1/* Low-level statistical profiling support function. Mostly POSIX.1 version.
2 Copyright (C) 1996-2018 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#include <sigsetops.h>
26
27#ifndef SIGPROF
28
29#include <gmon/profil.c>
30
31#else
32
33static u_short *samples;
34static size_t nsamples;
35static size_t pc_offset;
36static u_int pc_scale;
37
38static inline void
39profil_count (void *pc)
40{
41 size_t i = (pc - pc_offset - (void *) 0) / 2;
42
43 if (sizeof (unsigned long long int) > sizeof (size_t))
44 i = (unsigned long long int) i * pc_scale / 65536;
45 else
46 i = i / 65536 * pc_scale + i % 65536 * pc_scale / 65536;
47
48 if (i < nsamples)
49 ++samples[i];
50}
51
52/* Get the machine-dependent definition of `__profil_counter', the signal
53 handler for SIGPROF. It calls `profil_count' (above) with the PC of the
54 interrupted code. */
55#include "profil-counter.h"
56
57/* Enable statistical profiling, writing samples of the PC into at most
58 SIZE bytes of SAMPLE_BUFFER; every processor clock tick while profiling
59 is enabled, the system examines the user PC and increments
60 SAMPLE_BUFFER[((PC - OFFSET) / 2) * SCALE / 65536]. If SCALE is zero,
61 disable profiling. Returns zero on success, -1 on error. */
62
63int
64__profil (u_short *sample_buffer, size_t size, size_t offset, u_int scale)
65{
66 struct sigaction act;
67 struct itimerval timer;
68#if !IS_IN (rtld)
69 static struct sigaction oact;
70 static struct itimerval otimer;
71# define oact_ptr &oact
72# define otimer_ptr &otimer
73
74 if (sample_buffer == NULL)
75 {
76 /* Disable profiling. */
77 if (samples == NULL)
78 /* Wasn't turned on. */
79 return 0;
80
81 if (__setitimer (ITIMER_PROF, &otimer, NULL) < 0)
82 return -1;
83 samples = NULL;
84 return __sigaction (SIGPROF, &oact, NULL);
85 }
86
87 if (samples)
88 {
89 /* Was already turned on. Restore old timer and signal handler
90 first. */
91 if (__setitimer (ITIMER_PROF, &otimer, NULL) < 0
92 || __sigaction (SIGPROF, &oact, NULL) < 0)
93 return -1;
94 }
95#else
96 /* In ld.so profiling should never be disabled once it runs. */
97 //assert (sample_buffer != NULL);
98# define oact_ptr NULL
99# define otimer_ptr NULL
100#endif
101
102 samples = sample_buffer;
103 nsamples = size / sizeof *samples;
104 pc_offset = offset;
105 pc_scale = scale;
106
107 act.sa_handler = (sighandler_t) &__profil_counter;
108 act.sa_flags = SA_RESTART;
109 __sigfillset (&act.sa_mask);
110 if (__sigaction (SIGPROF, &act, oact_ptr) < 0)
111 return -1;
112
113 timer.it_value.tv_sec = 0;
114 timer.it_value.tv_usec = 1000000 / __profile_frequency ();
115 timer.it_interval = timer.it_value;
116 return __setitimer (ITIMER_PROF, &timer, otimer_ptr);
117}
118weak_alias (__profil, profil)
119
120#endif
121