mirror of
https://github.com/torvalds/linux.git
synced 2024-11-10 22:21:40 +00:00
tracing: Add synth_event_trace() and related functions
Add an exported function named synth_event_trace(), allowing modules or other kernel code to trace synthetic events. Also added are several functions that allow the same functionality to be broken out in a piecewise fashion, which are useful in situations where tracing an event from a full array of values would be cumbersome. Those functions are synth_event_trace_start/end() and synth_event_add_(next)_val(). Link: http://lkml.kernel.org/r/7a84de5f1854acf4144b57efe835ca645afa764f.1580323897.git.zanussi@kernel.org Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Tom Zanussi
Steven Rostedt (VMware)
parent
35ca5207c2
commit
8dcc53ad95
@ -416,6 +416,32 @@ extern int synth_event_add_fields(struct dynevent_cmd *cmd,
|
||||
#define synth_event_gen_cmd_end(cmd) \
|
||||
dynevent_create(cmd)
|
||||
|
||||
struct synth_event;
|
||||
|
||||
struct synth_event_trace_state {
|
||||
struct trace_event_buffer fbuffer;
|
||||
struct synth_trace_event *entry;
|
||||
struct trace_buffer *buffer;
|
||||
struct synth_event *event;
|
||||
unsigned int cur_field;
|
||||
unsigned int n_u64;
|
||||
bool enabled;
|
||||
bool add_next;
|
||||
bool add_name;
|
||||
};
|
||||
|
||||
extern int synth_event_trace(struct trace_event_file *file,
|
||||
unsigned int n_vals, ...);
|
||||
extern int synth_event_trace_array(struct trace_event_file *file, u64 *vals,
|
||||
unsigned int n_vals);
|
||||
extern int synth_event_trace_start(struct trace_event_file *file,
|
||||
struct synth_event_trace_state *trace_state);
|
||||
extern int synth_event_add_next_val(u64 val,
|
||||
struct synth_event_trace_state *trace_state);
|
||||
extern int synth_event_add_val(const char *field_name, u64 val,
|
||||
struct synth_event_trace_state *trace_state);
|
||||
extern int synth_event_trace_end(struct synth_event_trace_state *trace_state);
|
||||
|
||||
/*
|
||||
* Event file flags:
|
||||
* ENABLED - The event is enabled
|
||||
|
||||
@ -398,6 +398,7 @@ struct synth_field {
|
||||
char *type;
|
||||
char *name;
|
||||
size_t size;
|
||||
unsigned int offset;
|
||||
bool is_signed;
|
||||
bool is_string;
|
||||
};
|
||||
@ -668,6 +669,8 @@ static int synth_event_define_fields(struct trace_event_call *call)
|
||||
if (ret)
|
||||
break;
|
||||
|
||||
event->fields[i]->offset = n_u64;
|
||||
|
||||
if (event->fields[i]->is_string) {
|
||||
offset += STR_VAR_LEN_MAX;
|
||||
n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
|
||||
@ -1791,6 +1794,466 @@ void synth_event_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen)
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synth_event_cmd_init);
|
||||
|
||||
/**
|
||||
* synth_event_trace - Trace a synthetic event
|
||||
* @file: The trace_event_file representing the synthetic event
|
||||
* @n_vals: The number of values in vals
|
||||
* @args: Variable number of args containing the event values
|
||||
*
|
||||
* Trace a synthetic event using the values passed in the variable
|
||||
* argument list.
|
||||
*
|
||||
* The argument list should be a list 'n_vals' u64 values. The number
|
||||
* of vals must match the number of field in the synthetic event, and
|
||||
* must be in the same order as the synthetic event fields.
|
||||
*
|
||||
* All vals should be cast to u64, and string vals are just pointers
|
||||
* to strings, cast to u64. Strings will be copied into space
|
||||
* reserved in the event for the string, using these pointers.
|
||||
*
|
||||
* Return: 0 on success, err otherwise.
|
||||
*/
|
||||
int synth_event_trace(struct trace_event_file *file, unsigned int n_vals, ...)
|
||||
{
|
||||
struct trace_event_buffer fbuffer;
|
||||
struct synth_trace_event *entry;
|
||||
struct trace_buffer *buffer;
|
||||
struct synth_event *event;
|
||||
unsigned int i, n_u64;
|
||||
int fields_size = 0;
|
||||
va_list args;
|
||||
int ret = 0;
|
||||
|
||||
/*
|
||||
* Normal event generation doesn't get called at all unless
|
||||
* the ENABLED bit is set (which attaches the probe thus
|
||||
* allowing this code to be called, etc). Because this is
|
||||
* called directly by the user, we don't have that but we
|
||||
* still need to honor not logging when disabled.
|
||||
*/
|
||||
if (!(file->flags & EVENT_FILE_FL_ENABLED))
|
||||
return 0;
|
||||
|
||||
event = file->event_call->data;
|
||||
|
||||
if (n_vals != event->n_fields)
|
||||
return -EINVAL;
|
||||
|
||||
if (trace_trigger_soft_disabled(file))
|
||||
return -EINVAL;
|
||||
|
||||
fields_size = event->n_u64 * sizeof(u64);
|
||||
|
||||
/*
|
||||
* Avoid ring buffer recursion detection, as this event
|
||||
* is being performed within another event.
|
||||
*/
|
||||
buffer = file->tr->array_buffer.buffer;
|
||||
ring_buffer_nest_start(buffer);
|
||||
|
||||
entry = trace_event_buffer_reserve(&fbuffer, file,
|
||||
sizeof(*entry) + fields_size);
|
||||
if (!entry) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
va_start(args, n_vals);
|
||||
for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
|
||||
u64 val;
|
||||
|
||||
val = va_arg(args, u64);
|
||||
|
||||
if (event->fields[i]->is_string) {
|
||||
char *str_val = (char *)(long)val;
|
||||
char *str_field = (char *)&entry->fields[n_u64];
|
||||
|
||||
strscpy(str_field, str_val, STR_VAR_LEN_MAX);
|
||||
n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
|
||||
} else {
|
||||
entry->fields[n_u64] = val;
|
||||
n_u64++;
|
||||
}
|
||||
}
|
||||
va_end(args);
|
||||
|
||||
trace_event_buffer_commit(&fbuffer);
|
||||
out:
|
||||
ring_buffer_nest_end(buffer);
|
||||
|
||||
return ret;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synth_event_trace);
|
||||
|
||||
/**
|
||||
* synth_event_trace_array - Trace a synthetic event from an array
|
||||
* @file: The trace_event_file representing the synthetic event
|
||||
* @vals: Array of values
|
||||
* @n_vals: The number of values in vals
|
||||
*
|
||||
* Trace a synthetic event using the values passed in as 'vals'.
|
||||
*
|
||||
* The 'vals' array is just an array of 'n_vals' u64. The number of
|
||||
* vals must match the number of field in the synthetic event, and
|
||||
* must be in the same order as the synthetic event fields.
|
||||
*
|
||||
* All vals should be cast to u64, and string vals are just pointers
|
||||
* to strings, cast to u64. Strings will be copied into space
|
||||
* reserved in the event for the string, using these pointers.
|
||||
*
|
||||
* Return: 0 on success, err otherwise.
|
||||
*/
|
||||
int synth_event_trace_array(struct trace_event_file *file, u64 *vals,
|
||||
unsigned int n_vals)
|
||||
{
|
||||
struct trace_event_buffer fbuffer;
|
||||
struct synth_trace_event *entry;
|
||||
struct trace_buffer *buffer;
|
||||
struct synth_event *event;
|
||||
unsigned int i, n_u64;
|
||||
int fields_size = 0;
|
||||
int ret = 0;
|
||||
|
||||
/*
|
||||
* Normal event generation doesn't get called at all unless
|
||||
* the ENABLED bit is set (which attaches the probe thus
|
||||
* allowing this code to be called, etc). Because this is
|
||||
* called directly by the user, we don't have that but we
|
||||
* still need to honor not logging when disabled.
|
||||
*/
|
||||
if (!(file->flags & EVENT_FILE_FL_ENABLED))
|
||||
return 0;
|
||||
|
||||
event = file->event_call->data;
|
||||
|
||||
if (n_vals != event->n_fields)
|
||||
return -EINVAL;
|
||||
|
||||
if (trace_trigger_soft_disabled(file))
|
||||
return -EINVAL;
|
||||
|
||||
fields_size = event->n_u64 * sizeof(u64);
|
||||
|
||||
/*
|
||||
* Avoid ring buffer recursion detection, as this event
|
||||
* is being performed within another event.
|
||||
*/
|
||||
buffer = file->tr->array_buffer.buffer;
|
||||
ring_buffer_nest_start(buffer);
|
||||
|
||||
entry = trace_event_buffer_reserve(&fbuffer, file,
|
||||
sizeof(*entry) + fields_size);
|
||||
if (!entry) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
|
||||
if (event->fields[i]->is_string) {
|
||||
char *str_val = (char *)(long)vals[i];
|
||||
char *str_field = (char *)&entry->fields[n_u64];
|
||||
|
||||
strscpy(str_field, str_val, STR_VAR_LEN_MAX);
|
||||
n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
|
||||
} else {
|
||||
entry->fields[n_u64] = vals[i];
|
||||
n_u64++;
|
||||
}
|
||||
}
|
||||
|
||||
trace_event_buffer_commit(&fbuffer);
|
||||
out:
|
||||
ring_buffer_nest_end(buffer);
|
||||
|
||||
return ret;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synth_event_trace_array);
|
||||
|
||||
/**
|
||||
* synth_event_trace_start - Start piecewise synthetic event trace
|
||||
* @file: The trace_event_file representing the synthetic event
|
||||
* @trace_state: A pointer to object tracking the piecewise trace state
|
||||
*
|
||||
* Start the trace of a synthetic event field-by-field rather than all
|
||||
* at once.
|
||||
*
|
||||
* This function 'opens' an event trace, which means space is reserved
|
||||
* for the event in the trace buffer, after which the event's
|
||||
* individual field values can be set through either
|
||||
* synth_event_add_next_val() or synth_event_add_val().
|
||||
*
|
||||
* A pointer to a trace_state object is passed in, which will keep
|
||||
* track of the current event trace state until the event trace is
|
||||
* closed (and the event finally traced) using
|
||||
* synth_event_trace_end().
|
||||
*
|
||||
* Note that synth_event_trace_end() must be called after all values
|
||||
* have been added for each event trace, regardless of whether adding
|
||||
* all field values succeeded or not.
|
||||
*
|
||||
* Note also that for a given event trace, all fields must be added
|
||||
* using either synth_event_add_next_val() or synth_event_add_val()
|
||||
* but not both together or interleaved.
|
||||
*
|
||||
* Return: 0 on success, err otherwise.
|
||||
*/
|
||||
int synth_event_trace_start(struct trace_event_file *file,
|
||||
struct synth_event_trace_state *trace_state)
|
||||
{
|
||||
struct synth_trace_event *entry;
|
||||
int fields_size = 0;
|
||||
int ret = 0;
|
||||
|
||||
if (!trace_state) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
memset(trace_state, '\0', sizeof(*trace_state));
|
||||
|
||||
/*
|
||||
* Normal event tracing doesn't get called at all unless the
|
||||
* ENABLED bit is set (which attaches the probe thus allowing
|
||||
* this code to be called, etc). Because this is called
|
||||
* directly by the user, we don't have that but we still need
|
||||
* to honor not logging when disabled. For the the iterated
|
||||
* trace case, we save the enabed state upon start and just
|
||||
* ignore the following data calls.
|
||||
*/
|
||||
if (!(file->flags & EVENT_FILE_FL_ENABLED)) {
|
||||
trace_state->enabled = false;
|
||||
goto out;
|
||||
}
|
||||
|
||||
trace_state->enabled = true;
|
||||
|
||||
trace_state->event = file->event_call->data;
|
||||
|
||||
if (trace_trigger_soft_disabled(file)) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
fields_size = trace_state->event->n_u64 * sizeof(u64);
|
||||
|
||||
/*
|
||||
* Avoid ring buffer recursion detection, as this event
|
||||
* is being performed within another event.
|
||||
*/
|
||||
trace_state->buffer = file->tr->array_buffer.buffer;
|
||||
ring_buffer_nest_start(trace_state->buffer);
|
||||
|
||||
entry = trace_event_buffer_reserve(&trace_state->fbuffer, file,
|
||||
sizeof(*entry) + fields_size);
|
||||
if (!entry) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
trace_state->entry = entry;
|
||||
out:
|
||||
return ret;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synth_event_trace_start);
|
||||
|
||||
static int save_synth_val(struct synth_field *field, u64 val,
|
||||
struct synth_event_trace_state *trace_state)
|
||||
{
|
||||
struct synth_trace_event *entry = trace_state->entry;
|
||||
|
||||
if (field->is_string) {
|
||||
char *str_val = (char *)(long)val;
|
||||
char *str_field;
|
||||
|
||||
if (!str_val)
|
||||
return -EINVAL;
|
||||
|
||||
str_field = (char *)&entry->fields[field->offset];
|
||||
strscpy(str_field, str_val, STR_VAR_LEN_MAX);
|
||||
} else
|
||||
entry->fields[field->offset] = val;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* synth_event_add_next_val - Add the next field's value to an open synth trace
|
||||
* @val: The value to set the next field to
|
||||
* @trace_state: A pointer to object tracking the piecewise trace state
|
||||
*
|
||||
* Set the value of the next field in an event that's been opened by
|
||||
* synth_event_trace_start().
|
||||
*
|
||||
* The val param should be the value cast to u64. If the value points
|
||||
* to a string, the val param should be a char * cast to u64.
|
||||
*
|
||||
* This function assumes all the fields in an event are to be set one
|
||||
* after another - successive calls to this function are made, one for
|
||||
* each field, in the order of the fields in the event, until all
|
||||
* fields have been set. If you'd rather set each field individually
|
||||
* without regard to ordering, synth_event_add_val() can be used
|
||||
* instead.
|
||||
*
|
||||
* Note however that synth_event_add_next_val() and
|
||||
* synth_event_add_val() can't be intermixed for a given event trace -
|
||||
* one or the other but not both can be used at the same time.
|
||||
*
|
||||
* Note also that synth_event_trace_end() must be called after all
|
||||
* values have been added for each event trace, regardless of whether
|
||||
* adding all field values succeeded or not.
|
||||
*
|
||||
* Return: 0 on success, err otherwise.
|
||||
*/
|
||||
int synth_event_add_next_val(u64 val,
|
||||
struct synth_event_trace_state *trace_state)
|
||||
{
|
||||
struct synth_field *field;
|
||||
struct synth_event *event;
|
||||
int ret = 0;
|
||||
|
||||
if (!trace_state) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
/* can't mix add_next_synth_val() with add_synth_val() */
|
||||
if (trace_state->add_name) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
trace_state->add_next = true;
|
||||
|
||||
if (!trace_state->enabled)
|
||||
goto out;
|
||||
|
||||
event = trace_state->event;
|
||||
|
||||
if (trace_state->cur_field >= event->n_fields) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
field = event->fields[trace_state->cur_field++];
|
||||
ret = save_synth_val(field, val, trace_state);
|
||||
out:
|
||||
return ret;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synth_event_add_next_val);
|
||||
|
||||
static struct synth_field *find_synth_field(struct synth_event *event,
|
||||
const char *field_name)
|
||||
{
|
||||
struct synth_field *field = NULL;
|
||||
unsigned int i;
|
||||
|
||||
for (i = 0; i < event->n_fields; i++) {
|
||||
field = event->fields[i];
|
||||
if (strcmp(field->name, field_name) == 0)
|
||||
return field;
|
||||
}
|
||||
|
||||
return NULL;
|
||||
}
|
||||
|
||||
/**
|
||||
* synth_event_add_val - Add a named field's value to an open synth trace
|
||||
* @field_name: The name of the synthetic event field value to set
|
||||
* @val: The value to set the next field to
|
||||
* @trace_state: A pointer to object tracking the piecewise trace state
|
||||
*
|
||||
* Set the value of the named field in an event that's been opened by
|
||||
* synth_event_trace_start().
|
||||
*
|
||||
* The val param should be the value cast to u64. If the value points
|
||||
* to a string, the val param should be a char * cast to u64.
|
||||
*
|
||||
* This function looks up the field name, and if found, sets the field
|
||||
* to the specified value. This lookup makes this function more
|
||||
* expensive than synth_event_add_next_val(), so use that or the
|
||||
* none-piecewise synth_event_trace() instead if efficiency is more
|
||||
* important.
|
||||
*
|
||||
* Note however that synth_event_add_next_val() and
|
||||
* synth_event_add_val() can't be intermixed for a given event trace -
|
||||
* one or the other but not both can be used at the same time.
|
||||
*
|
||||
* Note also that synth_event_trace_end() must be called after all
|
||||
* values have been added for each event trace, regardless of whether
|
||||
* adding all field values succeeded or not.
|
||||
*
|
||||
* Return: 0 on success, err otherwise.
|
||||
*/
|
||||
int synth_event_add_val(const char *field_name, u64 val,
|
||||
struct synth_event_trace_state *trace_state)
|
||||
{
|
||||
struct synth_trace_event *entry;
|
||||
struct synth_event *event;
|
||||
struct synth_field *field;
|
||||
int ret = 0;
|
||||
|
||||
if (!trace_state) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
/* can't mix add_next_synth_val() with add_synth_val() */
|
||||
if (trace_state->add_next) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
trace_state->add_name = true;
|
||||
|
||||
if (!trace_state->enabled)
|
||||
goto out;
|
||||
|
||||
event = trace_state->event;
|
||||
entry = trace_state->entry;
|
||||
|
||||
field = find_synth_field(event, field_name);
|
||||
if (!field) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
ret = save_synth_val(field, val, trace_state);
|
||||
out:
|
||||
return ret;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synth_event_add_val);
|
||||
|
||||
/**
|
||||
* synth_event_trace_end - End piecewise synthetic event trace
|
||||
* @trace_state: A pointer to object tracking the piecewise trace state
|
||||
*
|
||||
* End the trace of a synthetic event opened by
|
||||
* synth_event_trace__start().
|
||||
*
|
||||
* This function 'closes' an event trace, which basically means that
|
||||
* it commits the reserved event and cleans up other loose ends.
|
||||
*
|
||||
* A pointer to a trace_state object is passed in, which will keep
|
||||
* track of the current event trace state opened with
|
||||
* synth_event_trace_start().
|
||||
*
|
||||
* Note that this function must be called after all values have been
|
||||
* added for each event trace, regardless of whether adding all field
|
||||
* values succeeded or not.
|
||||
*
|
||||
* Return: 0 on success, err otherwise.
|
||||
*/
|
||||
int synth_event_trace_end(struct synth_event_trace_state *trace_state)
|
||||
{
|
||||
if (!trace_state)
|
||||
return -EINVAL;
|
||||
|
||||
trace_event_buffer_commit(&trace_state->fbuffer);
|
||||
|
||||
ring_buffer_nest_end(trace_state->buffer);
|
||||
|
||||
return 0;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synth_event_trace_end);
|
||||
|
||||
static int create_synth_event(int argc, const char **argv)
|
||||
{
|
||||
const char *name = argv[0];
|
||||
|
||||
Loading…
Reference in New Issue
Block a user