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2004-08-15 Roland McGrath <roland@redhat.com> [BZ #227] * sysdeps/unix/sysv/linux/kernel-features.h (__ASSUME_BRK_PAGE_ROUNDED): New macro. * sysdeps/unix/sysv/linux/dl-sysdep.c (frob_brk) [! __ASSUME_BRK_PAGE_ROUNDED]: Adjust the break up if it falls within the partial page after the dynamic linker's own data segment.
57 lines
2.2 KiB
C
57 lines
2.2 KiB
C
/* Dynamic linker system dependencies for Linux.
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Copyright (C) 1995, 1997, 2001, 2004 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, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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/* Linux needs some special initialization, but otherwise uses
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the generic dynamic linker system interface code. */
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#include <unistd.h>
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#include <ldsodefs.h>
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#include "kernel-features.h"
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#define DL_SYSDEP_INIT frob_brk ()
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static inline void
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frob_brk (void)
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{
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__brk (0); /* Initialize the break. */
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#if ! __ASSUME_BRK_PAGE_ROUNDED
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/* If the dynamic linker was executed as a program, then the break may
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start immediately after our data segment. However, dl-minimal.c has
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already stolen the remainder of the page for internal allocations.
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If we don't adjust the break location recorded by the kernel, the
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normal program startup will inquire, find the value at our &_end,
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and start allocating its own data there, clobbering dynamic linker
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data structures allocated there during startup.
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Later Linux kernels have changed this behavior so that the initial
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break value is rounded up to the page boundary before we start. */
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extern void *__curbrk attribute_hidden;
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extern void _end attribute_hidden;
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void *const endpage = (void *) 0 + (((__curbrk - (void *) 0)
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+ GLRO(dl_pagesize) - 1)
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& -GLRO(dl_pagesize));
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if (__builtin_expect (__curbrk >= &_end && __curbrk < endpage, 0))
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__brk (endpage);
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#endif
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}
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#include <sysdeps/generic/dl-sysdep.c>
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