From patchwork Sun Aug 18 10:43:16 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 13767384 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E0436182B2; Sun, 18 Aug 2024 10:43:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723977801; cv=none; b=cQSVcZyb6fzzlA5smYCVY3cUFM/RDBZaNNkgAfGKNkarujGf6MmhylqXarAY9xp4lF0lAmWfO++HR2bj4w5DEWEhCgSEG2C/esUtpxuAXWhNnU4b3axXH585SssTTOmOphxphcv+ywgkXBU5imM7LAg+BMCZIxWRHjAXsFDbXqY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723977801; c=relaxed/simple; bh=tqxj0+ceBL7w+7fMBUuPblOkbw1rKdQ8Tw3Bs0li64E=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=b8kPqeGANfHoHkaAttbJhsrZSfSHSHUVF4gs033EhxaPWuYJsl8B++jOCyFXhFb7DK90Ch823v1Z3AlHBs6dOPZZogw5B9DEsCb++lAsLYy8OxNNi/RoeiRLitsjpwem5Bee2KcytMqufBoLjCoeQTTenfTF2132BT8hfR8EKGc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bkE2TUpz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bkE2TUpz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F23CCC32786; Sun, 18 Aug 2024 10:43:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1723977800; bh=tqxj0+ceBL7w+7fMBUuPblOkbw1rKdQ8Tw3Bs0li64E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bkE2TUpzRcENCRM20CHpda9h4l7IIqBZBe5fQPxXSvNrrRvLWzMXoooDHZOsoHwvU pmj0hAb/+hg8wtYo40uiM2KY50/RBb+D/sntm/Ya+dT5KFeTarnz2AJk0OIoCYTfyr YrFuVEralMkAi1CPN6nXETJ2yenJcaIePGBXUmeg+22Tt0X4QGq6FeZRib1nr93DNg dN57BQXd6PHPDN3VTh0ikP/cUFcvF4S8CwMWi4dQATSENxpkpydUpZDuaEloySKn9n fcCOFuyyo+KIoIUZoDMX7aKRf0pNXBEfACsOGxlFPdJr0wVVnGFsaYX1NE9LzQI7YH ZAVHkK0bvNFBg== From: "Masami Hiramatsu (Google)" To: Steven Rostedt Cc: Mathieu Desnoyers , don , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, mhiramat@kernel.org Subject: [PATCH v3 3/5] tracing/fprobe: Support raw tracepoint events on modules Date: Sun, 18 Aug 2024 19:43:16 +0900 Message-Id: <172397779651.286558.15903703620679186867.stgit@devnote2> X-Mailer: git-send-email 2.34.1 In-Reply-To: <172397776900.286558.8986646398199362026.stgit@devnote2> References: <172397776900.286558.8986646398199362026.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Masami Hiramatsu (Google) Support raw tracepoint event on module by fprobe events. Since it only uses for_each_kernel_tracepoint() to find a tracepoint, the tracepoints on modules are not handled. Thus if user specified a tracepoint on a module, it shows an error. This adds new for_each_module_tracepoint() API to tracepoint subsystem, and uses it to find tracepoints on modules. Reported-by: don Closes: https://lore.kernel.org/all/20240530215718.aeec973a1d0bf058d39cb1e3@kernel.org/ Signed-off-by: Masami Hiramatsu (Google) --- Changes in v2: - Fix build errors with CONFIG_MODULES=y. --- kernel/trace/trace_fprobe.c | 46 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 38 insertions(+), 8 deletions(-) diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c index 62e6a8f4aae9..8b1127e37da5 100644 --- a/kernel/trace/trace_fprobe.c +++ b/kernel/trace/trace_fprobe.c @@ -385,6 +385,7 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group, const char *event, const char *symbol, struct tracepoint *tpoint, + struct module *mod, int maxactive, int nargs, bool is_return) { @@ -405,6 +406,7 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group, tf->fp.entry_handler = fentry_dispatcher; tf->tpoint = tpoint; + tf->mod = mod; tf->fp.nr_maxactive = maxactive; ret = trace_probe_init(&tf->tp, event, group, false, nargs); @@ -895,8 +897,23 @@ static struct notifier_block tracepoint_module_nb = { struct __find_tracepoint_cb_data { const char *tp_name; struct tracepoint *tpoint; + struct module *mod; }; +static void __find_tracepoint_module_cb(struct tracepoint *tp, struct module *mod, void *priv) +{ + struct __find_tracepoint_cb_data *data = priv; + + if (!data->tpoint && !strcmp(data->tp_name, tp->name)) { + data->tpoint = tp; + data->mod = mod; + if (!try_module_get(data->mod)) { + data->tpoint = NULL; + data->mod = NULL; + } + } +} + static void __find_tracepoint_cb(struct tracepoint *tp, void *priv) { struct __find_tracepoint_cb_data *data = priv; @@ -905,14 +922,28 @@ static void __find_tracepoint_cb(struct tracepoint *tp, void *priv) data->tpoint = tp; } -static struct tracepoint *find_tracepoint(const char *tp_name) +/* + * Find a tracepoint from kernel and module. If the tracepoint is in a module, + * this increments the module refcount to prevent unloading until the + * trace_fprobe is registered to the list. After registering the trace_fprobe + * on the trace_fprobe list, the module refcount is decremented because + * tracepoint_probe_module_cb will handle it. + */ +static struct tracepoint *find_tracepoint(const char *tp_name, + struct module **tp_mod) { struct __find_tracepoint_cb_data data = { .tp_name = tp_name, + .mod = NULL, }; for_each_kernel_tracepoint(__find_tracepoint_cb, &data); + if (!data.tpoint && IS_ENABLED(CONFIG_MODULES)) { + for_each_module_tracepoint(__find_tracepoint_module_cb, &data); + *tp_mod = data.mod; + } + return data.tpoint; } @@ -996,6 +1027,7 @@ static int __trace_fprobe_create(int argc, const char *argv[]) char abuf[MAX_BTF_ARGS_LEN]; char *dbuf = NULL; bool is_tracepoint = false; + struct module *tp_mod = NULL; struct tracepoint *tpoint = NULL; struct traceprobe_parse_context ctx = { .flags = TPARG_FL_KERNEL | TPARG_FL_FPROBE, @@ -1080,7 +1112,7 @@ static int __trace_fprobe_create(int argc, const char *argv[]) if (is_tracepoint) { ctx.flags |= TPARG_FL_TPOINT; - tpoint = find_tracepoint(symbol); + tpoint = find_tracepoint(symbol, &tp_mod); if (!tpoint) { trace_probe_log_set_index(1); trace_probe_log_err(0, NO_TRACEPOINT); @@ -1110,8 +1142,8 @@ static int __trace_fprobe_create(int argc, const char *argv[]) goto out; /* setup a probe */ - tf = alloc_trace_fprobe(group, event, symbol, tpoint, maxactive, - argc, is_return); + tf = alloc_trace_fprobe(group, event, symbol, tpoint, tp_mod, + maxactive, argc, is_return); if (IS_ERR(tf)) { ret = PTR_ERR(tf); /* This must return -ENOMEM, else there is a bug */ @@ -1119,10 +1151,6 @@ static int __trace_fprobe_create(int argc, const char *argv[]) goto out; /* We know tf is not allocated */ } - if (is_tracepoint) - tf->mod = __module_text_address( - (unsigned long)tf->tpoint->probestub); - /* parse arguments */ for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) { trace_probe_log_set_index(i + 2); @@ -1155,6 +1183,8 @@ static int __trace_fprobe_create(int argc, const char *argv[]) } out: + if (tp_mod) + module_put(tp_mod); traceprobe_finish_parse(&ctx); trace_probe_log_clear(); kfree(new_argv);