/usr/lib/erlang/erts-6.2/include/internal/i386/spinlock.h is in erlang-dev 1:17.3-dfsg-4+deb8u2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 | /*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2005-2011. All Rights Reserved.
*
* The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved online at http://www.erlang.org/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* %CopyrightEnd%
*/
/*
* Native ethread spinlocks on x86/x86-64.
* Author: Mikael Pettersson.
*/
#ifndef ETHREAD_I386_SPINLOCK_H
#define ETHREAD_I386_SPINLOCK_H
#define ETHR_HAVE_NATIVE_SPINLOCKS 1
#define ETHR_NATIVE_SPINLOCK_IMPL "ethread"
/* A spinlock is the low byte of an aligned 32-bit integer.
* A non-zero value means that the lock is locked.
*/
typedef struct {
volatile unsigned int lock;
} ethr_native_spinlock_t;
#if defined(ETHR_TRY_INLINE_FUNCS) || defined(ETHR_AUX_IMPL__)
static ETHR_INLINE void
ethr_native_spinlock_init(ethr_native_spinlock_t *lock)
{
lock->lock = 0;
}
static ETHR_INLINE void
ethr_native_spin_unlock(ethr_native_spinlock_t *lock)
{
/* To unlock we move 0 to the lock.
* On i386 this needs to be a locked operation
* to avoid Pentium Pro errata 66 and 92.
*/
#if !defined(__x86_64__)
if (ETHR_X86_RUNTIME_CONF_HAVE_NO_SSE2__) {
char tmp = 0;
__asm__ __volatile__(
"xchgb %b0, %1"
: "=q"(tmp), "=m"(lock->lock)
: "0"(tmp) : "memory");
}
else
#endif
{
ETHR_MEMBAR(ETHR_LoadStore|ETHR_StoreStore);
*(unsigned char*)&lock->lock = 0;
}
}
static ETHR_INLINE int
ethr_native_spin_trylock(ethr_native_spinlock_t *lock)
{
char tmp = 1;
__asm__ __volatile__(
"xchgb %b0, %1"
: "=q"(tmp), "=m"(lock->lock)
: "0"(tmp) : "memory");
return tmp == 0;
}
static ETHR_INLINE int
ethr_native_spin_is_locked(ethr_native_spinlock_t *lock)
{
return *(volatile unsigned char*)&lock->lock != 0;
}
static ETHR_INLINE void
ethr_native_spin_lock(ethr_native_spinlock_t *lock)
{
for(;;) {
if (__builtin_expect(ethr_native_spin_trylock(lock) != 0, 1))
break;
do {
__asm__ __volatile__("rep;nop" : "=m"(lock->lock) : : "memory");
} while (ethr_native_spin_is_locked(lock));
}
}
#endif /* ETHR_TRY_INLINE_FUNCS */
#endif /* ETHREAD_I386_SPINLOCK_H */
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