From: Chunyan Zhang <zhang.chunyan@linaro.org>
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 V8 1/3] tracing: add a possibility of exporting function trace to other places instead of ring buffer only
Date: Fri, 18 Nov 2016 11:07:32 +0800 [thread overview]
Message-ID: <1479438454-28650-2-git-send-email-zhang.chunyan@linaro.org> (raw)
In-Reply-To: <1479438454-28650-1-git-send-email-zhang.chunyan@linaro.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 <zhang.chunyan@linaro.org>
---
include/linux/trace.h | 28 +++++++++++
kernel/trace/trace.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 156 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..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 <linux/poll.h>
#include <linux/nmi.h>
#include <linux/fs.h>
+#include <linux/trace.h>
#include <linux/sched/rt.h>
#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
--
2.7.4
next prev parent reply other threads:[~2016-11-18 3:09 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-18 3:07 [PATCH V8 0/3] Integration of function trace with System Trace IP blocks Chunyan Zhang
2016-11-18 3:07 ` Chunyan Zhang [this message]
2016-11-18 14:29 ` [PATCH V8 1/3] tracing: add a possibility of exporting function trace to other places instead of ring buffer only Steven Rostedt
2016-11-18 14:57 ` Alexander Shishkin
2016-11-18 16:45 ` Steven Rostedt
2016-11-21 3:18 ` Chunyan Zhang
2016-11-18 3:07 ` [PATCH V8 2/3] stm class: ftrace: Add ftrace-export-over-stm driver Chunyan Zhang
2016-11-18 14:45 ` Alexander Shishkin
2016-11-18 3:07 ` [PATCH V8 3/3] stm: Mark the functions of writing buffer with notrace Chunyan Zhang
2016-11-18 14:45 ` Alexander Shishkin
2016-11-21 2:24 ` Chunyan Zhang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1479438454-28650-2-git-send-email-zhang.chunyan@linaro.org \
--to=zhang.chunyan@linaro.org \
--cc=alexander.shishkin@linux.intel.com \
--cc=felipe.balbi@linux.intel.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mathieu.poirier@linaro.org \
--cc=mike.leach@arm.com \
--cc=mingo@redhat.com \
--cc=nicolas.guion@st.com \
--cc=philippe.langlais@st.com \
--cc=rostedt@goodmis.org \
--cc=tor@ti.com \
--cc=zhang.lyra@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).