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_lwp.c revision 1.1.6.1 
      1 /*	$NetBSD: _lwp.c,v 1.1.6.1 2012/04/17 00:05:15 yamt Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2009 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Christos Zoulas
      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 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 __RCSID("$NetBSD: _lwp.c,v 1.1.6.1 2012/04/17 00:05:15 yamt Exp $");
     35 #endif /* LIBC_SCCS and not lint */
     36 
     37 #include "namespace.h"
     38 #include <sys/types.h>
     39 #include <inttypes.h>
     40 #include <ucontext.h>
     41 #include <lwp.h>
     42 #include <stdlib.h>
     43 
     44 void
     45 _lwp_makecontext(ucontext_t *u, void (*start)(void *),
     46     void *arg, void *private, caddr_t stack_base, size_t stack_size)
     47 {
     48 	__greg_t *gr = u->uc_mcontext.__gregs;
     49 	int *sp;
     50 
     51 	getcontext(u);
     52 	u->uc_link = NULL;
     53 
     54 	u->uc_stack.ss_sp = stack_base;
     55 	u->uc_stack.ss_size = stack_size;
     56 
     57 	/* Align to a word */
     58 	/* LINTED uintptr_t is safe */
     59 	sp = (int *)((uintptr_t)(stack_base + stack_size) & ~0x3);
     60 
     61 	/*
     62 	 * Allocate necessary stack space for arguments including arg count
     63 	 * and call frame
     64 	 */
     65 	sp -= 1 + 1 + 5;
     66 
     67 	sp[0] = 0;			/* condition handler is null */
     68 	sp[1] = 0x20000000;		/* make this a CALLS frame */
     69 	sp[2] = 0;			/* saved argument pointer */
     70 	sp[3] = 0;			/* saved frame pointer */
     71 	sp[4] = (int)(uintptr_t)_lwp_exit + 2;/* return via _lwp_exit */
     72 	sp[5] = 1;			/* argc */
     73 	sp[6] = (int)(uintptr_t)arg;		/* argv */
     74 
     75 	gr[_REG_AP] = (__greg_t)(uintptr_t)(sp + 5);
     76 	gr[_REG_SP] = (__greg_t)(uintptr_t)sp;
     77 	gr[_REG_FP] = (__greg_t)(uintptr_t)sp;
     78 	gr[_REG_PC] = (__greg_t)(uintptr_t)start + 2;
     79 
     80 	/*
     81 	 * Push the TLS pointer onto the new stack also.
     82 	 * The _UC_TLSBASE flag tells the kernel to pop it and use it.
     83 	 */
     84 	*--sp = (int)(intptr_t)private;
     85 	gr[_REG_SP] = (__greg_t)(uintptr_t)sp;
     86 	u->uc_flags |= _UC_TLSBASE;
     87 }
     88