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      1 /*	$NetBSD: pthread_md.h,v 1.13 2023/05/25 14:30:03 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2001, 2007, 2008 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Nathan J. Williams.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  *
     31  * Adapted for x86_64 by fvdl (at) NetBSD.org
     32  */
     33 
     34 #ifndef _LIB_PTHREAD_X86_64_MD_H
     35 #define _LIB_PTHREAD_X86_64_MD_H
     36 
     37 #include <sys/ucontext.h>
     38 
     39 static inline unsigned long
     40 pthread__sp(void)
     41 {
     42 	unsigned long ret;
     43 	__asm("movq %%rsp, %0" : "=g" (ret));
     44 
     45 	return ret;
     46 }
     47 
     48 #define pthread__uc_sp(ucp) ((ucp)->uc_mcontext.__gregs[_REG_URSP])
     49 
     50 /*
     51  * Set initial, sane values for registers whose values aren't just
     52  * "don't care".
     53  * 0x23 is GSEL(GUDATA_SEL, SEL_UPL), and
     54  * 0x1b is GSEL(GUCODE_SEL, SEL_UPL).
     55  * 0x202 is PSL_USERSET.
     56  */
     57 #define _INITCONTEXT_U_MD(ucp)						\
     58 	(ucp)->uc_mcontext.__gregs[_REG_GS] = 0x23,			\
     59 	(ucp)->uc_mcontext.__gregs[_REG_FS] = 0x23,			\
     60 	(ucp)->uc_mcontext.__gregs[_REG_ES] = 0x23,			\
     61 	(ucp)->uc_mcontext.__gregs[_REG_DS] = 0x23,			\
     62 	(ucp)->uc_mcontext.__gregs[_REG_CS] = 0x1b,			\
     63 	(ucp)->uc_mcontext.__gregs[_REG_SS] = 0x23,			\
     64 	(ucp)->uc_mcontext.__gregs[_REG_RFL] = 0x202;
     65 
     66 #define	pthread__smt_pause()	__asm __volatile("rep; nop" ::: "memory")
     67 #define	pthread__smt_wait()	__asm __volatile("rep; nop" ::: "memory")
     68 
     69 /* Don't need additional memory barriers. */
     70 #define	PTHREAD__ATOMIC_IS_MEMBAR
     71 
     72 static inline void *
     73 _atomic_cas_ptr(volatile void *ptr, void *old, void *new)
     74 {
     75 	volatile uintptr_t *cast = ptr;
     76 	void *ret;
     77 
     78 	__asm __volatile ("lock; cmpxchgq %2, %1"
     79 		: "=a" (ret), "=m" (*cast)
     80 		: "r" (new), "m" (*cast), "0" (old));
     81 
     82 	return ret;
     83 }
     84 
     85 static inline void *
     86 _atomic_cas_ptr_ni(volatile void *ptr, void *old, void *new)
     87 {
     88 	volatile uintptr_t *cast = ptr;
     89 	void *ret;
     90 
     91 	__asm __volatile ("cmpxchgq %2, %1"
     92 		: "=a" (ret), "=m" (*cast)
     93 		: "r" (new), "m" (*cast), "0" (old));
     94 
     95 	return ret;
     96 }
     97 
     98 #endif /* _LIB_PTHREAD_X86_64_MD_H */
     99