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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_QSPINLOCK_PARAVIRT_H
#define __ASM_QSPINLOCK_PARAVIRT_H
#include <asm/ibt.h>
/*
* For x86-64, PV_CALLEE_SAVE_REGS_THUNK() saves and restores 8 64-bit
* registers. For i386, however, only 1 32-bit register needs to be saved
* and restored. So an optimized version of __pv_queued_spin_unlock() is
* hand-coded for 64-bit, but it isn't worthwhile to do it for 32-bit.
*/
#ifdef CONFIG_64BIT
__PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock_slowpath, ".spinlock.text");
#define __pv_queued_spin_unlock __pv_queued_spin_unlock
/*
* Optimized assembly version of __raw_callee_save___pv_queued_spin_unlock
* which combines the registers saving trunk and the body of the following
* C code. Note that it puts the code in the .spinlock.text section which
* is equivalent to adding __lockfunc in the C code:
*
* void __lockfunc __pv_queued_spin_unlock(struct qspinlock *lock)
* {
* u8 lockval = cmpxchg(&lock->locked, _Q_LOCKED_VAL, 0);
*
* if (likely(lockval == _Q_LOCKED_VAL))
* return;
* pv_queued_spin_unlock_slowpath(lock, lockval);
* }
*
* For x86-64,
* rdi = lock (first argument)
* rsi = lockval (second argument)
* rdx = internal variable (set to 0)
*/
#define PV_UNLOCK_ASM \
FRAME_BEGIN \
"push %rdx\n\t" \
"mov $0x1,%eax\n\t" \
"xor %edx,%edx\n\t" \
LOCK_PREFIX "cmpxchg %dl,(%rdi)\n\t" \
"cmp $0x1,%al\n\t" \
"jne .slowpath\n\t" \
"pop %rdx\n\t" \
FRAME_END \
ASM_RET \
".slowpath:\n\t" \
"push %rsi\n\t" \
"movzbl %al,%esi\n\t" \
"call __raw_callee_save___pv_queued_spin_unlock_slowpath\n\t" \
"pop %rsi\n\t" \
"pop %rdx\n\t" \
FRAME_END
DEFINE_PARAVIRT_ASM(__raw_callee_save___pv_queued_spin_unlock,
PV_UNLOCK_ASM, .spinlock.text);
#else /* CONFIG_64BIT */
extern void __lockfunc __pv_queued_spin_unlock(struct qspinlock *lock);
__PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_spin_unlock, ".spinlock.text");
#endif /* CONFIG_64BIT */
#endif
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