tracing/profile: Add filter support

- Add an ioctl to allocate a filter for a perf event.

- Free the filter when the associated perf event is to be freed.

- Do the filtering in perf_swevent_match().

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <4AD69546.8050401@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 109 insertions, 27 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index ffe53ddbe67a..4959ada9e0bb 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -743,7 +743,8 @@ filter_check_discard(struct ftrace_event_call *call, void *rec,
                      struct ring_buffer *buffer,
                      struct ring_buffer_event *event)
 {
-        if (unlikely(call->filter_active) && !filter_match_preds(call, rec)) {
+        if (unlikely(call->filter_active) &&
+            !filter_match_preds(call->filter, rec)) {
                 ring_buffer_discard_commit(buffer, event);
                 return 1;
         }
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 273845fce393..e27bb6acc2dd 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -21,6 +21,7 @@
 #include <linux/module.h>
 #include <linux/ctype.h>
 #include <linux/mutex.h>
+#include <linux/perf_event.h>
 
 #include "trace.h"
 #include "trace_output.h"
@@ -363,9 +364,8 @@ static void filter_build_regex(struct filter_pred *pred)
 }
 
 /* return 1 if event matches, 0 otherwise (discard) */
-int filter_match_preds(struct ftrace_event_call *call, void *rec)
+int filter_match_preds(struct event_filter *filter, void *rec)
 {
-        struct event_filter *filter = call->filter;
         int match, top = 0, val1 = 0, val2 = 0;
         int stack[MAX_FILTER_PRED];
         struct filter_pred *pred;
@@ -538,9 +538,8 @@ static void filter_disable_preds(struct ftrace_event_call *call)
                 filter->preds[i]->fn = filter_pred_none;
 }
 
-void destroy_preds(struct ftrace_event_call *call)
+static void __free_preds(struct event_filter *filter)
 {
-        struct event_filter *filter = call->filter;
         int i;
 
         if (!filter)
@@ -553,21 +552,24 @@ void destroy_preds(struct ftrace_event_call *call)
         kfree(filter->preds);
         kfree(filter->filter_string);
         kfree(filter);
+}
+
+void destroy_preds(struct ftrace_event_call *call)
+{
+        __free_preds(call->filter);
         call->filter = NULL;
+        call->filter_active = 0;
 }
 
-static int init_preds(struct ftrace_event_call *call)
+static struct event_filter *__alloc_preds(void)
 {
         struct event_filter *filter;
         struct filter_pred *pred;
         int i;
 
-        if (call->filter)
-                return 0;
-
-        filter = call->filter = kzalloc(sizeof(*filter), GFP_KERNEL);
-        if (!call->filter)
-                return -ENOMEM;
+        filter = kzalloc(sizeof(*filter), GFP_KERNEL);
+        if (!filter)
+                return ERR_PTR(-ENOMEM);
 
         filter->n_preds = 0;
 
@@ -583,12 +585,24 @@ static int init_preds(struct ftrace_event_call *call)
                 filter->preds[i] = pred;
         }
 
-        return 0;
+        return filter;
 
 oom:
-        destroy_preds(call);
+        __free_preds(filter);
+        return ERR_PTR(-ENOMEM);
+}
+
+static int init_preds(struct ftrace_event_call *call)
+{
+        if (call->filter)
+                return 0;
+
+        call->filter_active = 0;
+        call->filter = __alloc_preds();
+        if (IS_ERR(call->filter))
+                return PTR_ERR(call->filter);
 
-        return -ENOMEM;
+        return 0;
 }
 
 static int init_subsystem_preds(struct event_subsystem *system)
@@ -629,10 +643,10 @@ static void filter_free_subsystem_preds(struct event_subsystem *system)
 
 static int filter_add_pred_fn(struct filter_parse_state *ps,
                               struct ftrace_event_call *call,
+                              struct event_filter *filter,
                               struct filter_pred *pred,
                               filter_pred_fn_t fn)
 {
-        struct event_filter *filter = call->filter;
         int idx, err;
 
         if (filter->n_preds == MAX_FILTER_PRED) {
@@ -647,7 +661,6 @@ static int filter_add_pred_fn(struct filter_parse_state *ps,
                 return err;
 
         filter->n_preds++;
-        call->filter_active = 1;
 
         return 0;
 }
@@ -726,6 +739,7 @@ static filter_pred_fn_t select_comparison_fn(int op, int field_size,
 
 static int filter_add_pred(struct filter_parse_state *ps,
                            struct ftrace_event_call *call,
+                           struct event_filter *filter,
                            struct filter_pred *pred,
                            bool dry_run)
 {
@@ -795,7 +809,7 @@ static int filter_add_pred(struct filter_parse_state *ps,
 
 add_pred_fn:
         if (!dry_run)
-                return filter_add_pred_fn(ps, call, pred, fn);
+                return filter_add_pred_fn(ps, call, filter, pred, fn);
         return 0;
 }
 
@@ -1154,6 +1168,7 @@ static int check_preds(struct filter_parse_state *ps)
 }
 
 static int replace_preds(struct ftrace_event_call *call,
+                         struct event_filter *filter,
                          struct filter_parse_state *ps,
                          char *filter_string,
                          bool dry_run)
@@ -1200,7 +1215,7 @@ static int replace_preds(struct ftrace_event_call *call,
 add_pred:
                 if (!pred)
                         return -ENOMEM;
-                err = filter_add_pred(ps, call, pred, dry_run);
+                err = filter_add_pred(ps, call, filter, pred, dry_run);
                 filter_free_pred(pred);
                 if (err)
                         return err;
@@ -1216,6 +1231,7 @@ static int replace_system_preds(struct event_subsystem *system,
                                 char *filter_string)
 {
         struct ftrace_event_call *call;
+        struct event_filter *filter;
         int err;
         bool fail = true;
 
@@ -1228,17 +1244,19 @@ static int replace_system_preds(struct event_subsystem *system,
                         continue;
 
                 /* try to see if the filter can be applied */
-                err = replace_preds(call, ps, filter_string, true);
+                err = replace_preds(call, filter, ps, filter_string, true);
                 if (err)
                         continue;
 
                 /* really apply the filter */
                 filter_disable_preds(call);
-                err = replace_preds(call, ps, filter_string, false);
+                err = replace_preds(call, filter, ps, filter_string, false);
                 if (err)
                         filter_disable_preds(call);
-                else
-                        replace_filter_string(call->filter, filter_string);
+                else {
+                        call->filter_active = 1;
+                        replace_filter_string(filter, filter_string);
+                }
                 fail = false;
         }
 
@@ -1252,7 +1270,6 @@ static int replace_system_preds(struct event_subsystem *system,
 int apply_event_filter(struct ftrace_event_call *call, char *filter_string)
 {
         int err;
-
         struct filter_parse_state *ps;
 
         mutex_lock(&event_mutex);
@@ -1283,10 +1300,11 @@ int apply_event_filter(struct ftrace_event_call *call, char *filter_string)
                 goto out;
         }
 
-        err = replace_preds(call, ps, filter_string, false);
+        err = replace_preds(call, call->filter, ps, filter_string, false);
         if (err)
                 append_filter_err(ps, call->filter);
-
+        else
+                call->filter_active = 1;
 out:
         filter_opstack_clear(ps);
         postfix_clear(ps);
@@ -1301,7 +1319,6 @@ int apply_subsystem_event_filter(struct event_subsystem *system,
                                  char *filter_string)
 {
         int err;
-
         struct filter_parse_state *ps;
 
         mutex_lock(&event_mutex);
@@ -1345,3 +1362,67 @@ out_unlock:
         return err;
 }
 
+#ifdef CONFIG_EVENT_PROFILE
+
+void ftrace_profile_free_filter(struct perf_event *event)
+{
+        struct event_filter *filter = event->filter;
+
+        event->filter = NULL;
+        __free_preds(filter);
+}
+
+int ftrace_profile_set_filter(struct perf_event *event, int event_id,
+                              char *filter_str)
+{
+        int err;
+        struct event_filter *filter;
+        struct filter_parse_state *ps;
+        struct ftrace_event_call *call = NULL;
+
+        mutex_lock(&event_mutex);
+
+        list_for_each_entry(call, &ftrace_events, list) {
+                if (call->id == event_id)
+                        break;
+        }
+        if (!call)
+                return -EINVAL;
+
+        if (event->filter)
+                return -EEXIST;
+
+        filter = __alloc_preds();
+        if (IS_ERR(filter))
+                return PTR_ERR(filter);
+
+        err = -ENOMEM;
+        ps = kzalloc(sizeof(*ps), GFP_KERNEL);
+        if (!ps)
+                goto free_preds;
+
+        parse_init(ps, filter_ops, filter_str);
+        err = filter_parse(ps);
+        if (err)
+                goto free_ps;
+
+        err = replace_preds(call, filter, ps, filter_str, false);
+        if (!err)
+                event->filter = filter;
+
+free_ps:
+        filter_opstack_clear(ps);
+        postfix_clear(ps);
+        kfree(ps);
+
+free_preds:
+        if (err)
+                __free_preds(filter);
+
+        mutex_unlock(&event_mutex);
+
+        return err;
+}
+
+#endif /* CONFIG_EVENT_PROFILE */
+