lib/libc/arch/hppa/gen/makecontext.c

   1 /*      $NetBSD: makecontext.c,v 1.6 2012/03/22 12:31:32 skrll Exp $    */
   2
   3 /*-
   4  * Copyright (c) 2001 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Klaus Klein.
   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: makecontext.c,v 1.6 2012/03/22 12:31:32 skrll Exp $");
  35 #endif
  36
  37 #include <inttypes.h>
  38 #include <stddef.h>
  39 #include <ucontext.h>
  40 #include "extern.h"
  41
  42 #include <stdarg.h>
  43
  44 #include <sys/types.h>
  45 #include <machine/frame.h>
  46
  47 void __resumecontext(void) __dead;
  48
  49 void
  50 makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
  51 {
  52         __greg_t *gr = ucp->uc_mcontext.__gregs;
  53         __greg_t *gp, rp, fp;
  54         register __greg_t dp __asm("r27");
  55         uintptr_t *sp;
  56         int i;
  57         va_list ap;
  58
  59         /* LINTED uintptr_t is safe */
  60         sp  = (uintptr_t *)ucp->uc_stack.ss_sp;
  61         /* LINTED uintptr_t is safe */
  62         sp += 16;                       /* standard frame */
  63         sp += (argc >= 4 ? argc : 4);   /* Make room for >=4 arguments. */
  64         sp  = (uintptr_t *)
  65               ((uintptr_t)(sp + 16) & ~0x3f);   /* Align on 64-byte boundary. */
  66
  67         /* Save away the registers that we'll need. */
  68         gr[_REG_SP] = (__greg_t)sp;
  69         rp = (__greg_t)__resumecontext;
  70         if (rp & 2) {
  71                 gp = (__greg_t *)(rp & ~3);
  72                 rp = gp[0];
  73                 sp[-8] = gp[1];
  74         }
  75         gr[_REG_RP] = rp;
  76         fp = (__greg_t)func;
  77         if (fp & 2) {
  78                 gp = (__greg_t *)(fp & ~3);
  79                 fp = gp[0];
  80                 gr[_REG_R19] = gp[1];
  81         }
  82         gr[_REG_PCOQH] = fp | HPPA_PC_PRIV_USER;
  83         gr[_REG_PCOQT] = (fp + 4) | HPPA_PC_PRIV_USER;
  84         /* LINTED dp is reg27, ref. above, so initialized */
  85         gr[_REG_DP] = dp;
  86
  87         /* Construct argument list. */
  88         va_start(ap, argc);
  89         /* Up to the first four arguments are passed in %arg0-3. */
  90         for (i = 0; i < argc && i < 4; i++) {
  91                 /* LINTED uintptr_t is safe */
  92                 gr[_REG_ARG0 - i] = va_arg(ap, uintptr_t);
  93         }
  94         /* Pass remaining arguments on the stack below the %arg0-3 gap. */
  95         for (; i < argc; i++) {
  96                 /* LINTED uintptr_t is safe */
  97                 sp[-9 - i] = va_arg(ap, uintptr_t);
  98         }
  99         va_end(ap);
 100 }