sysdeps/posix/sprofil.c

   1 /* Copyright (C) 2001-2015 Free Software Foundation, Inc.
   2    Contributed by David Mosberger-Tang <davidm@hpl.hp.com>.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <assert.h>
  20 #include <signal.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24
  25 #include <sys/time.h>
  26 #include <sys/profil.h>
  27
  28 #ifndef SIGPROF
  29 # include <gmon/sprofil.c>
  30 #else
  31
  32 #include <libc-internal.h>
  33
  34 struct region
  35   {
  36     size_t offset;
  37     size_t nsamples;
  38     unsigned int scale;
  39     union
  40       {
  41         void *vp;
  42         unsigned short *us;
  43         unsigned int *ui;
  44       }
  45     sample;
  46     size_t start;
  47     size_t end;
  48   };
  49
  50 struct prof_info
  51   {
  52     unsigned int num_regions;
  53     struct region *region;
  54     struct region *last, *overflow;
  55     struct itimerval saved_timer;
  56     struct sigaction saved_action;
  57   };
  58
  59 static unsigned int overflow_counter;
  60
  61 static struct region default_overflow_region =
  62   {
  63     .offset     = 0,
  64     .nsamples   = 1,
  65     .scale      = 2,
  66     .sample     = { &overflow_counter },
  67     .start      = 0,
  68     .end        = ~(size_t) 0
  69   };
  70
  71 static struct prof_info prof_info;
  72
  73 static unsigned long int
  74 pc_to_index (size_t pc, size_t offset, unsigned int scale, int prof_uint)
  75 {
  76   size_t i = (pc - offset) / (prof_uint ? sizeof (int) : sizeof (short));
  77
  78   if (sizeof (unsigned long long int) > sizeof (size_t))
  79     return (unsigned long long int) i * scale / 65536;
  80   else
  81     return i / 65536 * scale + i % 65536 * scale / 65536;
  82 }
  83
  84 static inline size_t
  85 index_to_pc (unsigned long int n, size_t offset, unsigned int scale,
  86              int prof_uint)
  87 {
  88   size_t pc, bin_size = (prof_uint ? sizeof (int) : sizeof (short));
  89
  90   if (sizeof (unsigned long long int) > sizeof (size_t))
  91     pc = offset + (unsigned long long int) n * bin_size * 65536ull / scale;
  92   else
  93     pc = (offset + n * bin_size / scale * 65536
  94           + n * bin_size % scale * 65536 / scale);
  95
  96   if (pc_to_index (pc, offset, scale, prof_uint) < n)
  97     /* Adjust for rounding error.  */
  98     ++pc;
  99
 100   assert (pc_to_index (pc - 1, offset, scale, prof_uint) < n
 101           && pc_to_index (pc, offset, scale, prof_uint) >= n);
 102
 103   return pc;
 104 }
 105
 106 static void
 107 profil_count (void *pcp, int prof_uint)
 108 {
 109   struct region *region, *r = prof_info.last;
 110   size_t lo, hi, mid, pc = (unsigned long int) pcp;
 111   unsigned long int i;
 112
 113   /* Fast path: pc is in same region as before.  */
 114   if (pc >= r->start && pc < r->end)
 115     region = r;
 116   else
 117     {
 118       /* Slow path: do a binary search for the right region.  */
 119       lo = 0; hi = prof_info.num_regions - 1;
 120       while (lo <= hi)
 121         {
 122           mid = (lo + hi) / 2;
 123
 124           r = prof_info.region + mid;
 125           if (pc >= r->start && pc < r->end)
 126             {
 127               prof_info.last = r;
 128               region = r;
 129               break;
 130             }
 131
 132           if (pc < r->start)
 133             hi = mid - 1;
 134           else
 135             lo = mid + 1;
 136         }
 137
 138       /* No matching region: increment overflow count.  There is no point
 139          in updating the cache here, as it won't hit anyhow.  */
 140       region = prof_info.overflow;
 141     }
 142
 143   i = pc_to_index (pc, region->offset, region->scale, prof_uint);
 144   if (i < r->nsamples)
 145     {
 146       if (prof_uint)
 147         {
 148           if (r->sample.ui[i] < (unsigned int) ~0)
 149             ++r->sample.ui[i];
 150         }
 151       else
 152         {
 153           if (r->sample.us[i] < (unsigned short) ~0)
 154             ++r->sample.us[i];
 155         }
 156     }
 157   else
 158     {
 159       if (prof_uint)
 160         ++prof_info.overflow->sample.ui[0];
 161       else
 162         ++prof_info.overflow->sample.us[0];
 163     }
 164 }
 165
 166 static inline void
 167 profil_count_ushort (void *pcp)
 168 {
 169   profil_count (pcp, 0);
 170 }
 171
 172 static inline void
 173 profil_count_uint (void *pcp)
 174 {
 175   profil_count (pcp, 1);
 176 }
 177
 178 /* Get the machine-dependent definition of `__profil_counter', the signal
 179    handler for SIGPROF.  It calls `profil_count' (above) with the PC of the
 180    interrupted code.  */
 181 #define __profil_counter        __profil_counter_ushort
 182 #define profil_count(pc)        profil_count (pc, 0)
 183 #include <profil-counter.h>
 184
 185 #undef __profil_counter
 186 #undef profil_count
 187
 188 #define __profil_counter        __profil_counter_uint
 189 #define profil_count(pc)        profil_count (pc, 1)
 190 #include <profil-counter.h>
 191
 192 static int
 193 insert (int i, unsigned long int start, unsigned long int end, struct prof *p,
 194         int prof_uint)
 195 {
 196   struct region *r;
 197   size_t to_copy;
 198
 199   if (start >= end)
 200     return 0;           /* don't bother with empty regions */
 201
 202   if (prof_info.num_regions == 0)
 203     r = malloc (sizeof (*r));
 204   else
 205     r = realloc (prof_info.region, (prof_info.num_regions + 1) * sizeof (*r));
 206   if (r == NULL)
 207     return -1;
 208
 209   to_copy = prof_info.num_regions - i;
 210   if (to_copy > 0)
 211     memmove (r + i + 1, r + i, to_copy * sizeof (*r));
 212
 213   r[i].offset = p->pr_off;
 214   r[i].nsamples = p->pr_size / (prof_uint ? sizeof (int) : sizeof (short));
 215   r[i].scale = p->pr_scale;
 216   r[i].sample.vp = p->pr_base;
 217   r[i].start = start;
 218   r[i].end = end;
 219
 220   prof_info.region = r;
 221   ++prof_info.num_regions;
 222
 223   if (p->pr_off == 0 && p->pr_scale == 2)
 224     prof_info.overflow = r;
 225
 226   return 0;
 227 }
 228
 229 /* Add a new profiling region.  If the new region overlaps with
 230    existing ones, this may add multiple subregions so that the final
 231    data structure is free of overlaps.  The absence of overlaps makes
 232    it possible to use a binary search in profil_count().  Note that
 233    this function depends on new regions being presented in DECREASING
 234    ORDER of starting address.  */
 235
 236 static int
 237 add_region (struct prof *p, int prof_uint)
 238 {
 239   unsigned long int nsamples;
 240   size_t start, end;
 241   unsigned int i;
 242
 243   if (p->pr_scale < 2)
 244     return 0;
 245
 246   nsamples = p->pr_size / (prof_uint ? sizeof (int) : sizeof (short));
 247
 248   start = p->pr_off;
 249   end = index_to_pc (nsamples, p->pr_off, p->pr_scale, prof_uint);
 250
 251   /* Merge with existing regions.  */
 252   for (i = 0; i < prof_info.num_regions; ++i)
 253     {
 254       if (start < prof_info.region[i].start)
 255         {
 256           if (end < prof_info.region[i].start)
 257             break;
 258           else if (insert (i, start, prof_info.region[i].start, p, prof_uint)
 259                    < 0)
 260             return -1;
 261         }
 262       start = prof_info.region[i].end;
 263     }
 264   return insert (i, start, end, p, prof_uint);
 265 }
 266
 267 static int
 268 pcmp (const void *left, const void *right)
 269 {
 270   struct prof *l = *(struct prof **) left;
 271   struct prof *r = *(struct prof **) right;
 272
 273   if (l->pr_off < r->pr_off)
 274     return 1;
 275   else if (l->pr_off > r->pr_off)
 276     return -1;
 277   return 0;
 278 }
 279
 280 int
 281 __sprofil (struct prof *profp, int profcnt, struct timeval *tvp,
 282            unsigned int flags)
 283 {
 284   struct prof *p[profcnt];
 285   struct itimerval timer;
 286   struct sigaction act;
 287   int i;
 288
 289   if (tvp != NULL)
 290     {
 291       /* Return profiling period.  */
 292       unsigned long int t = 1000000 / __profile_frequency ();
 293       tvp->tv_sec  = t / 1000000;
 294       tvp->tv_usec = t % 1000000;
 295     }
 296
 297   if (prof_info.num_regions > 0)
 298     {
 299       /* Disable profiling.  */
 300       if (__setitimer (ITIMER_PROF, &prof_info.saved_timer, NULL) < 0)
 301         return -1;
 302
 303       if (__sigaction (SIGPROF, &prof_info.saved_action, NULL) < 0)
 304         return -1;
 305
 306       free (prof_info.region);
 307       return 0;
 308     }
 309
 310   prof_info.num_regions = 0;
 311   prof_info.region = NULL;
 312   prof_info.overflow = &default_overflow_region;
 313
 314   for (i = 0; i < profcnt; ++i)
 315     p[i] = profp + i;
 316
 317   /* Sort in order of decreasing starting address: */
 318   qsort (p, profcnt, sizeof (p[0]), pcmp);
 319
 320   /* Add regions in order of decreasing starting address: */
 321   for (i = 0; i < profcnt; ++i)
 322     if (add_region (p[i], (flags & PROF_UINT) != 0) < 0)
 323       {
 324         free (prof_info.region);
 325         prof_info.num_regions = 0;
 326         prof_info.region = NULL;
 327         return -1;
 328       }
 329
 330   if (prof_info.num_regions == 0)
 331     return 0;
 332
 333   prof_info.last = prof_info.region;
 334
 335   /* Install SIGPROF handler.  */
 336   if (flags & PROF_UINT)
 337     act.sa_handler = (sighandler_t) &__profil_counter_uint;
 338   else
 339     act.sa_handler = (sighandler_t) &__profil_counter_ushort;
 340   act.sa_flags = SA_RESTART;
 341   __sigfillset (&act.sa_mask);
 342   if (__sigaction (SIGPROF, &act, &prof_info.saved_action) < 0)
 343     return -1;
 344
 345   /* Setup profiling timer.  */
 346   timer.it_value.tv_sec  = 0;
 347   timer.it_value.tv_usec = 1;
 348   timer.it_interval = timer.it_value;
 349   return __setitimer (ITIMER_PROF, &timer, &prof_info.saved_timer);
 350 }
 351
 352 weak_alias (__sprofil, sprofil)
 353
 354 #endif /* SIGPROF */