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/* Copyright (C) 2001-2023 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, see
<https://www.gnu.org/licenses/>. */
/* This file contains a bit of information about the stack allocation
of the processor. */
#ifndef _STACKINFO_H
#define _STACKINFO_H 1
#include <elf.h>
#ifdef __ILP32__
# define RSP_REG "esp"
#else
# define RSP_REG "rsp"
#endif
/* On x86_64 the stack grows down. */
#define _STACK_GROWS_DOWN 1
/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
* present, but it is presumed absent. */
#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
/* Access to the stack pointer. The macros are used in alloca_account
for which they need to act as barriers as well, hence the additional
(unnecessary) parameters. */
#define stackinfo_get_sp() \
({ register void * p__ __asm__(RSP_REG); \
asm volatile("" : "=r" (p__)); \
p__; })
#define stackinfo_sub_sp(ptr) \
({ ptrdiff_t d__; \
asm volatile ("sub %%" RSP_REG " , %0" : "=r" (d__) : "0" (ptr)); \
d__; })
#endif /* stackinfo.h */
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