sysdeps/unix/sysv/linux/ia64/makecontext.c

   1 /* Copyright (C) 2001-2024 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <libintl.h>
  19 #include <stdarg.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <ucontext.h>
  23 #include <sys/rse.h>
  24 #include <link.h>
  25 #include <dl-fptr.h>
  26
  27
  28 #define PUSH(val)                               \
  29 do {                                            \
  30   if (ia64_rse_is_rnat_slot (rbs))              \
  31     *rbs++ = 0;                                 \
  32   *rbs++ = (val);                               \
  33 } while (0)
  34
  35
  36 /* This implementation can handle an ARGC value of at most 8 and
  37    values can be passed only in integer registers (r32-r39).  */
  38
  39 void
  40 __makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
  41 {
  42   mcontext_t *sc = &ucp->uc_mcontext;
  43   extern void __start_context (ucontext_t *link, long gp, ...);
  44   unsigned long stack_start, stack_end;
  45   va_list ap;
  46   unsigned long *rbs;
  47   int i;
  48
  49   stack_start = (long) sc->sc_stack.ss_sp;
  50   stack_end = (long) sc->sc_stack.ss_sp + sc->sc_stack.ss_size;
  51
  52   stack_start = (stack_start + 7) & -8;
  53   stack_end = stack_end & -16;
  54
  55   if (argc > 8)
  56     {
  57       fprintf (stderr, _("\
  58 makecontext: does not know how to handle more than 8 arguments\n"));
  59       exit (-1);
  60     }
  61
  62   /* set the entry point and global pointer: */
  63   sc->sc_br[0] = ELF_PTR_TO_FDESC (&__start_context)->ip;
  64   sc->sc_br[1] = ELF_PTR_TO_FDESC (func)->ip;
  65   sc->sc_gr[1] = ELF_PTR_TO_FDESC (func)->gp;
  66
  67   /* set up the call frame: */
  68   sc->sc_ar_pfs = ((sc->sc_ar_pfs & ~0x3fffffffffUL)
  69                    | (argc + 2) | ((argc + 2) << 7));
  70   rbs = (unsigned long *) stack_start;
  71   PUSH((long) ucp->uc_link);
  72   PUSH(ELF_PTR_TO_FDESC (&__start_context)->gp);
  73   va_start (ap, argc);
  74   for (i = 0; i < argc; ++i)
  75     PUSH(va_arg (ap, long));
  76   va_end (ap);
  77
  78   /* set the memory and register stack pointers: */
  79   sc->sc_ar_bsp = (long) rbs;
  80   sc->sc_gr[12] = stack_end - 16;
  81
  82   /* clear the NaT bits for r1 and r12: */
  83   sc->sc_nat &= ~((1 << 1) | (1 << 12));
  84   sc->sc_ar_rnat = 0;
  85 }
  86
  87 weak_alias (__makecontext, makecontext)