2 * ring buffer based function tracer
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
7 * Based on code from the latency_tracer, that is:
9 * Copyright (C) 2004-2006 Ingo Molnar
10 * Copyright (C) 2004 William Lee Irwin III
12 #include <linux/ring_buffer.h>
13 #include <linux/debugfs.h>
14 #include <linux/uaccess.h>
15 #include <linux/ftrace.h>
20 /* function tracing enabled */
21 static int ftrace_function_enabled;
23 static struct trace_array *func_trace;
25 static void tracing_start_function_trace(void);
26 static void tracing_stop_function_trace(void);
28 static int function_trace_init(struct trace_array *tr)
34 tracing_start_cmdline_record();
35 tracing_start_function_trace();
39 static void function_trace_reset(struct trace_array *tr)
41 tracing_stop_function_trace();
42 tracing_stop_cmdline_record();
45 static void function_trace_start(struct trace_array *tr)
47 tracing_reset_online_cpus(tr);
51 function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
53 struct trace_array *tr = func_trace;
54 struct trace_array_cpu *data;
60 if (unlikely(!ftrace_function_enabled))
64 resched = ftrace_preempt_disable();
65 local_save_flags(flags);
66 cpu = raw_smp_processor_id();
68 disabled = atomic_inc_return(&data->disabled);
70 if (likely(disabled == 1))
71 trace_function(tr, ip, parent_ip, flags, pc);
73 atomic_dec(&data->disabled);
74 ftrace_preempt_enable(resched);
78 function_trace_call(unsigned long ip, unsigned long parent_ip)
80 struct trace_array *tr = func_trace;
81 struct trace_array_cpu *data;
87 if (unlikely(!ftrace_function_enabled))
91 * Need to use raw, since this must be called before the
92 * recursive protection is performed.
94 local_irq_save(flags);
95 cpu = raw_smp_processor_id();
97 disabled = atomic_inc_return(&data->disabled);
99 if (likely(disabled == 1)) {
100 pc = preempt_count();
101 trace_function(tr, ip, parent_ip, flags, pc);
104 atomic_dec(&data->disabled);
105 local_irq_restore(flags);
109 function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
111 struct trace_array *tr = func_trace;
112 struct trace_array_cpu *data;
118 if (unlikely(!ftrace_function_enabled))
122 * Need to use raw, since this must be called before the
123 * recursive protection is performed.
125 local_irq_save(flags);
126 cpu = raw_smp_processor_id();
127 data = tr->data[cpu];
128 disabled = atomic_inc_return(&data->disabled);
130 if (likely(disabled == 1)) {
131 pc = preempt_count();
132 trace_function(tr, ip, parent_ip, flags, pc);
135 * __ftrace_trace_stack,
137 * function_stack_trace_call
141 __trace_stack(tr, flags, 5, pc);
144 atomic_dec(&data->disabled);
145 local_irq_restore(flags);
149 static struct ftrace_ops trace_ops __read_mostly =
151 .func = function_trace_call,
154 static struct ftrace_ops trace_stack_ops __read_mostly =
156 .func = function_stack_trace_call,
159 /* Our two options */
161 TRACE_FUNC_OPT_STACK = 0x1,
164 static struct tracer_opt func_opts[] = {
165 #ifdef CONFIG_STACKTRACE
166 { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
168 { } /* Always set a last empty entry */
171 static struct tracer_flags func_flags = {
172 .val = 0, /* By default: all flags disabled */
176 static void tracing_start_function_trace(void)
178 ftrace_function_enabled = 0;
180 if (trace_flags & TRACE_ITER_PREEMPTONLY)
181 trace_ops.func = function_trace_call_preempt_only;
183 trace_ops.func = function_trace_call;
185 if (func_flags.val & TRACE_FUNC_OPT_STACK)
186 register_ftrace_function(&trace_stack_ops);
188 register_ftrace_function(&trace_ops);
190 ftrace_function_enabled = 1;
193 static void tracing_stop_function_trace(void)
195 ftrace_function_enabled = 0;
197 if (func_flags.val & TRACE_FUNC_OPT_STACK)
198 unregister_ftrace_function(&trace_stack_ops);
200 unregister_ftrace_function(&trace_ops);
203 static int func_set_flag(u32 old_flags, u32 bit, int set)
205 if (bit == TRACE_FUNC_OPT_STACK) {
206 /* do nothing if already set */
207 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
211 unregister_ftrace_function(&trace_ops);
212 register_ftrace_function(&trace_stack_ops);
214 unregister_ftrace_function(&trace_stack_ops);
215 register_ftrace_function(&trace_ops);
224 static struct tracer function_trace __read_mostly =
227 .init = function_trace_init,
228 .reset = function_trace_reset,
229 .start = function_trace_start,
230 .wait_pipe = poll_wait_pipe,
231 .flags = &func_flags,
232 .set_flag = func_set_flag,
233 #ifdef CONFIG_FTRACE_SELFTEST
234 .selftest = trace_selftest_startup_function,
238 #ifdef CONFIG_DYNAMIC_FTRACE
240 ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
242 long *count = (long *)data;
257 ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
259 long *count = (long *)data;
261 if (!tracing_is_on())
274 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
275 struct ftrace_probe_ops *ops, void *data);
277 static struct ftrace_probe_ops traceon_probe_ops = {
278 .func = ftrace_traceon,
279 .print = ftrace_trace_onoff_print,
282 static struct ftrace_probe_ops traceoff_probe_ops = {
283 .func = ftrace_traceoff,
284 .print = ftrace_trace_onoff_print,
288 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
289 struct ftrace_probe_ops *ops, void *data)
291 char str[KSYM_SYMBOL_LEN];
292 long count = (long)data;
294 kallsyms_lookup(ip, NULL, NULL, NULL, str);
295 seq_printf(m, "%s:", str);
297 if (ops == &traceon_probe_ops)
298 seq_printf(m, "traceon");
300 seq_printf(m, "traceoff");
303 seq_printf(m, ":unlimited\n");
305 seq_printf(m, ":count=%ld\n", count);
311 ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
313 struct ftrace_probe_ops *ops;
315 /* we register both traceon and traceoff to this callback */
316 if (strcmp(cmd, "traceon") == 0)
317 ops = &traceon_probe_ops;
319 ops = &traceoff_probe_ops;
321 unregister_ftrace_function_probe_func(glob, ops);
327 ftrace_trace_onoff_callback(char *glob, char *cmd, char *param, int enable)
329 struct ftrace_probe_ops *ops;
330 void *count = (void *)-1;
334 /* hash funcs only work with set_ftrace_filter */
339 return ftrace_trace_onoff_unreg(glob+1, cmd, param);
341 /* we register both traceon and traceoff to this callback */
342 if (strcmp(cmd, "traceon") == 0)
343 ops = &traceon_probe_ops;
345 ops = &traceoff_probe_ops;
350 number = strsep(¶m, ":");
356 * We use the callback data field (which is a pointer)
359 ret = strict_strtoul(number, 0, (unsigned long *)&count);
364 ret = register_ftrace_function_probe(glob, ops, count);
369 static struct ftrace_func_command ftrace_traceon_cmd = {
371 .func = ftrace_trace_onoff_callback,
374 static struct ftrace_func_command ftrace_traceoff_cmd = {
376 .func = ftrace_trace_onoff_callback,
379 static int __init init_func_cmd_traceon(void)
383 ret = register_ftrace_command(&ftrace_traceoff_cmd);
387 ret = register_ftrace_command(&ftrace_traceon_cmd);
389 unregister_ftrace_command(&ftrace_traceoff_cmd);
393 static inline int init_func_cmd_traceon(void)
397 #endif /* CONFIG_DYNAMIC_FTRACE */
399 static __init int init_function_trace(void)
401 init_func_cmd_traceon();
402 return register_tracer(&function_trace);
404 device_initcall(init_function_trace);