Subversion Repositories HelenOS-historic

.global memcpy

.global memcpy_from_uspace

.global memcpy_to_uspace

.global memcpy_from_uspace_failover_address

.global memcpy_to_uspace_failover_address

#define MEMCPY_DST	%rdi

#define MEMCPY_SRC	%rsi

#define MEMCPY_SIZE	%rdx

/**

 * Copy memory from/to userspace.

 *

 * This is almost conventional memcpy().

 * The difference is that there is a failover part

 * to where control is returned from a page fault if

 * the page fault occurs during copy_from_uspace()

 * or copy_to_uspace().

 *

 * @param MEMCPY_DST	Destination address.

 * @param MEMCPY_SRC	Source address.

 * @param MEMCPY_SIZE	Number of bytes to copy.

 *

 * @retrun MEMCPY_SRC on success, 0 on failure.

 */

memcpy:

memcpy_from_uspace:

memcpy_to_uspace:

	movq MEMCPY_SRC, %rax

	movq MEMCPY_SIZE, %rcx

	shrq $3, %rcx			/* size / 8 */

	rep movsq			/* copy as much as possible word by word */

	movq MEMCPY_SIZE, %rcx

	andq $7, %rcx			/* size % 8 */

	jz 0f

	rep movsb			/* copy the rest byte by byte */

0:

	ret				/* return MEMCPY_SRC, success */

memcpy_from_uspace_failover_address:

memcpy_to_uspace_failover_address:

	xorq %rax, %rax			/* return 0, failure */

	ret