Commit | Line | Data |
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1f0d69a9 SR |
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/debugfs.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 | #include "trace.h" | |
17 | ||
2ed84eeb | 18 | #ifdef CONFIG_BRANCH_TRACER |
52f232cb | 19 | |
9f029e83 SR |
20 | static int branch_tracing_enabled __read_mostly; |
21 | static DEFINE_MUTEX(branch_tracing_mutex); | |
22 | static struct trace_array *branch_tracer; | |
52f232cb SR |
23 | |
24 | static void | |
9f029e83 | 25 | probe_likely_condition(struct ftrace_branch_data *f, int val, int expect) |
52f232cb | 26 | { |
9f029e83 | 27 | struct trace_array *tr = branch_tracer; |
52f232cb | 28 | struct ring_buffer_event *event; |
9f029e83 | 29 | struct trace_branch *entry; |
52f232cb SR |
30 | unsigned long flags, irq_flags; |
31 | int cpu, pc; | |
32 | const char *p; | |
33 | ||
34 | /* | |
35 | * I would love to save just the ftrace_likely_data pointer, but | |
36 | * this code can also be used by modules. Ugly things can happen | |
37 | * if the module is unloaded, and then we go and read the | |
38 | * pointer. This is slower, but much safer. | |
39 | */ | |
40 | ||
41 | if (unlikely(!tr)) | |
42 | return; | |
43 | ||
44 | local_irq_save(flags); | |
45 | cpu = raw_smp_processor_id(); | |
46 | if (atomic_inc_return(&tr->data[cpu]->disabled) != 1) | |
47 | goto out; | |
48 | ||
49 | event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry), | |
50 | &irq_flags); | |
51 | if (!event) | |
52 | goto out; | |
53 | ||
54 | pc = preempt_count(); | |
55 | entry = ring_buffer_event_data(event); | |
56 | tracing_generic_entry_update(&entry->ent, flags, pc); | |
9f029e83 | 57 | entry->ent.type = TRACE_BRANCH; |
52f232cb SR |
58 | |
59 | /* Strip off the path, only save the file */ | |
60 | p = f->file + strlen(f->file); | |
61 | while (p >= f->file && *p != '/') | |
62 | p--; | |
63 | p++; | |
64 | ||
65 | strncpy(entry->func, f->func, TRACE_FUNC_SIZE); | |
66 | strncpy(entry->file, p, TRACE_FILE_SIZE); | |
67 | entry->func[TRACE_FUNC_SIZE] = 0; | |
68 | entry->file[TRACE_FILE_SIZE] = 0; | |
69 | entry->line = f->line; | |
70 | entry->correct = val == expect; | |
71 | ||
72 | ring_buffer_unlock_commit(tr->buffer, event, irq_flags); | |
73 | ||
74 | out: | |
75 | atomic_dec(&tr->data[cpu]->disabled); | |
76 | local_irq_restore(flags); | |
77 | } | |
78 | ||
79 | static inline | |
9f029e83 | 80 | void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect) |
52f232cb | 81 | { |
9f029e83 | 82 | if (!branch_tracing_enabled) |
52f232cb SR |
83 | return; |
84 | ||
85 | probe_likely_condition(f, val, expect); | |
86 | } | |
87 | ||
9f029e83 | 88 | int enable_branch_tracing(struct trace_array *tr) |
52f232cb SR |
89 | { |
90 | int ret = 0; | |
91 | ||
9f029e83 SR |
92 | mutex_lock(&branch_tracing_mutex); |
93 | branch_tracer = tr; | |
52f232cb SR |
94 | /* |
95 | * Must be seen before enabling. The reader is a condition | |
96 | * where we do not need a matching rmb() | |
97 | */ | |
98 | smp_wmb(); | |
9f029e83 SR |
99 | branch_tracing_enabled++; |
100 | mutex_unlock(&branch_tracing_mutex); | |
52f232cb SR |
101 | |
102 | return ret; | |
103 | } | |
104 | ||
9f029e83 | 105 | void disable_branch_tracing(void) |
52f232cb | 106 | { |
9f029e83 | 107 | mutex_lock(&branch_tracing_mutex); |
52f232cb | 108 | |
9f029e83 | 109 | if (!branch_tracing_enabled) |
52f232cb SR |
110 | goto out_unlock; |
111 | ||
9f029e83 | 112 | branch_tracing_enabled--; |
52f232cb SR |
113 | |
114 | out_unlock: | |
9f029e83 | 115 | mutex_unlock(&branch_tracing_mutex); |
52f232cb | 116 | } |
80e5ea45 SR |
117 | |
118 | static void start_branch_trace(struct trace_array *tr) | |
119 | { | |
120 | enable_branch_tracing(tr); | |
121 | } | |
122 | ||
123 | static void stop_branch_trace(struct trace_array *tr) | |
124 | { | |
125 | disable_branch_tracing(); | |
126 | } | |
127 | ||
128 | static void branch_trace_init(struct trace_array *tr) | |
129 | { | |
130 | int cpu; | |
131 | ||
132 | for_each_online_cpu(cpu) | |
133 | tracing_reset(tr, cpu); | |
134 | ||
135 | start_branch_trace(tr); | |
136 | } | |
137 | ||
138 | static void branch_trace_reset(struct trace_array *tr) | |
139 | { | |
140 | stop_branch_trace(tr); | |
141 | } | |
142 | ||
143 | struct tracer branch_trace __read_mostly = | |
144 | { | |
145 | .name = "branch", | |
146 | .init = branch_trace_init, | |
147 | .reset = branch_trace_reset, | |
148 | #ifdef CONFIG_FTRACE_SELFTEST | |
149 | .selftest = trace_selftest_startup_branch, | |
150 | #endif | |
151 | }; | |
152 | ||
153 | __init static int init_branch_trace(void) | |
154 | { | |
155 | return register_tracer(&branch_trace); | |
156 | } | |
157 | ||
158 | device_initcall(init_branch_trace); | |
52f232cb SR |
159 | #else |
160 | static inline | |
9f029e83 | 161 | void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect) |
52f232cb SR |
162 | { |
163 | } | |
2ed84eeb | 164 | #endif /* CONFIG_BRANCH_TRACER */ |
52f232cb | 165 | |
9f029e83 | 166 | void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect) |
1f0d69a9 | 167 | { |
52f232cb SR |
168 | /* |
169 | * I would love to have a trace point here instead, but the | |
170 | * trace point code is so inundated with unlikely and likely | |
171 | * conditions that the recursive nightmare that exists is too | |
172 | * much to try to get working. At least for now. | |
173 | */ | |
174 | trace_likely_condition(f, val, expect); | |
175 | ||
1f0d69a9 SR |
176 | /* FIXME: Make this atomic! */ |
177 | if (val == expect) | |
178 | f->correct++; | |
179 | else | |
180 | f->incorrect++; | |
181 | } | |
182 | EXPORT_SYMBOL(ftrace_likely_update); | |
183 | ||
184 | struct ftrace_pointer { | |
185 | void *start; | |
186 | void *stop; | |
187 | }; | |
188 | ||
189 | static void * | |
190 | t_next(struct seq_file *m, void *v, loff_t *pos) | |
191 | { | |
192 | struct ftrace_pointer *f = m->private; | |
9f029e83 | 193 | struct ftrace_branch_data *p = v; |
1f0d69a9 SR |
194 | |
195 | (*pos)++; | |
196 | ||
197 | if (v == (void *)1) | |
198 | return f->start; | |
199 | ||
200 | ++p; | |
201 | ||
202 | if ((void *)p >= (void *)f->stop) | |
203 | return NULL; | |
204 | ||
205 | return p; | |
206 | } | |
207 | ||
208 | static void *t_start(struct seq_file *m, loff_t *pos) | |
209 | { | |
210 | void *t = (void *)1; | |
211 | loff_t l = 0; | |
212 | ||
213 | for (; t && l < *pos; t = t_next(m, t, &l)) | |
214 | ; | |
215 | ||
216 | return t; | |
217 | } | |
218 | ||
219 | static void t_stop(struct seq_file *m, void *p) | |
220 | { | |
221 | } | |
222 | ||
223 | static int t_show(struct seq_file *m, void *v) | |
224 | { | |
9f029e83 | 225 | struct ftrace_branch_data *p = v; |
1f0d69a9 SR |
226 | const char *f; |
227 | unsigned long percent; | |
228 | ||
229 | if (v == (void *)1) { | |
230 | seq_printf(m, " correct incorrect %% " | |
231 | " Function " | |
232 | " File Line\n" | |
233 | " ------- --------- - " | |
234 | " -------- " | |
235 | " ---- ----\n"); | |
236 | return 0; | |
237 | } | |
238 | ||
239 | /* Only print the file, not the path */ | |
240 | f = p->file + strlen(p->file); | |
241 | while (f >= p->file && *f != '/') | |
242 | f--; | |
243 | f++; | |
244 | ||
245 | if (p->correct) { | |
246 | percent = p->incorrect * 100; | |
247 | percent /= p->correct + p->incorrect; | |
248 | } else | |
249 | percent = p->incorrect ? 100 : 0; | |
250 | ||
251 | seq_printf(m, "%8lu %8lu %3lu ", p->correct, p->incorrect, percent); | |
252 | seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line); | |
253 | return 0; | |
254 | } | |
255 | ||
256 | static struct seq_operations tracing_likely_seq_ops = { | |
257 | .start = t_start, | |
258 | .next = t_next, | |
259 | .stop = t_stop, | |
260 | .show = t_show, | |
261 | }; | |
262 | ||
263 | static int tracing_likely_open(struct inode *inode, struct file *file) | |
264 | { | |
265 | int ret; | |
266 | ||
267 | ret = seq_open(file, &tracing_likely_seq_ops); | |
268 | if (!ret) { | |
269 | struct seq_file *m = file->private_data; | |
270 | m->private = (void *)inode->i_private; | |
271 | } | |
272 | ||
273 | return ret; | |
274 | } | |
275 | ||
276 | static struct file_operations tracing_likely_fops = { | |
277 | .open = tracing_likely_open, | |
278 | .read = seq_read, | |
279 | .llseek = seq_lseek, | |
280 | }; | |
281 | ||
282 | extern unsigned long __start_likely_profile[]; | |
283 | extern unsigned long __stop_likely_profile[]; | |
284 | extern unsigned long __start_unlikely_profile[]; | |
285 | extern unsigned long __stop_unlikely_profile[]; | |
286 | ||
287 | static struct ftrace_pointer ftrace_likely_pos = { | |
288 | .start = __start_likely_profile, | |
289 | .stop = __stop_likely_profile, | |
290 | }; | |
291 | ||
292 | static struct ftrace_pointer ftrace_unlikely_pos = { | |
293 | .start = __start_unlikely_profile, | |
294 | .stop = __stop_unlikely_profile, | |
295 | }; | |
296 | ||
9f029e83 | 297 | static __init int ftrace_branch_init(void) |
1f0d69a9 SR |
298 | { |
299 | struct dentry *d_tracer; | |
300 | struct dentry *entry; | |
301 | ||
302 | d_tracer = tracing_init_dentry(); | |
303 | ||
304 | entry = debugfs_create_file("profile_likely", 0444, d_tracer, | |
305 | &ftrace_likely_pos, | |
306 | &tracing_likely_fops); | |
307 | if (!entry) | |
308 | pr_warning("Could not create debugfs 'profile_likely' entry\n"); | |
309 | ||
310 | entry = debugfs_create_file("profile_unlikely", 0444, d_tracer, | |
311 | &ftrace_unlikely_pos, | |
312 | &tracing_likely_fops); | |
313 | if (!entry) | |
314 | pr_warning("Could not create debugfs" | |
315 | " 'profile_unlikely' entry\n"); | |
316 | ||
317 | return 0; | |
318 | } | |
319 | ||
9f029e83 | 320 | device_initcall(ftrace_branch_init); |