1/*
2 * unlikely profiler
3 *
4 * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
5 */
6#include <linux/kallsyms.h>
7#include <linux/seq_file.h>
8#include <linux/spinlock.h>
9#include <linux/irqflags.h>
10#include <linux/uaccess.h>
11#include <linux/module.h>
12#include <linux/ftrace.h>
13#include <linux/hash.h>
14#include <linux/fs.h>
15#include <asm/local.h>
16
17#include "trace.h"
18#include "trace_stat.h"
19#include "trace_output.h"
20
21#ifdef CONFIG_BRANCH_TRACER
22
23static struct tracer branch_trace;
24static int branch_tracing_enabled __read_mostly;
25static DEFINE_MUTEX(branch_tracing_mutex);
26
27static struct trace_array *branch_tracer;
28
29static void
30probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
31{
32	struct ftrace_event_call *call = &event_branch;
33	struct trace_array *tr = branch_tracer;
34	struct trace_array_cpu *data;
35	struct ring_buffer_event *event;
36	struct trace_branch *entry;
37	struct ring_buffer *buffer;
38	unsigned long flags;
39	int pc;
40	const char *p;
41
42	if (current->trace_recursion & TRACE_BRANCH_BIT)
43		return;
44
45	/*
46	 * I would love to save just the ftrace_likely_data pointer, but
47	 * this code can also be used by modules. Ugly things can happen
48	 * if the module is unloaded, and then we go and read the
49	 * pointer.  This is slower, but much safer.
50	 */
51
52	if (unlikely(!tr))
53		return;
54
55	raw_local_irq_save(flags);
56	current->trace_recursion |= TRACE_BRANCH_BIT;
57	data = this_cpu_ptr(tr->trace_buffer.data);
58	if (atomic_read(&data->disabled))
59		goto out;
60
61	pc = preempt_count();
62	buffer = tr->trace_buffer.buffer;
63	event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH,
64					  sizeof(*entry), flags, pc);
65	if (!event)
66		goto out;
67
68	entry	= ring_buffer_event_data(event);
69
70	/* Strip off the path, only save the file */
71	p = f->file + strlen(f->file);
72	while (p >= f->file && *p != '/')
73		p--;
74	p++;
75
76	strncpy(entry->func, f->func, TRACE_FUNC_SIZE);
77	strncpy(entry->file, p, TRACE_FILE_SIZE);
78	entry->func[TRACE_FUNC_SIZE] = 0;
79	entry->file[TRACE_FILE_SIZE] = 0;
80	entry->line = f->line;
81	entry->correct = val == expect;
82
83	if (!call_filter_check_discard(call, entry, buffer, event))
84		__buffer_unlock_commit(buffer, event);
85
86 out:
87	current->trace_recursion &= ~TRACE_BRANCH_BIT;
88	raw_local_irq_restore(flags);
89}
90
91static inline
92void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
93{
94	if (!branch_tracing_enabled)
95		return;
96
97	probe_likely_condition(f, val, expect);
98}
99
100int enable_branch_tracing(struct trace_array *tr)
101{
102	mutex_lock(&branch_tracing_mutex);
103	branch_tracer = tr;
104	/*
105	 * Must be seen before enabling. The reader is a condition
106	 * where we do not need a matching rmb()
107	 */
108	smp_wmb();
109	branch_tracing_enabled++;
110	mutex_unlock(&branch_tracing_mutex);
111
112	return 0;
113}
114
115void disable_branch_tracing(void)
116{
117	mutex_lock(&branch_tracing_mutex);
118
119	if (!branch_tracing_enabled)
120		goto out_unlock;
121
122	branch_tracing_enabled--;
123
124 out_unlock:
125	mutex_unlock(&branch_tracing_mutex);
126}
127
128static void start_branch_trace(struct trace_array *tr)
129{
130	enable_branch_tracing(tr);
131}
132
133static void stop_branch_trace(struct trace_array *tr)
134{
135	disable_branch_tracing();
136}
137
138static int branch_trace_init(struct trace_array *tr)
139{
140	start_branch_trace(tr);
141	return 0;
142}
143
144static void branch_trace_reset(struct trace_array *tr)
145{
146	stop_branch_trace(tr);
147}
148
149static enum print_line_t trace_branch_print(struct trace_iterator *iter,
150					    int flags, struct trace_event *event)
151{
152	struct trace_branch *field;
153
154	trace_assign_type(field, iter->ent);
155
156	trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n",
157			 field->correct ? "  ok  " : " MISS ",
158			 field->func,
159			 field->file,
160			 field->line);
161
162	return trace_handle_return(&iter->seq);
163}
164
165static void branch_print_header(struct seq_file *s)
166{
167	seq_puts(s, "#           TASK-PID    CPU#    TIMESTAMP  CORRECT"
168		    "  FUNC:FILE:LINE\n"
169		    "#              | |       |          |         |   "
170		    "    |\n");
171}
172
173static struct trace_event_functions trace_branch_funcs = {
174	.trace		= trace_branch_print,
175};
176
177static struct trace_event trace_branch_event = {
178	.type		= TRACE_BRANCH,
179	.funcs		= &trace_branch_funcs,
180};
181
182static struct tracer branch_trace __read_mostly =
183{
184	.name		= "branch",
185	.init		= branch_trace_init,
186	.reset		= branch_trace_reset,
187#ifdef CONFIG_FTRACE_SELFTEST
188	.selftest	= trace_selftest_startup_branch,
189#endif /* CONFIG_FTRACE_SELFTEST */
190	.print_header	= branch_print_header,
191};
192
193__init static int init_branch_tracer(void)
194{
195	int ret;
196
197	ret = register_ftrace_event(&trace_branch_event);
198	if (!ret) {
199		printk(KERN_WARNING "Warning: could not register "
200				    "branch events\n");
201		return 1;
202	}
203	return register_tracer(&branch_trace);
204}
205core_initcall(init_branch_tracer);
206
207#else
208static inline
209void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
210{
211}
212#endif /* CONFIG_BRANCH_TRACER */
213
214void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect)
215{
216	/*
217	 * I would love to have a trace point here instead, but the
218	 * trace point code is so inundated with unlikely and likely
219	 * conditions that the recursive nightmare that exists is too
220	 * much to try to get working. At least for now.
221	 */
222	trace_likely_condition(f, val, expect);
223
224	/* FIXME: Make this atomic! */
225	if (val == expect)
226		f->correct++;
227	else
228		f->incorrect++;
229}
230EXPORT_SYMBOL(ftrace_likely_update);
231
232extern unsigned long __start_annotated_branch_profile[];
233extern unsigned long __stop_annotated_branch_profile[];
234
235static int annotated_branch_stat_headers(struct seq_file *m)
236{
237	seq_puts(m, " correct incorrect  % "
238		    "       Function                "
239		    "  File              Line\n"
240		    " ------- ---------  - "
241		    "       --------                "
242		    "  ----              ----\n");
243	return 0;
244}
245
246static inline long get_incorrect_percent(struct ftrace_branch_data *p)
247{
248	long percent;
249
250	if (p->correct) {
251		percent = p->incorrect * 100;
252		percent /= p->correct + p->incorrect;
253	} else
254		percent = p->incorrect ? 100 : -1;
255
256	return percent;
257}
258
259static int branch_stat_show(struct seq_file *m, void *v)
260{
261	struct ftrace_branch_data *p = v;
262	const char *f;
263	long percent;
264
265	/* Only print the file, not the path */
266	f = p->file + strlen(p->file);
267	while (f >= p->file && *f != '/')
268		f--;
269	f++;
270
271	/*
272	 * The miss is overlayed on correct, and hit on incorrect.
273	 */
274	percent = get_incorrect_percent(p);
275
276	seq_printf(m, "%8lu %8lu ",  p->correct, p->incorrect);
277	if (percent < 0)
278		seq_puts(m, "  X ");
279	else
280		seq_printf(m, "%3ld ", percent);
281	seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line);
282	return 0;
283}
284
285static void *annotated_branch_stat_start(struct tracer_stat *trace)
286{
287	return __start_annotated_branch_profile;
288}
289
290static void *
291annotated_branch_stat_next(void *v, int idx)
292{
293	struct ftrace_branch_data *p = v;
294
295	++p;
296
297	if ((void *)p >= (void *)__stop_annotated_branch_profile)
298		return NULL;
299
300	return p;
301}
302
303static int annotated_branch_stat_cmp(void *p1, void *p2)
304{
305	struct ftrace_branch_data *a = p1;
306	struct ftrace_branch_data *b = p2;
307
308	long percent_a, percent_b;
309
310	percent_a = get_incorrect_percent(a);
311	percent_b = get_incorrect_percent(b);
312
313	if (percent_a < percent_b)
314		return -1;
315	if (percent_a > percent_b)
316		return 1;
317
318	if (a->incorrect < b->incorrect)
319		return -1;
320	if (a->incorrect > b->incorrect)
321		return 1;
322
323	/*
324	 * Since the above shows worse (incorrect) cases
325	 * first, we continue that by showing best (correct)
326	 * cases last.
327	 */
328	if (a->correct > b->correct)
329		return -1;
330	if (a->correct < b->correct)
331		return 1;
332
333	return 0;
334}
335
336static struct tracer_stat annotated_branch_stats = {
337	.name = "branch_annotated",
338	.stat_start = annotated_branch_stat_start,
339	.stat_next = annotated_branch_stat_next,
340	.stat_cmp = annotated_branch_stat_cmp,
341	.stat_headers = annotated_branch_stat_headers,
342	.stat_show = branch_stat_show
343};
344
345__init static int init_annotated_branch_stats(void)
346{
347	int ret;
348
349	ret = register_stat_tracer(&annotated_branch_stats);
350	if (!ret) {
351		printk(KERN_WARNING "Warning: could not register "
352				    "annotated branches stats\n");
353		return 1;
354	}
355	return 0;
356}
357fs_initcall(init_annotated_branch_stats);
358
359#ifdef CONFIG_PROFILE_ALL_BRANCHES
360
361extern unsigned long __start_branch_profile[];
362extern unsigned long __stop_branch_profile[];
363
364static int all_branch_stat_headers(struct seq_file *m)
365{
366	seq_puts(m, "   miss      hit    % "
367		    "       Function                "
368		    "  File              Line\n"
369		    " ------- ---------  - "
370		    "       --------                "
371		    "  ----              ----\n");
372	return 0;
373}
374
375static void *all_branch_stat_start(struct tracer_stat *trace)
376{
377	return __start_branch_profile;
378}
379
380static void *
381all_branch_stat_next(void *v, int idx)
382{
383	struct ftrace_branch_data *p = v;
384
385	++p;
386
387	if ((void *)p >= (void *)__stop_branch_profile)
388		return NULL;
389
390	return p;
391}
392
393static struct tracer_stat all_branch_stats = {
394	.name = "branch_all",
395	.stat_start = all_branch_stat_start,
396	.stat_next = all_branch_stat_next,
397	.stat_headers = all_branch_stat_headers,
398	.stat_show = branch_stat_show
399};
400
401__init static int all_annotated_branch_stats(void)
402{
403	int ret;
404
405	ret = register_stat_tracer(&all_branch_stats);
406	if (!ret) {
407		printk(KERN_WARNING "Warning: could not register "
408				    "all branches stats\n");
409		return 1;
410	}
411	return 0;
412}
413fs_initcall(all_annotated_branch_stats);
414#endif /* CONFIG_PROFILE_ALL_BRANCHES */
415