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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/x86/lib/cmpxchg.c
10817 views
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/*

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 * cmpxchg*() fallbacks for CPU not supporting these instructions

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 */

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#include <linux/kernel.h>

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#include <linux/smp.h>

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#include <linux/module.h>

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#ifndef CONFIG_X86_CMPXCHG

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unsigned long cmpxchg_386_u8(volatile void *ptr, u8 old, u8 new)

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{

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	u8 prev;

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	unsigned long flags;

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	/* Poor man's cmpxchg for 386. Unsuitable for SMP */

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	local_irq_save(flags);

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	prev = *(u8 *)ptr;

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	if (prev == old)

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		*(u8 *)ptr = new;

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	local_irq_restore(flags);

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	return prev;

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}

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EXPORT_SYMBOL(cmpxchg_386_u8);

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unsigned long cmpxchg_386_u16(volatile void *ptr, u16 old, u16 new)

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{

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	u16 prev;

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	unsigned long flags;

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	/* Poor man's cmpxchg for 386. Unsuitable for SMP */

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	local_irq_save(flags);

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	prev = *(u16 *)ptr;

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	if (prev == old)

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		*(u16 *)ptr = new;

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	local_irq_restore(flags);

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	return prev;

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}

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EXPORT_SYMBOL(cmpxchg_386_u16);

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unsigned long cmpxchg_386_u32(volatile void *ptr, u32 old, u32 new)

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{

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	u32 prev;

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	unsigned long flags;

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	/* Poor man's cmpxchg for 386. Unsuitable for SMP */

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	local_irq_save(flags);

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	prev = *(u32 *)ptr;

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	if (prev == old)

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		*(u32 *)ptr = new;

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	local_irq_restore(flags);

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	return prev;

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}

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EXPORT_SYMBOL(cmpxchg_386_u32);

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#endif

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