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
);