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