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/* Copyright (C) 2005-2021 Free Software Foundation, Inc.
Contributed by Richard Henderson <rth@redhat.com>.
This file is part of the GNU Offloading and Multi Processing Library
(libgomp).
Libgomp is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
Libgomp 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 General Public License for
more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* Provide target-specific access to the futex system call. */
#ifdef __x86_64__
# ifndef SYS_futex
# define SYS_futex 202
# endif
static inline int
__futex_wait (int *addr, int futex_op, int val)
{
int res;
register void *timeout __asm ("r10") = NULL;
__asm volatile ("syscall"
: "=a" (res)
: "0" (SYS_futex), "D" (addr), "S" (futex_op),
"d" (val), "r" (timeout)
: "r11", "rcx", "memory");
return res;
}
static inline int
__futex_wake (int *addr, int futex_op, int count)
{
int res;
__asm volatile ("syscall"
: "=a" (res)
: "0" (SYS_futex), "D" (addr), "S" (futex_op),
"d" (count)
: "r11", "rcx", "memory");
return res;
}
#else
# ifndef SYS_futex
# define SYS_futex 240
# endif
static inline int
__futex_wait (int *addr, int futex_op, int val)
{
int res;
void *timeout = NULL;
__asm volatile ("int $0x80"
: "=a" (res)
: "0" (SYS_futex), "b" (addr), "c" (futex_op),
"d" (val), "S" (timeout)
: "memory");
return res;
}
static inline int
__futex_wake (int *addr, int futex_op, int count)
{
int res;
__asm volatile ("int $0x80"
: "=a" (res)
: "0" (SYS_futex), "b" (addr), "c" (futex_op),
"d" (count)
: "memory");
return res;
}
#endif /* __x86_64__ */
static inline void
futex_wait (int *addr, int val)
{
int res = __futex_wait (addr, gomp_futex_wait, val);
if (__builtin_expect (res == -ENOSYS, 0))
{
gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
__futex_wait (addr, gomp_futex_wait, val);
}
}
static inline void
futex_wake (int *addr, int count)
{
int res = __futex_wake (addr, gomp_futex_wake, count);
if (__builtin_expect (res == -ENOSYS, 0))
{
gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
__futex_wake (addr, gomp_futex_wake, count);
}
}
static inline void
cpu_relax (void)
{
__builtin_ia32_pause ();
}
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