| 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 pc; |
| 40 | const char *p; |
| 41 | |
| 42 | if (current->trace_recursion & TRACE_BRANCH_BIT) |
| 43 | return; |
| 44 | |
| 45 | /* |
| 46 | * I would love to save just the ftrace_likely_data pointer, but |
| 47 | * this code can also be used by modules. Ugly things can happen |
| 48 | * if the module is unloaded, and then we go and read the |
| 49 | * pointer. This is slower, but much safer. |
| 50 | */ |
| 51 | |
| 52 | if (unlikely(!tr)) |
| 53 | return; |
| 54 | |
| 55 | raw_local_irq_save(flags); |
| 56 | current->trace_recursion |= TRACE_BRANCH_BIT; |
| 57 | data = this_cpu_ptr(tr->trace_buffer.data); |
| 58 | if (atomic_read(&data->disabled)) |
| 59 | goto out; |
| 60 | |
| 61 | pc = preempt_count(); |
| 62 | buffer = tr->trace_buffer.buffer; |
| 63 | event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH, |
| 64 | sizeof(*entry), flags, pc); |
| 65 | if (!event) |
| 66 | goto out; |
| 67 | |
| 68 | entry = ring_buffer_event_data(event); |
| 69 | |
| 70 | /* Strip off the path, only save the file */ |
| 71 | p = f->file + strlen(f->file); |
| 72 | while (p >= f->file && *p != '/') |
| 73 | p--; |
| 74 | p++; |
| 75 | |
| 76 | strncpy(entry->func, f->func, TRACE_FUNC_SIZE); |
| 77 | strncpy(entry->file, p, TRACE_FILE_SIZE); |
| 78 | entry->func[TRACE_FUNC_SIZE] = 0; |
| 79 | entry->file[TRACE_FILE_SIZE] = 0; |
| 80 | entry->line = f->line; |
| 81 | entry->correct = val == expect; |
| 82 | |
| 83 | if (!call_filter_check_discard(call, entry, buffer, event)) |
| 84 | __buffer_unlock_commit(buffer, event); |
| 85 | |
| 86 | out: |
| 87 | current->trace_recursion &= ~TRACE_BRANCH_BIT; |
| 88 | raw_local_irq_restore(flags); |
| 89 | } |
| 90 | |
| 91 | static inline |
| 92 | void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect) |
| 93 | { |
| 94 | if (!branch_tracing_enabled) |
| 95 | return; |
| 96 | |
| 97 | probe_likely_condition(f, val, expect); |
| 98 | } |
| 99 | |
| 100 | int enable_branch_tracing(struct trace_array *tr) |
| 101 | { |
| 102 | mutex_lock(&branch_tracing_mutex); |
| 103 | branch_tracer = tr; |
| 104 | /* |
| 105 | * Must be seen before enabling. The reader is a condition |
| 106 | * where we do not need a matching rmb() |
| 107 | */ |
| 108 | smp_wmb(); |
| 109 | branch_tracing_enabled++; |
| 110 | mutex_unlock(&branch_tracing_mutex); |
| 111 | |
| 112 | return 0; |
| 113 | } |
| 114 | |
| 115 | void disable_branch_tracing(void) |
| 116 | { |
| 117 | mutex_lock(&branch_tracing_mutex); |
| 118 | |
| 119 | if (!branch_tracing_enabled) |
| 120 | goto out_unlock; |
| 121 | |
| 122 | branch_tracing_enabled--; |
| 123 | |
| 124 | out_unlock: |
| 125 | mutex_unlock(&branch_tracing_mutex); |
| 126 | } |
| 127 | |
| 128 | static void start_branch_trace(struct trace_array *tr) |
| 129 | { |
| 130 | enable_branch_tracing(tr); |
| 131 | } |
| 132 | |
| 133 | static void stop_branch_trace(struct trace_array *tr) |
| 134 | { |
| 135 | disable_branch_tracing(); |
| 136 | } |
| 137 | |
| 138 | static int branch_trace_init(struct trace_array *tr) |
| 139 | { |
| 140 | start_branch_trace(tr); |
| 141 | return 0; |
| 142 | } |
| 143 | |
| 144 | static void branch_trace_reset(struct trace_array *tr) |
| 145 | { |
| 146 | stop_branch_trace(tr); |
| 147 | } |
| 148 | |
| 149 | static enum print_line_t trace_branch_print(struct trace_iterator *iter, |
| 150 | int flags, struct trace_event *event) |
| 151 | { |
| 152 | struct trace_branch *field; |
| 153 | |
| 154 | trace_assign_type(field, iter->ent); |
| 155 | |
| 156 | trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n", |
| 157 | field->correct ? " ok " : " MISS ", |
| 158 | field->func, |
| 159 | field->file, |
| 160 | field->line); |
| 161 | |
| 162 | return trace_handle_return(&iter->seq); |
| 163 | } |
| 164 | |
| 165 | static void branch_print_header(struct seq_file *s) |
| 166 | { |
| 167 | seq_puts(s, "# TASK-PID CPU# TIMESTAMP CORRECT" |
| 168 | " FUNC:FILE:LINE\n" |
| 169 | "# | | | | | " |
| 170 | " |\n"); |
| 171 | } |
| 172 | |
| 173 | static struct trace_event_functions trace_branch_funcs = { |
| 174 | .trace = trace_branch_print, |
| 175 | }; |
| 176 | |
| 177 | static struct trace_event trace_branch_event = { |
| 178 | .type = TRACE_BRANCH, |
| 179 | .funcs = &trace_branch_funcs, |
| 180 | }; |
| 181 | |
| 182 | static struct tracer branch_trace __read_mostly = |
| 183 | { |
| 184 | .name = "branch", |
| 185 | .init = branch_trace_init, |
| 186 | .reset = branch_trace_reset, |
| 187 | #ifdef CONFIG_FTRACE_SELFTEST |
| 188 | .selftest = trace_selftest_startup_branch, |
| 189 | #endif /* CONFIG_FTRACE_SELFTEST */ |
| 190 | .print_header = branch_print_header, |
| 191 | }; |
| 192 | |
| 193 | __init static int init_branch_tracer(void) |
| 194 | { |
| 195 | int ret; |
| 196 | |
| 197 | ret = register_trace_event(&trace_branch_event); |
| 198 | if (!ret) { |
| 199 | printk(KERN_WARNING "Warning: could not register " |
| 200 | "branch events\n"); |
| 201 | return 1; |
| 202 | } |
| 203 | return register_tracer(&branch_trace); |
| 204 | } |
| 205 | core_initcall(init_branch_tracer); |
| 206 | |
| 207 | #else |
| 208 | static inline |
| 209 | void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect) |
| 210 | { |
| 211 | } |
| 212 | #endif /* CONFIG_BRANCH_TRACER */ |
| 213 | |
| 214 | void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect) |
| 215 | { |
| 216 | /* |
| 217 | * I would love to have a trace point here instead, but the |
| 218 | * trace point code is so inundated with unlikely and likely |
| 219 | * conditions that the recursive nightmare that exists is too |
| 220 | * much to try to get working. At least for now. |
| 221 | */ |
| 222 | trace_likely_condition(f, val, expect); |
| 223 | |
| 224 | /* FIXME: Make this atomic! */ |
| 225 | if (val == expect) |
| 226 | f->correct++; |
| 227 | else |
| 228 | f->incorrect++; |
| 229 | } |
| 230 | EXPORT_SYMBOL(ftrace_likely_update); |
| 231 | |
| 232 | extern unsigned long __start_annotated_branch_profile[]; |
| 233 | extern unsigned long __stop_annotated_branch_profile[]; |
| 234 | |
| 235 | static int annotated_branch_stat_headers(struct seq_file *m) |
| 236 | { |
| 237 | seq_puts(m, " correct incorrect % " |
| 238 | " Function " |
| 239 | " File Line\n" |
| 240 | " ------- --------- - " |
| 241 | " -------- " |
| 242 | " ---- ----\n"); |
| 243 | return 0; |
| 244 | } |
| 245 | |
| 246 | static inline long get_incorrect_percent(struct ftrace_branch_data *p) |
| 247 | { |
| 248 | long percent; |
| 249 | |
| 250 | if (p->correct) { |
| 251 | percent = p->incorrect * 100; |
| 252 | percent /= p->correct + p->incorrect; |
| 253 | } else |
| 254 | percent = p->incorrect ? 100 : -1; |
| 255 | |
| 256 | return percent; |
| 257 | } |
| 258 | |
| 259 | static int branch_stat_show(struct seq_file *m, void *v) |
| 260 | { |
| 261 | struct ftrace_branch_data *p = v; |
| 262 | const char *f; |
| 263 | long percent; |
| 264 | |
| 265 | /* Only print the file, not the path */ |
| 266 | f = p->file + strlen(p->file); |
| 267 | while (f >= p->file && *f != '/') |
| 268 | f--; |
| 269 | f++; |
| 270 | |
| 271 | /* |
| 272 | * The miss is overlayed on correct, and hit on incorrect. |
| 273 | */ |
| 274 | percent = get_incorrect_percent(p); |
| 275 | |
| 276 | seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect); |
| 277 | if (percent < 0) |
| 278 | seq_puts(m, " X "); |
| 279 | else |
| 280 | seq_printf(m, "%3ld ", percent); |
| 281 | seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line); |
| 282 | return 0; |
| 283 | } |
| 284 | |
| 285 | static void *annotated_branch_stat_start(struct tracer_stat *trace) |
| 286 | { |
| 287 | return __start_annotated_branch_profile; |
| 288 | } |
| 289 | |
| 290 | static void * |
| 291 | annotated_branch_stat_next(void *v, int idx) |
| 292 | { |
| 293 | struct ftrace_branch_data *p = v; |
| 294 | |
| 295 | ++p; |
| 296 | |
| 297 | if ((void *)p >= (void *)__stop_annotated_branch_profile) |
| 298 | return NULL; |
| 299 | |
| 300 | return p; |
| 301 | } |
| 302 | |
| 303 | static int annotated_branch_stat_cmp(void *p1, void *p2) |
| 304 | { |
| 305 | struct ftrace_branch_data *a = p1; |
| 306 | struct ftrace_branch_data *b = p2; |
| 307 | |
| 308 | long percent_a, percent_b; |
| 309 | |
| 310 | percent_a = get_incorrect_percent(a); |
| 311 | percent_b = get_incorrect_percent(b); |
| 312 | |
| 313 | if (percent_a < percent_b) |
| 314 | return -1; |
| 315 | if (percent_a > percent_b) |
| 316 | return 1; |
| 317 | |
| 318 | if (a->incorrect < b->incorrect) |
| 319 | return -1; |
| 320 | if (a->incorrect > b->incorrect) |
| 321 | return 1; |
| 322 | |
| 323 | /* |
| 324 | * Since the above shows worse (incorrect) cases |
| 325 | * first, we continue that by showing best (correct) |
| 326 | * cases last. |
| 327 | */ |
| 328 | if (a->correct > b->correct) |
| 329 | return -1; |
| 330 | if (a->correct < b->correct) |
| 331 | return 1; |
| 332 | |
| 333 | return 0; |
| 334 | } |
| 335 | |
| 336 | static struct tracer_stat annotated_branch_stats = { |
| 337 | .name = "branch_annotated", |
| 338 | .stat_start = annotated_branch_stat_start, |
| 339 | .stat_next = annotated_branch_stat_next, |
| 340 | .stat_cmp = annotated_branch_stat_cmp, |
| 341 | .stat_headers = annotated_branch_stat_headers, |
| 342 | .stat_show = branch_stat_show |
| 343 | }; |
| 344 | |
| 345 | __init static int init_annotated_branch_stats(void) |
| 346 | { |
| 347 | int ret; |
| 348 | |
| 349 | ret = register_stat_tracer(&annotated_branch_stats); |
| 350 | if (!ret) { |
| 351 | printk(KERN_WARNING "Warning: could not register " |
| 352 | "annotated branches stats\n"); |
| 353 | return 1; |
| 354 | } |
| 355 | return 0; |
| 356 | } |
| 357 | fs_initcall(init_annotated_branch_stats); |
| 358 | |
| 359 | #ifdef CONFIG_PROFILE_ALL_BRANCHES |
| 360 | |
| 361 | extern unsigned long __start_branch_profile[]; |
| 362 | extern unsigned long __stop_branch_profile[]; |
| 363 | |
| 364 | static int all_branch_stat_headers(struct seq_file *m) |
| 365 | { |
| 366 | seq_puts(m, " miss hit % " |
| 367 | " Function " |
| 368 | " File Line\n" |
| 369 | " ------- --------- - " |
| 370 | " -------- " |
| 371 | " ---- ----\n"); |
| 372 | return 0; |
| 373 | } |
| 374 | |
| 375 | static void *all_branch_stat_start(struct tracer_stat *trace) |
| 376 | { |
| 377 | return __start_branch_profile; |
| 378 | } |
| 379 | |
| 380 | static void * |
| 381 | all_branch_stat_next(void *v, int idx) |
| 382 | { |
| 383 | struct ftrace_branch_data *p = v; |
| 384 | |
| 385 | ++p; |
| 386 | |
| 387 | if ((void *)p >= (void *)__stop_branch_profile) |
| 388 | return NULL; |
| 389 | |
| 390 | return p; |
| 391 | } |
| 392 | |
| 393 | static struct tracer_stat all_branch_stats = { |
| 394 | .name = "branch_all", |
| 395 | .stat_start = all_branch_stat_start, |
| 396 | .stat_next = all_branch_stat_next, |
| 397 | .stat_headers = all_branch_stat_headers, |
| 398 | .stat_show = branch_stat_show |
| 399 | }; |
| 400 | |
| 401 | __init static int all_annotated_branch_stats(void) |
| 402 | { |
| 403 | int ret; |
| 404 | |
| 405 | ret = register_stat_tracer(&all_branch_stats); |
| 406 | if (!ret) { |
| 407 | printk(KERN_WARNING "Warning: could not register " |
| 408 | "all branches stats\n"); |
| 409 | return 1; |
| 410 | } |
| 411 | return 0; |
| 412 | } |
| 413 | fs_initcall(all_annotated_branch_stats); |
| 414 | #endif /* CONFIG_PROFILE_ALL_BRANCHES */ |