diff options
| -rw-r--r-- | include/linux/trace_events.h | 26 | ||||
| -rw-r--r-- | kernel/trace/trace_events_hist.c | 463 |
2 files changed, 489 insertions, 0 deletions
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 07b83532a3c6..bf03d12efb28 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -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 diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 5a910bb193e9..4d56a4f0310d 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -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]; |