/* Stack executability handling for GNU dynamic linker.  OpenSolaris version.
   Copyright (C) 2003, 2004, 2008 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <ldsodefs.h>
#include <errno.h>
#include <sys/ucontext.h>
#include <sys/syscall.h>

/* There is no portable way to know the bounds of the initial thread's stack
   so as to mprotect it.  */

int
internal_function
_dl_make_stack_executable (void **stack_endp)
{
  /* We can get the stack base and size from getcontext.  */
  sysret_t ret;
  ucontext_t ctx;
  int errval = __systemcall (&ret, SYS_context, GETCONTEXT, &ctx);
  if (errval != 0)
    return errval;

  /* The given stack pointer better be in range.  */
  if (*stack_endp < ctx.uc_stack.ss_sp ||
        *stack_endp > (ctx.uc_stack.ss_sp + ctx.uc_stack.ss_size))
    return ENOTSUP;

  errval = __systemcall (&ret, SYS_mprotect, ctx.uc_stack.ss_sp,
      ctx.uc_stack.ss_size, PROT_READ | PROT_WRITE | PROT_EXEC);
  if (errval != 0)
    return errval;

  *stack_endp = NULL;
  return 0;
}
rtld_hidden_def (_dl_make_stack_executable)