sysdeps/x86_64/stackinfo.h

   1 /* Copyright (C) 2001, 2009, 2010 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 /* This file contains a bit of information about the stack allocation
  20    of the processor.  */
  21
  22 #ifndef _STACKINFO_H
  23 #define _STACKINFO_H    1
  24
  25 #include <elf.h>
  26
  27 /* On x86_64 the stack grows down.  */
  28 #define _STACK_GROWS_DOWN       1
  29
  30 /* Default to an executable stack.  PF_X can be overridden if PT_GNU_STACK is
  31  * present, but it is presumed absent.  */
  32 #define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
  33
  34 /* Access to the stack pointer.  The macros are used in alloca_account
  35    for which they need to act as barriers as well, hence the additional
  36    (unnecessary) parameters.  */
  37 #define stackinfo_get_sp() \
  38   ({ void *p__; asm volatile ("mov %%rsp, %0" : "=r" (p__)); p__; })
  39 #define stackinfo_sub_sp(ptr) \
  40   ({ ptrdiff_t d__;                                             \
  41      asm volatile ("sub %%rsp, %0" : "=r" (d__) : "0" (ptr));   \
  42      d__; })
  43
  44 #endif  /* stackinfo.h */