sysdeps/unix/sysv/linux/hppa/makecontext.c

   1 /* Create new context.
   2    Copyright (C) 2008, 2010 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Helge Deller <deller@gmx.de>, 2008.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <libintl.h>
  22 #include <stdarg.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <sysdep.h>
  26 #include <ucontext.h>
  27
  28 /* POSIX only supports integer arguments.  */
  29
  30 /* Stack must be 64-byte aligned at all times.  */
  31 #define STACK_ALIGN 64
  32 /* Size of frame marker in unsigned long words.  */
  33 #define FRAME_SIZE_UL 8
  34 /* Size of frame marker in bytes.  */
  35 #define FRAME_SIZE_BYTES (8 * sizeof(unsigned long))
  36 /* Size of X arguments in bytes.  */
  37 #define ARGS(x) (x * sizeof(unsigned long))
  38
  39 void
  40 __makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
  41 {
  42   unsigned long *sp, *osp;
  43   va_list ap;
  44   int i;
  45
  46   /* Create a 64-byte aligned frame to store args. Use ss_sp if
  47      it is available, otherwise be robust and use the currently
  48      saved stack pointer.  */
  49   if (ucp->uc_stack.ss_sp && ucp->uc_stack.ss_size)
  50     osp = (unsigned long *)ucp->uc_stack.ss_sp;
  51   else
  52     osp = (unsigned long *)ucp->uc_mcontext.sc_gr[30];
  53
  54   sp = (unsigned long *)((((unsigned long) osp)
  55                            + FRAME_SIZE_BYTES + ARGS(argc) + STACK_ALIGN)
  56                          & ~(STACK_ALIGN - 1));
  57
  58   /* Use new frame.  */
  59   ucp->uc_mcontext.sc_gr[30] = ((unsigned long) sp);
  60
  61   /* Finish frame setup.  */
  62   if (ucp->uc_link)
  63     {
  64       /* Returning to the next context and next frame.  */
  65       sp[-4/sizeof(unsigned long)] = ucp->uc_link->uc_mcontext.sc_gr[30];
  66       sp[-20/sizeof(unsigned long)] = ucp->uc_link->uc_mcontext.sc_gr[2];
  67     }
  68   else
  69     {
  70       /* This is the main context. No frame marker, and no return address.  */
  71       sp[-4/sizeof(unsigned long)] = 0x0;
  72       sp[-20/sizeof(unsigned long)] = 0x0;
  73     }
  74
  75   /* Store address to jump to.  */
  76   ucp->uc_mcontext.sc_gr[2] = (unsigned long) func;
  77
  78   /* Process arguments.  */
  79   va_start (ap, argc);
  80   for (i = 0; i < argc; ++i)
  81     {
  82       if (i < 4)
  83         {
  84           ucp->uc_mcontext.sc_gr[26-i] = va_arg (ap, int);
  85           continue;
  86         }
  87
  88       if ((i < 8) && (sizeof(unsigned long) == 8))
  89         {
  90           /* 64bit: r19-r22 are arg7-arg4.  */
  91           ucp->uc_mcontext.sc_gr[22+4-i] = va_arg (ap, int);
  92           continue;
  93         }
  94
  95       /* All other arguments go on the stack.  */
  96       sp[-1 * (FRAME_SIZE_UL + 1 + i)] = va_arg (ap, int);
  97     }
  98   va_end (ap);
  99 }
 100 weak_alias(__makecontext, makecontext)
 101