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[glibc.git] / sysdeps / i386 / stackinfo.h
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1 /* Copyright (C) 1999-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
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.
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.
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/>. */
18 /* This file contains a bit of information about the stack allocation
19 of the processor. */
21 #ifndef _STACKINFO_H
22 #define _STACKINFO_H 1
24 #include <elf.h>
26 /* On x86 the stack grows down. */
27 #define _STACK_GROWS_DOWN 1
29 /* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
30 * present, but it is presumed absent. */
31 #define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
33 /* Access to the stack pointer. The macros are used in alloca_account
34 for which they need to act as barriers as well, hence the additional
35 (unnecessary) parameters. */
36 #define stackinfo_get_sp() \
37 ({ void *p__; asm volatile ("mov %%esp, %0" : "=r" (p__)); p__; })
38 #define stackinfo_sub_sp(ptr) \
39 ({ ptrdiff_t d__; \
40 asm volatile ("sub %%esp, %0" : "=r" (d__) : "0" (ptr)); \
41 d__; })
43 #endif /* stackinfo.h */