| 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/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 | |
| 22 | static void |
| 23 | probe_sched_switch(struct rq *__rq, struct task_struct *prev, |
| 24 | struct task_struct *next) |
| 25 | { |
| 26 | struct trace_array_cpu *data; |
| 27 | unsigned long flags; |
| 28 | int cpu; |
| 29 | int pc; |
| 30 | |
| 31 | if (!sched_ref) |
| 32 | return; |
| 33 | |
| 34 | tracing_record_cmdline(prev); |
| 35 | tracing_record_cmdline(next); |
| 36 | |
| 37 | if (!tracer_enabled) |
| 38 | return; |
| 39 | |
| 40 | pc = preempt_count(); |
| 41 | local_irq_save(flags); |
| 42 | cpu = raw_smp_processor_id(); |
| 43 | data = ctx_trace->data[cpu]; |
| 44 | |
| 45 | if (likely(!atomic_read(&data->disabled))) |
| 46 | tracing_sched_switch_trace(ctx_trace, data, prev, next, flags, pc); |
| 47 | |
| 48 | local_irq_restore(flags); |
| 49 | } |
| 50 | |
| 51 | static void |
| 52 | probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee) |
| 53 | { |
| 54 | struct trace_array_cpu *data; |
| 55 | unsigned long flags; |
| 56 | int cpu, pc; |
| 57 | |
| 58 | if (!likely(tracer_enabled)) |
| 59 | return; |
| 60 | |
| 61 | pc = preempt_count(); |
| 62 | tracing_record_cmdline(current); |
| 63 | |
| 64 | local_irq_save(flags); |
| 65 | cpu = raw_smp_processor_id(); |
| 66 | data = ctx_trace->data[cpu]; |
| 67 | |
| 68 | if (likely(!atomic_read(&data->disabled))) |
| 69 | tracing_sched_wakeup_trace(ctx_trace, data, wakee, current, |
| 70 | flags, pc); |
| 71 | |
| 72 | local_irq_restore(flags); |
| 73 | } |
| 74 | |
| 75 | static void sched_switch_reset(struct trace_array *tr) |
| 76 | { |
| 77 | int cpu; |
| 78 | |
| 79 | tr->time_start = ftrace_now(tr->cpu); |
| 80 | |
| 81 | for_each_online_cpu(cpu) |
| 82 | tracing_reset(tr, cpu); |
| 83 | } |
| 84 | |
| 85 | static int tracing_sched_register(void) |
| 86 | { |
| 87 | int ret; |
| 88 | |
| 89 | ret = register_trace_sched_wakeup(probe_sched_wakeup); |
| 90 | if (ret) { |
| 91 | pr_info("wakeup trace: Couldn't activate tracepoint" |
| 92 | " probe to kernel_sched_wakeup\n"); |
| 93 | return ret; |
| 94 | } |
| 95 | |
| 96 | ret = register_trace_sched_wakeup_new(probe_sched_wakeup); |
| 97 | if (ret) { |
| 98 | pr_info("wakeup trace: Couldn't activate tracepoint" |
| 99 | " probe to kernel_sched_wakeup_new\n"); |
| 100 | goto fail_deprobe; |
| 101 | } |
| 102 | |
| 103 | ret = register_trace_sched_switch(probe_sched_switch); |
| 104 | if (ret) { |
| 105 | pr_info("sched trace: Couldn't activate tracepoint" |
| 106 | " probe to kernel_sched_schedule\n"); |
| 107 | goto fail_deprobe_wake_new; |
| 108 | } |
| 109 | |
| 110 | return ret; |
| 111 | fail_deprobe_wake_new: |
| 112 | unregister_trace_sched_wakeup_new(probe_sched_wakeup); |
| 113 | fail_deprobe: |
| 114 | unregister_trace_sched_wakeup(probe_sched_wakeup); |
| 115 | return ret; |
| 116 | } |
| 117 | |
| 118 | static void tracing_sched_unregister(void) |
| 119 | { |
| 120 | unregister_trace_sched_switch(probe_sched_switch); |
| 121 | unregister_trace_sched_wakeup_new(probe_sched_wakeup); |
| 122 | unregister_trace_sched_wakeup(probe_sched_wakeup); |
| 123 | } |
| 124 | |
| 125 | static void tracing_start_sched_switch(void) |
| 126 | { |
| 127 | mutex_lock(&sched_register_mutex); |
| 128 | if (!(sched_ref++)) |
| 129 | tracing_sched_register(); |
| 130 | mutex_unlock(&sched_register_mutex); |
| 131 | } |
| 132 | |
| 133 | static void tracing_stop_sched_switch(void) |
| 134 | { |
| 135 | mutex_lock(&sched_register_mutex); |
| 136 | if (!(--sched_ref)) |
| 137 | tracing_sched_unregister(); |
| 138 | mutex_unlock(&sched_register_mutex); |
| 139 | } |
| 140 | |
| 141 | void tracing_start_cmdline_record(void) |
| 142 | { |
| 143 | tracing_start_sched_switch(); |
| 144 | } |
| 145 | |
| 146 | void tracing_stop_cmdline_record(void) |
| 147 | { |
| 148 | tracing_stop_sched_switch(); |
| 149 | } |
| 150 | |
| 151 | /** |
| 152 | * tracing_start_sched_switch_record - start tracing context switches |
| 153 | * |
| 154 | * Turns on context switch tracing for a tracer. |
| 155 | */ |
| 156 | void tracing_start_sched_switch_record(void) |
| 157 | { |
| 158 | if (unlikely(!ctx_trace)) { |
| 159 | WARN_ON(1); |
| 160 | return; |
| 161 | } |
| 162 | |
| 163 | tracing_start_sched_switch(); |
| 164 | |
| 165 | mutex_lock(&sched_register_mutex); |
| 166 | tracer_enabled++; |
| 167 | mutex_unlock(&sched_register_mutex); |
| 168 | } |
| 169 | |
| 170 | /** |
| 171 | * tracing_stop_sched_switch_record - start tracing context switches |
| 172 | * |
| 173 | * Turns off context switch tracing for a tracer. |
| 174 | */ |
| 175 | void tracing_stop_sched_switch_record(void) |
| 176 | { |
| 177 | mutex_lock(&sched_register_mutex); |
| 178 | tracer_enabled--; |
| 179 | WARN_ON(tracer_enabled < 0); |
| 180 | mutex_unlock(&sched_register_mutex); |
| 181 | |
| 182 | tracing_stop_sched_switch(); |
| 183 | } |
| 184 | |
| 185 | /** |
| 186 | * tracing_sched_switch_assign_trace - assign a trace array for ctx switch |
| 187 | * @tr: trace array pointer to assign |
| 188 | * |
| 189 | * Some tracers might want to record the context switches in their |
| 190 | * trace. This function lets those tracers assign the trace array |
| 191 | * to use. |
| 192 | */ |
| 193 | void tracing_sched_switch_assign_trace(struct trace_array *tr) |
| 194 | { |
| 195 | ctx_trace = tr; |
| 196 | } |
| 197 | |
| 198 | static void start_sched_trace(struct trace_array *tr) |
| 199 | { |
| 200 | sched_switch_reset(tr); |
| 201 | tracing_start_sched_switch_record(); |
| 202 | } |
| 203 | |
| 204 | static void stop_sched_trace(struct trace_array *tr) |
| 205 | { |
| 206 | tracing_stop_sched_switch_record(); |
| 207 | } |
| 208 | |
| 209 | static int sched_switch_trace_init(struct trace_array *tr) |
| 210 | { |
| 211 | ctx_trace = tr; |
| 212 | start_sched_trace(tr); |
| 213 | return 0; |
| 214 | } |
| 215 | |
| 216 | static void sched_switch_trace_reset(struct trace_array *tr) |
| 217 | { |
| 218 | if (sched_ref) |
| 219 | stop_sched_trace(tr); |
| 220 | } |
| 221 | |
| 222 | static void sched_switch_trace_start(struct trace_array *tr) |
| 223 | { |
| 224 | sched_switch_reset(tr); |
| 225 | tracing_start_sched_switch(); |
| 226 | } |
| 227 | |
| 228 | static void sched_switch_trace_stop(struct trace_array *tr) |
| 229 | { |
| 230 | tracing_stop_sched_switch(); |
| 231 | } |
| 232 | |
| 233 | static struct tracer sched_switch_trace __read_mostly = |
| 234 | { |
| 235 | .name = "sched_switch", |
| 236 | .init = sched_switch_trace_init, |
| 237 | .reset = sched_switch_trace_reset, |
| 238 | .start = sched_switch_trace_start, |
| 239 | .stop = sched_switch_trace_stop, |
| 240 | #ifdef CONFIG_FTRACE_SELFTEST |
| 241 | .selftest = trace_selftest_startup_sched_switch, |
| 242 | #endif |
| 243 | }; |
| 244 | |
| 245 | __init static int init_sched_switch_trace(void) |
| 246 | { |
| 247 | return register_tracer(&sched_switch_trace); |
| 248 | } |
| 249 | device_initcall(init_sched_switch_trace); |
| 250 | |