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 | ||
52f232cb SR |
18 | #ifdef CONFIG_UNLIKELY_TRACER |
19 | ||
20 | static int unlikely_tracing_enabled __read_mostly; | |
21 | static DEFINE_MUTEX(unlikely_tracing_mutex); | |
22 | static struct trace_array *unlikely_tracer; | |
23 | ||
24 | static void | |
25 | probe_likely_condition(struct ftrace_likely_data *f, int val, int expect) | |
26 | { | |
27 | struct trace_array *tr = unlikely_tracer; | |
28 | struct ring_buffer_event *event; | |
29 | struct trace_unlikely *entry; | |
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); | |
57 | entry->ent.type = TRACE_UNLIKELY; | |
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 | |
80 | void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect) | |
81 | { | |
82 | if (!unlikely_tracing_enabled) | |
83 | return; | |
84 | ||
85 | probe_likely_condition(f, val, expect); | |
86 | } | |
87 | ||
88 | int enable_unlikely_tracing(struct trace_array *tr) | |
89 | { | |
90 | int ret = 0; | |
91 | ||
92 | mutex_lock(&unlikely_tracing_mutex); | |
93 | unlikely_tracer = tr; | |
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(); | |
99 | unlikely_tracing_enabled++; | |
100 | mutex_unlock(&unlikely_tracing_mutex); | |
101 | ||
102 | return ret; | |
103 | } | |
104 | ||
105 | void disable_unlikely_tracing(void) | |
106 | { | |
107 | mutex_lock(&unlikely_tracing_mutex); | |
108 | ||
109 | if (!unlikely_tracing_enabled) | |
110 | goto out_unlock; | |
111 | ||
112 | unlikely_tracing_enabled--; | |
113 | ||
114 | out_unlock: | |
115 | mutex_unlock(&unlikely_tracing_mutex); | |
116 | } | |
117 | #else | |
118 | static inline | |
119 | void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect) | |
120 | { | |
121 | } | |
122 | #endif /* CONFIG_UNLIKELY_TRACER */ | |
123 | ||
1f0d69a9 SR |
124 | void ftrace_likely_update(struct ftrace_likely_data *f, int val, int expect) |
125 | { | |
52f232cb SR |
126 | /* |
127 | * I would love to have a trace point here instead, but the | |
128 | * trace point code is so inundated with unlikely and likely | |
129 | * conditions that the recursive nightmare that exists is too | |
130 | * much to try to get working. At least for now. | |
131 | */ | |
132 | trace_likely_condition(f, val, expect); | |
133 | ||
1f0d69a9 SR |
134 | /* FIXME: Make this atomic! */ |
135 | if (val == expect) | |
136 | f->correct++; | |
137 | else | |
138 | f->incorrect++; | |
139 | } | |
140 | EXPORT_SYMBOL(ftrace_likely_update); | |
141 | ||
142 | struct ftrace_pointer { | |
143 | void *start; | |
144 | void *stop; | |
145 | }; | |
146 | ||
147 | static void * | |
148 | t_next(struct seq_file *m, void *v, loff_t *pos) | |
149 | { | |
150 | struct ftrace_pointer *f = m->private; | |
151 | struct ftrace_likely_data *p = v; | |
152 | ||
153 | (*pos)++; | |
154 | ||
155 | if (v == (void *)1) | |
156 | return f->start; | |
157 | ||
158 | ++p; | |
159 | ||
160 | if ((void *)p >= (void *)f->stop) | |
161 | return NULL; | |
162 | ||
163 | return p; | |
164 | } | |
165 | ||
166 | static void *t_start(struct seq_file *m, loff_t *pos) | |
167 | { | |
168 | void *t = (void *)1; | |
169 | loff_t l = 0; | |
170 | ||
171 | for (; t && l < *pos; t = t_next(m, t, &l)) | |
172 | ; | |
173 | ||
174 | return t; | |
175 | } | |
176 | ||
177 | static void t_stop(struct seq_file *m, void *p) | |
178 | { | |
179 | } | |
180 | ||
181 | static int t_show(struct seq_file *m, void *v) | |
182 | { | |
183 | struct ftrace_likely_data *p = v; | |
184 | const char *f; | |
185 | unsigned long percent; | |
186 | ||
187 | if (v == (void *)1) { | |
188 | seq_printf(m, " correct incorrect %% " | |
189 | " Function " | |
190 | " File Line\n" | |
191 | " ------- --------- - " | |
192 | " -------- " | |
193 | " ---- ----\n"); | |
194 | return 0; | |
195 | } | |
196 | ||
197 | /* Only print the file, not the path */ | |
198 | f = p->file + strlen(p->file); | |
199 | while (f >= p->file && *f != '/') | |
200 | f--; | |
201 | f++; | |
202 | ||
203 | if (p->correct) { | |
204 | percent = p->incorrect * 100; | |
205 | percent /= p->correct + p->incorrect; | |
206 | } else | |
207 | percent = p->incorrect ? 100 : 0; | |
208 | ||
209 | seq_printf(m, "%8lu %8lu %3lu ", p->correct, p->incorrect, percent); | |
210 | seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line); | |
211 | return 0; | |
212 | } | |
213 | ||
214 | static struct seq_operations tracing_likely_seq_ops = { | |
215 | .start = t_start, | |
216 | .next = t_next, | |
217 | .stop = t_stop, | |
218 | .show = t_show, | |
219 | }; | |
220 | ||
221 | static int tracing_likely_open(struct inode *inode, struct file *file) | |
222 | { | |
223 | int ret; | |
224 | ||
225 | ret = seq_open(file, &tracing_likely_seq_ops); | |
226 | if (!ret) { | |
227 | struct seq_file *m = file->private_data; | |
228 | m->private = (void *)inode->i_private; | |
229 | } | |
230 | ||
231 | return ret; | |
232 | } | |
233 | ||
234 | static struct file_operations tracing_likely_fops = { | |
235 | .open = tracing_likely_open, | |
236 | .read = seq_read, | |
237 | .llseek = seq_lseek, | |
238 | }; | |
239 | ||
240 | extern unsigned long __start_likely_profile[]; | |
241 | extern unsigned long __stop_likely_profile[]; | |
242 | extern unsigned long __start_unlikely_profile[]; | |
243 | extern unsigned long __stop_unlikely_profile[]; | |
244 | ||
245 | static struct ftrace_pointer ftrace_likely_pos = { | |
246 | .start = __start_likely_profile, | |
247 | .stop = __stop_likely_profile, | |
248 | }; | |
249 | ||
250 | static struct ftrace_pointer ftrace_unlikely_pos = { | |
251 | .start = __start_unlikely_profile, | |
252 | .stop = __stop_unlikely_profile, | |
253 | }; | |
254 | ||
255 | static __init int ftrace_unlikely_init(void) | |
256 | { | |
257 | struct dentry *d_tracer; | |
258 | struct dentry *entry; | |
259 | ||
260 | d_tracer = tracing_init_dentry(); | |
261 | ||
262 | entry = debugfs_create_file("profile_likely", 0444, d_tracer, | |
263 | &ftrace_likely_pos, | |
264 | &tracing_likely_fops); | |
265 | if (!entry) | |
266 | pr_warning("Could not create debugfs 'profile_likely' entry\n"); | |
267 | ||
268 | entry = debugfs_create_file("profile_unlikely", 0444, d_tracer, | |
269 | &ftrace_unlikely_pos, | |
270 | &tracing_likely_fops); | |
271 | if (!entry) | |
272 | pr_warning("Could not create debugfs" | |
273 | " 'profile_unlikely' entry\n"); | |
274 | ||
275 | return 0; | |
276 | } | |
277 | ||
278 | device_initcall(ftrace_unlikely_init); |