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);
52 TRACE_FUNC_OPT_STACK = 0x1,
55 static struct tracer_flags func_flags;
58 function_trace_call(unsigned long ip, unsigned long parent_ip,
59 struct ftrace_ops *op, struct pt_regs *pt_regs)
61 struct trace_array *tr = func_trace;
62 struct trace_array_cpu *data;
68 if (unlikely(!ftrace_function_enabled))
72 preempt_disable_notrace();
74 bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX);
78 cpu = smp_processor_id();
80 if (!atomic_read(&data->disabled)) {
81 local_save_flags(flags);
82 trace_function(tr, ip, parent_ip, flags, pc);
84 trace_clear_recursion(bit);
87 preempt_enable_notrace();
91 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
92 struct ftrace_ops *op, struct pt_regs *pt_regs)
94 struct trace_array *tr = func_trace;
95 struct trace_array_cpu *data;
101 if (unlikely(!ftrace_function_enabled))
105 * Need to use raw, since this must be called before the
106 * recursive protection is performed.
108 local_irq_save(flags);
109 cpu = raw_smp_processor_id();
110 data = tr->data[cpu];
111 disabled = atomic_inc_return(&data->disabled);
113 if (likely(disabled == 1)) {
114 pc = preempt_count();
115 trace_function(tr, ip, parent_ip, flags, pc);
118 * __ftrace_trace_stack,
120 * function_stack_trace_call
124 __trace_stack(tr, flags, 5, pc);
127 atomic_dec(&data->disabled);
128 local_irq_restore(flags);
132 static struct ftrace_ops trace_ops __read_mostly =
134 .func = function_trace_call,
135 .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
138 static struct ftrace_ops trace_stack_ops __read_mostly =
140 .func = function_stack_trace_call,
141 .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
144 static struct tracer_opt func_opts[] = {
145 #ifdef CONFIG_STACKTRACE
146 { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
148 { } /* Always set a last empty entry */
151 static struct tracer_flags func_flags = {
152 .val = 0, /* By default: all flags disabled */
156 static void tracing_start_function_trace(void)
158 ftrace_function_enabled = 0;
160 if (func_flags.val & TRACE_FUNC_OPT_STACK)
161 register_ftrace_function(&trace_stack_ops);
163 register_ftrace_function(&trace_ops);
165 ftrace_function_enabled = 1;
168 static void tracing_stop_function_trace(void)
170 ftrace_function_enabled = 0;
172 if (func_flags.val & TRACE_FUNC_OPT_STACK)
173 unregister_ftrace_function(&trace_stack_ops);
175 unregister_ftrace_function(&trace_ops);
178 static int func_set_flag(u32 old_flags, u32 bit, int set)
181 case TRACE_FUNC_OPT_STACK:
182 /* do nothing if already set */
183 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
187 unregister_ftrace_function(&trace_ops);
188 register_ftrace_function(&trace_stack_ops);
190 unregister_ftrace_function(&trace_stack_ops);
191 register_ftrace_function(&trace_ops);
202 static struct tracer function_trace __read_mostly =
205 .init = function_trace_init,
206 .reset = function_trace_reset,
207 .start = function_trace_start,
208 .wait_pipe = poll_wait_pipe,
209 .flags = &func_flags,
210 .set_flag = func_set_flag,
211 #ifdef CONFIG_FTRACE_SELFTEST
212 .selftest = trace_selftest_startup_function,
216 #ifdef CONFIG_DYNAMIC_FTRACE
218 ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
220 long *count = (long *)data;
235 ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
237 long *count = (long *)data;
239 if (!tracing_is_on())
252 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
253 struct ftrace_probe_ops *ops, void *data);
255 static struct ftrace_probe_ops traceon_probe_ops = {
256 .func = ftrace_traceon,
257 .print = ftrace_trace_onoff_print,
260 static struct ftrace_probe_ops traceoff_probe_ops = {
261 .func = ftrace_traceoff,
262 .print = ftrace_trace_onoff_print,
266 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
267 struct ftrace_probe_ops *ops, void *data)
269 long count = (long)data;
271 seq_printf(m, "%ps:", (void *)ip);
273 if (ops == &traceon_probe_ops)
274 seq_printf(m, "traceon");
276 seq_printf(m, "traceoff");
279 seq_printf(m, ":unlimited\n");
281 seq_printf(m, ":count=%ld\n", count);
287 ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
289 struct ftrace_probe_ops *ops;
291 /* we register both traceon and traceoff to this callback */
292 if (strcmp(cmd, "traceon") == 0)
293 ops = &traceon_probe_ops;
295 ops = &traceoff_probe_ops;
297 unregister_ftrace_function_probe_func(glob, ops);
303 ftrace_trace_onoff_callback(struct ftrace_hash *hash,
304 char *glob, char *cmd, char *param, int enable)
306 struct ftrace_probe_ops *ops;
307 void *count = (void *)-1;
311 /* hash funcs only work with set_ftrace_filter */
316 return ftrace_trace_onoff_unreg(glob+1, cmd, param);
318 /* we register both traceon and traceoff to this callback */
319 if (strcmp(cmd, "traceon") == 0)
320 ops = &traceon_probe_ops;
322 ops = &traceoff_probe_ops;
327 number = strsep(¶m, ":");
333 * We use the callback data field (which is a pointer)
336 ret = kstrtoul(number, 0, (unsigned long *)&count);
341 ret = register_ftrace_function_probe(glob, ops, count);
343 return ret < 0 ? ret : 0;
346 static struct ftrace_func_command ftrace_traceon_cmd = {
348 .func = ftrace_trace_onoff_callback,
351 static struct ftrace_func_command ftrace_traceoff_cmd = {
353 .func = ftrace_trace_onoff_callback,
356 static int __init init_func_cmd_traceon(void)
360 ret = register_ftrace_command(&ftrace_traceoff_cmd);
364 ret = register_ftrace_command(&ftrace_traceon_cmd);
366 unregister_ftrace_command(&ftrace_traceoff_cmd);
370 static inline int init_func_cmd_traceon(void)
374 #endif /* CONFIG_DYNAMIC_FTRACE */
376 static __init int init_function_trace(void)
378 init_func_cmd_traceon();
379 return register_tracer(&function_trace);
381 core_initcall(init_function_trace);