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 | ||
072b40a1 | 44 | raw_local_irq_save(flags); |
52f232cb SR |
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); | |
072b40a1 | 76 | raw_local_irq_restore(flags); |
52f232cb SR |
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 | ||
1c80025a | 128 | static int branch_trace_init(struct trace_array *tr) |
80e5ea45 SR |
129 | { |
130 | int cpu; | |
131 | ||
132 | for_each_online_cpu(cpu) | |
133 | tracing_reset(tr, cpu); | |
134 | ||
135 | start_branch_trace(tr); | |
1c80025a | 136 | return 0; |
80e5ea45 SR |
137 | } |
138 | ||
139 | static void branch_trace_reset(struct trace_array *tr) | |
140 | { | |
141 | stop_branch_trace(tr); | |
142 | } | |
143 | ||
144 | struct tracer branch_trace __read_mostly = | |
145 | { | |
146 | .name = "branch", | |
147 | .init = branch_trace_init, | |
148 | .reset = branch_trace_reset, | |
149 | #ifdef CONFIG_FTRACE_SELFTEST | |
150 | .selftest = trace_selftest_startup_branch, | |
151 | #endif | |
152 | }; | |
153 | ||
154 | __init static int init_branch_trace(void) | |
155 | { | |
156 | return register_tracer(&branch_trace); | |
157 | } | |
158 | ||
159 | device_initcall(init_branch_trace); | |
52f232cb SR |
160 | #else |
161 | static inline | |
9f029e83 | 162 | void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect) |
52f232cb SR |
163 | { |
164 | } | |
2ed84eeb | 165 | #endif /* CONFIG_BRANCH_TRACER */ |
52f232cb | 166 | |
9f029e83 | 167 | void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect) |
1f0d69a9 | 168 | { |
52f232cb SR |
169 | /* |
170 | * I would love to have a trace point here instead, but the | |
171 | * trace point code is so inundated with unlikely and likely | |
172 | * conditions that the recursive nightmare that exists is too | |
173 | * much to try to get working. At least for now. | |
174 | */ | |
175 | trace_likely_condition(f, val, expect); | |
176 | ||
1f0d69a9 SR |
177 | /* FIXME: Make this atomic! */ |
178 | if (val == expect) | |
179 | f->correct++; | |
180 | else | |
181 | f->incorrect++; | |
182 | } | |
183 | EXPORT_SYMBOL(ftrace_likely_update); | |
184 | ||
185 | struct ftrace_pointer { | |
186 | void *start; | |
187 | void *stop; | |
188 | }; | |
189 | ||
190 | static void * | |
191 | t_next(struct seq_file *m, void *v, loff_t *pos) | |
192 | { | |
193 | struct ftrace_pointer *f = m->private; | |
9f029e83 | 194 | struct ftrace_branch_data *p = v; |
1f0d69a9 SR |
195 | |
196 | (*pos)++; | |
197 | ||
198 | if (v == (void *)1) | |
199 | return f->start; | |
200 | ||
201 | ++p; | |
202 | ||
203 | if ((void *)p >= (void *)f->stop) | |
204 | return NULL; | |
205 | ||
206 | return p; | |
207 | } | |
208 | ||
209 | static void *t_start(struct seq_file *m, loff_t *pos) | |
210 | { | |
211 | void *t = (void *)1; | |
212 | loff_t l = 0; | |
213 | ||
214 | for (; t && l < *pos; t = t_next(m, t, &l)) | |
215 | ; | |
216 | ||
217 | return t; | |
218 | } | |
219 | ||
220 | static void t_stop(struct seq_file *m, void *p) | |
221 | { | |
222 | } | |
223 | ||
224 | static int t_show(struct seq_file *m, void *v) | |
225 | { | |
9f029e83 | 226 | struct ftrace_branch_data *p = v; |
1f0d69a9 | 227 | const char *f; |
bac28bfe | 228 | long percent; |
1f0d69a9 SR |
229 | |
230 | if (v == (void *)1) { | |
231 | seq_printf(m, " correct incorrect %% " | |
232 | " Function " | |
233 | " File Line\n" | |
234 | " ------- --------- - " | |
235 | " -------- " | |
236 | " ---- ----\n"); | |
237 | return 0; | |
238 | } | |
239 | ||
240 | /* Only print the file, not the path */ | |
241 | f = p->file + strlen(p->file); | |
242 | while (f >= p->file && *f != '/') | |
243 | f--; | |
244 | f++; | |
245 | ||
246 | if (p->correct) { | |
247 | percent = p->incorrect * 100; | |
248 | percent /= p->correct + p->incorrect; | |
249 | } else | |
bac28bfe | 250 | percent = p->incorrect ? 100 : -1; |
1f0d69a9 | 251 | |
bac28bfe SR |
252 | seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect); |
253 | if (percent < 0) | |
254 | seq_printf(m, " X "); | |
255 | else | |
256 | seq_printf(m, "%3ld ", percent); | |
1f0d69a9 SR |
257 | seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line); |
258 | return 0; | |
259 | } | |
260 | ||
261 | static struct seq_operations tracing_likely_seq_ops = { | |
262 | .start = t_start, | |
263 | .next = t_next, | |
264 | .stop = t_stop, | |
265 | .show = t_show, | |
266 | }; | |
267 | ||
45b79749 | 268 | static int tracing_branch_open(struct inode *inode, struct file *file) |
1f0d69a9 SR |
269 | { |
270 | int ret; | |
271 | ||
272 | ret = seq_open(file, &tracing_likely_seq_ops); | |
273 | if (!ret) { | |
274 | struct seq_file *m = file->private_data; | |
275 | m->private = (void *)inode->i_private; | |
276 | } | |
277 | ||
278 | return ret; | |
279 | } | |
280 | ||
45b79749 SR |
281 | static const struct file_operations tracing_branch_fops = { |
282 | .open = tracing_branch_open, | |
1f0d69a9 SR |
283 | .read = seq_read, |
284 | .llseek = seq_lseek, | |
285 | }; | |
286 | ||
45b79749 SR |
287 | extern unsigned long __start_annotated_branch_profile[]; |
288 | extern unsigned long __stop_annotated_branch_profile[]; | |
1f0d69a9 | 289 | |
45b79749 SR |
290 | static const struct ftrace_pointer ftrace_annotated_branch_pos = { |
291 | .start = __start_annotated_branch_profile, | |
292 | .stop = __stop_annotated_branch_profile, | |
1f0d69a9 SR |
293 | }; |
294 | ||
9f029e83 | 295 | static __init int ftrace_branch_init(void) |
1f0d69a9 SR |
296 | { |
297 | struct dentry *d_tracer; | |
298 | struct dentry *entry; | |
299 | ||
300 | d_tracer = tracing_init_dentry(); | |
301 | ||
45b79749 SR |
302 | entry = debugfs_create_file("profile_annotated_branch", 0444, d_tracer, |
303 | &ftrace_annotated_branch_pos, | |
304 | &tracing_branch_fops); | |
1f0d69a9 | 305 | if (!entry) |
45b79749 SR |
306 | pr_warning("Could not create debugfs " |
307 | "'profile_annotatet_branch' entry\n"); | |
1f0d69a9 SR |
308 | |
309 | return 0; | |
310 | } | |
311 | ||
9f029e83 | 312 | device_initcall(ftrace_branch_init); |