50 lines
1.7 KiB
C
50 lines
1.7 KiB
C
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/* Copyright (C) 2001-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* This file contains a bit of information about the stack allocation
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of the processor. */
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#ifndef _STACKINFO_H
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#define _STACKINFO_H 1
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#include <elf.h>
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#ifdef __ILP32__
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# define RSP_REG "esp"
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#else
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# define RSP_REG "rsp"
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#endif
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/* On x86_64 the stack grows down. */
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#define _STACK_GROWS_DOWN 1
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/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
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* present, but it is presumed absent. */
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#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
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/* Access to the stack pointer. The macros are used in alloca_account
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for which they need to act as barriers as well, hence the additional
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(unnecessary) parameters. */
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#define stackinfo_get_sp() \
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({ void *p__; asm volatile ("mov %%" RSP_REG ", %0" : "=r" (p__)); p__; })
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#define stackinfo_sub_sp(ptr) \
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({ ptrdiff_t d__; \
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asm volatile ("sub %%" RSP_REG " , %0" : "=r" (d__) : "0" (ptr)); \
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d__; })
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#endif /* stackinfo.h */
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