From patchwork Sat Jul 1 08:08:16 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jackie Liu X-Patchwork-Id: 13299000 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 7CF4B441B for ; Sat, 1 Jul 2023 08:08:33 +0000 (UTC) Received: from out-24.mta0.migadu.com (out-24.mta0.migadu.com [IPv6:2001:41d0:1004:224b::18]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DBC76B0 for ; Sat, 1 Jul 2023 01:08:30 -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=1688198908; 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=qIyMz2czfMAGGjfJ22MsX2tzifZepv8wr+AdouQjvjE=; b=FTPSk3gomX++e0cZVdMdHfJgb5/ghUsaAeMPVENmjcFoaDIDJk7FMgevQauzCeG3dp9CzE mYMExkbW+ZvoELNl+Dw3ZPdvSFc61mvOVJNjghjDQea5AUwcLHtsbjphe99n8Zn63v9Tzl qOw1rHrG5CdBVnTyD+hm3UyW4Jp53LA= 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 Subject: [PATCH v2 1/2] libbpf: kprobe.multi: cross filter using available_filter_functions and kallsyms Date: Sat, 1 Jul 2023 16:08:16 +0800 Message-Id: <20230701080817.1768865-1-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,URIBL_BLOCKED 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. Suggested-by: Jiri Olsa Suggested-by: Andrii Nakryiko Signed-off-by: Jackie Liu --- 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..8ea13de02c67 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[256]; + 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, "%s%*[^\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 Sat Jul 1 08:08:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jackie Liu X-Patchwork-Id: 13299001 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 A73CC5239 for ; Sat, 1 Jul 2023 08:08:36 +0000 (UTC) Received: from out-5.mta0.migadu.com (out-5.mta0.migadu.com [91.218.175.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4BA4CA2 for ; Sat, 1 Jul 2023 01:08:34 -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=1688198912; 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=tQoPy2oC72AU6UlKRf9pLai6dEbOpRXLZp1z98k33+0=; b=omzbFpGNt1nYrJagkfIzsjlYlNA0aKwh2BzZcExbgq0SkU1p8O0CYkcRBv0y7/4kpK4M4E 8PzHDEe7O0TJaUvBXl26B982nfgxGIlo2oERuQk728vcfkzng7JkJgasNG//q3igw1qJ3W G99sKQByVJg5W7/Cv55X8Z/oeewly3c= 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 Subject: [PATCH v2 2/2] libbpf: kprobe.multi: Filter with available_filter_functions_addrs Date: Sat, 1 Jul 2023 16:08:17 +0800 Message-Id: <20230701080817.1768865-2-liu.yun@linux.dev> In-Reply-To: <20230701080817.1768865-1-liu.yun@linux.dev> References: <20230701080817.1768865-1-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,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED 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 --- 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 8ea13de02c67..1ec861ad52a6 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[256]; + 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 %s%*[^\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) {