f787e138aa
This implements mmap fallback for a brk failure during TLS allocation. scripts/tls-elf-edit.py is updated to support the new patching method. The script no longer requires that in the input object is of ET_DYN type. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
83 lines
2.4 KiB
C
83 lines
2.4 KiB
C
/* Early memory allocation for the dynamic loader. Generic version.
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Copyright (C) 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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/* Mark symbols hidden in static PIE for early self relocation to work. */
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#if BUILD_PIE_DEFAULT
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# pragma GCC visibility push(hidden)
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#endif
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#include <startup.h>
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#include <ldsodefs.h>
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#include <stddef.h>
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#include <string.h>
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#include <sysdep.h>
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#include <unistd.h>
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#include <brk_call.h>
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#include <mmap_call.h>
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/* Defined in brk.c. */
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extern void *__curbrk;
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void *
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_dl_early_allocate (size_t size)
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{
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void *result;
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if (__curbrk != NULL)
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/* If the break has been initialized, brk must have run before,
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so just call it once more. */
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{
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result = __sbrk (size);
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if (result == (void *) -1)
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result = NULL;
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}
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else
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{
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/* If brk has not been invoked, there is no need to update
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__curbrk. The first call to brk will take care of that. */
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void *previous = __brk_call (0);
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result = __brk_call (previous + size);
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if (result == previous)
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result = NULL;
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else
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result = previous;
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}
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/* If brk fails, fall back to mmap. This can happen due to
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unfortunate ASLR layout decisions and kernel bugs, particularly
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for static PIE. */
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if (result == NULL)
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{
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long int ret;
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int prot = PROT_READ | PROT_WRITE;
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int flags = MAP_PRIVATE | MAP_ANONYMOUS;
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#ifdef __NR_mmap2
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ret = MMAP_CALL_INTERNAL (mmap2, 0, size, prot, flags, -1, 0);
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#else
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ret = MMAP_CALL_INTERNAL (mmap, 0, size, prot, flags, -1, 0);
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#endif
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if (INTERNAL_SYSCALL_ERROR_P (ret))
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result = NULL;
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else
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result = (void *) ret;
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}
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return result;
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}
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