diff options
Diffstat (limited to 'sysdeps/unix/sysv')
| -rw-r--r-- | sysdeps/unix/sysv/linux/x86/lowlevellock.h | 87 |
1 files changed, 0 insertions, 87 deletions
diff --git a/sysdeps/unix/sysv/linux/x86/lowlevellock.h b/sysdeps/unix/sysv/linux/x86/lowlevellock.h deleted file mode 100644 index 7205bcadfd..0000000000 --- a/sysdeps/unix/sysv/linux/x86/lowlevellock.h +++ /dev/null @@ -1,87 +0,0 @@ -/* Low-level lock implementation, x86 version. - Copyright (C) 2019-2021 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/>. */ - -#ifndef _X86_64_LOWLEVELLOCK_H -#define _X86_64_LOWLEVELLOCK_H 1 - -#ifndef __ASSEMBLER__ -#include <sysdeps/nptl/lowlevellock.h> -#include <single-thread.h> - -/* The lll_trylock, lll_lock, and lll_unlock implements a single-thread - optimization using the cmpxchgl instruction. It checks if the process - is single thread and avoid a more expensive atomic instruction. */ - -/* The single-thread optimization only works for libc itself, we need - atomicity for libpthread in case of shared futexes. */ -#if !IS_IN(libc) -# define is_single_thread 0 -#else -# define is_single_thread SINGLE_THREAD_P -#endif - -/* In the __lllc_as we simply return the value in %eax after the cmpxchg - instruction. In case the operation succeeded this value is zero. In case - the operation failed, the cmpxchg instruction has loaded the current value - of the memory work which is guaranteed to be nonzero. */ -static inline int -__attribute__ ((always_inline)) -__lll_cas_lock (int *futex) -{ - int ret; - asm volatile ("cmpxchgl %2, %1" - : "=a" (ret), "=m" (*futex) - : "r" (1), "m" (*futex), "0" (0) - : "memory"); - return ret; -} - -#undef lll_trylock -#define lll_trylock(lock) \ - ({ \ - int __ret; \ - if (is_single_thread) \ - __ret = __lll_cas_lock (&(lock)); \ - else \ - __ret = __lll_trylock (&(lock)); \ - __ret; \ - }) - -#undef lll_lock -#define lll_lock(lock, private) \ - ((void) \ - ({ \ - if (is_single_thread) \ - __lll_cas_lock (&(lock)); \ - else \ - __lll_lock (&(lock), private); \ - })) - -#undef lll_unlock -#define lll_unlock(lock, private) \ - ((void) \ - ({ \ - if (is_single_thread) \ - (lock)--; \ - else \ - __lll_unlock (&(lock), private); \ - })) - -#endif /* !__ASSEMBLER__ */ - -#endif /* lowlevellock.h */ |