1/* Low-level statistical profiling support function. Mostly POSIX.1 version.
2 Copyright (C) 1996-2016 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 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 <sys/types.h>
20#include <unistd.h>
21#include <errno.h>
22#include <signal.h>
23#include <sys/time.h>
24#include <libc-internal.h>
25
26#ifndef SIGPROF
27
28#include <gmon/profil.c>
29
30#else
31
32static u_short *samples;
33static size_t nsamples;
34static size_t pc_offset;
35static u_int pc_scale;
36
37static inline void
38profil_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
62int
63__profil (u_short *sample_buffer, size_t size, size_t offset, u_int scale)
64{
65 struct sigaction act;
66 struct itimerval timer;
67#if !IS_IN (rtld)
68 static struct sigaction oact;
69 static struct itimerval otimer;
70# define oact_ptr &oact
71# define otimer_ptr &otimer
72
73 if (sample_buffer == NULL)
74 {
75 /* Disable profiling. */
76 if (samples == NULL)
77 /* Wasn't turned on. */
78 return 0;
79
80 if (__setitimer (ITIMER_PROF, &otimer, NULL) < 0)
81 return -1;
82 samples = NULL;
83 return __sigaction (SIGPROF, &oact, NULL);
84 }
85
86 if (samples)
87 {
88 /* Was already turned on. Restore old timer and signal handler
89 first. */
90 if (__setitimer (ITIMER_PROF, &otimer, NULL) < 0
91 || __sigaction (SIGPROF, &oact, NULL) < 0)
92 return -1;
93 }
94#else
95 /* In ld.so profiling should never be disabled once it runs. */
96 //assert (sample_buffer != NULL);
97# define oact_ptr NULL
98# define otimer_ptr NULL
99#endif
100
101 samples = sample_buffer;
102 nsamples = size / sizeof *samples;
103 pc_offset = offset;
104 pc_scale = scale;
105
106 act.sa_handler = (sighandler_t) &__profil_counter;
107 act.sa_flags = SA_RESTART;
108 __sigfillset (&act.sa_mask);
109 if (__sigaction (SIGPROF, &act, oact_ptr) < 0)
110 return -1;
111
112 timer.it_value.tv_sec = 0;
113 timer.it_value.tv_usec = 1000000 / __profile_frequency ();
114 timer.it_interval = timer.it_value;
115 return __setitimer (ITIMER_PROF, &timer, otimer_ptr);
116}
117weak_alias (__profil, profil)
118
119#endif
120