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1 /*
2 * trace context switch
3 *
4 * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
5 *
6 */
7 #include <linux/module.h>
8 #include <linux/fs.h>
9 #include <linux/debugfs.h>
10 #include <linux/kallsyms.h>
11 #include <linux/uaccess.h>
12 #include <linux/ftrace.h>
13 #include <trace/events/sched.h>
14
15 #include "trace.h"
16
17 static struct trace_array *ctx_trace;
18 static int __read_mostly tracer_enabled;
19 static int sched_ref;
20 static DEFINE_MUTEX(sched_register_mutex);
21 static int sched_stopped;
22
23
24 void
25 tracing_sched_switch_trace(struct trace_array *tr,
26 struct task_struct *prev,
27 struct task_struct *next,
28 unsigned long flags, int pc)
29 {
30 struct ftrace_event_call *call = &event_context_switch;
31 struct ring_buffer *buffer = tr->buffer;
32 struct ring_buffer_event *event;
33 struct ctx_switch_entry *entry;
34
35 event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
36 sizeof(*entry), flags, pc);
37 if (!event)
38 return;
39 entry = ring_buffer_event_data(event);
40 entry->prev_pid = prev->pid;
41 entry->prev_prio = prev->prio;
42 entry->prev_state = prev->state;
43 entry->next_pid = next->pid;
44 entry->next_prio = next->prio;
45 entry->next_state = next->state;
46 entry->next_cpu = task_cpu(next);
47
48 if (!filter_check_discard(call, entry, buffer, event))
49 trace_buffer_unlock_commit(buffer, event, flags, pc);
50 }
51
52 static void
53 probe_sched_switch(void *ignore, struct task_struct *prev, struct task_struct *next)
54 {
55 struct trace_array_cpu *data;
56 unsigned long flags;
57 int cpu;
58 int pc;
59
60 if (unlikely(!sched_ref))
61 return;
62
63 tracing_record_cmdline(prev);
64 tracing_record_cmdline(next);
65
66 if (!tracer_enabled || sched_stopped)
67 return;
68
69 pc = preempt_count();
70 local_irq_save(flags);
71 cpu = raw_smp_processor_id();
72 data = ctx_trace->data[cpu];
73
74 if (likely(!atomic_read(&data->disabled)))
75 tracing_sched_switch_trace(ctx_trace, prev, next, flags, pc);
76
77 local_irq_restore(flags);
78 }
79
80 void
81 tracing_sched_wakeup_trace(struct trace_array *tr,
82 struct task_struct *wakee,
83 struct task_struct *curr,
84 unsigned long flags, int pc)
85 {
86 struct ftrace_event_call *call = &event_wakeup;
87 struct ring_buffer_event *event;
88 struct ctx_switch_entry *entry;
89 struct ring_buffer *buffer = tr->buffer;
90
91 event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
92 sizeof(*entry), flags, pc);
93 if (!event)
94 return;
95 entry = ring_buffer_event_data(event);
96 entry->prev_pid = curr->pid;
97 entry->prev_prio = curr->prio;
98 entry->prev_state = curr->state;
99 entry->next_pid = wakee->pid;
100 entry->next_prio = wakee->prio;
101 entry->next_state = wakee->state;
102 entry->next_cpu = task_cpu(wakee);
103
104 if (!filter_check_discard(call, entry, buffer, event))
105 trace_buffer_unlock_commit(buffer, event, flags, pc);
106 }
107
108 static void
109 probe_sched_wakeup(void *ignore, struct task_struct *wakee, int success)
110 {
111 struct trace_array_cpu *data;
112 unsigned long flags;
113 int cpu, pc;
114
115 if (unlikely(!sched_ref))
116 return;
117
118 tracing_record_cmdline(current);
119
120 if (!tracer_enabled || sched_stopped)
121 return;
122
123 pc = preempt_count();
124 local_irq_save(flags);
125 cpu = raw_smp_processor_id();
126 data = ctx_trace->data[cpu];
127
128 if (likely(!atomic_read(&data->disabled)))
129 tracing_sched_wakeup_trace(ctx_trace, wakee, current,
130 flags, pc);
131
132 local_irq_restore(flags);
133 }
134
135 static int tracing_sched_register(void)
136 {
137 int ret;
138
139 ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
140 if (ret) {
141 pr_info("wakeup trace: Couldn't activate tracepoint"
142 " probe to kernel_sched_wakeup\n");
143 return ret;
144 }
145
146 ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
147 if (ret) {
148 pr_info("wakeup trace: Couldn't activate tracepoint"
149 " probe to kernel_sched_wakeup_new\n");
150 goto fail_deprobe;
151 }
152
153 ret = register_trace_sched_switch(probe_sched_switch, NULL);
154 if (ret) {
155 pr_info("sched trace: Couldn't activate tracepoint"
156 " probe to kernel_sched_switch\n");
157 goto fail_deprobe_wake_new;
158 }
159
160 return ret;
161 fail_deprobe_wake_new:
162 unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
163 fail_deprobe:
164 unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
165 return ret;
166 }
167
168 static void tracing_sched_unregister(void)
169 {
170 unregister_trace_sched_switch(probe_sched_switch, NULL);
171 unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
172 unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
173 }
174
175 static void tracing_start_sched_switch(void)
176 {
177 mutex_lock(&sched_register_mutex);
178 if (!(sched_ref++))
179 tracing_sched_register();
180 mutex_unlock(&sched_register_mutex);
181 }
182
183 static void tracing_stop_sched_switch(void)
184 {
185 mutex_lock(&sched_register_mutex);
186 if (!(--sched_ref))
187 tracing_sched_unregister();
188 mutex_unlock(&sched_register_mutex);
189 }
190
191 void tracing_start_cmdline_record(void)
192 {
193 tracing_start_sched_switch();
194 }
195
196 void tracing_stop_cmdline_record(void)
197 {
198 tracing_stop_sched_switch();
199 }
200
201 /**
202 * tracing_start_sched_switch_record - start tracing context switches
203 *
204 * Turns on context switch tracing for a tracer.
205 */
206 void tracing_start_sched_switch_record(void)
207 {
208 if (unlikely(!ctx_trace)) {
209 WARN_ON(1);
210 return;
211 }
212
213 tracing_start_sched_switch();
214
215 mutex_lock(&sched_register_mutex);
216 tracer_enabled++;
217 mutex_unlock(&sched_register_mutex);
218 }
219
220 /**
221 * tracing_stop_sched_switch_record - start tracing context switches
222 *
223 * Turns off context switch tracing for a tracer.
224 */
225 void tracing_stop_sched_switch_record(void)
226 {
227 mutex_lock(&sched_register_mutex);
228 tracer_enabled--;
229 WARN_ON(tracer_enabled < 0);
230 mutex_unlock(&sched_register_mutex);
231
232 tracing_stop_sched_switch();
233 }
234
235 /**
236 * tracing_sched_switch_assign_trace - assign a trace array for ctx switch
237 * @tr: trace array pointer to assign
238 *
239 * Some tracers might want to record the context switches in their
240 * trace. This function lets those tracers assign the trace array
241 * to use.
242 */
243 void tracing_sched_switch_assign_trace(struct trace_array *tr)
244 {
245 ctx_trace = tr;
246 }
247