/*

 * Portions Copyright 2008 VMware, Inc.

 */

/* include/asm-x86_64/rwlock.h

 *

 *	Helpers used by both rw spinlocks and rw semaphores.

 *

 *	Based in part on code from semaphore.h and

 *	spinlock.h Copyright 1996 Linus Torvalds.

 *

 *	Copyright 1999 Red Hat, Inc.

 *	Copyright 2001,2002 SuSE labs 

 *

 *	Written by Benjamin LaHaise.

 *

 *	This program is free software; you can redistribute it and/or

 *	modify it under the terms of the GNU General Public License

 *	as published by the Free Software Foundation; either version

 *	2 of the License, or (at your option) any later version.

 */

#ifndef _ASM_X86_64_RWLOCK_H

#define _ASM_X86_64_RWLOCK_H

#define RW_LOCK_BIAS		 0x01000000

#define RW_LOCK_BIAS_STR	 "0x01000000"

#if defined(__VMKLNX__)

#define __build_read_lock(rw)   \

	asm volatile(LOCK_PREFIX "subl $1,(%0)\n\t" \

                     "js 2f\n" \

                     "cmpb $0, vmk_AtomicUseFence(%%rip)\n" \

                     "jne 4f\n" \

                     "1:\n" \

                     LOCK_SECTION_START("") \

                     "2:\tcmpb $0, vmk_AtomicUseFence(%%rip)\n" \

                     "je 3f\n" \

                     "lfence\n" \

                     "3:\tcall __read_lock_failed\n\t" \

                     "jmp 1b\n" \

                     "4:\tlfence\n" \

                     "jmp 1b\n" \

                     LOCK_SECTION_END \

		     ::"D" (rw), "i" (RW_LOCK_BIAS) : "memory")

#define __build_write_lock(rw) \

	asm volatile(LOCK_PREFIX "subl %1,(%0)\n\t" \

		     "jnz 2f\n" \

                     "cmpb $0, vmk_AtomicUseFence(%%rip)\n" \

                     "jne 4f\n" \

                     "1:\n" \

                     LOCK_SECTION_START("") \

                     "2:\tcmpb $0, vmk_AtomicUseFence(%%rip)\n" \

                     "je 3f\n" \

                     "lfence\n" \

                     "3:\tcall __write_lock_failed\n\t" \

                     "jmp 1b\n" \

                     "4:\tlfence\n" \

                     "jmp 1b\n" \

                     LOCK_SECTION_END \

		     ::"D" (rw), "i" (RW_LOCK_BIAS) : "memory")

#else /* !defined(__VMKLNX__) */

#define __build_read_lock(rw)   \

	asm volatile(LOCK_PREFIX "subl $1,(%0)\n\t" \

		     "jns 1f\n" \

		     "call __read_lock_failed\n" \

		     "1:\n" \

		     ::"D" (rw), "i" (RW_LOCK_BIAS) : "memory")

#define __build_write_lock(rw) \

	asm volatile(LOCK_PREFIX "subl %1,(%0)\n\t" \

		     "jz 1f\n" \

		     "\tcall __write_lock_failed\n\t" \

		     "1:\n" \

		     ::"D" (rw), "i" (RW_LOCK_BIAS) : "memory")

#endif /* defined(__VMKLNX__) */

#endif