lib/libc/arch/vax/gen/_lwp.c

   1 /*      $NetBSD: _lwp.c,v 1.3 2012/03/22 17:32:22 christos 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 1.3 2012/03/22 17:32:22 christos 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 }