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3b2b88ccee
This patch replaces _dl_stack_flags global variable by _dl_stack_prot_flags. The advantage is that any convertion from p_flags to final used mprotect flags occurs at loading of p_flags. It avoids repeated spurious convertions of _dl_stack_flags, for example in allocate_thread_stack. This modification was suggested in: https://sourceware.org/pipermail/libc-alpha/2025-March/165537.html Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
77 lines
2.6 KiB
C
77 lines
2.6 KiB
C
/* Details about the machine's stack: wrapper header.
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Copyright (C) 2014-2025 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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#ifndef _INCLUDE_STACKINFO_H
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#define _INCLUDE_STACKINFO_H 1
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/* A sysdeps/.../stackinfo.h file defines details for the CPU.
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It is obliged to define either _STACK_GROWS_DOWN or _STACK_GROWS_UP. */
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#include_next <stackinfo.h>
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#if defined _STACK_GROWS_DOWN && _STACK_GROWS_DOWN
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# ifdef _STACK_GROWS_UP
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# error "stackinfo.h should not define both!"
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# else
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# define _STACK_GROWS_UP 0
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# endif
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#elif defined _STACK_GROWS_UP && _STACK_GROWS_UP
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# ifdef _STACK_GROWS_DOWN
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# error "stackinfo.h should not define both!"
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# else
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# define _STACK_GROWS_DOWN 0
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# endif
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#else
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# error "stackinfo.h must define _STACK_GROWS_UP or _STACK_GROWS_DOWN!"
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#endif
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#include <sys/mman.h>
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#include <link.h>
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/* ELF uses the PF_x macros to specify the segment permissions, mmap
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uses PROT_xxx. In most cases the three macros have the values 1, 2,
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and 4 but not in a matching order. The following macros allows
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converting from the PF_x values to PROT_xxx values. */
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#define PF_TO_PROT \
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((PROT_READ << (PF_R * 4)) \
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| (PROT_WRITE << (PF_W * 4)) \
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| (PROT_EXEC << (PF_X * 4)) \
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| ((PROT_READ | PROT_WRITE) << ((PF_R | PF_W) * 4)) \
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| ((PROT_READ | PROT_EXEC) << ((PF_R | PF_X) * 4)) \
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| ((PROT_WRITE | PROT_EXEC) << (PF_W | PF_X) * 4) \
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| ((PROT_READ | PROT_WRITE | PROT_EXEC) << ((PF_R | PF_W | PF_X) * 4)))
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static inline int
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pf_to_prot (ElfW(Word) value)
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{
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#if (PF_R | PF_W | PF_X) == 7 && (PROT_READ | PROT_WRITE | PROT_EXEC) == 7
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return (PF_TO_PROT >> ((value & (PF_R | PF_W | PF_X)) * 4)) & 0xf;
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#else
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ElfW(Word) ret = 0;
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if (value & PF_R)
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ret |= PROT_READ;
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if (value & PF_W)
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ret |= PROT_WRITE;
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if (value & PF_X)
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ret |= PROT_EXEC;
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return ret;
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#endif
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}
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#endif /* include/stackinfo.h */
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