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_lwp.c revision 1.7 
      1 /*	$NetBSD: _lwp.c,v 1.7 2012/03/17 20:48:58 martin Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2002 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 #if defined(LIBC_SCCS) && !defined(lint)
     31 __RCSID("$NetBSD: _lwp.c,v 1.7 2012/03/17 20:48:58 martin Exp $");
     32 #endif /* LIBC_SCCS and not lint */
     33 
     34 #include "namespace.h"
     35 #include <sys/types.h>
     36 #include <ucontext.h>
     37 #include <lwp.h>
     38 #include <stdlib.h>
     39 
     40 void
     41 _lwp_makecontext(ucontext_t *u, void (*start)(void *),
     42 		      void *arg, void *private,
     43 		      caddr_t stack_base, size_t stack_size)
     44 {
     45 	__greg_t *gr;
     46 	unsigned long *sp;
     47 
     48 	getcontext(u);
     49 	gr = u->uc_mcontext.__gregs;
     50 
     51 	u->uc_link = NULL;
     52 
     53 	u->uc_stack.ss_sp = stack_base;
     54 	u->uc_stack.ss_size = stack_size;
     55 
     56 	/*LINTED*/
     57 	sp = (ulong *)(stack_base + stack_size);
     58 	sp = (ulong *)((ulong)sp & ~0x0f);
     59 
     60 	sp -= 8 + 8 + 6;
     61 
     62 	sp[8]  = (ulong)arg;
     63 	sp[14] = (ulong)sp - 2047;
     64 	sp[15] = (ulong)_lwp_exit - 8;
     65 
     66 	/*LINTED*/
     67 	sp = (ulong *)((caddr_t)sp - 2047);
     68 
     69 	gr[_REG_PC] = (ulong) start;
     70 	gr[_REG_nPC] = (ulong) start + 4;
     71 
     72 	gr[_REG_O0] = (ulong) arg;
     73 	gr[_REG_O6] = (ulong) sp;
     74 	gr[_REG_O7] = (ulong)_lwp_exit - 8;
     75 	gr[_REG_G7] = (ulong)private;
     76 }
     77