From patchwork Tue Oct 18 08:08:58 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chunyan Zhang X-Patchwork-Id: 9381545 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 99F1260487 for ; Tue, 18 Oct 2016 08:11:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8C9B028C44 for ; Tue, 18 Oct 2016 08:11:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 805EA28DC3; Tue, 18 Oct 2016 08:11:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED, T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id E8C5F28C44 for ; Tue, 18 Oct 2016 08:11:29 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1bwPTL-0008Iv-NT; Tue, 18 Oct 2016 08:10:07 +0000 Received: from mail-pf0-x230.google.com ([2607:f8b0:400e:c00::230]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1bwPTE-00082B-Lx for linux-arm-kernel@lists.infradead.org; Tue, 18 Oct 2016 08:10:02 +0000 Received: by mail-pf0-x230.google.com with SMTP id s8so90491337pfj.2 for ; Tue, 18 Oct 2016 01:09:40 -0700 (PDT) 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=o9K0ecKGfCLZvbQ3AKLSnseXxXviVR6YlOQIdBpx3eo=; b=EzHXVoG8XJtajXe3HaEIRCpFCeDo7RLmNEng5rljQeFeXXWJfAhJ+0mNCGJYjQEuPw KSviSs4pn8xo1NR/9VhXW+9aGUtJ7y6iumminr7WMnPLBYuU0tb6aNGUfkGik4DhIxQm KZftNrNm1V4hbKOX5sooTO0+IqptzqsuHvyTw= 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=o9K0ecKGfCLZvbQ3AKLSnseXxXviVR6YlOQIdBpx3eo=; b=goY5e4jyWlICtHJ3IoBw7QXuCIbB3CSCZzG+S8pUZ0XdionJLY6bSxGWtwHDzP+/K0 PV9oUykDTCQ6EtQ/yRLSSykTAunfbnaBEt4EV11PITghP7eaJoOpo8zoccNXbPMa+EuW P5iTBR4d185lBTjt5zf5JQ0n+jA6epI2JC9WPgknhc/TzSLh+NUIdojwftexwg6dbALy RBxm+u/Kd6obtSBQ8Lr83UlOoXp3RRgFygL7D2fyyhD2j88VEf4Px0RoC3r1a0f0ogbA v2fgEEJkiwEXsXFgHD/w206qjdM+ix6jRxSeqkl3CiTEigjaYWtIy4QVkcxSpQQhXb1n Trcw== X-Gm-Message-State: AA6/9RmhkwH8BHaJSC9jg8PQKJVBGtmGh7+4tR9oWI2M8m/+ScvyvBd3lRdXH+ms8piJ4B/6 X-Received: by 10.99.55.21 with SMTP id e21mr2180300pga.60.1476778179666; Tue, 18 Oct 2016 01:09:39 -0700 (PDT) Received: from ubuntu16.spreadtrum.com ([175.111.195.49]) by smtp.gmail.com with ESMTPSA id m25sm2409807pfg.14.2016.10.18.01.09.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 18 Oct 2016 01:09:38 -0700 (PDT) From: Chunyan Zhang To: rostedt@goodmis.org, mathieu.poirier@linaro.org, alexander.shishkin@linux.intel.com, mingo@redhat.com Subject: [PATCH V7 1/3] tracing: add a possibility of exporting function trace to other places instead of ring buffer only Date: Tue, 18 Oct 2016 16:08:58 +0800 Message-Id: <1476778140-10319-2-git-send-email-zhang.chunyan@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1476778140-10319-1-git-send-email-zhang.chunyan@linaro.org> References: <1476778140-10319-1-git-send-email-zhang.chunyan@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20161018_011000_847933_AB72C239 X-CRM114-Status: GOOD ( 18.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: felipe.balbi@linux.intel.com, zhang.lyra@gmail.com, linux-kernel@vger.kernel.org, tor@ti.com, philippe.langlais@st.com, mike.leach@arm.com, nicolas.guion@st.com, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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 | 132 +++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 159 insertions(+), 1 deletion(-) create mode 100644 include/linux/trace.h diff --git a/include/linux/trace.h b/include/linux/trace.h new file mode 100644 index 0000000..eb1c5b8 --- /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 char *, 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..db94ec1 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 +2129,132 @@ 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); + + if (export->write) + export->write((char *)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 +2273,11 @@ 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