1 | /* Low-level statistical profiling support function. Mostly POSIX.1 version. |
2 | Copyright (C) 1996-2017 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 | |
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 | 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 | } |
117 | weak_alias (__profil, profil) |
118 | |
119 | #endif |
120 | |