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