summaryrefslogtreecommitdiffstats
path: root/kernel/trace/trace_functions.c
blob: c7b83d03ff681ed74418c007e1a680f7636b3c69 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
/*
 * ring buffer based function tracer
 *
 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
 *
 * Based on code from the latency_tracer, that is:
 *
 *  Copyright (C) 2004-2006 Ingo Molnar
 *  Copyright (C) 2004 Nadia Yvette Chambers
 */
#include <linux/ring_buffer.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/fs.h>

#include "trace.h"

/* function tracing enabled */
static int			ftrace_function_enabled;

static struct trace_array	*func_trace;

static void tracing_start_function_trace(void);
static void tracing_stop_function_trace(void);

static int function_trace_init(struct trace_array *tr)
{
	func_trace = tr;
	tr->cpu = get_cpu();
	put_cpu();

	tracing_start_cmdline_record();
	tracing_start_function_trace();
	return 0;
}

static void function_trace_reset(struct trace_array *tr)
{
	tracing_stop_function_trace();
	tracing_stop_cmdline_record();
}

static void function_trace_start(struct trace_array *tr)
{
	tracing_reset_online_cpus(tr);
}

static void
function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip,
				 struct ftrace_ops *op, struct pt_regs *pt_regs)
{
	struct trace_array *tr = func_trace;
	struct trace_array_cpu *data;
	unsigned long flags;
	long disabled;
	int cpu;
	int pc;

	if (unlikely(!ftrace_function_enabled))
		return;

	pc = preempt_count();
	preempt_disable_notrace();
	local_save_flags(flags);
	cpu = raw_smp_processor_id();
	data = tr->data[cpu];
	disabled = atomic_inc_return(&data->disabled);

	if (likely(disabled == 1))
		trace_function(tr, ip, parent_ip, flags, pc);

	atomic_dec(&data->disabled);
	preempt_enable_notrace();
}

/* Our option */
enum {
	TRACE_FUNC_OPT_STACK	= 0x1,
};

static struct tracer_flags func_flags;

static void
function_trace_call(unsigned long ip, unsigned long parent_ip,
		    struct ftrace_ops *op, struct pt_regs *pt_regs)

{
	struct trace_array *tr = func_trace;
	struct trace_array_cpu *data;
	unsigned long flags;
	long disabled;
	int cpu;
	int pc;

	if (unlikely(!ftrace_function_enabled))
		return;

	/*
	 * Need to use raw, since this must be called before the
	 * recursive protection is performed.
	 */
	local_irq_save(flags);
	cpu = raw_smp_processor_id();
	data = tr->data[cpu];
	disabled = atomic_inc_return(&data->disabled);

	if (likely(disabled == 1)) {
		pc = preempt_count();
		trace_function(tr, ip, parent_ip, flags, pc);
	}

	atomic_dec(&data->disabled);
	local_irq_restore(flags);
}

static void
function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
			  struct ftrace_ops *op, struct pt_regs *pt_regs)
{
	struct trace_array *tr = func_trace;
	struct trace_array_cpu *data;
	unsigned long flags;
	long disabled;
	int cpu;
	int pc;

	if (unlikely(!ftrace_function_enabled))
		return;

	/*
	 * Need to use raw, since this must be called before the
	 * recursive protection is performed.
	 */
	local_irq_save(flags);
	cpu = raw_smp_processor_id();
	data = tr->data[cpu];
	disabled = atomic_inc_return(&data->disabled);

	if (likely(disabled == 1)) {
		pc = preempt_count();
		trace_function(tr, ip, parent_ip, flags, pc);
		/*
		 * skip over 5 funcs:
		 *    __ftrace_trace_stack,
		 *    __trace_stack,
		 *    function_stack_trace_call
		 *    ftrace_list_func
		 *    ftrace_call
		 */
		__trace_stack(tr, flags, 5, pc);
	}

	atomic_dec(&data->disabled);
	local_irq_restore(flags);
}


static struct ftrace_ops trace_ops __read_mostly =
{
	.func = function_trace_call,
	.flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
};

static struct ftrace_ops trace_stack_ops __read_mostly =
{
	.func = function_stack_trace_call,
	.flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
};

static struct tracer_opt func_opts[] = {
#ifdef CONFIG_STACKTRACE
	{ TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
#endif
	{ } /* Always set a last empty entry */
};

static struct tracer_flags func_flags = {
	.val = 0, /* By default: all flags disabled */
	.opts = func_opts
};

static void tracing_start_function_trace(void)
{
	ftrace_function_enabled = 0;

	if (trace_flags & TRACE_ITER_PREEMPTONLY)
		trace_ops.func = function_trace_call_preempt_only;
	else
		trace_ops.func = function_trace_call;

	if (func_flags.val & TRACE_FUNC_OPT_STACK)
		register_ftrace_function(&trace_stack_ops);
	else
		register_ftrace_function(&trace_ops);

	ftrace_function_enabled = 1;
}

static void tracing_stop_function_trace(void)
{
	ftrace_function_enabled = 0;

	if (func_flags.val & TRACE_FUNC_OPT_STACK)
		unregister_ftrace_function(&trace_stack_ops);
	else
		unregister_ftrace_function(&trace_ops);
}

static int func_set_flag(u32 old_flags, u32 bit, int set)
{
	switch (bit) {
	case TRACE_FUNC_OPT_STACK:
		/* do nothing if already set */
		if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
			break;

		if (set) {
			unregister_ftrace_function(&trace_ops);
			register_ftrace_function(&trace_stack_ops);
		} else {
			unregister_ftrace_function(&trace_stack_ops);
			register_ftrace_function(&trace_ops);
		}

		break;
	default:
		return -EINVAL;
	}

	return 0;
}

static struct tracer function_trace __read_mostly =
{
	.name		= "function",
	.init		= function_trace_init,
	.reset		= function_trace_reset,
	.start		= function_trace_start,
	.wait_pipe	= poll_wait_pipe,
	.flags		= &func_flags,
	.set_flag	= func_set_flag,
#ifdef CONFIG_FTRACE_SELFTEST
	.selftest	= trace_selftest_startup_function,
#endif
};

#ifdef CONFIG_DYNAMIC_FTRACE
static void
ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
{
	long *count = (long *)data;

	if (tracing_is_on())
		return;

	if (!*count)
		return;

	if (*count != -1)
		(*count)--;

	tracing_on();
}

static void
ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
{
	long *count = (long *)data;

	if (!tracing_is_on())
		return;

	if (!*count)
		return;

	if (*count != -1)
		(*count)--;

	tracing_off();
}

static int
ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
			 struct ftrace_probe_ops *ops, void *data);

static struct ftrace_probe_ops traceon_probe_ops = {
	.func			= ftrace_traceon,
	.print			= ftrace_trace_onoff_print,
};

static struct ftrace_probe_ops traceoff_probe_ops = {
	.func			= ftrace_traceoff,
	.print			= ftrace_trace_onoff_print,
};

static int
ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
			 struct ftrace_probe_ops *ops, void *data)
{
	long count = (long)data;

	seq_printf(m, "%ps:", (void *)ip);

	if (ops == &traceon_probe_ops)
		seq_printf(m, "traceon");
	else
		seq_printf(m, "traceoff");

	if (count == -1)
		seq_printf(m, ":unlimited\n");
	else
		seq_printf(m, ":count=%ld\n", count);

	return 0;
}

static int
ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
{
	struct ftrace_probe_ops *ops;

	/* we register both traceon and traceoff to this callback */
	if (strcmp(cmd, "traceon") == 0)
		ops = &traceon_probe_ops;
	else
		ops = &traceoff_probe_ops;

	unregister_ftrace_function_probe_func(glob, ops);

	return 0;
}

static int
ftrace_trace_onoff_callback(struct ftrace_hash *hash,
			    char *glob, char *cmd, char *param, int enable)
{
	struct ftrace_probe_ops *ops;
	void *count = (void *)-1;
	char *number;
	int ret;

	/* hash funcs only work with set_ftrace_filter */
	if (!enable)
		return -EINVAL;

	if (glob[0] == '!')
		return ftrace_trace_onoff_unreg(glob+1, cmd, param);

	/* we register both traceon and traceoff to this callback */
	if (strcmp(cmd, "traceon") == 0)
		ops = &traceon_probe_ops;
	else
		ops = &traceoff_probe_ops;

	if (!param)
		goto out_reg;

	number = strsep(&param, ":");

	if (!strlen(number))
		goto out_reg;

	/*
	 * We use the callback data field (which is a pointer)
	 * as our counter.
	 */
	ret = strict_strtoul(number, 0, (unsigned long *)&count);
	if (ret)
		return ret;

 out_reg:
	ret = register_ftrace_function_probe(glob, ops, count);

	return ret < 0 ? ret : 0;
}

static struct ftrace_func_command ftrace_traceon_cmd = {
	.name			= "traceon",
	.func			= ftrace_trace_onoff_callback,
};

static struct ftrace_func_command ftrace_traceoff_cmd = {
	.name			= "traceoff",
	.func			= ftrace_trace_onoff_callback,
};

static int __init init_func_cmd_traceon(void)
{
	int ret;

	ret = register_ftrace_command(&ftrace_traceoff_cmd);
	if (ret)
		return ret;

	ret = register_ftrace_command(&ftrace_traceon_cmd);
	if (ret)
		unregister_ftrace_command(&ftrace_traceoff_cmd);
	return ret;
}
#else
static inline int init_func_cmd_traceon(void)
{
	return 0;
}
#endif /* CONFIG_DYNAMIC_FTRACE */

static __init int init_function_trace(void)
{
	init_func_cmd_traceon();
	return register_tracer(&function_trace);
}
device_initcall(init_function_trace);