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/* Atomic operations. PowerPC64 version.
Copyright (C) 2003-2025 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/>. */
/* 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 1
#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) load.
In powerpc64 register values are 64-bit by default, including oldval.
The value in old val unknown sign extension, lwarx loads the 32-bit
value as unsigned. So we explicitly clear the high 32 bits in oldval. */
#define __arch_compare_and_exchange_bool_32_acq(mem, newval, oldval) \
({ \
unsigned int __tmp, __tmp2; \
__asm __volatile (" clrldi %1,%1,32\n" \
"1: lwarx %0,0,%2" MUTEX_HINT_ACQ "\n" \
" subf. %0,%1,%0\n" \
" bne 2f\n" \
" stwcx. %4,0,%2\n" \
" bne- 1b\n" \
"2: " __ARCH_ACQ_INSTR \
: "=&r" (__tmp), "=r" (__tmp2) \
: "b" (mem), "1" (oldval), "r" (newval) \
: "cr0", "memory"); \
__tmp != 0; \
})
/*
* Only powerpc64 processors support Load doubleword and reserve index (ldarx)
* and Store doubleword conditional indexed (stdcx) instructions. So here
* we define the 64-bit forms.
*/
#define __arch_compare_and_exchange_bool_64_acq(mem, newval, oldval) \
({ \
unsigned long __tmp; \
__asm __volatile ( \
"1: ldarx %0,0,%1" MUTEX_HINT_ACQ "\n" \
" subf. %0,%2,%0\n" \
" bne 2f\n" \
" stdcx. %3,0,%1\n" \
" bne- 1b\n" \
"2: " __ARCH_ACQ_INSTR \
: "=&r" (__tmp) \
: "b" (mem), "r" (oldval), "r" (newval) \
: "cr0", "memory"); \
__tmp != 0; \
})
#define __arch_compare_and_exchange_val_64_acq(mem, newval, oldval) \
({ \
__typeof (*(mem)) __tmp; \
__typeof (mem) __memp = (mem); \
__asm __volatile ( \
"1: ldarx %0,0,%1" MUTEX_HINT_ACQ "\n" \
" cmpd %0,%2\n" \
" bne 2f\n" \
" stdcx. %3,0,%1\n" \
" bne- 1b\n" \
"2: " __ARCH_ACQ_INSTR \
: "=&r" (__tmp) \
: "b" (__memp), "r" (oldval), "r" (newval) \
: "cr0", "memory"); \
__tmp; \
})
#define __arch_compare_and_exchange_val_64_rel(mem, newval, oldval) \
({ \
__typeof (*(mem)) __tmp; \
__typeof (mem) __memp = (mem); \
__asm __volatile (__ARCH_REL_INSTR "\n" \
"1: ldarx %0,0,%1" MUTEX_HINT_REL "\n" \
" cmpd %0,%2\n" \
" bne 2f\n" \
" stdcx. %3,0,%1\n" \
" bne- 1b\n" \
"2: " \
: "=&r" (__tmp) \
: "b" (__memp), "r" (oldval), "r" (newval) \
: "cr0", "memory"); \
__tmp; \
})
#define __arch_atomic_exchange_64_acq(mem, value) \
({ \
__typeof (*mem) __val; \
__asm __volatile (__ARCH_REL_INSTR "\n" \
"1: ldarx %0,0,%2" MUTEX_HINT_ACQ "\n" \
" stdcx. %3,0,%2\n" \
" bne- 1b\n" \
" " __ARCH_ACQ_INSTR \
: "=&r" (__val), "=m" (*mem) \
: "b" (mem), "r" (value), "m" (*mem) \
: "cr0", "memory"); \
__val; \
})
#define __arch_atomic_exchange_64_rel(mem, value) \
({ \
__typeof (*mem) __val; \
__asm __volatile (__ARCH_REL_INSTR "\n" \
"1: ldarx %0,0,%2" MUTEX_HINT_REL "\n" \
" stdcx. %3,0,%2\n" \
" bne- 1b" \
: "=&r" (__val), "=m" (*mem) \
: "b" (mem), "r" (value), "m" (*mem) \
: "cr0", "memory"); \
__val; \
})
#define __arch_atomic_exchange_and_add_64(mem, value) \
({ \
__typeof (*mem) __val, __tmp; \
__asm __volatile ("1: ldarx %0,0,%3\n" \
" add %1,%0,%4\n" \
" stdcx. %1,0,%3\n" \
" bne- 1b" \
: "=&b" (__val), "=&r" (__tmp), "=m" (*mem) \
: "b" (mem), "r" (value), "m" (*mem) \
: "cr0", "memory"); \
__val; \
})
#define __arch_atomic_exchange_and_add_64_acq(mem, value) \
({ \
__typeof (*mem) __val, __tmp; \
__asm __volatile ("1: ldarx %0,0,%3" MUTEX_HINT_ACQ "\n" \
" add %1,%0,%4\n" \
" stdcx. %1,0,%3\n" \
" bne- 1b\n" \
__ARCH_ACQ_INSTR \
: "=&b" (__val), "=&r" (__tmp), "=m" (*mem) \
: "b" (mem), "r" (value), "m" (*mem) \
: "cr0", "memory"); \
__val; \
})
#define __arch_atomic_exchange_and_add_64_rel(mem, value) \
({ \
__typeof (*mem) __val, __tmp; \
__asm __volatile (__ARCH_REL_INSTR "\n" \
"1: ldarx %0,0,%3" MUTEX_HINT_REL "\n" \
" add %1,%0,%4\n" \
" stdcx. %1,0,%3\n" \
" bne- 1b" \
: "=&b" (__val), "=&r" (__tmp), "=m" (*mem) \
: "b" (mem), "r" (value), "m" (*mem) \
: "cr0", "memory"); \
__val; \
})
#define __arch_atomic_increment_val_64(mem) \
({ \
__typeof (*(mem)) __val; \
__asm __volatile ("1: ldarx %0,0,%2\n" \
" addi %0,%0,1\n" \
" stdcx. %0,0,%2\n" \
" bne- 1b" \
: "=&b" (__val), "=m" (*mem) \
: "b" (mem), "m" (*mem) \
: "cr0", "memory"); \
__val; \
})
#define __arch_atomic_decrement_val_64(mem) \
({ \
__typeof (*(mem)) __val; \
__asm __volatile ("1: ldarx %0,0,%2\n" \
" subi %0,%0,1\n" \
" stdcx. %0,0,%2\n" \
" bne- 1b" \
: "=&b" (__val), "=m" (*mem) \
: "b" (mem), "m" (*mem) \
: "cr0", "memory"); \
__val; \
})
#define __arch_atomic_decrement_if_positive_64(mem) \
({ int __val, __tmp; \
__asm __volatile ("1: ldarx %0,0,%3\n" \
" cmpdi 0,%0,0\n" \
" addi %1,%0,-1\n" \
" ble 2f\n" \
" stdcx. %1,0,%3\n" \
" bne- 1b\n" \
"2: " __ARCH_ACQ_INSTR \
: "=&b" (__val), "=&r" (__tmp), "=m" (*mem) \
: "b" (mem), "m" (*mem) \
: "cr0", "memory"); \
__val; \
})
/*
* All powerpc64 processors support the new "light weight" sync (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")
/*
* 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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