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tracing: Add 'onmatch' hist trigger action support
authorTom Zanussi <tom.zanussi@linux.intel.com>
Tue, 16 Jan 2018 02:52:00 +0000 (20:52 -0600)
committerSteven Rostedt (VMware) <rostedt@goodmis.org>
Sat, 10 Mar 2018 21:05:59 +0000 (16:05 -0500)
Add an 'onmatch(matching.event).<synthetic_event_name>(param list)'
hist trigger action which is invoked with the set of variables or
event fields named in the 'param list'.  The result is the generation
of a synthetic event that consists of the values contained in those
variables and/or fields at the time the invoking event was hit.

As an example the below defines a simple synthetic event using a
variable defined on the sched_wakeup_new event, and shows the event
definition with unresolved fields, since the sched_wakeup_new event
with the testpid variable hasn't been defined yet:

    # echo 'wakeup_new_test pid_t pid; int prio' >> \
      /sys/kernel/debug/tracing/synthetic_events

    # cat /sys/kernel/debug/tracing/synthetic_events
      wakeup_new_test pid_t pid; int prio

The following hist trigger both defines a testpid variable and
specifies an onmatch() trace action that uses that variable along with
a non-variable field to generate a wakeup_new_test synthetic event
whenever a sched_wakeup_new event occurs, which because of the 'if
comm == "cyclictest"' filter only happens when the executable is
cyclictest:

    # echo 'hist:testpid=pid:keys=$testpid:\
      onmatch(sched.sched_wakeup_new).wakeup_new_test($testpid, prio) \
        if comm=="cyclictest"' >> \
      /sys/kernel/debug/tracing/events/sched/sched_wakeup_new/trigger

Creating and displaying a histogram based on those events is now just
a matter of using the fields and new synthetic event in the
tracing/events/synthetic directory, as usual:

    # echo 'hist:keys=pid,prio:sort=pid,prio' >> \
      /sys/kernel/debug/tracing/events/synthetic/wakeup_new_test/trigger

Link: http://lkml.kernel.org/r/8c2a574bcb7530c876629c901ecd23911b14afe8.1516069914.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Rajvi Jingar <rajvi.jingar@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
kernel/trace/trace_events_hist.c

index ad96fd1..9ac6089 100644 (file)
@@ -285,6 +285,8 @@ struct hist_trigger_data {
        struct action_data              *actions[HIST_ACTIONS_MAX];
        unsigned int                    n_actions;
 
+       struct hist_field               *synth_var_refs[SYNTH_FIELDS_MAX];
+       unsigned int                    n_synth_var_refs;
        struct field_var                *field_vars[SYNTH_FIELDS_MAX];
        unsigned int                    n_field_vars;
        unsigned int                    n_field_var_str;
@@ -321,7 +323,18 @@ typedef void (*action_fn_t) (struct hist_trigger_data *hist_data,
 
 struct action_data {
        action_fn_t             fn;
-       unsigned int            var_ref_idx;
+       unsigned int            n_params;
+       char                    *params[SYNTH_FIELDS_MAX];
+
+       union {
+               struct {
+                       unsigned int            var_ref_idx;
+                       char                    *match_event;
+                       char                    *match_event_system;
+                       char                    *synth_event_name;
+                       struct synth_event      *synth_event;
+               } onmatch;
+       };
 };
 
 static LIST_HEAD(synth_event_list);
@@ -887,6 +900,21 @@ static struct synth_event *alloc_synth_event(char *event_name, int n_fields,
        return event;
 }
 
+static void action_trace(struct hist_trigger_data *hist_data,
+                        struct tracing_map_elt *elt, void *rec,
+                        struct ring_buffer_event *rbe,
+                        struct action_data *data, u64 *var_ref_vals)
+{
+       struct synth_event *event = data->onmatch.synth_event;
+
+       trace_synth(event, var_ref_vals, data->onmatch.var_ref_idx);
+}
+
+struct hist_var_data {
+       struct list_head list;
+       struct hist_trigger_data *hist_data;
+};
+
 static void add_or_delete_synth_event(struct synth_event *event, int delete)
 {
        if (delete)
@@ -1124,11 +1152,6 @@ static u64 hist_field_timestamp(struct hist_field *hist_field,
        return ts;
 }
 
-struct hist_var_data {
-       struct list_head list;
-       struct hist_trigger_data *hist_data;
-};
-
 static struct hist_field *
 check_field_for_var_ref(struct hist_field *hist_field,
                        struct hist_trigger_data *var_data,
@@ -1194,6 +1217,14 @@ static struct hist_field *find_var_ref(struct hist_trigger_data *hist_data,
                        return found;
        }
 
+       for (i = 0; i < hist_data->n_synth_var_refs; i++) {
+               hist_field = hist_data->synth_var_refs[i];
+               found = check_field_for_var_refs(hist_data, hist_field,
+                                                var_data, var_idx, 0);
+               if (found)
+                       return found;
+       }
+
        return found;
 }
 
@@ -1422,6 +1453,37 @@ static struct hist_field *find_file_var(struct trace_event_file *file,
        return NULL;
 }
 
+static struct hist_field *
+find_match_var(struct hist_trigger_data *hist_data, char *var_name)
+{
+       struct trace_array *tr = hist_data->event_file->tr;
+       struct hist_field *hist_field, *found = NULL;
+       struct trace_event_file *file;
+       unsigned int i;
+
+       for (i = 0; i < hist_data->n_actions; i++) {
+               struct action_data *data = hist_data->actions[i];
+
+               if (data->fn == action_trace) {
+                       char *system = data->onmatch.match_event_system;
+                       char *event_name = data->onmatch.match_event;
+
+                       file = find_var_file(tr, system, event_name, var_name);
+                       if (!file)
+                               continue;
+                       hist_field = find_file_var(file, var_name);
+                       if (hist_field) {
+                               if (found) {
+                                       return ERR_PTR(-EINVAL);
+                               }
+
+                               found = hist_field;
+                       }
+               }
+       }
+       return found;
+}
+
 static struct hist_field *find_event_var(struct hist_trigger_data *hist_data,
                                         char *system,
                                         char *event_name,
@@ -1431,6 +1493,14 @@ static struct hist_field *find_event_var(struct hist_trigger_data *hist_data,
        struct hist_field *hist_field = NULL;
        struct trace_event_file *file;
 
+       if (!system || !event_name) {
+               hist_field = find_match_var(hist_data, var_name);
+               if (IS_ERR(hist_field))
+                       return NULL;
+               if (hist_field)
+                       return hist_field;
+       }
+
        file = find_var_file(tr, system, event_name, var_name);
        if (!file)
                return NULL;
@@ -1622,11 +1692,21 @@ static void destroy_hist_trigger_attrs(struct hist_trigger_attrs *attrs)
 
 static int parse_action(char *str, struct hist_trigger_attrs *attrs)
 {
-       int ret = 0;
+       int ret = -EINVAL;
 
        if (attrs->n_actions >= HIST_ACTIONS_MAX)
                return ret;
 
+       if ((strncmp(str, "onmatch(", strlen("onmatch(")) == 0)) {
+               attrs->action_str[attrs->n_actions] = kstrdup(str, GFP_KERNEL);
+               if (!attrs->action_str[attrs->n_actions]) {
+                       ret = -ENOMEM;
+                       return ret;
+               }
+               attrs->n_actions++;
+               ret = 0;
+       }
+
        return ret;
 }
 
@@ -2635,7 +2715,7 @@ find_synthetic_field_var(struct hist_trigger_data *target_hist_data,
  *
  * Return: The variable created for the field.
  */
-struct hist_field *
+static struct hist_field *
 create_field_var_hist(struct hist_trigger_data *target_hist_data,
                      char *subsys_name, char *event_name, char *field_name)
 {
@@ -2748,7 +2828,7 @@ create_field_var_hist(struct hist_trigger_data *target_hist_data,
        return event_var;
 }
 
-struct hist_field *
+static struct hist_field *
 find_target_event_var(struct hist_trigger_data *hist_data,
                      char *subsys_name, char *event_name, char *var_name)
 {
@@ -2919,7 +2999,7 @@ static struct field_var *create_field_var(struct hist_trigger_data *hist_data,
  *
  * Return: The variable created for the field.
  */
-struct field_var *
+static struct field_var *
 create_target_field_var(struct hist_trigger_data *target_hist_data,
                        char *subsys_name, char *event_name, char *var_name)
 {
@@ -2943,6 +3023,27 @@ create_target_field_var(struct hist_trigger_data *target_hist_data,
        return create_field_var(target_hist_data, file, var_name);
 }
 
+static void onmatch_destroy(struct action_data *data)
+{
+       unsigned int i;
+
+       mutex_lock(&synth_event_mutex);
+
+       kfree(data->onmatch.match_event);
+       kfree(data->onmatch.match_event_system);
+       kfree(data->onmatch.synth_event_name);
+
+       for (i = 0; i < data->n_params; i++)
+               kfree(data->params[i]);
+
+       if (data->onmatch.synth_event)
+               data->onmatch.synth_event->ref--;
+
+       kfree(data);
+
+       mutex_unlock(&synth_event_mutex);
+}
+
 static void destroy_field_var(struct field_var *field_var)
 {
        if (!field_var)
@@ -2962,8 +3063,8 @@ static void destroy_field_vars(struct hist_trigger_data *hist_data)
                destroy_field_var(hist_data->field_vars[i]);
 }
 
-void save_field_var(struct hist_trigger_data *hist_data,
-                   struct field_var *field_var)
+static void save_field_var(struct hist_trigger_data *hist_data,
+                          struct field_var *field_var)
 {
        hist_data->field_vars[hist_data->n_field_vars++] = field_var;
 
@@ -2971,6 +3072,304 @@ void save_field_var(struct hist_trigger_data *hist_data,
                hist_data->n_field_var_str++;
 }
 
+
+static void destroy_synth_var_refs(struct hist_trigger_data *hist_data)
+{
+       unsigned int i;
+
+       for (i = 0; i < hist_data->n_synth_var_refs; i++)
+               destroy_hist_field(hist_data->synth_var_refs[i], 0);
+}
+
+static void save_synth_var_ref(struct hist_trigger_data *hist_data,
+                        struct hist_field *var_ref)
+{
+       hist_data->synth_var_refs[hist_data->n_synth_var_refs++] = var_ref;
+
+       hist_data->var_refs[hist_data->n_var_refs] = var_ref;
+       var_ref->var_ref_idx = hist_data->n_var_refs++;
+}
+
+static int check_synth_field(struct synth_event *event,
+                            struct hist_field *hist_field,
+                            unsigned int field_pos)
+{
+       struct synth_field *field;
+
+       if (field_pos >= event->n_fields)
+               return -EINVAL;
+
+       field = event->fields[field_pos];
+
+       if (strcmp(field->type, hist_field->type) != 0)
+               return -EINVAL;
+
+       return 0;
+}
+
+static int parse_action_params(char *params, struct action_data *data)
+{
+       char *param, *saved_param;
+       int ret = 0;
+
+       while (params) {
+               if (data->n_params >= SYNTH_FIELDS_MAX)
+                       goto out;
+
+               param = strsep(&params, ",");
+               if (!param) {
+                       ret = -EINVAL;
+                       goto out;
+               }
+
+               param = strstrip(param);
+               if (strlen(param) < 2) {
+                       ret = -EINVAL;
+                       goto out;
+               }
+
+               saved_param = kstrdup(param, GFP_KERNEL);
+               if (!saved_param) {
+                       ret = -ENOMEM;
+                       goto out;
+               }
+
+               data->params[data->n_params++] = saved_param;
+       }
+ out:
+       return ret;
+}
+
+static struct hist_field *
+onmatch_find_var(struct hist_trigger_data *hist_data, struct action_data *data,
+                char *system, char *event, char *var)
+{
+       struct hist_field *hist_field;
+
+       var++; /* skip '$' */
+
+       hist_field = find_target_event_var(hist_data, system, event, var);
+       if (!hist_field) {
+               if (!system) {
+                       system = data->onmatch.match_event_system;
+                       event = data->onmatch.match_event;
+               }
+
+               hist_field = find_event_var(hist_data, system, event, var);
+       }
+
+       return hist_field;
+}
+
+static struct hist_field *
+onmatch_create_field_var(struct hist_trigger_data *hist_data,
+                        struct action_data *data, char *system,
+                        char *event, char *var)
+{
+       struct hist_field *hist_field = NULL;
+       struct field_var *field_var;
+
+       /*
+        * First try to create a field var on the target event (the
+        * currently being defined).  This will create a variable for
+        * unqualified fields on the target event, or if qualified,
+        * target fields that have qualified names matching the target.
+        */
+       field_var = create_target_field_var(hist_data, system, event, var);
+
+       if (field_var && !IS_ERR(field_var)) {
+               save_field_var(hist_data, field_var);
+               hist_field = field_var->var;
+       } else {
+               field_var = NULL;
+               /*
+                * If no explicit system.event is specfied, default to
+                * looking for fields on the onmatch(system.event.xxx)
+                * event.
+                */
+               if (!system) {
+                       system = data->onmatch.match_event_system;
+                       event = data->onmatch.match_event;
+               }
+
+               /*
+                * At this point, we're looking at a field on another
+                * event.  Because we can't modify a hist trigger on
+                * another event to add a variable for a field, we need
+                * to create a new trigger on that event and create the
+                * variable at the same time.
+                */
+               hist_field = create_field_var_hist(hist_data, system, event, var);
+               if (IS_ERR(hist_field))
+                       goto free;
+       }
+ out:
+       return hist_field;
+ free:
+       destroy_field_var(field_var);
+       hist_field = NULL;
+       goto out;
+}
+
+static int onmatch_create(struct hist_trigger_data *hist_data,
+                         struct trace_event_file *file,
+                         struct action_data *data)
+{
+       char *event_name, *param, *system = NULL;
+       struct hist_field *hist_field, *var_ref;
+       unsigned int i, var_ref_idx;
+       unsigned int field_pos = 0;
+       struct synth_event *event;
+       int ret = 0;
+
+       mutex_lock(&synth_event_mutex);
+       event = find_synth_event(data->onmatch.synth_event_name);
+       if (!event) {
+               mutex_unlock(&synth_event_mutex);
+               return -EINVAL;
+       }
+       event->ref++;
+       mutex_unlock(&synth_event_mutex);
+
+       var_ref_idx = hist_data->n_var_refs;
+
+       for (i = 0; i < data->n_params; i++) {
+               char *p;
+
+               p = param = kstrdup(data->params[i], GFP_KERNEL);
+               if (!param) {
+                       ret = -ENOMEM;
+                       goto err;
+               }
+
+               system = strsep(&param, ".");
+               if (!param) {
+                       param = (char *)system;
+                       system = event_name = NULL;
+               } else {
+                       event_name = strsep(&param, ".");
+                       if (!param) {
+                               kfree(p);
+                               ret = -EINVAL;
+                               goto err;
+                       }
+               }
+
+               if (param[0] == '$')
+                       hist_field = onmatch_find_var(hist_data, data, system,
+                                                     event_name, param);
+               else
+                       hist_field = onmatch_create_field_var(hist_data, data,
+                                                             system,
+                                                             event_name,
+                                                             param);
+
+               if (!hist_field) {
+                       kfree(p);
+                       ret = -EINVAL;
+                       goto err;
+               }
+
+               if (check_synth_field(event, hist_field, field_pos) == 0) {
+                       var_ref = create_var_ref(hist_field, system, event_name);
+                       if (!var_ref) {
+                               kfree(p);
+                               ret = -ENOMEM;
+                               goto err;
+                       }
+
+                       save_synth_var_ref(hist_data, var_ref);
+                       field_pos++;
+                       kfree(p);
+                       continue;
+               }
+
+               kfree(p);
+               ret = -EINVAL;
+               goto err;
+       }
+
+       if (field_pos != event->n_fields) {
+               ret = -EINVAL;
+               goto err;
+       }
+
+       data->fn = action_trace;
+       data->onmatch.synth_event = event;
+       data->onmatch.var_ref_idx = var_ref_idx;
+ out:
+       return ret;
+ err:
+       mutex_lock(&synth_event_mutex);
+       event->ref--;
+       mutex_unlock(&synth_event_mutex);
+
+       goto out;
+}
+
+static struct action_data *onmatch_parse(struct trace_array *tr, char *str)
+{
+       char *match_event, *match_event_system;
+       char *synth_event_name, *params;
+       struct action_data *data;
+       int ret = -EINVAL;
+
+       data = kzalloc(sizeof(*data), GFP_KERNEL);
+       if (!data)
+               return ERR_PTR(-ENOMEM);
+
+       match_event = strsep(&str, ")");
+       if (!match_event || !str)
+               goto free;
+
+       match_event_system = strsep(&match_event, ".");
+       if (!match_event)
+               goto free;
+
+       if (IS_ERR(event_file(tr, match_event_system, match_event)))
+               goto free;
+
+       data->onmatch.match_event = kstrdup(match_event, GFP_KERNEL);
+       if (!data->onmatch.match_event) {
+               ret = -ENOMEM;
+               goto free;
+       }
+
+       data->onmatch.match_event_system = kstrdup(match_event_system, GFP_KERNEL);
+       if (!data->onmatch.match_event_system) {
+               ret = -ENOMEM;
+               goto free;
+       }
+
+       strsep(&str, ".");
+       if (!str)
+               goto free;
+
+       synth_event_name = strsep(&str, "(");
+       if (!synth_event_name || !str)
+               goto free;
+
+       data->onmatch.synth_event_name = kstrdup(synth_event_name, GFP_KERNEL);
+       if (!data->onmatch.synth_event_name) {
+               ret = -ENOMEM;
+               goto free;
+       }
+
+       params = strsep(&str, ")");
+       if (!params || !str || (str && strlen(str)))
+               goto free;
+
+       ret = parse_action_params(params, data);
+       if (ret)
+               goto free;
+ out:
+       return data;
+ free:
+       onmatch_destroy(data);
+       data = ERR_PTR(ret);
+       goto out;
+}
+
 static int create_hitcount_val(struct hist_trigger_data *hist_data)
 {
        hist_data->fields[HITCOUNT_IDX] =
@@ -3395,18 +3794,39 @@ static void destroy_actions(struct hist_trigger_data *hist_data)
        for (i = 0; i < hist_data->n_actions; i++) {
                struct action_data *data = hist_data->actions[i];
 
-               kfree(data);
+               if (data->fn == action_trace)
+                       onmatch_destroy(data);
+               else
+                       kfree(data);
        }
 }
 
 static int parse_actions(struct hist_trigger_data *hist_data)
 {
+       struct trace_array *tr = hist_data->event_file->tr;
+       struct action_data *data;
        unsigned int i;
        int ret = 0;
        char *str;
 
        for (i = 0; i < hist_data->attrs->n_actions; i++) {
                str = hist_data->attrs->action_str[i];
+
+               if (strncmp(str, "onmatch(", strlen("onmatch(")) == 0) {
+                       char *action_str = str + strlen("onmatch(");
+
+                       data = onmatch_parse(tr, action_str);
+                       if (IS_ERR(data)) {
+                               ret = PTR_ERR(data);
+                               break;
+                       }
+                       data->fn = action_trace;
+               } else {
+                       ret = -EINVAL;
+                       break;
+               }
+
+               hist_data->actions[hist_data->n_actions++] = data;
        }
 
        return ret;
@@ -3421,11 +3841,50 @@ static int create_actions(struct hist_trigger_data *hist_data,
 
        for (i = 0; i < hist_data->attrs->n_actions; i++) {
                data = hist_data->actions[i];
+
+               if (data->fn == action_trace) {
+                       ret = onmatch_create(hist_data, file, data);
+                       if (ret)
+                               return ret;
+               }
        }
 
        return ret;
 }
 
+static void print_onmatch_spec(struct seq_file *m,
+                              struct hist_trigger_data *hist_data,
+                              struct action_data *data)
+{
+       unsigned int i;
+
+       seq_printf(m, ":onmatch(%s.%s).", data->onmatch.match_event_system,
+                  data->onmatch.match_event);
+
+       seq_printf(m, "%s(", data->onmatch.synth_event->name);
+
+       for (i = 0; i < data->n_params; i++) {
+               if (i)
+                       seq_puts(m, ",");
+               seq_printf(m, "%s", data->params[i]);
+       }
+
+       seq_puts(m, ")");
+}
+
+static void print_actions_spec(struct seq_file *m,
+                              struct hist_trigger_data *hist_data)
+{
+       unsigned int i;
+
+       for (i = 0; i < hist_data->n_actions; i++) {
+               struct action_data *data = hist_data->actions[i];
+
+               if (data->fn == action_trace)
+                       print_onmatch_spec(m, hist_data, data);
+       }
+}
+
 static void destroy_field_var_hists(struct hist_trigger_data *hist_data)
 {
        unsigned int i;
@@ -3448,6 +3907,7 @@ static void destroy_hist_data(struct hist_trigger_data *hist_data)
        destroy_actions(hist_data);
        destroy_field_vars(hist_data);
        destroy_field_var_hists(hist_data);
+       destroy_synth_var_refs(hist_data);
 
        kfree(hist_data);
 }
@@ -4004,6 +4464,8 @@ static int event_hist_trigger_print(struct seq_file *m,
        }
        seq_printf(m, ":size=%u", (1 << hist_data->map->map_bits));
 
+       print_actions_spec(m, hist_data);
+
        if (data->filter_str)
                seq_printf(m, " if %s", data->filter_str);