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