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tracing: Add 'onmatch' hist trigger action support 

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>
This commit is contained in:
Tom Zanussi 2018-01-15 20:52:00 -06:00 committed by Steven Rostedt (VMware)
parent 02205a6752
commit c282a386a3
1 changed files with 475 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

488
kernel/trace/trace_events_hist.c
View 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);