From patchwork Wed Oct 18 14:40:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Francis Laniel X-Patchwork-Id: 13427203 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 5D88B17731 for ; Wed, 18 Oct 2023 14:41:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="FQMjO0kL" Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B893210D; Wed, 18 Oct 2023 07:40:58 -0700 (PDT) Received: from pwmachine.numericable.fr (unknown [188.24.154.80]) by linux.microsoft.com (Postfix) with ESMTPSA id 5688720B74C1; Wed, 18 Oct 2023 07:40:56 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 5688720B74C1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1697640058; bh=ZyhmO3X6jBWaHqcLJasVL9JKLb1Dgh5tpNMbuRYa2ik=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FQMjO0kLaNOHH1rthm3YX7spa7A90Q8QVHXqVikjkfWN+6bcWWrma6ygpS5FtXO79 MrxIIywW4yN/Hn+3nD0VDMsUDoGUoFrv/ckDcJMog+PT5FoIr5Ss+A8SszB8VUi6Aw h4aLTyOwkk6tJ+q0JmtogLYfJAOdiLdjbkt6lbaQ= From: Francis Laniel To: linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , stable@vger.kernel.org, Francis Laniel , Steven Rostedt , linux-kernel@vger.kernel.org Subject: [PATCH v5 1/2] tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols Date: Wed, 18 Oct 2023 17:40:29 +0300 Message-Id: <20231018144030.86885-2-flaniel@linux.microsoft.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231018144030.86885-1-flaniel@linux.microsoft.com> References: <20231018144030.86885-1-flaniel@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-17.5 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_BLOCKED, SPF_HELO_PASS,SPF_PASS,USER_IN_DEF_DKIM_WL,USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Previously to this commit, if func matches several symbols, a kprobe, being either sysfs or PMU, would only be installed for the first matching address. This could lead to some misunderstanding when some BPF code was never called because it was attached to a function which was indeed not called, because the effectively called one has no kprobes attached. So, this commit returns EADDRNOTAVAIL when func matches several symbols. This way, user needs to use address to remove the ambiguity. Suggested-by: Masami Hiramatsu Signed-off-by: Francis Laniel Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kernel.org/ --- kernel/trace/trace_kprobe.c | 63 +++++++++++++++++++++++++++++++++++++ kernel/trace/trace_probe.h | 1 + 2 files changed, 64 insertions(+) -- 2.34.1 diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 3d7a180a8427..a8fef6ab0872 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -705,6 +705,25 @@ static struct notifier_block trace_kprobe_module_nb = { .priority = 1 /* Invoked after kprobe module callback */ }; +static int count_symbols(void *data, unsigned long unused) +{ + unsigned int *count = data; + + (*count)++; + + return 0; +} + +static unsigned int number_of_same_symbols(char *func_name) +{ + unsigned int count; + + count = 0; + kallsyms_on_each_match_symbol(count_symbols, func_name, &count); + + return count; +} + static int __trace_kprobe_create(int argc, const char *argv[]) { /* @@ -836,6 +855,31 @@ static int __trace_kprobe_create(int argc, const char *argv[]) } } + if (symbol && !strchr(symbol, ':')) { + unsigned int count; + + count = number_of_same_symbols(symbol); + if (count > 1) { + /* + * Users should use ADDR to remove the ambiguity of + * using KSYM only. + */ + trace_probe_log_err(0, NON_UNIQ_SYMBOL); + ret = -EADDRNOTAVAIL; + + goto error; + } else if (count == 0) { + /* + * We can return ENOENT earlier than when register the + * kprobe. + */ + trace_probe_log_err(0, BAD_PROBE_ADDR); + ret = -ENOENT; + + goto error; + } + } + trace_probe_log_set_index(0); if (event) { ret = traceprobe_parse_event_name(&event, &group, gbuf, @@ -1695,6 +1739,7 @@ static int unregister_kprobe_event(struct trace_kprobe *tk) } #ifdef CONFIG_PERF_EVENTS + /* create a trace_kprobe, but don't add it to global lists */ struct trace_event_call * create_local_trace_kprobe(char *func, void *addr, unsigned long offs, @@ -1705,6 +1750,24 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs, int ret; char *event; + if (func) { + unsigned int count; + + count = number_of_same_symbols(func); + if (count > 1) + /* + * Users should use addr to remove the ambiguity of + * using func only. + */ + return ERR_PTR(-EADDRNOTAVAIL); + else if (count == 0) + /* + * We can return ENOENT earlier than when register the + * kprobe. + */ + return ERR_PTR(-ENOENT); + } + /* * local trace_kprobes are not added to dyn_event, so they are never * searched in find_trace_kprobe(). Therefore, there is no concern of diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index 02b432ae7513..850d9ecb6765 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -450,6 +450,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call, C(BAD_MAXACT, "Invalid maxactive number"), \ C(MAXACT_TOO_BIG, "Maxactive is too big"), \ C(BAD_PROBE_ADDR, "Invalid probed address or symbol"), \ + C(NON_UNIQ_SYMBOL, "The symbol is not unique"), \ C(BAD_RETPROBE, "Retprobe address must be an function entry"), \ C(NO_TRACEPOINT, "Tracepoint is not found"), \ C(BAD_ADDR_SUFFIX, "Invalid probed address suffix"), \ From patchwork Wed Oct 18 14:40:30 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Francis Laniel X-Patchwork-Id: 13427204 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 5F12C37CA0 for ; Wed, 18 Oct 2023 14:41:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="jj8G1UuN" Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id C4679112; Wed, 18 Oct 2023 07:41:04 -0700 (PDT) Received: from pwmachine.numericable.fr (unknown [188.24.154.80]) by linux.microsoft.com (Postfix) with ESMTPSA id E6C8E20B74C2; Wed, 18 Oct 2023 07:41:01 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com E6C8E20B74C2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1697640064; bh=xfU7t1LgNcdblzWvppUIKK8lYqVIT5V5QuCHhVdi4XA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jj8G1UuN9Bk/jt7qcdNl+3JbxLcchuZl5ENkdpTuNUHmsmpsB+5UyK3Da+JmSQxRE iByd2j7wE4UOQvR9Pj58rqHZZb03r+jez6TUt9GqPMe+z43DeK3+J5EEri0uGVFWcw IO4XORpsoyWdS8ndO6+MKMW5RVrWhs8Z3mrBTyWo= From: Francis Laniel To: linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , stable@vger.kernel.org, Francis Laniel , Steven Rostedt , Shuah Khan , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v5 2/2] selftests/ftrace: Add new test case which checks non unique symbol Date: Wed, 18 Oct 2023 17:40:30 +0300 Message-Id: <20231018144030.86885-3-flaniel@linux.microsoft.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231018144030.86885-1-flaniel@linux.microsoft.com> References: <20231018144030.86885-1-flaniel@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-17.5 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_BLOCKED, SPF_HELO_PASS,SPF_PASS,USER_IN_DEF_DKIM_WL,USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net If name_show() is non unique, this test will try to install a kprobe on this function which should fail returning EADDRNOTAVAIL. On kernel where name_show() is not unique, this test is skipped. Signed-off-by: Francis Laniel --- .../ftrace/test.d/kprobe/kprobe_non_uniq_symbol.tc | 13 +++++++++++++ 1 file changed, 13 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/kprobe_non_uniq_symbol.tc -- 2.34.1 diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_non_uniq_symbol.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_non_uniq_symbol.tc new file mode 100644 index 000000000000..bc9514428dba --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_non_uniq_symbol.tc @@ -0,0 +1,13 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Test failure of registering kprobe on non unique symbol +# requires: kprobe_events + +SYMBOL='name_show' + +# We skip this test on kernel where SYMBOL is unique or does not exist. +if [ "$(grep -c -E "[[:alnum:]]+ t ${SYMBOL}" /proc/kallsyms)" -le '1' ]; then + exit_unsupported +fi + +! echo "p:test_non_unique ${SYMBOL}" > kprobe_events