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Message-Id: <1327776209-4883-6-git-send-email-jolsa@redhat.com>
Date: Sat, 28 Jan 2012 19:43:27 +0100
From: Jiri Olsa <jolsa@...hat.com>
To: rostedt@...dmis.org, fweisbec@...il.com, mingo@...hat.com,
paulus@...ba.org, acme@...stprotocols.net, a.p.zijlstra@...llo.nl
Cc: linux-kernel@...r.kernel.org, aarapov@...hat.com,
Jiri Olsa <jolsa@...hat.com>
Subject: [PATCH 5/7] ftrace, perf: Add support to use function tracepoint in perf
Adding perf registration support for the ftrace function event,
so it is now possible to register it via perf interface.
The perf_event struct statically contains ftrace_ops as a handle
for function tracer. The function tracer is registered/unregistered
in open/close actions.
To be efficient, we enable/disable ftrace_ops each time the traced
process is scheduled in/out (via TRACE_REG_PERF_(ADD|DELL) handlers).
This way tracing is enabled only when the process is running.
Intentionally using this way instead of the event's hw state
PERF_HES_STOPPED, which would not disable the ftrace_ops.
It is now possible to use function trace within perf commands
like:
perf record -e ftrace:function ls
perf stat -e ftrace:function ls
Allowed only for root.
Signed-off-by: Jiri Olsa <jolsa@...hat.com>
---
include/linux/perf_event.h | 3 +
kernel/trace/trace.h | 2 +
kernel/trace/trace_event_perf.c | 90 +++++++++++++++++++++++++++++++++++++++
kernel/trace/trace_export.c | 28 ++++++++++++
4 files changed, 123 insertions(+), 0 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 412b790..92a056f 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -859,6 +859,9 @@ struct perf_event {
#ifdef CONFIG_EVENT_TRACING
struct ftrace_event_call *tp_event;
struct event_filter *filter;
+#ifdef CONFIG_FUNCTION_TRACER
+ struct ftrace_ops ftrace_ops;
+#endif
#endif
#ifdef CONFIG_CGROUP_PERF
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 0eaf077..8ff7324 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -591,6 +591,8 @@ static inline int ftrace_trace_task(struct task_struct *task)
static inline int ftrace_is_dead(void) { return 0; }
#endif
+int ftrace_event_is_function(struct ftrace_event_call *call);
+
/*
* struct trace_parser - servers for reading the user input separated by spaces
* @cont: set if the input is not complete - no final space char was found
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index d72af0b..8ee0461 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -24,6 +24,11 @@ static int total_ref_count;
static int perf_trace_event_perm(struct ftrace_event_call *tp_event,
struct perf_event *p_event)
{
+ /* The ftrace function trace is allowed only for root. */
+ if (ftrace_event_is_function(tp_event) &&
+ perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
/* No tracing, just counting, so no obvious leak */
if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
return 0;
@@ -250,3 +255,88 @@ __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
return raw_data;
}
EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
+
+
+static void
+perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip)
+{
+ struct ftrace_entry *entry;
+ struct hlist_head *head;
+ struct pt_regs regs;
+ int rctx;
+
+#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
+ sizeof(u64)) - sizeof(u32))
+
+ BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
+
+ perf_fetch_caller_regs(®s);
+
+ entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);
+ if (!entry)
+ return;
+
+ entry->ip = ip;
+ entry->parent_ip = parent_ip;
+
+ head = this_cpu_ptr(event_function.perf_events);
+ perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
+ 1, ®s, head);
+
+#undef ENTRY_SIZE
+}
+
+static int perf_ftrace_function_register(struct perf_event *event)
+{
+ struct ftrace_ops *ops = &event->ftrace_ops;
+
+ ops->flags |= FTRACE_OPS_FL_CONTROL;
+ ops->func = perf_ftrace_function_call;
+ return register_ftrace_function(ops);
+}
+
+static int perf_ftrace_function_unregister(struct perf_event *event)
+{
+ struct ftrace_ops *ops = &event->ftrace_ops;
+ return unregister_ftrace_function(ops);
+}
+
+static void perf_ftrace_function_enable(struct perf_event *event)
+{
+ ftrace_function_local_enable(&event->ftrace_ops);
+}
+
+static void perf_ftrace_function_disable(struct perf_event *event)
+{
+ ftrace_function_local_disable(&event->ftrace_ops);
+}
+
+int perf_ftrace_event_register(struct ftrace_event_call *call,
+ enum trace_reg type, void *data)
+{
+ int etype = call->event.type;
+
+ if (etype != TRACE_FN)
+ return -EINVAL;
+
+ switch (type) {
+ case TRACE_REG_REGISTER:
+ case TRACE_REG_UNREGISTER:
+ break;
+ case TRACE_REG_PERF_REGISTER:
+ case TRACE_REG_PERF_UNREGISTER:
+ return 0;
+ case TRACE_REG_PERF_OPEN:
+ return perf_ftrace_function_register(data);
+ case TRACE_REG_PERF_CLOSE:
+ return perf_ftrace_function_unregister(data);
+ case TRACE_REG_PERF_ADD:
+ perf_ftrace_function_enable(data);
+ return 0;
+ case TRACE_REG_PERF_DEL:
+ perf_ftrace_function_disable(data);
+ return 0;
+ }
+
+ return -EINVAL;
+}
diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
index bbeec31..867653c 100644
--- a/kernel/trace/trace_export.c
+++ b/kernel/trace/trace_export.c
@@ -131,6 +131,28 @@ ftrace_define_fields_##name(struct ftrace_event_call *event_call) \
#include "trace_entries.h"
+static int ftrace_event_class_register(struct ftrace_event_call *call,
+ enum trace_reg type, void *data)
+{
+ switch (type) {
+ case TRACE_REG_PERF_REGISTER:
+ case TRACE_REG_PERF_UNREGISTER:
+ return 0;
+ case TRACE_REG_PERF_OPEN:
+ case TRACE_REG_PERF_CLOSE:
+ case TRACE_REG_PERF_ADD:
+ case TRACE_REG_PERF_DEL:
+#ifdef CONFIG_PERF_EVENTS
+ return perf_ftrace_event_register(call, type, data);
+#endif
+ case TRACE_REG_REGISTER:
+ case TRACE_REG_UNREGISTER:
+ break;
+ }
+
+ return -EINVAL;
+}
+
#undef __entry
#define __entry REC
@@ -159,6 +181,7 @@ struct ftrace_event_class event_class_ftrace_##call = { \
.system = __stringify(TRACE_SYSTEM), \
.define_fields = ftrace_define_fields_##call, \
.fields = LIST_HEAD_INIT(event_class_ftrace_##call.fields),\
+ .reg = ftrace_event_class_register, \
}; \
\
struct ftrace_event_call __used event_##call = { \
@@ -170,4 +193,9 @@ struct ftrace_event_call __used event_##call = { \
struct ftrace_event_call __used \
__attribute__((section("_ftrace_events"))) *__event_##call = &event_##call;
+int ftrace_event_is_function(struct ftrace_event_call *call)
+{
+ return call == &event_function;
+}
+
#include "trace_entries.h"
--
1.7.1
--
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