From patchwork Wed Jul 5 03:34:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jackie Liu X-Patchwork-Id: 13301628 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 8F11CA3D for ; Wed, 5 Jul 2023 03:35:07 +0000 (UTC) Received: from out-26.mta1.migadu.com (out-26.mta1.migadu.com [IPv6:2001:41d0:203:375::1a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9FAF01B6 for ; Tue, 4 Jul 2023 20:35:04 -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=1688528102; 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=Q+cfHeIp8VlYn6yx+ntM6kY14/3fMDyQhzpaaEhJUv4=; b=Hz59IYRfcWRTiAxSjNuhxR8AN0+M2AfOXjfOIJrBY1rkH3tdDQ9yPQQyWeakf5LGVPvKEm ALO2zs4DLWUszEn7Dg8GVg4TXBQpsVwYFmP7C761CU7udIO7CCSsae4Z6Y001Hl8VFpDGy 6fR92Gc4r/GOAryeYUufNRzGeQCBjwM= 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 v6 1/2] libbpf: kprobe.multi: cross filter using available_filter_functions and kallsyms Date: Wed, 5 Jul 2023 11:34:56 +0800 Message-Id: <20230705033457.3778537-1-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. 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 --- v5->v6: fix crash by not init "const char *syms" v4->v5: simplified code tools/lib/bpf/libbpf.c | 106 +++++++++++++++++++++++++++++++++++++---- 1 file changed, 96 insertions(+), 10 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 214f828ece6b..3b5a12ca47bf 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) { @@ -10539,14 +10545,26 @@ 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 avail_compare_function(const void *a, const void *b) +{ + return strcmp(*(const char **)a, *(const char **)b); +} + +struct avail_kallsyms_data { + const char **syms; + size_t cnt; + struct kprobe_multi_resolve *res; +}; + +static int avail_kallsyms_cb(unsigned long long sym_addr, char sym_type, + const char *sym_name, void *ctx) { - struct kprobe_multi_resolve *res = ctx; + struct avail_kallsyms_data *data = ctx; + struct kprobe_multi_resolve *res = data->res; int err; - if (!glob_match(sym_name, res->pattern)) + if (!bsearch(&sym_name, data->syms, data->cnt, sizeof(void *), + avail_compare_function)) return 0; err = libbpf_ensure_mem((void **) &res->addrs, &res->cap, sizeof(unsigned long), @@ -10558,6 +10576,78 @@ resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type, return 0; } +static int libbpf_available_kallsyms_parse(struct kprobe_multi_resolve *res) +{ + struct avail_kallsyms_data data; + char sym_name[500]; + const char *available_functions_file = tracefs_available_filter_functions(); + FILE *f; + int err = 0, ret, i; + const char **syms = NULL; + size_t cap = 0, cnt = 0; + + f = fopen(available_functions_file, "r"); + if (!f) { + err = -errno; + pr_warn("failed to open %s\n", available_functions_file); + return err; + } + + 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 **)&syms, &cap, sizeof(void *), + cnt + 1); + if (err) + goto cleanup; + + name = strdup(sym_name); + if (!name) { + err = -errno; + goto cleanup; + } + + syms[cnt++] = name; + } + fclose(f); + + /* not found entry, return direct */ + if (!cnt) + return -ENOENT; + + /* sort available functions */ + qsort(syms, cnt, sizeof(void *), avail_compare_function); + + data.syms = syms; + data.res = res; + data.cnt = cnt; + libbpf_kallsyms_parse(avail_kallsyms_cb, &data); + + if (!res->cnt) + err = -ENOENT; + +cleanup: + for (i = 0; i < cnt; i++) + free((char *)syms[i]); + free(syms); + + return err; +} + struct bpf_link * bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, const char *pattern, @@ -10594,13 +10684,9 @@ 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) { - err = -ENOENT; - goto error; - } addrs = res.addrs; cnt = res.cnt; } From patchwork Wed Jul 5 03:34:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jackie Liu X-Patchwork-Id: 13301629 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 E062AA3D for ; Wed, 5 Jul 2023 03:35:08 +0000 (UTC) Received: from out-63.mta1.migadu.com (out-63.mta1.migadu.com [95.215.58.63]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B105D1B6 for ; Tue, 4 Jul 2023 20:35:07 -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=1688528106; 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=2DUWdqbi/cMdtcU2E/avtcOex/3nglq71XobCy+V9V4=; b=v9nwXEpAgW2Kc/iTRRnNHZ/XrBXO858gj+8q3ufjWHH+Zq7p4GpweFBqDCRMALdUbDYxBh 78AhR427Ll9EmKFMBm0KdVXowEq6oJPKyGxoiynRCzxedw24bkTBfekAvwWIMwMEbpHcYY t2Lj8omkj1og7pybdc4Qq96D7i55+Ug= 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 v6 2/2] libbpf: kprobe.multi: Filter with available_filter_functions_addrs Date: Wed, 5 Jul 2023 11:34:57 +0800 Message-Id: <20230705033457.3778537-2-liu.yun@linux.dev> In-Reply-To: <20230705033457.3778537-1-liu.yun@linux.dev> References: <20230705033457.3778537-1-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 | 62 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 61 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 3b5a12ca47bf..edc93684cdb8 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) { @@ -10648,6 +10654,57 @@ 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; + goto cleanup; + } + + 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) + goto cleanup; + + res->addrs[res->cnt++] = (unsigned long) sym_addr; + } + + if (!res->cnt) + err = -ENOENT; + +cleanup: + fclose(f); + return err; +} + struct bpf_link * bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, const char *pattern, @@ -10684,7 +10741,10 @@ 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; addrs = res.addrs;