1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * trace helpers.
  4 *
  5 * Copyright (C) 2022 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
  6 */
  7
  8#include <sys/sendfile.h>
  9#include <tracefs.h>
 10#include <signal.h>
 11#include <stdlib.h>
 12#include <unistd.h>
 13#include <errno.h>
 14
 15#include <rv.h>
 16#include <trace.h>
 17#include <utils.h>
 18
 19/*
 20 * create_instance - create a trace instance with *instance_name
 21 */
 22static struct tracefs_instance *create_instance(char *instance_name)
 23{
 24	return tracefs_instance_create(instance_name);
 25}
 26
 27/*
 28 * destroy_instance - remove a trace instance and free the data
 29 */
 30static void destroy_instance(struct tracefs_instance *inst)
 31{
 32	tracefs_instance_destroy(inst);
 33	tracefs_instance_free(inst);
 34}
 35
 36/**
 37 * collect_registered_events - call the existing callback function for the event
 38 *
 39 * If an event has a registered callback function, call it.
 40 * Otherwise, ignore the event.
 41 *
 42 * Returns 0 if the event was collected, 1 if the tool should stop collecting trace.
 43 */
 44int
 45collect_registered_events(struct tep_event *event, struct tep_record *record,
 46			  int cpu, void *context)
 47{
 48	struct trace_instance *trace = context;
 49	struct trace_seq *s = trace->seq;
 50
 51	if (should_stop())
 52		return 1;
 53
 54	if (!event->handler)
 55		return 0;
 56
 57	event->handler(s, record, event, context);
 58
 59	return 0;
 60}
 61
 62/**
 63 * trace_instance_destroy - destroy and free a rv trace instance
 64 */
 65void trace_instance_destroy(struct trace_instance *trace)
 66{
 67	if (trace->inst) {
 68		destroy_instance(trace->inst);
 69		trace->inst = NULL;
 70	}
 71
 72	if (trace->seq) {
 73		free(trace->seq);
 74		trace->seq = NULL;
 75	}
 76
 77	if (trace->tep) {
 78		tep_free(trace->tep);
 79		trace->tep = NULL;
 80	}
 81}
 82
 83/**
 84 * trace_instance_init - create an trace instance
 85 *
 86 * It is more than the tracefs instance, as it contains other
 87 * things required for the tracing, such as the local events and
 88 * a seq file.
 89 *
 90 * Note that the trace instance is returned disabled. This allows
 91 * the tool to apply some other configs, like setting priority
 92 * to the kernel threads, before starting generating trace entries.
 93 *
 94 * Returns 0 on success, non-zero otherwise.
 95 */
 96int trace_instance_init(struct trace_instance *trace, char *name)
 97{
 98	trace->seq = calloc(1, sizeof(*trace->seq));
 99	if (!trace->seq)
100		goto out_err;
101
102	trace_seq_init(trace->seq);
103
104	trace->inst = create_instance(name);
105	if (!trace->inst)
106		goto out_err;
107
108	trace->tep = tracefs_local_events(NULL);
109	if (!trace->tep)
110		goto out_err;
111
112	/*
113	 * Let the main enable the record after setting some other
114	 * things such as the priority of the tracer's threads.
115	 */
116	tracefs_trace_off(trace->inst);
117
118	return 0;
119
120out_err:
121	trace_instance_destroy(trace);
122	return 1;
123}
124
125/**
126 * trace_instance_start - start tracing a given rv instance
127 *
128 * Returns 0 on success, -1 otherwise.
129 */
130int trace_instance_start(struct trace_instance *trace)
131{
132	return tracefs_trace_on(trace->inst);
133}