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