49 lines
2.1 KiB
ArmAsm
49 lines
2.1 KiB
ArmAsm
/*
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* Copyright (C) 2018 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 <private/bionic_asm.h>
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// For arm32 and -mtp=soft, the compiler uses this function to read the thread
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// pointer for ELF TLS accesses. With -mtp=cp15, the compiler inlines the call
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// instead. GCC defaults to -mtp=auto, which inlines this function with
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// -march=armv7-a. Clang does not yet implement -mtp=auto, and instead defaults
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// to -mtp=soft.
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// - https://bugs.llvm.org/show_bug.cgi?id=38394.
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// - https://reviews.llvm.org/D34878?id=114573.
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//
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// This function must preserve every register except r0, ip, lr, and cpsr.
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//
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// See "Run-time ABI for the ARM Architecture"
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// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0043d/IHI0043D_rtabi.pdf
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//
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ENTRY(__aeabi_read_tp)
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// __get_tls()
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mrc p15, 0, r0, c13, c0, 3
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bx lr
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END(__aeabi_read_tp)
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