clflush、clflushopt、clwb、pcommit、ntstore

clwb(addr);
sfence();
PCOMMIT();	// 已弃用？
sfence();
*addr = balabala;

#define mb() 	asm volatile("mfence":::"memory")

static void clflush_cache_range_opt(void *vaddr, unsigned int size)
{
	const unsigned long clflush_size = boot_cpu_data.x86_clflush_size;
	void *p = (void *)((unsigned long)vaddr & ~(clflush_size - 1));
	void *vend = vaddr + size;

	if (p >= vend)
		return;

	for (; p < vend; p += clflush_size)
		clflushopt(p);
}
/**
 * clflush_cache_range - flush a cache range with clflush
 * @vaddr:	virtual start address
 * @size:	number of bytes to flush
 *
 * CLFLUSHOPT is an unordered instruction which needs fencing with MFENCE or
 * SFENCE to avoid ordering issues.
 */
void clflush_cache_range(void *vaddr, unsigned int size)
{
	mb();
	clflush_cache_range_opt(vaddr, size);
	mb();
}
EXPORT_SYMBOL_GPL(clflush_cache_range);