170 lines
6.9 KiB
C
170 lines
6.9 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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/* This file contains dummy references to libgcc.a functions to force the
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* dynamic linker to copy their definition into the final libc.so binary.
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*
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* They are required to ensure backwards binary compatibility with
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* libc.so provided by the platform and binaries built with the NDK or
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* different versions/configurations of toolchains.
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*
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* Now, for a more elaborate description of the issue:
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*
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* libgcc.a is a compiler-specific library containing various helper
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* functions used to implement certain operations that are not necessarily
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* supported by the target CPU. For example, integer division doesn't have a
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* corresponding CPU instruction on ARMv5, and is instead implemented in the
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* compiler-generated machine code as a call to an __idiv helper function.
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*
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* Normally, one has to place libgcc.a in the link command used to generate
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* target binaries (shared libraries and executables) after all objects and
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* static libraries, but before dependent shared libraries, i.e. something
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* like:
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* gcc <options> -o libfoo.so foo.a libgcc.a -lc -lm
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*
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* This ensures that any helper function needed by the code in foo.a is copied
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* into the final libfoo.so. However, doing so will link a bunch of other __cxa
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* functions from libgcc.a into each .so and executable, causing 4k+ increase
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* in every binary. Therefore the Android platform build system has been
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* using this instead:
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*
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* gcc <options> -o libfoo.so foo.a -lc -lm libgcc.a
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*
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* The problem with this is that if one helper function needed by foo.a has
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* already been copied into libc.so or libm.so, then nothing will be copied
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* into libfoo.so. Instead, a symbol import definition will be added to it
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* so libfoo.so can directly call the one in libc.so at runtime.
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*
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* When refreshing toolchains for new versions or using different architecture
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* flags, the set of helper functions copied to libc.so may change, which
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* resulted in some native shared libraries generated with the NDK or prebuilts
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* from vendors to fail to load properly.
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*
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* The NDK has been fixed after 1.6_r1 to use the correct link command, so
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* any native shared library generated with it should now be safe from that
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* problem. On the other hand, existing shared libraries distributed with
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* applications that were generated with a previous version of the NDK
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* still need all 1.5/1.6 helper functions in libc.so and libm.so
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*
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* After 3.2, the toolchain was updated again, adding __aeabi_f2uiz to the
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* list of requirements. Technically, this is due to mis-linked NDK libraries
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* but it is easier to add a single function here than asking several app
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* developers to fix their build.
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*
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* The __aeabi_idiv function is added to the list since cortex-a15 supports
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* HW idiv instructions so the system libc.so doesn't pull in the reference to
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* __aeabi_idiv but legacy libraries built against cortex-a9 targets still need
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* it.
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*
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* Final note: some of the functions below should really be in libm.so to
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* completely reflect the state of 1.5/1.6 system images. However,
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* since libm.so depends on libc.so, it's easier to put all of
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* these in libc.so instead, since the dynamic linker will always
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* search in libc.so before libm.so for dependencies.
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*/
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#define COMPAT_FUNCTIONS_LIST \
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XX(__adddf3) \
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XX(__addsf3) \
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XX(__aeabi_cdcmpeq) \
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XX(__aeabi_cdcmple) \
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XX(__aeabi_cdrcmple) \
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XX(__aeabi_d2f) \
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XX(__aeabi_d2iz) \
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XX(__aeabi_dadd) \
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XX(__aeabi_dcmpeq) \
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XX(__aeabi_dcmpge) \
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XX(__aeabi_dcmpgt) \
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XX(__aeabi_dcmple) \
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XX(__aeabi_dcmplt) \
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XX(__aeabi_dcmpun) \
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XX(__aeabi_ddiv) \
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XX(__aeabi_dmul) \
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XX(__aeabi_drsub) \
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XX(__aeabi_dsub) \
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XX(__aeabi_f2d) \
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XX(__aeabi_f2iz) \
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XX(__aeabi_f2uiz) \
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XX(__aeabi_fadd) \
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XX(__aeabi_fcmpun) \
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XX(__aeabi_fdiv) \
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XX(__aeabi_fmul) \
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XX(__aeabi_frsub) \
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XX(__aeabi_fsub) \
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XX(__aeabi_i2d) \
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XX(__aeabi_i2f) \
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XX(__aeabi_idiv) \
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XX(__aeabi_l2d) \
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XX(__aeabi_l2f) \
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XX(__aeabi_lasr) \
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XX(__aeabi_lmul) \
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XX(__aeabi_llsl) \
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XX(__aeabi_llsr) \
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XX(__aeabi_ui2d) \
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XX(__aeabi_ui2f) \
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XX(__aeabi_ul2d) \
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XX(__aeabi_ul2f) \
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XX(__cmpdf2) \
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XX(__divdf3) \
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XX(__divsf3) \
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XX(__eqdf2) \
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XX(__extendsfdf2) \
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XX(__fixdfsi) \
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XX(__fixsfsi) \
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XX(__floatdidf) \
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XX(__floatdisf) \
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XX(__floatsidf) \
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XX(__floatsisf) \
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XX(__floatundidf) \
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XX(__floatundisf) \
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XX(__floatunsidf) \
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XX(__floatunsisf) \
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XX(__gedf2) \
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XX(__gtdf2) \
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XX(__ledf2) \
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XX(__ltdf2) \
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XX(__muldf3) \
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XX(__muldi3) \
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XX(__mulsf3) \
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XX(__nedf2) \
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XX(__subdf3) \
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XX(__subsf3) \
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XX(__truncdfsf2) \
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XX(__unorddf2) \
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XX(__unordsf2) \
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#define XX(f) extern void f(void);
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COMPAT_FUNCTIONS_LIST
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#undef XX
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void __bionic_libgcc_compat_hooks(void)
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{
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#define XX(f) f();
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COMPAT_FUNCTIONS_LIST
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#undef XX
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}
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