x86/mm: Add kerneldoc comments for pcommit_sfence()

		: [pax] "a" (p));

}

/**

 * pcommit_sfence() - persistent commit and fence

 *

 * The PCOMMIT instruction ensures that data that has been flushed from the

 * processor's cache hierarchy with CLWB, CLFLUSHOPT or CLFLUSH is accepted to

 * memory and is durable on the DIMM.  The primary use case for this is

 * persistent memory.

 *

 * This function shows how to properly use CLWB/CLFLUSHOPT/CLFLUSH and PCOMMIT

 * with appropriate fencing.

 *

 * Example:

 * void flush_and_commit_buffer(void *vaddr, unsigned int size)

 * {

 *         unsigned long clflush_mask = boot_cpu_data.x86_clflush_size - 1;

 *         void *vend = vaddr + size;

 *         void *p;

 *

 *         for (p = (void *)((unsigned long)vaddr & ~clflush_mask);

 *              p < vend; p += boot_cpu_data.x86_clflush_size)

 *                 clwb(p);

 *

 *         // SFENCE to order CLWB/CLFLUSHOPT/CLFLUSH cache flushes

 *         // MFENCE via mb() also works

 *         wmb();

 *

 *         // PCOMMIT and the required SFENCE for ordering

 *         pcommit_sfence();

 * }

 *

 * After this function completes the data pointed to by 'vaddr' has been

 * accepted to memory and will be durable if the 'vaddr' points to persistent

 * memory.

 *

 * PCOMMIT must always be ordered by an MFENCE or SFENCE, so to help simplify

 * things we include both the PCOMMIT and the required SFENCE in the

 * alternatives generated by pcommit_sfence().

 */

static inline void pcommit_sfence(void)

{

	alternative(ASM_NOP7,