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 cpu, pc; 40 const char *p; 41 42 /* 43 * I would love to save just the ftrace_likely_data pointer, but 44 * this code can also be used by modules. Ugly things can happen 45 * if the module is unloaded, and then we go and read the 46 * pointer. This is slower, but much safer. 47 */ 48 49 if (unlikely(!tr)) 50 return; 51 52 local_irq_save(flags); 53 cpu = raw_smp_processor_id(); 54 data = per_cpu_ptr(tr->trace_buffer.data, cpu); 55 if (atomic_inc_return(&data->disabled) != 1) 56 goto out; 57 58 pc = preempt_count(); 59 buffer = tr->trace_buffer.buffer; 60 event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH, 61 sizeof(*entry), flags, pc); 62 if (!event) 63 goto out; 64 65 entry = ring_buffer_event_data(event); 66 67 /* Strip off the path, only save the file */ 68 p = f->file + strlen(f->file); 69 while (p >= f->file && *p != '/') 70 p--; 71 p++; 72 73 strncpy(entry->func, f->func, TRACE_FUNC_SIZE); 74 strncpy(entry->file, p, TRACE_FILE_SIZE); 75 entry->func[TRACE_FUNC_SIZE] = 0; 76 entry->file[TRACE_FILE_SIZE] = 0; 77 entry->line = f->line; 78 entry->correct = val == expect; 79 80 if (!call_filter_check_discard(call, entry, buffer, event)) 81 __buffer_unlock_commit(buffer, event); 82 83 out: 84 atomic_dec(&data->disabled); 85 local_irq_restore(flags); 86 } 87 88 static inline 89 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect) 90 { 91 if (!branch_tracing_enabled) 92 return; 93 94 probe_likely_condition(f, val, expect); 95 } 96 97 int enable_branch_tracing(struct trace_array *tr) 98 { 99 mutex_lock(&branch_tracing_mutex); 100 branch_tracer = tr; 101 /* 102 * Must be seen before enabling. The reader is a condition 103 * where we do not need a matching rmb() 104 */ 105 smp_wmb(); 106 branch_tracing_enabled++; 107 mutex_unlock(&branch_tracing_mutex); 108 109 return 0; 110 } 111 112 void disable_branch_tracing(void) 113 { 114 mutex_lock(&branch_tracing_mutex); 115 116 if (!branch_tracing_enabled) 117 goto out_unlock; 118 119 branch_tracing_enabled--; 120 121 out_unlock: 122 mutex_unlock(&branch_tracing_mutex); 123 } 124 125 static void start_branch_trace(struct trace_array *tr) 126 { 127 enable_branch_tracing(tr); 128 } 129 130 static void stop_branch_trace(struct trace_array *tr) 131 { 132 disable_branch_tracing(); 133 } 134 135 static int branch_trace_init(struct trace_array *tr) 136 { 137 start_branch_trace(tr); 138 return 0; 139 } 140 141 static void branch_trace_reset(struct trace_array *tr) 142 { 143 stop_branch_trace(tr); 144 } 145 146 static enum print_line_t trace_branch_print(struct trace_iterator *iter, 147 int flags, struct trace_event *event) 148 { 149 struct trace_branch *field; 150 151 trace_assign_type(field, iter->ent); 152 153 trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n", 154 field->correct ? " ok " : " MISS ", 155 field->func, 156 field->file, 157 field->line); 158 159 return trace_handle_return(&iter->seq); 160 } 161 162 static void branch_print_header(struct seq_file *s) 163 { 164 seq_puts(s, "# TASK-PID CPU# TIMESTAMP CORRECT" 165 " FUNC:FILE:LINE\n" 166 "# | | | | | " 167 " |\n"); 168 } 169 170 static struct trace_event_functions trace_branch_funcs = { 171 .trace = trace_branch_print, 172 }; 173 174 static struct trace_event trace_branch_event = { 175 .type = TRACE_BRANCH, 176 .funcs = &trace_branch_funcs, 177 }; 178 179 static struct tracer branch_trace __read_mostly = 180 { 181 .name = "branch", 182 .init = branch_trace_init, 183 .reset = branch_trace_reset, 184 #ifdef CONFIG_FTRACE_SELFTEST 185 .selftest = trace_selftest_startup_branch, 186 #endif /* CONFIG_FTRACE_SELFTEST */ 187 .print_header = branch_print_header, 188 }; 189 190 __init static int init_branch_tracer(void) 191 { 192 int ret; 193 194 ret = register_trace_event(&trace_branch_event); 195 if (!ret) { 196 printk(KERN_WARNING "Warning: could not register " 197 "branch events\n"); 198 return 1; 199 } 200 return register_tracer(&branch_trace); 201 } 202 core_initcall(init_branch_tracer); 203 204 #else 205 static inline 206 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect) 207 { 208 } 209 #endif /* CONFIG_BRANCH_TRACER */ 210 211 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect) 212 { 213 /* 214 * I would love to have a trace point here instead, but the 215 * trace point code is so inundated with unlikely and likely 216 * conditions that the recursive nightmare that exists is too 217 * much to try to get working. At least for now. 218 */ 219 trace_likely_condition(f, val, expect); 220 221 /* FIXME: Make this atomic! */ 222 if (val == expect) 223 f->correct++; 224 else 225 f->incorrect++; 226 } 227 EXPORT_SYMBOL(ftrace_likely_update); 228 229 extern unsigned long __start_annotated_branch_profile[]; 230 extern unsigned long __stop_annotated_branch_profile[]; 231 232 static int annotated_branch_stat_headers(struct seq_file *m) 233 { 234 seq_puts(m, " correct incorrect % " 235 " Function " 236 " File Line\n" 237 " ------- --------- - " 238 " -------- " 239 " ---- ----\n"); 240 return 0; 241 } 242 243 static inline long get_incorrect_percent(struct ftrace_branch_data *p) 244 { 245 long percent; 246 247 if (p->correct) { 248 percent = p->incorrect * 100; 249 percent /= p->correct + p->incorrect; 250 } else 251 percent = p->incorrect ? 100 : -1; 252 253 return percent; 254 } 255 256 static int branch_stat_show(struct seq_file *m, void *v) 257 { 258 struct ftrace_branch_data *p = v; 259 const char *f; 260 long percent; 261 262 /* Only print the file, not the path */ 263 f = p->file + strlen(p->file); 264 while (f >= p->file && *f != '/') 265 f--; 266 f++; 267 268 /* 269 * The miss is overlayed on correct, and hit on incorrect. 270 */ 271 percent = get_incorrect_percent(p); 272 273 seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect); 274 if (percent < 0) 275 seq_puts(m, " X "); 276 else 277 seq_printf(m, "%3ld ", percent); 278 seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line); 279 return 0; 280 } 281 282 static void *annotated_branch_stat_start(struct tracer_stat *trace) 283 { 284 return __start_annotated_branch_profile; 285 } 286 287 static void * 288 annotated_branch_stat_next(void *v, int idx) 289 { 290 struct ftrace_branch_data *p = v; 291 292 ++p; 293 294 if ((void *)p >= (void *)__stop_annotated_branch_profile) 295 return NULL; 296 297 return p; 298 } 299 300 static int annotated_branch_stat_cmp(void *p1, void *p2) 301 { 302 struct ftrace_branch_data *a = p1; 303 struct ftrace_branch_data *b = p2; 304 305 long percent_a, percent_b; 306 307 percent_a = get_incorrect_percent(a); 308 percent_b = get_incorrect_percent(b); 309 310 if (percent_a < percent_b) 311 return -1; 312 if (percent_a > percent_b) 313 return 1; 314 315 if (a->incorrect < b->incorrect) 316 return -1; 317 if (a->incorrect > b->incorrect) 318 return 1; 319 320 /* 321 * Since the above shows worse (incorrect) cases 322 * first, we continue that by showing best (correct) 323 * cases last. 324 */ 325 if (a->correct > b->correct) 326 return -1; 327 if (a->correct < b->correct) 328 return 1; 329 330 return 0; 331 } 332 333 static struct tracer_stat annotated_branch_stats = { 334 .name = "branch_annotated", 335 .stat_start = annotated_branch_stat_start, 336 .stat_next = annotated_branch_stat_next, 337 .stat_cmp = annotated_branch_stat_cmp, 338 .stat_headers = annotated_branch_stat_headers, 339 .stat_show = branch_stat_show 340 }; 341 342 __init static int init_annotated_branch_stats(void) 343 { 344 int ret; 345 346 ret = register_stat_tracer(&annotated_branch_stats); 347 if (!ret) { 348 printk(KERN_WARNING "Warning: could not register " 349 "annotated branches stats\n"); 350 return 1; 351 } 352 return 0; 353 } 354 fs_initcall(init_annotated_branch_stats); 355 356 #ifdef CONFIG_PROFILE_ALL_BRANCHES 357 358 extern unsigned long __start_branch_profile[]; 359 extern unsigned long __stop_branch_profile[]; 360 361 static int all_branch_stat_headers(struct seq_file *m) 362 { 363 seq_puts(m, " miss hit % " 364 " Function " 365 " File Line\n" 366 " ------- --------- - " 367 " -------- " 368 " ---- ----\n"); 369 return 0; 370 } 371 372 static void *all_branch_stat_start(struct tracer_stat *trace) 373 { 374 return __start_branch_profile; 375 } 376 377 static void * 378 all_branch_stat_next(void *v, int idx) 379 { 380 struct ftrace_branch_data *p = v; 381 382 ++p; 383 384 if ((void *)p >= (void *)__stop_branch_profile) 385 return NULL; 386 387 return p; 388 } 389 390 static struct tracer_stat all_branch_stats = { 391 .name = "branch_all", 392 .stat_start = all_branch_stat_start, 393 .stat_next = all_branch_stat_next, 394 .stat_headers = all_branch_stat_headers, 395 .stat_show = branch_stat_show 396 }; 397 398 __init static int all_annotated_branch_stats(void) 399 { 400 int ret; 401 402 ret = register_stat_tracer(&all_branch_stats); 403 if (!ret) { 404 printk(KERN_WARNING "Warning: could not register " 405 "all branches stats\n"); 406 return 1; 407 } 408 return 0; 409 } 410 fs_initcall(all_annotated_branch_stats); 411 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 412