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;
  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         int ret = 0;
  95
  96         mutex_lock(&branch_tracing_mutex);
  97         branch_tracer = tr;
  98         /*
  99          * Must be seen before enabling. The reader is a condition
 100          * where we do not need a matching rmb()
 101          */
 102         smp_wmb();
 103         branch_tracing_enabled++;
 104         mutex_unlock(&branch_tracing_mutex);
 105
 106         return ret;
 107 }
 108
 109 void disable_branch_tracing(void)
 110 {
 111         mutex_lock(&branch_tracing_mutex);
 112
 113         if (!branch_tracing_enabled)
 114                 goto out_unlock;
 115
 116         branch_tracing_enabled--;
 117
 118  out_unlock:
 119         mutex_unlock(&branch_tracing_mutex);
 120 }
 121
 122 static void start_branch_trace(struct trace_array *tr)
 123 {
 124         enable_branch_tracing(tr);
 125 }
 126
 127 static void stop_branch_trace(struct trace_array *tr)
 128 {
 129         disable_branch_tracing();
 130 }
 131
 132 static int branch_trace_init(struct trace_array *tr)
 133 {
 134         tracing_reset_online_cpus(tr);
 135         start_branch_trace(tr);
 136         return 0;
 137 }
 138
 139 static void branch_trace_reset(struct trace_array *tr)
 140 {
 141         stop_branch_trace(tr);
 142 }
 143
 144 static enum print_line_t trace_branch_print(struct trace_iterator *iter,
 145                                             int flags)
 146 {
 147         struct trace_branch *field;
 148
 149         trace_assign_type(field, iter->ent);
 150
 151         if (trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n",
 152                              field->correct ? "  ok  " : " MISS ",
 153                              field->func,
 154                              field->file,
 155                              field->line))
 156                 return TRACE_TYPE_PARTIAL_LINE;
 157
 158         return TRACE_TYPE_HANDLED;
 159 }
 160
 161
 162 static struct trace_event trace_branch_event = {
 163         .type           = TRACE_BRANCH,
 164         .trace          = trace_branch_print,
 165         .latency_trace  = trace_branch_print,
 166 };
 167
 168 static struct tracer branch_trace __read_mostly =
 169 {
 170         .name           = "branch",
 171         .init           = branch_trace_init,
 172         .reset          = branch_trace_reset,
 173 #ifdef CONFIG_FTRACE_SELFTEST
 174         .selftest       = trace_selftest_startup_branch,
 175 #endif /* CONFIG_FTRACE_SELFTEST */
 176 };
 177
 178 __init static int init_branch_tracer(void)
 179 {
 180         int ret;
 181
 182         ret = register_ftrace_event(&trace_branch_event);
 183         if (!ret) {
 184                 printk(KERN_WARNING "Warning: could not register "
 185                                     "branch events\n");
 186                 return 1;
 187         }
 188         return register_tracer(&branch_trace);
 189 }
 190 device_initcall(init_branch_tracer);
 191
 192 #else
 193 static inline
 194 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
 195 {
 196 }
 197 #endif /* CONFIG_BRANCH_TRACER */
 198
 199 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect)
 200 {
 201         /*
 202          * I would love to have a trace point here instead, but the
 203          * trace point code is so inundated with unlikely and likely
 204          * conditions that the recursive nightmare that exists is too
 205          * much to try to get working. At least for now.
 206          */
 207         trace_likely_condition(f, val, expect);
 208
 209         /* FIXME: Make this atomic! */
 210         if (val == expect)
 211                 f->correct++;
 212         else
 213                 f->incorrect++;
 214 }
 215 EXPORT_SYMBOL(ftrace_likely_update);
 216
 217 extern unsigned long __start_annotated_branch_profile[];
 218 extern unsigned long __stop_annotated_branch_profile[];
 219
 220 static int annotated_branch_stat_headers(struct seq_file *m)
 221 {
 222         seq_printf(m, " correct incorrect  %% ");
 223         seq_printf(m, "       Function                "
 224                               "  File              Line\n"
 225                               " ------- ---------  - "
 226                               "       --------                "
 227                               "  ----              ----\n");
 228         return 0;
 229 }
 230
 231 static inline long get_incorrect_percent(struct ftrace_branch_data *p)
 232 {
 233         long percent;
 234
 235         if (p->correct) {
 236                 percent = p->incorrect * 100;
 237                 percent /= p->correct + p->incorrect;
 238         } else
 239                 percent = p->incorrect ? 100 : -1;
 240
 241         return percent;
 242 }
 243
 244 static int branch_stat_show(struct seq_file *m, void *v)
 245 {
 246         struct ftrace_branch_data *p = v;
 247         const char *f;
 248         long percent;
 249
 250         /* Only print the file, not the path */
 251         f = p->file + strlen(p->file);
 252         while (f >= p->file && *f != '/')
 253                 f--;
 254         f++;
 255
 256         /*
 257          * The miss is overlayed on correct, and hit on incorrect.
 258          */
 259         percent = get_incorrect_percent(p);
 260
 261         seq_printf(m, "%8lu %8lu ",  p->correct, p->incorrect);
 262         if (percent < 0)
 263                 seq_printf(m, "  X ");
 264         else
 265                 seq_printf(m, "%3ld ", percent);
 266         seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line);
 267         return 0;
 268 }
 269
 270 static void *annotated_branch_stat_start(void)
 271 {
 272         return __start_annotated_branch_profile;
 273 }
 274
 275 static void *
 276 annotated_branch_stat_next(void *v, int idx)
 277 {
 278         struct ftrace_branch_data *p = v;
 279
 280         ++p;
 281
 282         if ((void *)p >= (void *)__stop_annotated_branch_profile)
 283                 return NULL;
 284
 285         return p;
 286 }
 287
 288 static int annotated_branch_stat_cmp(void *p1, void *p2)
 289 {
 290         struct ftrace_branch_data *a = p1;
 291         struct ftrace_branch_data *b = p2;
 292
 293         long percent_a, percent_b;
 294
 295         percent_a = get_incorrect_percent(a);
 296         percent_b = get_incorrect_percent(b);
 297
 298         if (percent_a < percent_b)
 299                 return -1;
 300         if (percent_a > percent_b)
 301                 return 1;
 302         else
 303                 return 0;
 304 }
 305
 306 static struct tracer_stat annotated_branch_stats = {
 307         .name = "branch_annotated",
 308         .stat_start = annotated_branch_stat_start,
 309         .stat_next = annotated_branch_stat_next,
 310         .stat_cmp = annotated_branch_stat_cmp,
 311         .stat_headers = annotated_branch_stat_headers,
 312         .stat_show = branch_stat_show
 313 };
 314
 315 __init static int init_annotated_branch_stats(void)
 316 {
 317         int ret;
 318
 319         ret = register_stat_tracer(&annotated_branch_stats);
 320         if (!ret) {
 321                 printk(KERN_WARNING "Warning: could not register "
 322                                     "annotated branches stats\n");
 323                 return 1;
 324         }
 325         return 0;
 326 }
 327 fs_initcall(init_annotated_branch_stats);
 328
 329 #ifdef CONFIG_PROFILE_ALL_BRANCHES
 330
 331 extern unsigned long __start_branch_profile[];
 332 extern unsigned long __stop_branch_profile[];
 333
 334 static int all_branch_stat_headers(struct seq_file *m)
 335 {
 336         seq_printf(m, "   miss      hit    %% ");
 337         seq_printf(m, "       Function                "
 338                               "  File              Line\n"
 339                               " ------- ---------  - "
 340                               "       --------                "
 341                               "  ----              ----\n");
 342         return 0;
 343 }
 344
 345 static void *all_branch_stat_start(void)
 346 {
 347         return __start_branch_profile;
 348 }
 349
 350 static void *
 351 all_branch_stat_next(void *v, int idx)
 352 {
 353         struct ftrace_branch_data *p = v;
 354
 355         ++p;
 356
 357         if ((void *)p >= (void *)__stop_branch_profile)
 358                 return NULL;
 359
 360         return p;
 361 }
 362
 363 static struct tracer_stat all_branch_stats = {
 364         .name = "branch_all",
 365         .stat_start = all_branch_stat_start,
 366         .stat_next = all_branch_stat_next,
 367         .stat_headers = all_branch_stat_headers,
 368         .stat_show = branch_stat_show
 369 };
 370
 371 __init static int all_annotated_branch_stats(void)
 372 {
 373         int ret;
 374
 375         ret = register_stat_tracer(&all_branch_stats);
 376         if (!ret) {
 377                 printk(KERN_WARNING "Warning: could not register "
 378                                     "all branches stats\n");
 379                 return 1;
 380         }
 381         return 0;
 382 }
 383 fs_initcall(all_annotated_branch_stats);
 384 #endif /* CONFIG_PROFILE_ALL_BRANCHES */