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

   1 /* Copyright (C) 2011 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <stdarg.h>
  20 #include <stdio.h>
  21 #include <stdint.h>
  22 #include <stdlib.h>
  23 #include <ucontext.h>
  24 #include <arch/abi.h>
  25
  26 void
  27 __makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
  28 {
  29   extern void __startcontext (void);
  30   uint_reg_t *sp, *args;
  31   va_list ap;
  32   int i;
  33
  34   /* Initialize the top of stack. */
  35   sp = (uint_reg_t *) ((((intptr_t) ucp->uc_stack.ss_sp
  36                          + ucp->uc_stack.ss_size) & -16L) - 16);
  37
  38   /* Allow room for memory-passed arguments if necessary. */
  39   if (argc > 10)
  40     sp -= 2 + (argc - 10);
  41
  42   sp[0] = sp[1] = 0;
  43
  44   /* Set parameters.  */
  45   va_start (ap, argc);
  46   args = &ucp->uc_mcontext.gregs[0];
  47   for (i = 0; i < argc; i++)
  48     {
  49       if (i == 10)
  50         args = &sp[2];
  51       *args++ = va_arg (ap, long);
  52     }
  53   va_end (ap);
  54
  55   /* Pass (*func) to __startcontext in pc.  */
  56   ucp->uc_mcontext.pc = (long) func;
  57
  58   /* Set stack pointer.  */
  59   ucp->uc_mcontext.sp = (long) sp;
  60
  61   /* Set the return address to trampoline.  */
  62   ucp->uc_mcontext.lr = (long) __startcontext;
  63
  64   /* Pass ucp->uc_link to __start_context in r30.  */
  65   ucp->uc_mcontext.gregs[30] = (long) ucp->uc_link;
  66 }
  67 weak_alias (__makecontext, makecontext)