From patchwork Mon Nov 21 07:57:18 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chunyan Zhang X-Patchwork-Id: 83189 Delivered-To: patch@linaro.org Received: by 10.140.97.165 with SMTP id m34csp1368673qge; Mon, 21 Nov 2016 00:09:26 -0800 (PST) X-Received: by 10.55.19.144 with SMTP id 16mr13932144qkt.22.1479715765962; Mon, 21 Nov 2016 00:09:25 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id c190si12766177qkd.5.2016.11.21.00.09.25; Mon, 21 Nov 2016 00:09:25 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752625AbcKUIJR (ORCPT + 26 others); Mon, 21 Nov 2016 03:09:17 -0500 Received: from mail-pg0-f43.google.com ([74.125.83.43]:33733 "EHLO mail-pg0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750944AbcKUIJP (ORCPT ); Mon, 21 Nov 2016 03:09:15 -0500 Received: by mail-pg0-f43.google.com with SMTP id 3so128216227pgd.0 for ; Mon, 21 Nov 2016 00:09:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=Yj4CeY1g9O92B/aHQJ/8G4wt3Ekw2A/B+heFxRPqsoU=; b=BIw90P8Ne3eCQwRmvc3cj6oylA10vxYa5F7BS5amsxUhQxIhrPdBJhReIamuJwV17v zDCzUCFKB2fMIToT2MA4oePMrC8Hv94hDJwXLWRegPlhUOaw4Bg8FSFVmsRjCSuTdW7Z hGHuP88Dh3hwl3bCHcLJ8Y1FawC3ftAcbaeqg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=Yj4CeY1g9O92B/aHQJ/8G4wt3Ekw2A/B+heFxRPqsoU=; b=ZaoE7bM9hN0teeHoDuXEqBVQ9fNuqYwNRTO4gDfduIVhYkv1jBX2myvN0E8MYcNrZA CiOMLLcZCp9ucPKRKRZioZfk/4Ycyd9z+zAUQ9H2L6Ou/SFH1zFKjnxD8AH3H98wD493 3R/9aPbUtD8WsqTPOWmVvzknLFzN901tpbm+EU3u1MpFakX1eweAUoHuIphh6cIzSdqn oEEcYxEW0XLePcKaGROdmMkpI3RplrOvQamxL+xJvM+1R0EGnIpCWn9afWlTgsX/JTbt Hxtk8V2ubml4Y17WVeOWZ+4jkxixqPCUW9GC9f7MEBE6gLL8Ptls+cUHIV9mW1yi3Npi I57A== X-Gm-Message-State: AKaTC02TbkfPN1NYo8+beu7FoWhwOI78+buTNiSc9pwksSg8V9xxYH5qEVgOFe2cMq2g9pcr X-Received: by 10.99.120.13 with SMTP id t13mr28395813pgc.17.1479715754815; Mon, 21 Nov 2016 00:09:14 -0800 (PST) Received: from localhost.localdomain ([175.111.195.49]) by smtp.gmail.com with ESMTPSA id s2sm35183093pfi.10.2016.11.21.00.09.09 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 21 Nov 2016 00:09:14 -0800 (PST) From: Chunyan Zhang To: rostedt@goodmis.org, mathieu.poirier@linaro.org, alexander.shishkin@linux.intel.com, mingo@redhat.com Cc: mike.leach@arm.com, tor@ti.com, philippe.langlais@st.com, nicolas.guion@st.com, felipe.balbi@linux.intel.com, zhang.lyra@gmail.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH V9 1/6] tracing: add a possibility of exporting function trace to other places instead of ring buffer only Date: Mon, 21 Nov 2016 15:57:18 +0800 Message-Id: <1479715043-6534-2-git-send-email-zhang.chunyan@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1479715043-6534-1-git-send-email-zhang.chunyan@linaro.org> References: <1479715043-6534-1-git-send-email-zhang.chunyan@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently Function traces can be only exported to ring buffer, this patch added trace_export concept which can process traces and export them to a registered destination as an addition to the current only one output of Ftrace - i.e. ring buffer. In this way, if we want Function traces to be sent to other destination rather than ring buffer only, we just need to register a new trace_export and implement its own .write() function for writing traces to storage. With this patch, only Function trace (trace type is TRACE_FN) is supported. Signed-off-by: Chunyan Zhang --- include/linux/trace.h | 28 +++++++++++ kernel/trace/trace.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 156 insertions(+), 1 deletion(-) create mode 100644 include/linux/trace.h -- 2.7.4 diff --git a/include/linux/trace.h b/include/linux/trace.h new file mode 100644 index 0000000..9330a58 --- /dev/null +++ b/include/linux/trace.h @@ -0,0 +1,28 @@ +#ifndef _LINUX_TRACE_H +#define _LINUX_TRACE_H + +#ifdef CONFIG_TRACING +/* + * The trace export - an export of Ftrace output. The trace_export + * can process traces and export them to a registered destination as + * an addition to the current only output of Ftrace - i.e. ring buffer. + * + * If you want traces to be sent to some other place rather than ring + * buffer only, just need to register a new trace_export and implement + * its own .write() function for writing traces to the storage. + * + * next - pointer to the next trace_export + * write - copy traces which have been delt with ->commit() to + * the destination + */ +struct trace_export { + struct trace_export __rcu *next; + void (*write)(const void *, unsigned int); +}; + +int register_ftrace_export(struct trace_export *export); +int unregister_ftrace_export(struct trace_export *export); + +#endif /* CONFIG_TRACING */ + +#endif /* _LINUX_TRACE_H */ diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8696ce6..038291d 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -40,6 +40,7 @@ #include #include #include +#include #include #include "trace.h" @@ -2128,6 +2129,129 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr, ftrace_trace_userstack(buffer, flags, pc); } +static void +trace_process_export(struct trace_export *export, + struct ring_buffer_event *event) +{ + struct trace_entry *entry; + unsigned int size = 0; + + entry = ring_buffer_event_data(event); + size = ring_buffer_event_length(event); + export->write(entry, size); +} + +static DEFINE_MUTEX(ftrace_export_lock); + +static struct trace_export __rcu *ftrace_exports_list __read_mostly; + +static DEFINE_STATIC_KEY_FALSE(ftrace_exports_enabled); + +static inline void ftrace_exports_enable(void) +{ + static_branch_enable(&ftrace_exports_enabled); +} + +static inline void ftrace_exports_disable(void) +{ + static_branch_disable(&ftrace_exports_enabled); +} + +void ftrace_exports(struct ring_buffer_event *event) +{ + struct trace_export *export; + + preempt_disable_notrace(); + + export = rcu_dereference_raw_notrace(ftrace_exports_list); + while (export) { + trace_process_export(export, event); + export = rcu_dereference_raw_notrace(export->next); + } + + preempt_enable_notrace(); +} + +static inline void +add_trace_export(struct trace_export **list, struct trace_export *export) +{ + rcu_assign_pointer(export->next, *list); + /* + * We are entering export into the list but another + * CPU might be walking that list. We need to make sure + * the export->next pointer is valid before another CPU sees + * the export pointer included into the list. + */ + rcu_assign_pointer(*list, export); +} + +static inline int +rm_trace_export(struct trace_export **list, struct trace_export *export) +{ + struct trace_export **p; + + for (p = list; *p != NULL; p = &(*p)->next) + if (*p == export) + break; + + if (*p != export) + return -1; + + rcu_assign_pointer(*p, (*p)->next); + + return 0; +} + +static inline void +add_ftrace_export(struct trace_export **list, struct trace_export *export) +{ + if (*list == NULL) + ftrace_exports_enable(); + + add_trace_export(list, export); +} + +static inline int +rm_ftrace_export(struct trace_export **list, struct trace_export *export) +{ + int ret; + + ret = rm_trace_export(list, export); + if (*list == NULL) + ftrace_exports_disable(); + + return ret; +} + +int register_ftrace_export(struct trace_export *export) +{ + if (WARN_ON_ONCE(!export->write)) + return -1; + + mutex_lock(&ftrace_export_lock); + + add_ftrace_export(&ftrace_exports_list, export); + + mutex_unlock(&ftrace_export_lock); + + return 0; +} +EXPORT_SYMBOL_GPL(register_ftrace_export); + +int unregister_ftrace_export(struct trace_export *export) +{ + int ret; + + mutex_lock(&ftrace_export_lock); + + ret = rm_ftrace_export(&ftrace_exports_list, export); + + mutex_unlock(&ftrace_export_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(unregister_ftrace_export); + void trace_function(struct trace_array *tr, unsigned long ip, unsigned long parent_ip, unsigned long flags, @@ -2146,8 +2270,11 @@ trace_function(struct trace_array *tr, entry->ip = ip; entry->parent_ip = parent_ip; - if (!call_filter_check_discard(call, entry, buffer, event)) + if (!call_filter_check_discard(call, entry, buffer, event)) { + if (static_branch_unlikely(&ftrace_exports_enabled)) + ftrace_exports(event); __buffer_unlock_commit(buffer, event); + } } #ifdef CONFIG_STACKTRACE