sysdeps/posix/profil.c

   1 /* Low-level statistical profiling support function.  Mostly POSIX.1 version.
   2 Copyright (C) 1996 Free Software Foundation, Inc.
   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 Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 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 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <sys/types.h>
  21 #include <unistd.h>
  22 #include <errno.h>
  23 #include <signal.h>
  24 #include <sys/time.h>
  25
  26 #ifndef SIGPROF
  27
  28 #include_next <profil.c>
  29
  30 #else
  31
  32 static u_short *samples;
  33 static size_t nsamples;
  34 static size_t pc_offset;
  35 static u_int pc_scale;
  36
  37 static inline void
  38 profil_count (void *pc)
  39 {
  40   size_t i = (pc - pc_offset - (void *) 0) / 2;
  41
  42   if (sizeof (unsigned long long int) > sizeof (size_t))
  43     i = (unsigned long long int) i * pc_scale / 65536;
  44   else
  45     i = i / 65536 * pc_scale + i % 65536 * pc_scale / 65536;
  46
  47   if (i < nsamples)
  48     ++samples[i];
  49 }
  50
  51 /* Get the machine-dependent definition of `profil_counter', the signal
  52    handler for SIGPROF.  It calls `profil_count' (above) with the PC of the
  53    interrupted code.  */
  54 #include "profil-counter.h"
  55
  56 /* Enable statistical profiling, writing samples of the PC into at most
  57    SIZE bytes of SAMPLE_BUFFER; every processor clock tick while profiling
  58    is enabled, the system examines the user PC and increments
  59    SAMPLE_BUFFER[((PC - OFFSET) / 2) * SCALE / 65536].  If SCALE is zero,
  60    disable profiling.  Returns zero on success, -1 on error.  */
  61
  62 int
  63 profil (u_short *sample_buffer, size_t size, size_t offset, u_int scale)
  64 {
  65   static struct sigaction act, oact;
  66   static struct itimerval timer, otimer;
  67
  68   if (sample_buffer == NULL)
  69     {
  70       /* Disable profiling.  */
  71       if (samples == NULL)
  72         /* Wasn't turned on.  */
  73         return 0;
  74
  75       if (setitimer (ITIMER_PROF, &otimer, NULL) < 0)
  76         return -1;
  77       samples = NULL;
  78       return sigaction (SIGPROF, &oact, NULL);
  79     }
  80
  81  if (samples)
  82     {
  83       /* Was already turned on.  Restore old timer and signal handler
  84          first.  */
  85       if (setitimer (ITIMER_PROF, &otimer, NULL) < 0
  86           || sigaction (SIGPROF, &oact, NULL) < 0)
  87         return -1;
  88     }
  89
  90   samples = sample_buffer;
  91   nsamples = size / sizeof *samples;
  92   pc_offset = offset;
  93   pc_scale = scale;
  94
  95   act.sa_handler = (sighandler_t) &profil_counter;
  96   act.sa_flags = SA_RESTART;
  97   sigfillset (&act.sa_mask);
  98   if (sigaction (SIGPROF, &act, &oact) < 0)
  99     return -1;
 100
 101   timer.it_value.tv_sec = 0;
 102   timer.it_value.tv_usec = 1;
 103   timer.it_interval = timer.it_value;
 104   return setitimer (ITIMER_PROF, &timer, &otimer);
 105 }
 106
 107 #endif