3 files changed, 175 insertions, 6 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index d9eb39e4bb38..f267723c3c52 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -804,6 +804,18 @@ struct ftrace_event_call {
 #endif
 };
 
+struct event_subsystem {
+        struct list_head        list;
+        const char              *name;
+        struct dentry           *entry;
+        struct filter_pred      **preds;
+};
+
+#define events_for_each(event)                                          \
+        for (event = __start_ftrace_events;                             \
+             (unsigned long)event < (unsigned long)__stop_ftrace_events; \
+             event++)
+
 #define MAX_FILTER_PRED 8
 
 struct filter_pred;
@@ -832,6 +844,9 @@ extern int filter_add_pred(struct ftrace_event_call *call,
                            struct filter_pred *pred);
 extern void filter_free_preds(struct ftrace_event_call *call);
 extern int filter_match_preds(struct ftrace_event_call *call, void *rec);
+extern void filter_free_subsystem_preds(struct event_subsystem *system);
+extern int filter_add_subsystem_pred(struct event_subsystem *system,
+                                     struct filter_pred *pred);
 
 void event_trace_printk(unsigned long ip, const char *fmt, ...);
 extern struct ftrace_event_call __start_ftrace_events[];
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 97470c48956e..97d4daaddd9a 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -524,6 +524,71 @@ event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
         return cnt;
 }
 
+static ssize_t
+subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
+                      loff_t *ppos)
+{
+        struct event_subsystem *system = filp->private_data;
+        struct trace_seq *s;
+        int r;
+
+        if (*ppos)
+                return 0;
+
+        s = kmalloc(sizeof(*s), GFP_KERNEL);
+        if (!s)
+                return -ENOMEM;
+
+        trace_seq_init(s);
+
+        r = filter_print_preds(system->preds, s->buffer);
+        r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, r);
+
+        kfree(s);
+
+        return r;
+}
+
+static ssize_t
+subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
+                       loff_t *ppos)
+{
+        struct event_subsystem *system = filp->private_data;
+        char buf[64], *pbuf = buf;
+        struct filter_pred *pred;
+        int err;
+
+        if (cnt >= sizeof(buf))
+                return -EINVAL;
+
+        if (copy_from_user(&buf, ubuf, cnt))
+                return -EFAULT;
+
+        pred = kzalloc(sizeof(*pred), GFP_KERNEL);
+        if (!pred)
+                return -ENOMEM;
+
+        err = filter_parse(&pbuf, pred);
+        if (err < 0) {
+                filter_free_pred(pred);
+                return err;
+        }
+
+        if (pred->clear) {
+                filter_free_subsystem_preds(system);
+                return cnt;
+        }
+
+        if (filter_add_subsystem_pred(system, pred)) {
+                filter_free_pred(pred);
+                return -EINVAL;
+        }
+
+        *ppos += cnt;
+
+        return cnt;
+}
+
 static const struct seq_operations show_event_seq_ops = {
         .start = t_start,
         .next = t_next,
@@ -575,6 +640,12 @@ static const struct file_operations ftrace_event_filter_fops = {
         .write = event_filter_write,
 };
 
+static const struct file_operations ftrace_subsystem_filter_fops = {
+        .open = tracing_open_generic,
+        .read = subsystem_filter_read,
+        .write = subsystem_filter_write,
+};
+
 static struct dentry *event_trace_events_dir(void)
 {
         static struct dentry *d_tracer;
@@ -595,18 +666,13 @@ static struct dentry *event_trace_events_dir(void)
         return d_events;
 }
 
-struct event_subsystem {
-        struct list_head        list;
-        const char              *name;
-        struct dentry           *entry;
-};
-
 static LIST_HEAD(event_subsystems);
 
 static struct dentry *
 event_subsystem_dir(const char *name, struct dentry *d_events)
 {
         struct event_subsystem *system;
+        struct dentry *entry;
 
         /* First see if we did not already create this dir */
         list_for_each_entry(system, &event_subsystems, list) {
@@ -633,6 +699,14 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
         system->name = name;
         list_add(&system->list, &event_subsystems);
 
+        system->preds = NULL;
+
+        entry = debugfs_create_file("filter", 0444, system->entry, system,
+                                    &ftrace_subsystem_filter_fops);
+        if (!entry)
+                pr_warning("Could not create debugfs "
+                           "'%s/filter' entry\n", name);
+
         return system->entry;
 }
 
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 8e8c5fa25be9..1ab20cee0e4c 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -181,6 +181,27 @@ void filter_free_preds(struct ftrace_event_call *call)
         }
 }
 
+void filter_free_subsystem_preds(struct event_subsystem *system)
+{
+        struct ftrace_event_call *call = __start_ftrace_events;
+        int i;
+
+        if (system->preds) {
+                for (i = 0; i < MAX_FILTER_PRED; i++)
+                        filter_free_pred(system->preds[i]);
+                kfree(system->preds);
+                system->preds = NULL;
+        }
+
+        events_for_each(call) {
+                if (!call->name || !call->regfunc)
+                        continue;
+
+                if (!strcmp(call->system, system->name))
+                        filter_free_preds(call);
+        }
+}
+
 static int __filter_add_pred(struct ftrace_event_call *call,
                              struct filter_pred *pred)
 {
@@ -250,6 +271,65 @@ int filter_add_pred(struct ftrace_event_call *call, struct filter_pred *pred)
         return __filter_add_pred(call, pred);
 }
 
+static struct filter_pred *copy_pred(struct filter_pred *pred)
+{
+        struct filter_pred *new_pred = kmalloc(sizeof(*pred), GFP_KERNEL);
+        if (!new_pred)
+                return NULL;
+
+        memcpy(new_pred, pred, sizeof(*pred));
+        if (pred->str_val) {
+                new_pred->str_val = kstrdup(pred->str_val, GFP_KERNEL);
+                new_pred->field_name = kstrdup(pred->field_name, GFP_KERNEL);
+                if (!new_pred->str_val) {
+                        kfree(new_pred);
+                        return NULL;
+                }
+        }
+
+        return new_pred;
+}
+
+int filter_add_subsystem_pred(struct event_subsystem *system,
+                              struct filter_pred *pred)
+{
+        struct ftrace_event_call *call = __start_ftrace_events;
+        struct filter_pred *event_pred;
+        int i;
+
+        if (system->preds && !pred->compound)
+                filter_free_subsystem_preds(system);
+
+        if (!system->preds) {
+                system->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
+                                        GFP_KERNEL);
+                if (!system->preds)
+                        return -ENOMEM;
+        }
+
+        for (i = 0; i < MAX_FILTER_PRED; i++) {
+                if (!system->preds[i]) {
+                        system->preds[i] = pred;
+                        break;
+                }
+                if (i == MAX_FILTER_PRED - 1)
+                        return -EINVAL;
+        }
+
+        events_for_each(call) {
+                if (!call->name || !call->regfunc)
+                        continue;
+
+                if (!strcmp(call->system, system->name)) {
+                        event_pred = copy_pred(pred);
+                        if (event_pred)
+                                filter_add_pred(call, event_pred);
+                }
+        }
+
+        return 0;
+}
+
 int filter_parse(char **pbuf, struct filter_pred *pred)
 {
         char *tmp, *tok, *val_str = NULL;