trace, documentation: Fix branch profiling location in debugfs
[linux-2.6.git] / kernel / trace / trace_sched_switch.c
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                 ring_buffer_unlock_commit(buffer, event);
106         ftrace_trace_stack(tr->buffer, flags, 6, pc);
107         ftrace_trace_userstack(tr->buffer, flags, pc);
108 }
109
110 static void
111 probe_sched_wakeup(void *ignore, struct task_struct *wakee, int success)
112 {
113         struct trace_array_cpu *data;
114         unsigned long flags;
115         int cpu, pc;
116
117         if (unlikely(!sched_ref))
118                 return;
119
120         tracing_record_cmdline(current);
121
122         if (!tracer_enabled || sched_stopped)
123                 return;
124
125         pc = preempt_count();
126         local_irq_save(flags);
127         cpu = raw_smp_processor_id();
128         data = ctx_trace->data[cpu];
129
130         if (likely(!atomic_read(&data->disabled)))
131                 tracing_sched_wakeup_trace(ctx_trace, wakee, current,
132                                            flags, pc);
133
134         local_irq_restore(flags);
135 }
136
137 static int tracing_sched_register(void)
138 {
139         int ret;
140
141         ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
142         if (ret) {
143                 pr_info("wakeup trace: Couldn't activate tracepoint"
144                         " probe to kernel_sched_wakeup\n");
145                 return ret;
146         }
147
148         ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
149         if (ret) {
150                 pr_info("wakeup trace: Couldn't activate tracepoint"
151                         " probe to kernel_sched_wakeup_new\n");
152                 goto fail_deprobe;
153         }
154
155         ret = register_trace_sched_switch(probe_sched_switch, NULL);
156         if (ret) {
157                 pr_info("sched trace: Couldn't activate tracepoint"
158                         " probe to kernel_sched_switch\n");
159                 goto fail_deprobe_wake_new;
160         }
161
162         return ret;
163 fail_deprobe_wake_new:
164         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
165 fail_deprobe:
166         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
167         return ret;
168 }
169
170 static void tracing_sched_unregister(void)
171 {
172         unregister_trace_sched_switch(probe_sched_switch, NULL);
173         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
174         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
175 }
176
177 static void tracing_start_sched_switch(void)
178 {
179         mutex_lock(&sched_register_mutex);
180         if (!(sched_ref++))
181                 tracing_sched_register();
182         mutex_unlock(&sched_register_mutex);
183 }
184
185 static void tracing_stop_sched_switch(void)
186 {
187         mutex_lock(&sched_register_mutex);
188         if (!(--sched_ref))
189                 tracing_sched_unregister();
190         mutex_unlock(&sched_register_mutex);
191 }
192
193 void tracing_start_cmdline_record(void)
194 {
195         tracing_start_sched_switch();
196 }
197
198 void tracing_stop_cmdline_record(void)
199 {
200         tracing_stop_sched_switch();
201 }
202
203 /**
204  * tracing_start_sched_switch_record - start tracing context switches
205  *
206  * Turns on context switch tracing for a tracer.
207  */
208 void tracing_start_sched_switch_record(void)
209 {
210         if (unlikely(!ctx_trace)) {
211                 WARN_ON(1);
212                 return;
213         }
214
215         tracing_start_sched_switch();
216
217         mutex_lock(&sched_register_mutex);
218         tracer_enabled++;
219         mutex_unlock(&sched_register_mutex);
220 }
221
222 /**
223  * tracing_stop_sched_switch_record - start tracing context switches
224  *
225  * Turns off context switch tracing for a tracer.
226  */
227 void tracing_stop_sched_switch_record(void)
228 {
229         mutex_lock(&sched_register_mutex);
230         tracer_enabled--;
231         WARN_ON(tracer_enabled < 0);
232         mutex_unlock(&sched_register_mutex);
233
234         tracing_stop_sched_switch();
235 }
236
237 /**
238  * tracing_sched_switch_assign_trace - assign a trace array for ctx switch
239  * @tr: trace array pointer to assign
240  *
241  * Some tracers might want to record the context switches in their
242  * trace. This function lets those tracers assign the trace array
243  * to use.
244  */
245 void tracing_sched_switch_assign_trace(struct trace_array *tr)
246 {
247         ctx_trace = tr;
248 }
249