git.oblomov.eu Git - linux-2.6/blob - kernel/trace/trace_branch.c

   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, irq_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         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
  56                                          &irq_flags);
  57         if (!event)
  58                 goto out;
  59
  60         pc = preempt_count();
  61         entry   = ring_buffer_event_data(event);
  62         tracing_generic_entry_update(&entry->ent, flags, pc);
  63         entry->ent.type         = TRACE_BRANCH;
  64
  65         /* Strip off the path, only save the file */
  66         p = f->file + strlen(f->file);
  67         while (p >= f->file && *p != '/')
  68                 p--;
  69         p++;
  70
  71         strncpy(entry->func, f->func, TRACE_FUNC_SIZE);
  72         strncpy(entry->file, p, TRACE_FILE_SIZE);
  73         entry->func[TRACE_FUNC_SIZE] = 0;
  74         entry->file[TRACE_FILE_SIZE] = 0;
  75         entry->line = f->line;
  76         entry->correct = val == expect;
  77
  78         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
  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         int ret = 0;
  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 ret;
 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         tracing_reset_online_cpus(tr);
 137         start_branch_trace(tr);
 138         return 0;
 139 }
 140
 141 static void branch_trace_reset(struct trace_array *tr)
 142 {
 143         stop_branch_trace(tr);
 144 }
 145
 146 static int
 147 trace_print_print(struct trace_seq *s, struct trace_entry *entry, int flags)
 148 {
 149         struct print_entry *field;
 150
 151         trace_assign_type(field, entry);
 152
 153         if (seq_print_ip_sym(s, field->ip, flags))
 154                 goto partial;
 155
 156         if (trace_seq_printf(s, ": %s", field->buf))
 157                 goto partial;
 158
 159  partial:
 160         return TRACE_TYPE_PARTIAL_LINE;
 161 }
 162
 163 static int trace_branch_print(struct trace_iterator *iter, int flags)
 164 {
 165         struct trace_branch *field;
 166
 167         trace_assign_type(field, iter->ent);
 168
 169         if (trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n",
 170                              field->correct ? "  ok  " : " MISS ",
 171                              field->func,
 172                              field->file,
 173                              field->line))
 174                 return TRACE_TYPE_PARTIAL_LINE;
 175
 176         return 0;
 177 }
 178
 179
 180 static struct trace_event trace_branch_event = {
 181         .type           = TRACE_BRANCH,
 182         .trace          = trace_branch_print,
 183         .latency_trace  = trace_branch_print,
 184         .raw            = trace_nop_print,
 185         .hex            = trace_nop_print,
 186         .binary         = trace_nop_print,
 187 };
 188
 189 static struct tracer branch_trace __read_mostly =
 190 {
 191         .name           = "branch",
 192         .init           = branch_trace_init,
 193         .reset          = branch_trace_reset,
 194 #ifdef CONFIG_FTRACE_SELFTEST
 195         .selftest       = trace_selftest_startup_branch,
 196 #endif /* CONFIG_FTRACE_SELFTEST */
 197 };
 198
 199 __init static int init_branch_tracer(void)
 200 {
 201         int ret;
 202
 203         ret = register_ftrace_event(&trace_branch_event);
 204         if (!ret) {
 205                 printk(KERN_WARNING "Warning: could not register "
 206                                     "branch events\n");
 207                 return 1;
 208         }
 209         return register_tracer(&branch_trace);
 210 }
 211 device_initcall(init_branch_tracer);
 212
 213 #else
 214 static inline
 215 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
 216 {
 217 }
 218 #endif /* CONFIG_BRANCH_TRACER */
 219
 220 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect)
 221 {
 222         /*
 223          * I would love to have a trace point here instead, but the
 224          * trace point code is so inundated with unlikely and likely
 225          * conditions that the recursive nightmare that exists is too
 226          * much to try to get working. At least for now.
 227          */
 228         trace_likely_condition(f, val, expect);
 229
 230         /* FIXME: Make this atomic! */
 231         if (val == expect)
 232                 f->correct++;
 233         else
 234                 f->incorrect++;
 235 }
 236 EXPORT_SYMBOL(ftrace_likely_update);
 237
 238 extern unsigned long __start_annotated_branch_profile[];
 239 extern unsigned long __stop_annotated_branch_profile[];
 240
 241 static int annotated_branch_stat_headers(struct seq_file *m)
 242 {
 243         seq_printf(m, " correct incorrect  %% ");
 244         seq_printf(m, "       Function                "
 245                               "  File              Line\n"
 246                               " ------- ---------  - "
 247                               "       --------                "
 248                               "  ----              ----\n");
 249         return 0;
 250 }
 251
 252 static inline long get_incorrect_percent(struct ftrace_branch_data *p)
 253 {
 254         long percent;
 255
 256         if (p->correct) {
 257                 percent = p->incorrect * 100;
 258                 percent /= p->correct + p->incorrect;
 259         } else
 260                 percent = p->incorrect ? 100 : -1;
 261
 262         return percent;
 263 }
 264
 265 static int branch_stat_show(struct seq_file *m, void *v)
 266 {
 267         struct ftrace_branch_data *p = v;
 268         const char *f;
 269         long percent;
 270
 271         /* Only print the file, not the path */
 272         f = p->file + strlen(p->file);
 273         while (f >= p->file && *f != '/')
 274                 f--;
 275         f++;
 276
 277         /*
 278          * The miss is overlayed on correct, and hit on incorrect.
 279          */
 280         percent = get_incorrect_percent(p);
 281
 282         seq_printf(m, "%8lu %8lu ",  p->correct, p->incorrect);
 283         if (percent < 0)
 284                 seq_printf(m, "  X ");
 285         else
 286                 seq_printf(m, "%3ld ", percent);
 287         seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line);
 288         return 0;
 289 }
 290
 291 static void *annotated_branch_stat_start(void)
 292 {
 293         return __start_annotated_branch_profile;
 294 }
 295
 296 static void *
 297 annotated_branch_stat_next(void *v, int idx)
 298 {
 299         struct ftrace_branch_data *p = v;
 300
 301         ++p;
 302
 303         if ((void *)p >= (void *)__stop_annotated_branch_profile)
 304                 return NULL;
 305
 306         return p;
 307 }
 308
 309 static int annotated_branch_stat_cmp(void *p1, void *p2)
 310 {
 311         struct ftrace_branch_data *a = p1;
 312         struct ftrace_branch_data *b = p2;
 313
 314         long percent_a, percent_b;
 315
 316         percent_a = get_incorrect_percent(a);
 317         percent_b = get_incorrect_percent(b);
 318
 319         if (percent_a < percent_b)
 320                 return -1;
 321         if (percent_a > percent_b)
 322                 return 1;
 323         else
 324                 return 0;
 325 }
 326
 327 static struct tracer_stat annotated_branch_stats = {
 328         .name = "branch_annotated",
 329         .stat_start = annotated_branch_stat_start,
 330         .stat_next = annotated_branch_stat_next,
 331         .stat_cmp = annotated_branch_stat_cmp,
 332         .stat_headers = annotated_branch_stat_headers,
 333         .stat_show = branch_stat_show
 334 };
 335
 336 __init static int init_annotated_branch_stats(void)
 337 {
 338         int ret;
 339
 340         ret = register_stat_tracer(&annotated_branch_stats);
 341         if (!ret) {
 342                 printk(KERN_WARNING "Warning: could not register "
 343                                     "annotated branches stats\n");
 344                 return 1;
 345         }
 346         return 0;
 347 }
 348 fs_initcall(init_annotated_branch_stats);
 349
 350 #ifdef CONFIG_PROFILE_ALL_BRANCHES
 351
 352 extern unsigned long __start_branch_profile[];
 353 extern unsigned long __stop_branch_profile[];
 354
 355 static int all_branch_stat_headers(struct seq_file *m)
 356 {
 357         seq_printf(m, "   miss      hit    %% ");
 358         seq_printf(m, "       Function                "
 359                               "  File              Line\n"
 360                               " ------- ---------  - "
 361                               "       --------                "
 362                               "  ----              ----\n");
 363         return 0;
 364 }
 365
 366 static void *all_branch_stat_start(void)
 367 {
 368         return __start_branch_profile;
 369 }
 370
 371 static void *
 372 all_branch_stat_next(void *v, int idx)
 373 {
 374         struct ftrace_branch_data *p = v;
 375
 376         ++p;
 377
 378         if ((void *)p >= (void *)__stop_branch_profile)
 379                 return NULL;
 380
 381         return p;
 382 }
 383
 384 static struct tracer_stat all_branch_stats = {
 385         .name = "branch_all",
 386         .stat_start = all_branch_stat_start,
 387         .stat_next = all_branch_stat_next,
 388         .stat_headers = all_branch_stat_headers,
 389         .stat_show = branch_stat_show
 390 };
 391
 392 __init static int all_annotated_branch_stats(void)
 393 {
 394         int ret;
 395
 396         ret = register_stat_tracer(&all_branch_stats);
 397         if (!ret) {
 398                 printk(KERN_WARNING "Warning: could not register "
 399                                     "all branches stats\n");
 400                 return 1;
 401         }
 402         return 0;
 403 }
 404 fs_initcall(all_annotated_branch_stats);
 405 #endif /* CONFIG_PROFILE_ALL_BRANCHES */