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}
134