From patchwork Sat Jul 1 07:26:14 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jackie Liu X-Patchwork-Id: 13298979 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 C41A53C17 for ; Sat, 1 Jul 2023 07:26:30 +0000 (UTC) Received: from out-47.mta1.migadu.com (out-47.mta1.migadu.com [IPv6:2001:41d0:203:375::2f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B11FE124 for ; Sat, 1 Jul 2023 00:26:28 -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=1688196387; 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=PU8MVTS5iSblFN+czK849B5LhYjbHSRPsMr+U0OiQ3A=; b=rgkZJlZ5nZ8OapfWboUqSsqQRIpfnVivEq9PRnvXSRNzSMfY97rlZkIAfJ2NIqaIZl/18y 814vSTuel7xvqEGusCir3Sk0sbdkkdGvwGhdbLwcx2wjjTMZd2lIuStqbgjoJlynApeeg5 f5iYnaICDT1GuXq93aSq6X3DL+/u4m0= 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 1/2] libbpf: kprobe.multi: cross filter using available_filter_functions and kallsyms Date: Sat, 1 Jul 2023 15:26:14 +0800 Message-Id: <20230701072615.1765388-1-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 | 121 ++++++++++++++++++++++++++++++++++++----- 1 file changed, 108 insertions(+), 13 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 214f828ece6b..e26afcd1ff2d 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 +10545,112 @@ 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; + break; + } + + 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 cleanup; + } + + 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; + } + fclose(f); + +cleanup: + for (i = 0; i < infos.cnt; i++) + free((char *)infos.syms[i]); + free(infos.syms); + + return err; } struct bpf_link * @@ -10594,7 +10689,7 @@ 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 07:26:15 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jackie Liu X-Patchwork-Id: 13298980 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 66590440D for ; Sat, 1 Jul 2023 07:26:35 +0000 (UTC) Received: from out-55.mta1.migadu.com (out-55.mta1.migadu.com [95.215.58.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BA01124 for ; Sat, 1 Jul 2023 00:26:33 -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=1688196390; 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=Fc6kNEnKEDisN8fkvZE+NZnmsBe3FA1ObxZlSip7IwA=; b=n8ZmWzzKaaPfLbOhyOm2PGi7UVsHExfkxsoc8eDK7jJaAj76zUX34smLqJ+RTAfsEi/KEO UmRYynm5oM/VNrqi3as14maiXSD+vbcjB3GWmv+E7lua9FsTFJcviUDe+Ax0vd6sJ2E3t8 oi4D5I8d+2UQRf1lETTfnSNUY9Miods= 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 2/2] libbpf: kprobe.multi: Filter with available_filter_functions_addrs Date: Sat, 1 Jul 2023 15:26:15 +0800 Message-Id: <20230701072615.1765388-2-liu.yun@linux.dev> In-Reply-To: <20230701072615.1765388-1-liu.yun@linux.dev> References: <20230701072615.1765388-1-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 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 e26afcd1ff2d..c9dbc95b1541 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) { @@ -10653,6 +10659,53 @@ 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, @@ -10689,7 +10742,10 @@ 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) {