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 23 static struct tracer branch_trace; 24 static int branch_tracing_enabled __read_mostly; 25 static DEFINE_MUTEX(branch_tracing_mutex); 26 27 static struct trace_array *branch_tracer; 28 29 static void 30 probe_likely_condition(struct ftrace_likely_data *f, int val, int expect) 31 { 32 struct trace_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->data.file + strlen(f->data.file); 72 while (p >= f->data.file && *p != '/') 73 p--; 74 p++; 75 76 strncpy(entry->func, f->data.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->constant = f->constant; 81 entry->line = f->data.line; 82 entry->correct = val == expect; 83 84 if (!call_filter_check_discard(call, entry, buffer, event)) 85 trace_buffer_unlock_commit_nostack(buffer, event); 86 87 out: 88 current->trace_recursion &= ~TRACE_BRANCH_BIT; 89 raw_local_irq_restore(flags); 90 } 91 92 static inline 93 void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect) 94 { 95 if (!branch_tracing_enabled) 96 return; 97 98 probe_likely_condition(f, val, expect); 99 } 100 101 int enable_branch_tracing(struct trace_array *tr) 102 { 103 mutex_lock(&branch_tracing_mutex); 104 branch_tracer = tr; 105 /* 106 * Must be seen before enabling. The reader is a condition 107 * where we do not need a matching rmb() 108 */ 109 smp_wmb(); 110 branch_tracing_enabled++; 111 mutex_unlock(&branch_tracing_mutex); 112 113 return 0; 114 } 115 116 void disable_branch_tracing(void) 117 { 118 mutex_lock(&branch_tracing_mutex); 119 120 if (!branch_tracing_enabled) 121 goto out_unlock; 122 123 branch_tracing_enabled--; 124 125 out_unlock: 126 mutex_unlock(&branch_tracing_mutex); 127 } 128 129 static int branch_trace_init(struct trace_array *tr) 130 { 131 return enable_branch_tracing(tr); 132 } 133 134 static void branch_trace_reset(struct trace_array *tr) 135 { 136 disable_branch_tracing(); 137 } 138 139 static enum print_line_t trace_branch_print(struct trace_iterator *iter, 140 int flags, struct trace_event *event) 141 { 142 struct trace_branch *field; 143 144 trace_assign_type(field, iter->ent); 145 146 trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n", 147 field->correct ? " ok " : " MISS ", 148 field->func, 149 field->file, 150 field->line); 151 152 return trace_handle_return(&iter->seq); 153 } 154 155 static void branch_print_header(struct seq_file *s) 156 { 157 seq_puts(s, "# TASK-PID CPU# TIMESTAMP CORRECT" 158 " FUNC:FILE:LINE\n" 159 "# | | | | | " 160 " |\n"); 161 } 162 163 static struct trace_event_functions trace_branch_funcs = { 164 .trace = trace_branch_print, 165 }; 166 167 static struct trace_event trace_branch_event = { 168 .type = TRACE_BRANCH, 169 .funcs = &trace_branch_funcs, 170 }; 171 172 static struct tracer branch_trace __read_mostly = 173 { 174 .name = "branch", 175 .init = branch_trace_init, 176 .reset = branch_trace_reset, 177 #ifdef CONFIG_FTRACE_SELFTEST 178 .selftest = trace_selftest_startup_branch, 179 #endif /* CONFIG_FTRACE_SELFTEST */ 180 .print_header = branch_print_header, 181 }; 182 183 __init static int init_branch_tracer(void) 184 { 185 int ret; 186 187 ret = register_trace_event(&trace_branch_event); 188 if (!ret) { 189 printk(KERN_WARNING "Warning: could not register " 190 "branch events\n"); 191 return 1; 192 } 193 return register_tracer(&branch_trace); 194 } 195 core_initcall(init_branch_tracer); 196 197 #else 198 static inline 199 void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect) 200 { 201 } 202 #endif /* CONFIG_BRANCH_TRACER */ 203 204 void ftrace_likely_update(struct ftrace_likely_data *f, int val, 205 int expect, int is_constant) 206 { 207 /* A constant is always correct */ 208 if (is_constant) { 209 f->constant++; 210 val = expect; 211 } 212 /* 213 * I would love to have a trace point here instead, but the 214 * trace point code is so inundated with unlikely and likely 215 * conditions that the recursive nightmare that exists is too 216 * much to try to get working. At least for now. 217 */ 218 trace_likely_condition(f, val, expect); 219 220 /* FIXME: Make this atomic! */ 221 if (val == expect) 222 f->data.correct++; 223 else 224 f->data.incorrect++; 225 } 226 EXPORT_SYMBOL(ftrace_likely_update); 227 228 extern unsigned long __start_annotated_branch_profile[]; 229 extern unsigned long __stop_annotated_branch_profile[]; 230 231 static int annotated_branch_stat_headers(struct seq_file *m) 232 { 233 seq_puts(m, " correct incorrect % " 234 " Function " 235 " File Line\n" 236 " ------- --------- - " 237 " -------- " 238 " ---- ----\n"); 239 return 0; 240 } 241 242 static inline long get_incorrect_percent(struct ftrace_branch_data *p) 243 { 244 long percent; 245 246 if (p->correct) { 247 percent = p->incorrect * 100; 248 percent /= p->correct + p->incorrect; 249 } else 250 percent = p->incorrect ? 100 : -1; 251 252 return percent; 253 } 254 255 static const char *branch_stat_process_file(struct ftrace_branch_data *p) 256 { 257 const char *f; 258 259 /* Only print the file, not the path */ 260 f = p->file + strlen(p->file); 261 while (f >= p->file && *f != '/') 262 f--; 263 return ++f; 264 } 265 266 static void branch_stat_show(struct seq_file *m, 267 struct ftrace_branch_data *p, const char *f) 268 { 269 long percent; 270 271 /* 272 * The miss is overlayed on correct, and hit on incorrect. 273 */ 274 percent = get_incorrect_percent(p); 275 276 if (percent < 0) 277 seq_puts(m, " X "); 278 else 279 seq_printf(m, "%3ld ", percent); 280 281 seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line); 282 } 283 284 static int branch_stat_show_normal(struct seq_file *m, 285 struct ftrace_branch_data *p, const char *f) 286 { 287 seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect); 288 branch_stat_show(m, p, f); 289 return 0; 290 } 291 292 static int annotate_branch_stat_show(struct seq_file *m, void *v) 293 { 294 struct ftrace_likely_data *p = v; 295 const char *f; 296 int l; 297 298 f = branch_stat_process_file(&p->data); 299 300 if (!p->constant) 301 return branch_stat_show_normal(m, &p->data, f); 302 303 l = snprintf(NULL, 0, "/%lu", p->constant); 304 l = l > 8 ? 0 : 8 - l; 305 306 seq_printf(m, "%8lu/%lu %*lu ", 307 p->data.correct, p->constant, l, p->data.incorrect); 308 branch_stat_show(m, &p->data, f); 309 return 0; 310 } 311 312 static void *annotated_branch_stat_start(struct tracer_stat *trace) 313 { 314 return __start_annotated_branch_profile; 315 } 316 317 static void * 318 annotated_branch_stat_next(void *v, int idx) 319 { 320 struct ftrace_likely_data *p = v; 321 322 ++p; 323 324 if ((void *)p >= (void *)__stop_annotated_branch_profile) 325 return NULL; 326 327 return p; 328 } 329 330 static int annotated_branch_stat_cmp(void *p1, void *p2) 331 { 332 struct ftrace_branch_data *a = p1; 333 struct ftrace_branch_data *b = p2; 334 335 long percent_a, percent_b; 336 337 percent_a = get_incorrect_percent(a); 338 percent_b = get_incorrect_percent(b); 339 340 if (percent_a < percent_b) 341 return -1; 342 if (percent_a > percent_b) 343 return 1; 344 345 if (a->incorrect < b->incorrect) 346 return -1; 347 if (a->incorrect > b->incorrect) 348 return 1; 349 350 /* 351 * Since the above shows worse (incorrect) cases 352 * first, we continue that by showing best (correct) 353 * cases last. 354 */ 355 if (a->correct > b->correct) 356 return -1; 357 if (a->correct < b->correct) 358 return 1; 359 360 return 0; 361 } 362 363 static struct tracer_stat annotated_branch_stats = { 364 .name = "branch_annotated", 365 .stat_start = annotated_branch_stat_start, 366 .stat_next = annotated_branch_stat_next, 367 .stat_cmp = annotated_branch_stat_cmp, 368 .stat_headers = annotated_branch_stat_headers, 369 .stat_show = annotate_branch_stat_show 370 }; 371 372 __init static int init_annotated_branch_stats(void) 373 { 374 int ret; 375 376 ret = register_stat_tracer(&annotated_branch_stats); 377 if (!ret) { 378 printk(KERN_WARNING "Warning: could not register " 379 "annotated branches stats\n"); 380 return 1; 381 } 382 return 0; 383 } 384 fs_initcall(init_annotated_branch_stats); 385 386 #ifdef CONFIG_PROFILE_ALL_BRANCHES 387 388 extern unsigned long __start_branch_profile[]; 389 extern unsigned long __stop_branch_profile[]; 390 391 static int all_branch_stat_headers(struct seq_file *m) 392 { 393 seq_puts(m, " miss hit % " 394 " Function " 395 " File Line\n" 396 " ------- --------- - " 397 " -------- " 398 " ---- ----\n"); 399 return 0; 400 } 401 402 static void *all_branch_stat_start(struct tracer_stat *trace) 403 { 404 return __start_branch_profile; 405 } 406 407 static void * 408 all_branch_stat_next(void *v, int idx) 409 { 410 struct ftrace_branch_data *p = v; 411 412 ++p; 413 414 if ((void *)p >= (void *)__stop_branch_profile) 415 return NULL; 416 417 return p; 418 } 419 420 static int all_branch_stat_show(struct seq_file *m, void *v) 421 { 422 struct ftrace_branch_data *p = v; 423 const char *f; 424 425 f = branch_stat_process_file(p); 426 return branch_stat_show_normal(m, p, f); 427 } 428 429 static struct tracer_stat all_branch_stats = { 430 .name = "branch_all", 431 .stat_start = all_branch_stat_start, 432 .stat_next = all_branch_stat_next, 433 .stat_headers = all_branch_stat_headers, 434 .stat_show = all_branch_stat_show 435 }; 436 437 __init static int all_annotated_branch_stats(void) 438 { 439 int ret; 440 441 ret = register_stat_tracer(&all_branch_stats); 442 if (!ret) { 443 printk(KERN_WARNING "Warning: could not register " 444 "all branches stats\n"); 445 return 1; 446 } 447 return 0; 448 } 449 fs_initcall(all_annotated_branch_stats); 450 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 451