mirror of
https://sourceware.org/git/glibc.git
synced 2025-10-28 23:34:53 +03:00
2b778ceb40
I used these shell commands: ../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright (cd ../glibc && git commit -am"[this commit message]") and then ignored the output, which consisted lines saying "FOO: warning: copyright statement not found" for each of 6694 files FOO. I then removed trailing white space from benchtests/bench-pthread-locks.c and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this diagnostic from Savannah: remote: *** pre-commit check failed ... remote: *** error: lines with trailing whitespace found remote: error: hook declined to update refs/heads/master
111 lines
3.4 KiB
C
111 lines
3.4 KiB
C
/* Get the frequency of the time base.
|
|
Copyright (C) 2012-2021 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <stdint.h>
|
|
#include <string.h>
|
|
|
|
#include <libc-internal.h>
|
|
#include <not-cancel.h>
|
|
#include <sysdep-vdso.h>
|
|
|
|
static uint64_t
|
|
get_timebase_freq_fallback (void)
|
|
{
|
|
hp_timing_t result = 0L;
|
|
|
|
/* We read the information from the /proc filesystem. /proc/cpuinfo
|
|
contains at least one line like:
|
|
timebase : 33333333
|
|
We search for this line and convert the number into an integer. */
|
|
int fd = __open_nocancel ("/proc/cpuinfo", O_RDONLY);
|
|
if (__glibc_unlikely (fd == -1))
|
|
return result;
|
|
|
|
/* The timebase will be in the 1st 1024 bytes for systems with up
|
|
to 8 processors. If the first read returns less then 1024
|
|
bytes read, we have the whole cpuinfo and can start the scan.
|
|
Otherwise we will have to read more to insure we have the
|
|
timebase value in the scan. */
|
|
char buf[1024];
|
|
ssize_t n;
|
|
|
|
n = __read_nocancel (fd, buf, sizeof (buf));
|
|
if (n == sizeof (buf))
|
|
{
|
|
/* We are here because the 1st read returned exactly sizeof
|
|
(buf) bytes. This implies that we are not at EOF and may
|
|
not have read the timebase value yet. So we need to read
|
|
more bytes until we know we have EOF. We copy the lower
|
|
half of buf to the upper half and read sizeof (buf)/2
|
|
bytes into the lower half of buf and repeat until we
|
|
reach EOF. We can assume that the timebase will be in
|
|
the last 512 bytes of cpuinfo, so two 512 byte half_bufs
|
|
will be sufficient to contain the timebase and will
|
|
handle the case where the timebase spans the half_buf
|
|
boundry. */
|
|
const ssize_t half_buf = sizeof (buf) / 2;
|
|
while (n >= half_buf)
|
|
{
|
|
memcpy (buf, buf + half_buf, half_buf);
|
|
n = __read_nocancel (fd, buf + half_buf, half_buf);
|
|
}
|
|
if (n >= 0)
|
|
n += half_buf;
|
|
}
|
|
__close_nocancel (fd);
|
|
|
|
if (__glibc_likely (n > 0))
|
|
{
|
|
char *mhz = memmem (buf, n, "timebase", 7);
|
|
|
|
if (__glibc_likely (mhz != NULL))
|
|
{
|
|
char *endp = buf + n;
|
|
|
|
/* Search for the beginning of the string. */
|
|
while (mhz < endp && (*mhz < '0' || *mhz > '9') && *mhz != '\n')
|
|
++mhz;
|
|
|
|
while (mhz < endp && *mhz != '\n')
|
|
{
|
|
if (*mhz >= '0' && *mhz <= '9')
|
|
{
|
|
result *= 10;
|
|
result += *mhz - '0';
|
|
}
|
|
|
|
++mhz;
|
|
}
|
|
}
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
uint64_t
|
|
__get_timebase_freq (void)
|
|
{
|
|
/* The vDSO does not have a fallback mechanism (such calling a syscall). */
|
|
uint64_t (*vdsop)(void) = GLRO(dl_vdso_get_tbfreq);
|
|
if (vdsop == NULL)
|
|
return get_timebase_freq_fallback ();
|
|
|
|
return INTERNAL_VSYSCALL_CALL_TYPE (vdsop, uint64_t, 0);
|
|
}
|
|
weak_alias (__get_timebase_freq, __ppc_get_timebase_freq)
|