + + while (true) { + unsigned long long sym_addr; + + ret = fscanf(f, "%llx %*c %499s%*[^\n]\n", &sym_addr, sym_name); + if (ret == EOF && feof(f)) + break; + + if (ret != 2) { + pr_warn("failed to read kallsyms entry: %d\n", ret); + err = -EINVAL; + break; + } + + if (!glob_match(sym_name, res->pattern)) + continue; + + if (!bsearch(&sym_name, infos.syms, infos.cnt, sizeof(void *), + bsearch_compare_function)) + continue; + + err = libbpf_ensure_mem((void **)&res->addrs, &res->cap, + sizeof(unsigned long), res->cnt + 1); + if (err) + break; + + res->addrs[res->cnt++] = (unsigned long) sym_addr; + } + +cleanup: + fclose(f); +free_infos: + for (i = 0; i < infos.cnt; i++) + free((char *)infos.syms[i]); + free(infos.syms); + + return err; } struct bpf_link * @@ -10594,7 +10690,7 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, return libbpf_err_ptr(-EINVAL); if (pattern) { - err = libbpf_kallsyms_parse(resolve_kprobe_multi_cb, &res); + err = libbpf_available_kallsyms_parse(&res); if (err) goto error; if (!res.cnt) { From patchwork Mon Jul 3 01:36:18 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jackie Liu X-Patchwork-Id: 13299559 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 E0AA9362 for ; Mon, 3 Jul 2023 01:36:35 +0000 (UTC) Received: from out-44.mta0.migadu.com (out-44.mta0.migadu.com [91.218.175.44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9883312E for ; Sun, 2 Jul 2023 18:36:34 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1688348192; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Lqfjsuzdor6LuXvbg9kXgTTUkl0kzrzGTuJgjyCzwPs=; b=OosijDitxuvGtTosWx+HNw9bq2alipW/y5PYHlMWypOvT5LrNoMZS5AngjOhWU/3BkMxnN v6EYRfnxp8hnMn5UY3ysAI1MNN0J7AFQ2IdWJhzaJTQrP8QwtGYetVoipCAB/GPs5XqVPF pfB1KxiFDQGhB5BAieTs6s4ihiAtPKw= From: Jackie Liu To: olsajiri@gmail.com, andrii@kernel.org Cc: martin.lau@linux.dev, song@kernel.org, yhs@fb.com, bpf@vger.kernel.org, liuyun01@kylinos.cn, lkp@intel.com Subject: [PATCH v3 2/2] libbpf: kprobe.multi: Filter with available_filter_functions_addrs Date: Mon, 3 Jul 2023 09:36:18 +0800 Message-Id: <20230703013618.1959621-2-liu.yun@linux.dev> In-Reply-To: <20230703013618.1959621-1-liu.yun@linux.dev> References: <20230703013618.1959621-1-liu.yun@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net From: Jackie Liu Now, we provide a new available_filter_functions_addrs interface, which can help us not need to cross-validate available_filter_functions and kallsyms, which can effectively improve efficiency. For example, on my device, the sample program [1] of start time: $ sudo ./funccount "tcp_*" before after 1.2s 1.0s [1]: https://github.com/JackieLiu1/ketones/tree/master/src/funccount Signed-off-by: Jackie Liu --- v2->v3: fix 'fscanf' may overflow tools/lib/bpf/libbpf.c | 58 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 57 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 232268215bb7..afdbd30ac7e0 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -10230,6 +10230,12 @@ static const char *tracefs_available_filter_functions(void) TRACEFS"/available_filter_functions"; } +static const char *tracefs_available_filter_functions_addrs(void) +{ + return use_debugfs() ? DEBUGFS"/available_filter_functions_addrs" : + TRACEFS"/available_filter_functions_addrs"; +} + static void gen_kprobe_legacy_event_name(char *buf, size_t buf_sz, const char *kfunc_name, size_t offset) { @@ -10654,6 +10660,53 @@ static int libbpf_available_kallsyms_parse(struct kprobe_multi_resolve *res) return err; } +static bool has_available_filter_functions_addrs(void) +{ + return access(tracefs_available_filter_functions_addrs(), R_OK) != -1; +} + +static int libbpf_available_kprobes_parse(struct kprobe_multi_resolve *res) +{ + char sym_name[500]; + FILE *f; + int ret, err = 0; + unsigned long long sym_addr; + const char *available_path = tracefs_available_filter_functions_addrs(); + + f = fopen(available_path, "r"); + if (!f) { + err = -errno; + pr_warn("failed to open %s.\n", available_path); + return err; + } + + while (true) { + ret = fscanf(f, "%llx %499s%*[^\n]\n", &sym_addr, sym_name); + if (ret == EOF && feof(f)) + break; + + if (ret != 2) { + pr_warn("failed to read available kprobe entry: %d\n", + ret); + err = -EINVAL; + break; + } + + if (!glob_match(sym_name, res->pattern)) + continue; + + err = libbpf_ensure_mem((void **) &res->addrs, &res->cap, + sizeof(unsigned long), res->cnt + 1); + if (err) + break; + + res->addrs[res->cnt++] = (unsigned long) sym_addr; + } + + fclose(f); + return err; +} + struct bpf_link * bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, const char *pattern, @@ -10690,7 +10743,10 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, return libbpf_err_ptr(-EINVAL); if (pattern) { - err = libbpf_available_kallsyms_parse(&res); + if (has_available_filter_functions_addrs()) + err = libbpf_available_kprobes_parse(&res); + else + err = libbpf_available_kallsyms_parse(&res); if (err) goto error; if (!res.cnt) {