tracing/kprobes: Add probe handler dispatcher to support perf and ftrace concurrent use

Add kprobe_dispatcher and kretprobe_dispatcher to dispatch event
in both profile and tracing handlers.

This allows simultaneous kprobe uses by ftrace and perf.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
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: 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: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20090914204920.18779.57555.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 63 insertions, 22 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index ea0db8eee570..70b632c3bd08 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)
 {