47d27aa79c
To take advantage of file-backed huge pages for the text segments of key shared libraries (go/android-hugepages), the dynamic linker must load candidate ELF files at an appropriately aligned address and mark executable segments with MADV_HUGEPAGE. This patches uses segments' p_align values to determine when a file is PMD aligned (2MB alignment), and performs load operations accordingly. Bug: 158135888 Test: Verified PMD aligned libraries are backed with huge pages on supporting kernel versions. Change-Id: Ia2367fd5652f663d50103e18f7695c59dc31c7b9
44 lines
1.8 KiB
C++
44 lines
1.8 KiB
C++
/*
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* Copyright (C) 2021 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 <string>
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#include <android-base/file.h>
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#include "linker.h"
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bool get_transparent_hugepages_supported() {
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static bool transparent_hugepages_supported = []() {
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std::string enabled;
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if (!android::base::ReadFileToString("/sys/kernel/mm/transparent_hugepage/enabled", &enabled)) {
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return false;
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}
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return enabled.find("[never]") == std::string::npos;
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};
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return transparent_hugepages_supported;
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}
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