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