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 trace_array *tr = branch_tracer; 34 struct ring_buffer_event *event; 35 struct trace_branch *entry; 36 unsigned long flags; 37 int cpu, pc; 38 const char *p; 39 40 /* 41 * I would love to save just the ftrace_likely_data pointer, but 42 * this code can also be used by modules. Ugly things can happen 43 * if the module is unloaded, and then we go and read the 44 * pointer. This is slower, but much safer. 45 */ 46 47 if (unlikely(!tr)) 48 return; 49 50 local_irq_save(flags); 51 cpu = raw_smp_processor_id(); 52 if (atomic_inc_return(&tr->data[cpu]->disabled) != 1) 53 goto out; 54 55 pc = preempt_count(); 56 event = trace_buffer_lock_reserve(tr, TRACE_BRANCH, 57 sizeof(*entry), flags, pc); 58 if (!event) 59 goto out; 60 61 entry = ring_buffer_event_data(event); 62 63 /* Strip off the path, only save the file */ 64 p = f->file + strlen(f->file); 65 while (p >= f->file && *p != '/') 66 p--; 67 p++; 68 69 strncpy(entry->func, f->func, TRACE_FUNC_SIZE); 70 strncpy(entry->file, p, TRACE_FILE_SIZE); 71 entry->func[TRACE_FUNC_SIZE] = 0; 72 entry->file[TRACE_FILE_SIZE] = 0; 73 entry->line = f->line; 74 entry->correct = val == expect; 75 76 ring_buffer_unlock_commit(tr->buffer, event); 77 78 out: 79 atomic_dec(&tr->data[cpu]->disabled); 80 local_irq_restore(flags); 81 } 82 83 static inline 84 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect) 85 { 86 if (!branch_tracing_enabled) 87 return; 88 89 probe_likely_condition(f, val, expect); 90 } 91 92 int enable_branch_tracing(struct trace_array *tr) 93 { 94 mutex_lock(&branch_tracing_mutex); 95 branch_tracer = tr; 96 /* 97 * Must be seen before enabling. The reader is a condition 98 * where we do not need a matching rmb() 99 */ 100 smp_wmb(); 101 branch_tracing_enabled++; 102 mutex_unlock(&branch_tracing_mutex); 103 104 return 0; 105 } 106 107 void disable_branch_tracing(void) 108 { 109 mutex_lock(&branch_tracing_mutex); 110 111 if (!branch_tracing_enabled) 112 goto out_unlock; 113 114 branch_tracing_enabled--; 115 116 out_unlock: 117 mutex_unlock(&branch_tracing_mutex); 118 } 119 120 static void start_branch_trace(struct trace_array *tr) 121 { 122 enable_branch_tracing(tr); 123 } 124 125 static void stop_branch_trace(struct trace_array *tr) 126 { 127 disable_branch_tracing(); 128 } 129 130 static int branch_trace_init(struct trace_array *tr) 131 { 132 start_branch_trace(tr); 133 return 0; 134 } 135 136 static void branch_trace_reset(struct trace_array *tr) 137 { 138 stop_branch_trace(tr); 139 } 140 141 static enum print_line_t trace_branch_print(struct trace_iterator *iter, 142 int flags) 143 { 144 struct trace_branch *field; 145 146 trace_assign_type(field, iter->ent); 147 148 if (trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n", 149 field->correct ? " ok " : " MISS ", 150 field->func, 151 field->file, 152 field->line)) 153 return TRACE_TYPE_PARTIAL_LINE; 154 155 return TRACE_TYPE_HANDLED; 156 } 157 158 static void branch_print_header(struct seq_file *s) 159 { 160 seq_puts(s, "# TASK-PID CPU# TIMESTAMP CORRECT" 161 " FUNC:FILE:LINE\n"); 162 seq_puts(s, "# | | | | | " 163 " |\n"); 164 } 165 166 static struct trace_event trace_branch_event = { 167 .type = TRACE_BRANCH, 168 .trace = trace_branch_print, 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_ftrace_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 device_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_printf(m, " correct incorrect %% "); 227 seq_printf(m, " 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_printf(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(void) 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 else 307 return 0; 308 } 309 310 static struct tracer_stat annotated_branch_stats = { 311 .name = "branch_annotated", 312 .stat_start = annotated_branch_stat_start, 313 .stat_next = annotated_branch_stat_next, 314 .stat_cmp = annotated_branch_stat_cmp, 315 .stat_headers = annotated_branch_stat_headers, 316 .stat_show = branch_stat_show 317 }; 318 319 __init static int init_annotated_branch_stats(void) 320 { 321 int ret; 322 323 ret = register_stat_tracer(&annotated_branch_stats); 324 if (!ret) { 325 printk(KERN_WARNING "Warning: could not register " 326 "annotated branches stats\n"); 327 return 1; 328 } 329 return 0; 330 } 331 fs_initcall(init_annotated_branch_stats); 332 333 #ifdef CONFIG_PROFILE_ALL_BRANCHES 334 335 extern unsigned long __start_branch_profile[]; 336 extern unsigned long __stop_branch_profile[]; 337 338 static int all_branch_stat_headers(struct seq_file *m) 339 { 340 seq_printf(m, " miss hit %% "); 341 seq_printf(m, " Function " 342 " File Line\n" 343 " ------- --------- - " 344 " -------- " 345 " ---- ----\n"); 346 return 0; 347 } 348 349 static void *all_branch_stat_start(void) 350 { 351 return __start_branch_profile; 352 } 353 354 static void * 355 all_branch_stat_next(void *v, int idx) 356 { 357 struct ftrace_branch_data *p = v; 358 359 ++p; 360 361 if ((void *)p >= (void *)__stop_branch_profile) 362 return NULL; 363 364 return p; 365 } 366 367 static struct tracer_stat all_branch_stats = { 368 .name = "branch_all", 369 .stat_start = all_branch_stat_start, 370 .stat_next = all_branch_stat_next, 371 .stat_headers = all_branch_stat_headers, 372 .stat_show = branch_stat_show 373 }; 374 375 __init static int all_annotated_branch_stats(void) 376 { 377 int ret; 378 379 ret = register_stat_tracer(&all_branch_stats); 380 if (!ret) { 381 printk(KERN_WARNING "Warning: could not register " 382 "all branches stats\n"); 383 return 1; 384 } 385 return 0; 386 } 387 fs_initcall(all_annotated_branch_stats); 388 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 389