1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * unlikely profiler 4 * 5 * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> 6 */ 7 #include <linux/kallsyms.h> 8 #include <linux/seq_file.h> 9 #include <linux/spinlock.h> 10 #include <linux/irqflags.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_likely_data *f, int val, int expect) 32 { 33 struct trace_event_call *call = &event_branch; 34 struct trace_array *tr = branch_tracer; 35 struct trace_array_cpu *data; 36 struct ring_buffer_event *event; 37 struct trace_branch *entry; 38 struct ring_buffer *buffer; 39 unsigned long flags; 40 int pc; 41 const char *p; 42 43 if (current->trace_recursion & TRACE_BRANCH_BIT) 44 return; 45 46 /* 47 * I would love to save just the ftrace_likely_data pointer, but 48 * this code can also be used by modules. Ugly things can happen 49 * if the module is unloaded, and then we go and read the 50 * pointer. This is slower, but much safer. 51 */ 52 53 if (unlikely(!tr)) 54 return; 55 56 raw_local_irq_save(flags); 57 current->trace_recursion |= TRACE_BRANCH_BIT; 58 data = this_cpu_ptr(tr->trace_buffer.data); 59 if (atomic_read(&data->disabled)) 60 goto out; 61 62 pc = preempt_count(); 63 buffer = tr->trace_buffer.buffer; 64 event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH, 65 sizeof(*entry), flags, pc); 66 if (!event) 67 goto out; 68 69 entry = ring_buffer_event_data(event); 70 71 /* Strip off the path, only save the file */ 72 p = f->data.file + strlen(f->data.file); 73 while (p >= f->data.file && *p != '/') 74 p--; 75 p++; 76 77 strncpy(entry->func, f->data.func, TRACE_FUNC_SIZE); 78 strncpy(entry->file, p, TRACE_FILE_SIZE); 79 entry->func[TRACE_FUNC_SIZE] = 0; 80 entry->file[TRACE_FILE_SIZE] = 0; 81 entry->constant = f->constant; 82 entry->line = f->data.line; 83 entry->correct = val == expect; 84 85 if (!call_filter_check_discard(call, entry, buffer, event)) 86 trace_buffer_unlock_commit_nostack(buffer, event); 87 88 out: 89 current->trace_recursion &= ~TRACE_BRANCH_BIT; 90 raw_local_irq_restore(flags); 91 } 92 93 static inline 94 void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect) 95 { 96 if (!branch_tracing_enabled) 97 return; 98 99 probe_likely_condition(f, val, expect); 100 } 101 102 int enable_branch_tracing(struct trace_array *tr) 103 { 104 mutex_lock(&branch_tracing_mutex); 105 branch_tracer = tr; 106 /* 107 * Must be seen before enabling. The reader is a condition 108 * where we do not need a matching rmb() 109 */ 110 smp_wmb(); 111 branch_tracing_enabled++; 112 mutex_unlock(&branch_tracing_mutex); 113 114 return 0; 115 } 116 117 void disable_branch_tracing(void) 118 { 119 mutex_lock(&branch_tracing_mutex); 120 121 if (!branch_tracing_enabled) 122 goto out_unlock; 123 124 branch_tracing_enabled--; 125 126 out_unlock: 127 mutex_unlock(&branch_tracing_mutex); 128 } 129 130 static int branch_trace_init(struct trace_array *tr) 131 { 132 return enable_branch_tracing(tr); 133 } 134 135 static void branch_trace_reset(struct trace_array *tr) 136 { 137 disable_branch_tracing(); 138 } 139 140 static enum print_line_t trace_branch_print(struct trace_iterator *iter, 141 int flags, struct trace_event *event) 142 { 143 struct trace_branch *field; 144 145 trace_assign_type(field, iter->ent); 146 147 trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n", 148 field->correct ? " ok " : " MISS ", 149 field->func, 150 field->file, 151 field->line); 152 153 return trace_handle_return(&iter->seq); 154 } 155 156 static void branch_print_header(struct seq_file *s) 157 { 158 seq_puts(s, "# TASK-PID CPU# TIMESTAMP CORRECT" 159 " FUNC:FILE:LINE\n" 160 "# | | | | | " 161 " |\n"); 162 } 163 164 static struct trace_event_functions trace_branch_funcs = { 165 .trace = trace_branch_print, 166 }; 167 168 static struct trace_event trace_branch_event = { 169 .type = TRACE_BRANCH, 170 .funcs = &trace_branch_funcs, 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_trace_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 core_initcall(init_branch_tracer); 197 198 #else 199 static inline 200 void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect) 201 { 202 } 203 #endif /* CONFIG_BRANCH_TRACER */ 204 205 void ftrace_likely_update(struct ftrace_likely_data *f, int val, 206 int expect, int is_constant) 207 { 208 /* A constant is always correct */ 209 if (is_constant) { 210 f->constant++; 211 val = 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->data.correct++; 224 else 225 f->data.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 const char *branch_stat_process_file(struct ftrace_branch_data *p) 257 { 258 const char *f; 259 260 /* Only print the file, not the path */ 261 f = p->file + strlen(p->file); 262 while (f >= p->file && *f != '/') 263 f--; 264 return ++f; 265 } 266 267 static void branch_stat_show(struct seq_file *m, 268 struct ftrace_branch_data *p, const char *f) 269 { 270 long percent; 271 272 /* 273 * The miss is overlayed on correct, and hit on incorrect. 274 */ 275 percent = get_incorrect_percent(p); 276 277 if (percent < 0) 278 seq_puts(m, " X "); 279 else 280 seq_printf(m, "%3ld ", percent); 281 282 seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line); 283 } 284 285 static int branch_stat_show_normal(struct seq_file *m, 286 struct ftrace_branch_data *p, const char *f) 287 { 288 seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect); 289 branch_stat_show(m, p, f); 290 return 0; 291 } 292 293 static int annotate_branch_stat_show(struct seq_file *m, void *v) 294 { 295 struct ftrace_likely_data *p = v; 296 const char *f; 297 int l; 298 299 f = branch_stat_process_file(&p->data); 300 301 if (!p->constant) 302 return branch_stat_show_normal(m, &p->data, f); 303 304 l = snprintf(NULL, 0, "/%lu", p->constant); 305 l = l > 8 ? 0 : 8 - l; 306 307 seq_printf(m, "%8lu/%lu %*lu ", 308 p->data.correct, p->constant, l, p->data.incorrect); 309 branch_stat_show(m, &p->data, f); 310 return 0; 311 } 312 313 static void *annotated_branch_stat_start(struct tracer_stat *trace) 314 { 315 return __start_annotated_branch_profile; 316 } 317 318 static void * 319 annotated_branch_stat_next(void *v, int idx) 320 { 321 struct ftrace_likely_data *p = v; 322 323 ++p; 324 325 if ((void *)p >= (void *)__stop_annotated_branch_profile) 326 return NULL; 327 328 return p; 329 } 330 331 static int annotated_branch_stat_cmp(void *p1, void *p2) 332 { 333 struct ftrace_branch_data *a = p1; 334 struct ftrace_branch_data *b = p2; 335 336 long percent_a, percent_b; 337 338 percent_a = get_incorrect_percent(a); 339 percent_b = get_incorrect_percent(b); 340 341 if (percent_a < percent_b) 342 return -1; 343 if (percent_a > percent_b) 344 return 1; 345 346 if (a->incorrect < b->incorrect) 347 return -1; 348 if (a->incorrect > b->incorrect) 349 return 1; 350 351 /* 352 * Since the above shows worse (incorrect) cases 353 * first, we continue that by showing best (correct) 354 * cases last. 355 */ 356 if (a->correct > b->correct) 357 return -1; 358 if (a->correct < b->correct) 359 return 1; 360 361 return 0; 362 } 363 364 static struct tracer_stat annotated_branch_stats = { 365 .name = "branch_annotated", 366 .stat_start = annotated_branch_stat_start, 367 .stat_next = annotated_branch_stat_next, 368 .stat_cmp = annotated_branch_stat_cmp, 369 .stat_headers = annotated_branch_stat_headers, 370 .stat_show = annotate_branch_stat_show 371 }; 372 373 __init static int init_annotated_branch_stats(void) 374 { 375 int ret; 376 377 ret = register_stat_tracer(&annotated_branch_stats); 378 if (!ret) { 379 printk(KERN_WARNING "Warning: could not register " 380 "annotated branches stats\n"); 381 return 1; 382 } 383 return 0; 384 } 385 fs_initcall(init_annotated_branch_stats); 386 387 #ifdef CONFIG_PROFILE_ALL_BRANCHES 388 389 extern unsigned long __start_branch_profile[]; 390 extern unsigned long __stop_branch_profile[]; 391 392 static int all_branch_stat_headers(struct seq_file *m) 393 { 394 seq_puts(m, " miss hit % " 395 " Function " 396 " File Line\n" 397 " ------- --------- - " 398 " -------- " 399 " ---- ----\n"); 400 return 0; 401 } 402 403 static void *all_branch_stat_start(struct tracer_stat *trace) 404 { 405 return __start_branch_profile; 406 } 407 408 static void * 409 all_branch_stat_next(void *v, int idx) 410 { 411 struct ftrace_branch_data *p = v; 412 413 ++p; 414 415 if ((void *)p >= (void *)__stop_branch_profile) 416 return NULL; 417 418 return p; 419 } 420 421 static int all_branch_stat_show(struct seq_file *m, void *v) 422 { 423 struct ftrace_branch_data *p = v; 424 const char *f; 425 426 f = branch_stat_process_file(p); 427 return branch_stat_show_normal(m, p, f); 428 } 429 430 static struct tracer_stat all_branch_stats = { 431 .name = "branch_all", 432 .stat_start = all_branch_stat_start, 433 .stat_next = all_branch_stat_next, 434 .stat_headers = all_branch_stat_headers, 435 .stat_show = all_branch_stat_show 436 }; 437 438 __init static int all_annotated_branch_stats(void) 439 { 440 int ret; 441 442 ret = register_stat_tracer(&all_branch_stats); 443 if (!ret) { 444 printk(KERN_WARNING "Warning: could not register " 445 "all branches stats\n"); 446 return 1; 447 } 448 return 0; 449 } 450 fs_initcall(all_annotated_branch_stats); 451 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 452