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 ftrace_event_call *call = &event_branch; 34 struct trace_array *tr = branch_tracer; 35 struct ring_buffer_event *event; 36 struct trace_branch *entry; 37 unsigned long flags; 38 int cpu, pc; 39 const char *p; 40 41 /* 42 * I would love to save just the ftrace_likely_data pointer, but 43 * this code can also be used by modules. Ugly things can happen 44 * if the module is unloaded, and then we go and read the 45 * pointer. This is slower, but much safer. 46 */ 47 48 if (unlikely(!tr)) 49 return; 50 51 local_irq_save(flags); 52 cpu = raw_smp_processor_id(); 53 if (atomic_inc_return(&tr->data[cpu]->disabled) != 1) 54 goto out; 55 56 pc = preempt_count(); 57 event = trace_buffer_lock_reserve(tr, TRACE_BRANCH, 58 sizeof(*entry), flags, pc); 59 if (!event) 60 goto out; 61 62 entry = ring_buffer_event_data(event); 63 64 /* Strip off the path, only save the file */ 65 p = f->file + strlen(f->file); 66 while (p >= f->file && *p != '/') 67 p--; 68 p++; 69 70 strncpy(entry->func, f->func, TRACE_FUNC_SIZE); 71 strncpy(entry->file, p, TRACE_FILE_SIZE); 72 entry->func[TRACE_FUNC_SIZE] = 0; 73 entry->file[TRACE_FILE_SIZE] = 0; 74 entry->line = f->line; 75 entry->correct = val == expect; 76 77 if (!filter_check_discard(call, entry, tr->buffer, event)) 78 ring_buffer_unlock_commit(tr->buffer, event); 79 80 out: 81 atomic_dec(&tr->data[cpu]->disabled); 82 local_irq_restore(flags); 83 } 84 85 static inline 86 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect) 87 { 88 if (!branch_tracing_enabled) 89 return; 90 91 probe_likely_condition(f, val, expect); 92 } 93 94 int enable_branch_tracing(struct trace_array *tr) 95 { 96 mutex_lock(&branch_tracing_mutex); 97 branch_tracer = tr; 98 /* 99 * Must be seen before enabling. The reader is a condition 100 * where we do not need a matching rmb() 101 */ 102 smp_wmb(); 103 branch_tracing_enabled++; 104 mutex_unlock(&branch_tracing_mutex); 105 106 return 0; 107 } 108 109 void disable_branch_tracing(void) 110 { 111 mutex_lock(&branch_tracing_mutex); 112 113 if (!branch_tracing_enabled) 114 goto out_unlock; 115 116 branch_tracing_enabled--; 117 118 out_unlock: 119 mutex_unlock(&branch_tracing_mutex); 120 } 121 122 static void start_branch_trace(struct trace_array *tr) 123 { 124 enable_branch_tracing(tr); 125 } 126 127 static void stop_branch_trace(struct trace_array *tr) 128 { 129 disable_branch_tracing(); 130 } 131 132 static int branch_trace_init(struct trace_array *tr) 133 { 134 start_branch_trace(tr); 135 return 0; 136 } 137 138 static void branch_trace_reset(struct trace_array *tr) 139 { 140 stop_branch_trace(tr); 141 } 142 143 static enum print_line_t trace_branch_print(struct trace_iterator *iter, 144 int flags) 145 { 146 struct trace_branch *field; 147 148 trace_assign_type(field, iter->ent); 149 150 if (trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n", 151 field->correct ? " ok " : " MISS ", 152 field->func, 153 field->file, 154 field->line)) 155 return TRACE_TYPE_PARTIAL_LINE; 156 157 return TRACE_TYPE_HANDLED; 158 } 159 160 static void branch_print_header(struct seq_file *s) 161 { 162 seq_puts(s, "# TASK-PID CPU# TIMESTAMP CORRECT" 163 " FUNC:FILE:LINE\n"); 164 seq_puts(s, "# | | | | | " 165 " |\n"); 166 } 167 168 static struct trace_event trace_branch_event = { 169 .type = TRACE_BRANCH, 170 .trace = trace_branch_print, 171 }; 172 173 static struct tracer branch_trace __read_mostly = 174 { 175 .name = "branch", 176 .init = branch_trace_init, 177 .reset = branch_trace_reset, 178 #ifdef CONFIG_FTRACE_SELFTEST 179 .selftest = trace_selftest_startup_branch, 180 #endif /* CONFIG_FTRACE_SELFTEST */ 181 .print_header = branch_print_header, 182 }; 183 184 __init static int init_branch_tracer(void) 185 { 186 int ret; 187 188 ret = register_ftrace_event(&trace_branch_event); 189 if (!ret) { 190 printk(KERN_WARNING "Warning: could not register " 191 "branch events\n"); 192 return 1; 193 } 194 return register_tracer(&branch_trace); 195 } 196 device_initcall(init_branch_tracer); 197 198 #else 199 static inline 200 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect) 201 { 202 } 203 #endif /* CONFIG_BRANCH_TRACER */ 204 205 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect) 206 { 207 /* 208 * I would love to have a trace point here instead, but the 209 * trace point code is so inundated with unlikely and likely 210 * conditions that the recursive nightmare that exists is too 211 * much to try to get working. At least for now. 212 */ 213 trace_likely_condition(f, val, expect); 214 215 /* FIXME: Make this atomic! */ 216 if (val == expect) 217 f->correct++; 218 else 219 f->incorrect++; 220 } 221 EXPORT_SYMBOL(ftrace_likely_update); 222 223 extern unsigned long __start_annotated_branch_profile[]; 224 extern unsigned long __stop_annotated_branch_profile[]; 225 226 static int annotated_branch_stat_headers(struct seq_file *m) 227 { 228 seq_printf(m, " correct incorrect %% "); 229 seq_printf(m, " Function " 230 " File Line\n" 231 " ------- --------- - " 232 " -------- " 233 " ---- ----\n"); 234 return 0; 235 } 236 237 static inline long get_incorrect_percent(struct ftrace_branch_data *p) 238 { 239 long percent; 240 241 if (p->correct) { 242 percent = p->incorrect * 100; 243 percent /= p->correct + p->incorrect; 244 } else 245 percent = p->incorrect ? 100 : -1; 246 247 return percent; 248 } 249 250 static int branch_stat_show(struct seq_file *m, void *v) 251 { 252 struct ftrace_branch_data *p = v; 253 const char *f; 254 long percent; 255 256 /* Only print the file, not the path */ 257 f = p->file + strlen(p->file); 258 while (f >= p->file && *f != '/') 259 f--; 260 f++; 261 262 /* 263 * The miss is overlayed on correct, and hit on incorrect. 264 */ 265 percent = get_incorrect_percent(p); 266 267 seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect); 268 if (percent < 0) 269 seq_printf(m, " X "); 270 else 271 seq_printf(m, "%3ld ", percent); 272 seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line); 273 return 0; 274 } 275 276 static void *annotated_branch_stat_start(struct tracer_stat *trace) 277 { 278 return __start_annotated_branch_profile; 279 } 280 281 static void * 282 annotated_branch_stat_next(void *v, int idx) 283 { 284 struct ftrace_branch_data *p = v; 285 286 ++p; 287 288 if ((void *)p >= (void *)__stop_annotated_branch_profile) 289 return NULL; 290 291 return p; 292 } 293 294 static int annotated_branch_stat_cmp(void *p1, void *p2) 295 { 296 struct ftrace_branch_data *a = p1; 297 struct ftrace_branch_data *b = p2; 298 299 long percent_a, percent_b; 300 301 percent_a = get_incorrect_percent(a); 302 percent_b = get_incorrect_percent(b); 303 304 if (percent_a < percent_b) 305 return -1; 306 if (percent_a > percent_b) 307 return 1; 308 else 309 return 0; 310 } 311 312 static struct tracer_stat annotated_branch_stats = { 313 .name = "branch_annotated", 314 .stat_start = annotated_branch_stat_start, 315 .stat_next = annotated_branch_stat_next, 316 .stat_cmp = annotated_branch_stat_cmp, 317 .stat_headers = annotated_branch_stat_headers, 318 .stat_show = branch_stat_show 319 }; 320 321 __init static int init_annotated_branch_stats(void) 322 { 323 int ret; 324 325 ret = register_stat_tracer(&annotated_branch_stats); 326 if (!ret) { 327 printk(KERN_WARNING "Warning: could not register " 328 "annotated branches stats\n"); 329 return 1; 330 } 331 return 0; 332 } 333 fs_initcall(init_annotated_branch_stats); 334 335 #ifdef CONFIG_PROFILE_ALL_BRANCHES 336 337 extern unsigned long __start_branch_profile[]; 338 extern unsigned long __stop_branch_profile[]; 339 340 static int all_branch_stat_headers(struct seq_file *m) 341 { 342 seq_printf(m, " miss hit %% "); 343 seq_printf(m, " Function " 344 " File Line\n" 345 " ------- --------- - " 346 " -------- " 347 " ---- ----\n"); 348 return 0; 349 } 350 351 static void *all_branch_stat_start(struct tracer_stat *trace) 352 { 353 return __start_branch_profile; 354 } 355 356 static void * 357 all_branch_stat_next(void *v, int idx) 358 { 359 struct ftrace_branch_data *p = v; 360 361 ++p; 362 363 if ((void *)p >= (void *)__stop_branch_profile) 364 return NULL; 365 366 return p; 367 } 368 369 static struct tracer_stat all_branch_stats = { 370 .name = "branch_all", 371 .stat_start = all_branch_stat_start, 372 .stat_next = all_branch_stat_next, 373 .stat_headers = all_branch_stat_headers, 374 .stat_show = branch_stat_show 375 }; 376 377 __init static int all_annotated_branch_stats(void) 378 { 379 int ret; 380 381 ret = register_stat_tracer(&all_branch_stats); 382 if (!ret) { 383 printk(KERN_WARNING "Warning: could not register " 384 "all branches stats\n"); 385 return 1; 386 } 387 return 0; 388 } 389 fs_initcall(all_annotated_branch_stats); 390 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 391