1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * trace context switch
4 *
5 * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
6 *
7 */
8 #include <linux/module.h>
9 #include <linux/kallsyms.h>
10 #include <linux/uaccess.h>
11 #include <linux/ftrace.h>
12 #include <trace/events/sched.h>
13
14 #include "trace.h"
15
16 #define RECORD_CMDLINE 1
17 #define RECORD_TGID 2
18
19 static int sched_cmdline_ref;
20 static int sched_tgid_ref;
21 static DEFINE_MUTEX(sched_register_mutex);
22
23 static void
probe_sched_switch(void * ignore,bool preempt,struct task_struct * prev,struct task_struct * next,unsigned int prev_state)24 probe_sched_switch(void *ignore, bool preempt,
25 struct task_struct *prev, struct task_struct *next,
26 unsigned int prev_state)
27 {
28 int flags;
29
30 flags = (RECORD_TGID * !!sched_tgid_ref) +
31 (RECORD_CMDLINE * !!sched_cmdline_ref);
32
33 if (!flags)
34 return;
35 tracing_record_taskinfo_sched_switch(prev, next, flags);
36 }
37
38 static void
probe_sched_wakeup(void * ignore,struct task_struct * wakee)39 probe_sched_wakeup(void *ignore, struct task_struct *wakee)
40 {
41 int flags;
42
43 flags = (RECORD_TGID * !!sched_tgid_ref) +
44 (RECORD_CMDLINE * !!sched_cmdline_ref);
45
46 if (!flags)
47 return;
48 tracing_record_taskinfo_sched_switch(current, wakee, flags);
49 }
50
tracing_sched_register(void)51 static int tracing_sched_register(void)
52 {
53 int ret;
54
55 ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
56 if (ret) {
57 pr_info("wakeup trace: Couldn't activate tracepoint"
58 " probe to kernel_sched_wakeup\n");
59 return ret;
60 }
61
62 ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
63 if (ret) {
64 pr_info("wakeup trace: Couldn't activate tracepoint"
65 " probe to kernel_sched_wakeup_new\n");
66 goto fail_deprobe;
67 }
68
69 ret = register_trace_sched_switch(probe_sched_switch, NULL);
70 if (ret) {
71 pr_info("sched trace: Couldn't activate tracepoint"
72 " probe to kernel_sched_switch\n");
73 goto fail_deprobe_wake_new;
74 }
75
76 return ret;
77 fail_deprobe_wake_new:
78 unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
79 fail_deprobe:
80 unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
81 return ret;
82 }
83
tracing_sched_unregister(void)84 static void tracing_sched_unregister(void)
85 {
86 unregister_trace_sched_switch(probe_sched_switch, NULL);
87 unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
88 unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
89 }
90
tracing_start_sched_switch(int ops)91 static void tracing_start_sched_switch(int ops)
92 {
93 bool sched_register;
94
95 mutex_lock(&sched_register_mutex);
96 sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
97
98 switch (ops) {
99 case RECORD_CMDLINE:
100 sched_cmdline_ref++;
101 break;
102
103 case RECORD_TGID:
104 sched_tgid_ref++;
105 break;
106 }
107
108 if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
109 tracing_sched_register();
110 mutex_unlock(&sched_register_mutex);
111 }
112
tracing_stop_sched_switch(int ops)113 static void tracing_stop_sched_switch(int ops)
114 {
115 mutex_lock(&sched_register_mutex);
116
117 switch (ops) {
118 case RECORD_CMDLINE:
119 sched_cmdline_ref--;
120 break;
121
122 case RECORD_TGID:
123 sched_tgid_ref--;
124 break;
125 }
126
127 if (!sched_cmdline_ref && !sched_tgid_ref)
128 tracing_sched_unregister();
129 mutex_unlock(&sched_register_mutex);
130 }
131
tracing_start_cmdline_record(void)132 void tracing_start_cmdline_record(void)
133 {
134 tracing_start_sched_switch(RECORD_CMDLINE);
135 }
136
tracing_stop_cmdline_record(void)137 void tracing_stop_cmdline_record(void)
138 {
139 tracing_stop_sched_switch(RECORD_CMDLINE);
140 }
141
tracing_start_tgid_record(void)142 void tracing_start_tgid_record(void)
143 {
144 tracing_start_sched_switch(RECORD_TGID);
145 }
146
tracing_stop_tgid_record(void)147 void tracing_stop_tgid_record(void)
148 {
149 tracing_stop_sched_switch(RECORD_TGID);
150 }
151