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/* Atomic operations. PowerPC32 version.
Copyright (C) 2003-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
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/>. */
/* POWER6 adds a "Mutex Hint" to the Load and Reserve instruction.
This is a hint to the hardware to expect additional updates adjacent
to the lock word or not. If we are acquiring a Mutex, the hint
should be true. Otherwise we releasing a Mutex or doing a simple
atomic operation. In that case we don't expect additional updates
adjacent to the lock word after the Store Conditional and the hint
should be false. */
#if defined _ARCH_PWR6 || defined _ARCH_PWR6X
# define MUTEX_HINT_ACQ ",1"
# define MUTEX_HINT_REL ",0"
#else
# define MUTEX_HINT_ACQ
# define MUTEX_HINT_REL
#endif
#define __HAVE_64B_ATOMICS 0
#define USE_ATOMIC_COMPILER_BUILTINS 0
#define ATOMIC_EXCHANGE_USES_CAS 1
/*
* The 32-bit exchange_bool is different on powerpc64 because the subf
* does signed 64-bit arithmetic while the lwarx is 32-bit unsigned
* (a load word and zero (high 32) form). So powerpc64 has a slightly
* different version in sysdeps/powerpc/powerpc64/atomic-machine.h.
*/
#define __arch_compare_and_exchange_bool_32_acq(mem, newval, oldval) \
({ \
unsigned int __tmp; \
__asm __volatile ( \
"1: lwarx %0,0,%1" MUTEX_HINT_ACQ "\n" \
" subf. %0,%2,%0\n" \
" bne 2f\n" \
" stwcx. %3,0,%1\n" \
" bne- 1b\n" \
"2: " __ARCH_ACQ_INSTR \
: "=&r" (__tmp) \
: "b" (mem), "r" (oldval), "r" (newval) \
: "cr0", "memory"); \
__tmp != 0; \
})
/* Powerpc32 processors don't implement the 64-bit (doubleword) forms of
load and reserve (ldarx) and store conditional (stdcx.) instructions.
So for powerpc32 we stub out the 64-bit forms. */
#define __arch_compare_and_exchange_bool_64_acq(mem, newval, oldval) \
(abort (), 0)
#define __arch_compare_and_exchange_val_64_acq(mem, newval, oldval) \
(abort (), (__typeof (*mem)) 0)
#define __arch_compare_and_exchange_val_64_rel(mem, newval, oldval) \
(abort (), (__typeof (*mem)) 0)
#define __arch_atomic_exchange_64_acq(mem, value) \
({ abort (); (*mem) = (value); })
#define __arch_atomic_exchange_64_rel(mem, value) \
({ abort (); (*mem) = (value); })
#define __arch_atomic_exchange_and_add_64(mem, value) \
({ abort (); (*mem) = (value); })
#define __arch_atomic_exchange_and_add_64_acq(mem, value) \
({ abort (); (*mem) = (value); })
#define __arch_atomic_exchange_and_add_64_rel(mem, value) \
({ abort (); (*mem) = (value); })
#define __arch_atomic_increment_val_64(mem) \
({ abort (); (*mem)++; })
#define __arch_atomic_decrement_val_64(mem) \
({ abort (); (*mem)--; })
#define __arch_atomic_decrement_if_positive_64(mem) \
({ abort (); (*mem)--; })
#ifdef _ARCH_PWR4
/*
* Newer powerpc64 processors support the new "light weight" sync (lwsync)
* So if the build is using -mcpu=[power4,power5,power5+,970] we can
* safely use lwsync.
*/
# define atomic_read_barrier() __asm ("lwsync" ::: "memory")
/*
* "light weight" sync can also be used for the release barrier.
*/
# define __ARCH_REL_INSTR "lwsync"
# define atomic_write_barrier() __asm ("lwsync" ::: "memory")
#else
/*
* Older powerpc32 processors don't support the new "light weight"
* sync (lwsync). So the only safe option is to use normal sync
* for all powerpc32 applications.
*/
# define atomic_read_barrier() __asm ("sync" ::: "memory")
# define atomic_write_barrier() __asm ("sync" ::: "memory")
#endif
/*
* Include the rest of the atomic ops macros which are common to both
* powerpc32 and powerpc64.
*/
#include_next <atomic-machine.h>
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