22a6a058c7
arm32 has two special APIs to find exidx exception handling info, dl_unwind_find_exidx and __gnu_Unwind_Find_exdix. The two functions have identical behavior and function prototypes. libgcc's arm32 unwinder calls __gnu_Unwind_Find_exdix, whereas LLVM's libunwind previously called __gnu_Unwind_Find_exdix, but switched to dl_unwind_find_exidx as a result of three patches (D30306, D30681, D39468). In Bionic, for dynamic linking, __gnu_Unwind_Find_exdix in libc.so calls dl_unwind_find_exidx in libdl.so. For static executables, though, __gnu_Unwind_Find_exdix in libc.a used the __exidx_* symbols, while dl_unwind_find_exidx in libdl.a(libdl_static.o) was a return-0 no-op. To fix the LLVM unwinder, replace the no-op dl_unwind_find_exidx in libdl.a with a real function in libc.a(exidx_static.o), and have the GNU function call the dl function for more consistency with dynamic linking. dl_iterate_phdr follows a similar pattern, where the function exists in libc.a and libdl.so (not libc.so or libdl.a). This change makes unwinding work with an updated libunwind_llvm on arm32, and it helps to allow unwinding in static executables without libdl.a. Bug: https://github.com/android/ndk/issues/1094 Bug: http://b/141485154 Test: NDK tests, bionic unit tests Change-Id: Ieeeb9b39a0e28544e21f9afe6fe51ef10d7c828c
43 lines
1.1 KiB
C++
43 lines
1.1 KiB
C++
/*
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* Copyright (C) 2007 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <dlfcn.h>
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#include <link.h>
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#include <stdlib.h>
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void* dlopen(const char* /*filename*/, int /*flag*/) {
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return nullptr;
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}
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char* dlerror() {
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return const_cast<char*>("libdl.a is a stub --- use libdl.so instead");
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}
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void* dlsym(void* /*handle*/, const char* /*symbol*/) {
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return nullptr;
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}
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void* dlvsym(void* /*handle*/, const char* /*symbol*/, const char* /*version*/) {
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return nullptr;
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}
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int dladdr(const void* /*addr*/, Dl_info* /*info*/) {
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return 0;
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}
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int dlclose(void* /*handle*/) {
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return -1;
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}
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