77 lines
2.9 KiB
C++
77 lines
2.9 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <errno.h>
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#include <stdint.h>
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#include <sys/mman.h>
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#include <unistd.h>
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#include "platform/bionic/macros.h"
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#include "private/ErrnoRestorer.h"
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// mmap2(2) is like mmap(2), but the offset is in 4096-byte blocks, not bytes.
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extern "C" void* __mmap2(void*, size_t, int, int, int, size_t);
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#define MMAP2_SHIFT 12 // 2**12 == 4096
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static bool kernel_has_MADV_MERGEABLE = true;
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void* mmap64(void* addr, size_t size, int prot, int flags, int fd, off64_t offset) {
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if (offset < 0 || (offset & ((1UL << MMAP2_SHIFT)-1)) != 0) {
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errno = EINVAL;
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return MAP_FAILED;
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}
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// prevent allocations large enough for `end - start` to overflow
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size_t rounded = __BIONIC_ALIGN(size, PAGE_SIZE);
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if (rounded < size || rounded > PTRDIFF_MAX) {
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errno = ENOMEM;
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return MAP_FAILED;
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}
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bool is_private_anonymous =
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(flags & (MAP_PRIVATE | MAP_ANONYMOUS)) == (MAP_PRIVATE | MAP_ANONYMOUS);
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bool is_stack_or_grows_down = (flags & (MAP_STACK | MAP_GROWSDOWN)) != 0;
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void* result = __mmap2(addr, size, prot, flags, fd, offset >> MMAP2_SHIFT);
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if (result != MAP_FAILED && kernel_has_MADV_MERGEABLE &&
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is_private_anonymous && !is_stack_or_grows_down) {
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ErrnoRestorer errno_restorer;
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int rc = madvise(result, size, MADV_MERGEABLE);
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if (rc == -1 && errno == EINVAL) {
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kernel_has_MADV_MERGEABLE = false;
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}
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}
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return result;
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}
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void* mmap(void* addr, size_t size, int prot, int flags, int fd, off_t offset) {
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return mmap64(addr, size, prot, flags, fd, static_cast<off64_t>(offset));
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}
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