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 Nadia Yvette Chambers
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,
52 struct ftrace_ops *op, struct pt_regs *pt_regs)
54 struct trace_array *tr = func_trace;
55 struct trace_array_cpu *data;
61 if (unlikely(!ftrace_function_enabled))
65 preempt_disable_notrace();
66 local_save_flags(flags);
67 cpu = raw_smp_processor_id();
69 disabled = atomic_inc_return(&data->disabled);
71 if (likely(disabled == 1))
72 trace_function(tr, ip, parent_ip, flags, pc);
74 atomic_dec(&data->disabled);
75 preempt_enable_notrace();
80 TRACE_FUNC_OPT_STACK = 0x1,
83 static struct tracer_flags func_flags;
86 function_trace_call(unsigned long ip, unsigned long parent_ip,
87 struct ftrace_ops *op, struct pt_regs *pt_regs)
90 struct trace_array *tr = func_trace;
91 struct trace_array_cpu *data;
97 if (unlikely(!ftrace_function_enabled))
101 * Need to use raw, since this must be called before the
102 * recursive protection is performed.
104 local_irq_save(flags);
105 cpu = raw_smp_processor_id();
106 data = tr->data[cpu];
107 disabled = atomic_inc_return(&data->disabled);
109 if (likely(disabled == 1)) {
110 pc = preempt_count();
111 trace_function(tr, ip, parent_ip, flags, pc);
114 atomic_dec(&data->disabled);
115 local_irq_restore(flags);
119 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
120 struct ftrace_ops *op, struct pt_regs *pt_regs)
122 struct trace_array *tr = func_trace;
123 struct trace_array_cpu *data;
129 if (unlikely(!ftrace_function_enabled))
133 * Need to use raw, since this must be called before the
134 * recursive protection is performed.
136 local_irq_save(flags);
137 cpu = raw_smp_processor_id();
138 data = tr->data[cpu];
139 disabled = atomic_inc_return(&data->disabled);
141 if (likely(disabled == 1)) {
142 pc = preempt_count();
143 trace_function(tr, ip, parent_ip, flags, pc);
146 * __ftrace_trace_stack,
148 * function_stack_trace_call
152 __trace_stack(tr, flags, 5, pc);
155 atomic_dec(&data->disabled);
156 local_irq_restore(flags);
160 static struct ftrace_ops trace_ops __read_mostly =
162 .func = function_trace_call,
163 .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
166 static struct ftrace_ops trace_stack_ops __read_mostly =
168 .func = function_stack_trace_call,
169 .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
172 static struct tracer_opt func_opts[] = {
173 #ifdef CONFIG_STACKTRACE
174 { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
176 { } /* Always set a last empty entry */
179 static struct tracer_flags func_flags = {
180 .val = 0, /* By default: all flags disabled */
184 static void tracing_start_function_trace(void)
186 ftrace_function_enabled = 0;
188 if (trace_flags & TRACE_ITER_PREEMPTONLY)
189 trace_ops.func = function_trace_call_preempt_only;
191 trace_ops.func = function_trace_call;
193 if (func_flags.val & TRACE_FUNC_OPT_STACK)
194 register_ftrace_function(&trace_stack_ops);
196 register_ftrace_function(&trace_ops);
198 ftrace_function_enabled = 1;
201 static void tracing_stop_function_trace(void)
203 ftrace_function_enabled = 0;
205 if (func_flags.val & TRACE_FUNC_OPT_STACK)
206 unregister_ftrace_function(&trace_stack_ops);
208 unregister_ftrace_function(&trace_ops);
211 static int func_set_flag(u32 old_flags, u32 bit, int set)
214 case TRACE_FUNC_OPT_STACK:
215 /* do nothing if already set */
216 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
220 unregister_ftrace_function(&trace_ops);
221 register_ftrace_function(&trace_stack_ops);
223 unregister_ftrace_function(&trace_stack_ops);
224 register_ftrace_function(&trace_ops);
235 static struct tracer function_trace __read_mostly =
238 .init = function_trace_init,
239 .reset = function_trace_reset,
240 .start = function_trace_start,
241 .wait_pipe = poll_wait_pipe,
242 .flags = &func_flags,
243 .set_flag = func_set_flag,
244 #ifdef CONFIG_FTRACE_SELFTEST
245 .selftest = trace_selftest_startup_function,
249 #ifdef CONFIG_DYNAMIC_FTRACE
251 ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
253 long *count = (long *)data;
268 ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
270 long *count = (long *)data;
272 if (!tracing_is_on())
285 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
286 struct ftrace_probe_ops *ops, void *data);
288 static struct ftrace_probe_ops traceon_probe_ops = {
289 .func = ftrace_traceon,
290 .print = ftrace_trace_onoff_print,
293 static struct ftrace_probe_ops traceoff_probe_ops = {
294 .func = ftrace_traceoff,
295 .print = ftrace_trace_onoff_print,
299 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
300 struct ftrace_probe_ops *ops, void *data)
302 long count = (long)data;
304 seq_printf(m, "%ps:", (void *)ip);
306 if (ops == &traceon_probe_ops)
307 seq_printf(m, "traceon");
309 seq_printf(m, "traceoff");
312 seq_printf(m, ":unlimited\n");
314 seq_printf(m, ":count=%ld\n", count);
320 ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
322 struct ftrace_probe_ops *ops;
324 /* we register both traceon and traceoff to this callback */
325 if (strcmp(cmd, "traceon") == 0)
326 ops = &traceon_probe_ops;
328 ops = &traceoff_probe_ops;
330 unregister_ftrace_function_probe_func(glob, ops);
336 ftrace_trace_onoff_callback(struct ftrace_hash *hash,
337 char *glob, char *cmd, char *param, int enable)
339 struct ftrace_probe_ops *ops;
340 void *count = (void *)-1;
344 /* hash funcs only work with set_ftrace_filter */
349 return ftrace_trace_onoff_unreg(glob+1, cmd, param);
351 /* we register both traceon and traceoff to this callback */
352 if (strcmp(cmd, "traceon") == 0)
353 ops = &traceon_probe_ops;
355 ops = &traceoff_probe_ops;
360 number = strsep(¶m, ":");
366 * We use the callback data field (which is a pointer)
369 ret = kstrtoul(number, 0, (unsigned long *)&count);
374 ret = register_ftrace_function_probe(glob, ops, count);
376 return ret < 0 ? ret : 0;
379 static struct ftrace_func_command ftrace_traceon_cmd = {
381 .func = ftrace_trace_onoff_callback,
384 static struct ftrace_func_command ftrace_traceoff_cmd = {
386 .func = ftrace_trace_onoff_callback,
389 static int __init init_func_cmd_traceon(void)
393 ret = register_ftrace_command(&ftrace_traceoff_cmd);
397 ret = register_ftrace_command(&ftrace_traceon_cmd);
399 unregister_ftrace_command(&ftrace_traceoff_cmd);
403 static inline int init_func_cmd_traceon(void)
407 #endif /* CONFIG_DYNAMIC_FTRACE */
409 static __init int init_function_trace(void)
411 init_func_cmd_traceon();
412 return register_tracer(&function_trace);
414 core_initcall(init_function_trace);