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 */
22 static 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 */
30 static 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 */
44 int
45 collect_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 */
65 void 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 */
96 int 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
120 out_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 */
130 int trace_instance_start(struct trace_instance *trace)
131 {
132 return tracefs_trace_on(trace->inst);
133 }
134
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