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Subject[PATCH tracing/kprobes 4/6] tracing/kprobes: Add probe handler dispatcher for support perf and ftrace
Date
Add kprobe_dispatcher and kretprobe_dispatcher for dispatching event
to both of profile handler and tracing handler.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
---
kernel/trace/trace_kprobe.c | 85 ++++++++++++++++++++++++++++++++-----------
1 files changed, 63 insertions(+), 22 deletions(-)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index ea0db8e..70b632c 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -185,10 +185,15 @@ struct probe_arg {
const char *name;
};

+/* Flags for trace_probe */
+#define TP_FLAG_TRACE 1
+#define TP_FLAG_PROFILE 2
+
struct trace_probe {
struct list_head list;
struct kretprobe rp; /* Use rp.kp for kprobe use */
unsigned long nhit;
+ unsigned int flags; /* For TP_FLAG_* */
const char *symbol; /* symbol name */
struct ftrace_event_call call;
struct trace_event event;
@@ -200,10 +205,6 @@ struct trace_probe {
(offsetof(struct trace_probe, args) + \
(sizeof(struct probe_arg) * (n)))

-static int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs);
-static int kretprobe_trace_func(struct kretprobe_instance *ri,
- struct pt_regs *regs);
-
static __kprobes int probe_is_return(struct trace_probe *tp)
{
return tp->rp.handler != NULL;
@@ -263,6 +264,10 @@ static void unregister_probe_event(struct trace_probe *tp);
static DEFINE_MUTEX(probe_lock);
static LIST_HEAD(probe_list);

+static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
+static int kretprobe_dispatcher(struct kretprobe_instance *ri,
+ struct pt_regs *regs);
+
/*
* Allocate new trace_probe and initialize it (including kprobes).
*/
@@ -288,11 +293,10 @@ static struct trace_probe *alloc_trace_probe(const char *group,
} else
tp->rp.kp.addr = addr;

- /* Set handler here for checking whether this probe is return or not. */
if (is_return)
- tp->rp.handler = kretprobe_trace_func;
+ tp->rp.handler = kretprobe_dispatcher;
else
- tp->rp.kp.pre_handler = kprobe_trace_func;
+ tp->rp.kp.pre_handler = kprobe_dispatcher;

if (!event)
goto error;
@@ -379,6 +383,7 @@ static int register_trace_probe(struct trace_probe *tp)
goto end;
}

+ tp->flags = TP_FLAG_TRACE;
if (probe_is_return(tp))
ret = register_kretprobe(&tp->rp);
else
@@ -987,23 +992,24 @@ static int probe_event_enable(struct ftrace_event_call *call)
{
struct trace_probe *tp = (struct trace_probe *)call->data;

- if (probe_is_return(tp)) {
- tp->rp.handler = kretprobe_trace_func;
+ tp->flags |= TP_FLAG_TRACE;
+ if (probe_is_return(tp))
return enable_kretprobe(&tp->rp);
- } else {
- tp->rp.kp.pre_handler = kprobe_trace_func;
+ else
return enable_kprobe(&tp->rp.kp);
- }
}

static void probe_event_disable(struct ftrace_event_call *call)
{
struct trace_probe *tp = (struct trace_probe *)call->data;

- if (probe_is_return(tp))
- disable_kretprobe(&tp->rp);
- else
- disable_kprobe(&tp->rp.kp);
+ tp->flags &= ~TP_FLAG_TRACE;
+ if (!(tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE))) {
+ if (probe_is_return(tp))
+ disable_kretprobe(&tp->rp);
+ else
+ disable_kprobe(&tp->rp.kp);
+ }
}

static int probe_event_raw_init(struct ftrace_event_call *event_call)
@@ -1212,22 +1218,57 @@ static int probe_profile_enable(struct ftrace_event_call *call)
if (atomic_inc_return(&call->profile_count))
return 0;

- if (probe_is_return(tp)) {
- tp->rp.handler = kretprobe_profile_func;
+ tp->flags |= TP_FLAG_PROFILE;
+ if (probe_is_return(tp))
return enable_kretprobe(&tp->rp);
- } else {
- tp->rp.kp.pre_handler = kprobe_profile_func;
+ else
return enable_kprobe(&tp->rp.kp);
- }
}

static void probe_profile_disable(struct ftrace_event_call *call)
{
+ struct trace_probe *tp = (struct trace_probe *)call->data;
+
if (atomic_add_negative(-1, &call->profile_count))
- probe_event_disable(call);
+ tp->flags &= ~TP_FLAG_PROFILE;
+
+ if (!(tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE))) {
+ if (probe_is_return(tp))
+ disable_kretprobe(&tp->rp);
+ else
+ disable_kprobe(&tp->rp.kp);
+ }
}
+#endif /* CONFIG_EVENT_PROFILE */
+
+
+static __kprobes
+int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
+{
+ struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);

+ if (tp->flags & TP_FLAG_TRACE)
+ kprobe_trace_func(kp, regs);
+#ifdef CONFIG_EVENT_PROFILE
+ if (tp->flags & TP_FLAG_PROFILE)
+ kprobe_profile_func(kp, regs);
#endif /* CONFIG_EVENT_PROFILE */
+ return 0; /* We don't tweek kernel, so just return 0 */
+}
+
+static __kprobes
+int kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+ struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
+
+ if (tp->flags & TP_FLAG_TRACE)
+ kretprobe_trace_func(ri, regs);
+#ifdef CONFIG_EVENT_PROFILE
+ if (tp->flags & TP_FLAG_PROFILE)
+ kretprobe_profile_func(ri, regs);
+#endif /* CONFIG_EVENT_PROFILE */
+ return 0; /* We don't tweek kernel, so just return 0 */
+}

static int register_probe_event(struct trace_probe *tp)
{

--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com


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