7752bcb234
__libc_shared_globals() is available in dynamic modules as soon as relocation has finished (i.e. after ifuncs run). Before ifuncs have run, the android_set_abort_message() function already doesn't work because it calls public APIs via the PLT. (If this matters, we can use a static bool variable to enable android_set_abort_message after libc initialization). __libc_shared_globals() is hidden, so it's available in the linker immediately (i.e. before relocation). TLS memory (e.g. errno) currently isn't accessible until after relocation, but a later patch fixes that. Bug: none Test: bionic unit tests Change-Id: Ied4433758ed2da9ee404c6158e319cf502d05a53
90 lines
3.5 KiB
C++
90 lines
3.5 KiB
C++
/*
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* Copyright (C) 2017 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 <android/set_abort_message.h>
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#include <pthread.h>
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#include <stdint.h>
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#include <stddef.h>
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#include <string.h>
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#include <sys/mman.h>
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#include "private/bionic_defs.h"
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#include "private/bionic_globals.h"
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#include "private/ScopedPthreadMutexLocker.h"
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struct abort_msg_t {
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size_t size;
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char msg[0];
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};
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static_assert(
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offsetof(abort_msg_t, msg) == sizeof(size_t),
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"The in-memory layout of abort_msg_t is not consistent with what libdebuggerd expects.");
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struct magic_abort_msg_t {
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uint64_t magic1;
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uint64_t magic2;
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abort_msg_t msg;
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};
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static_assert(offsetof(magic_abort_msg_t, msg) == 2 * sizeof(uint64_t),
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"The in-memory layout of magic_abort_msg_t is not consistent with what automated "
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"tools expect.");
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[[clang::optnone]]
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static void fill_abort_message_magic(magic_abort_msg_t* new_magic_abort_message) {
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// 128-bit magic for the abort message. Chosen by fair dice roll.
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// This function is intentionally deoptimized to avoid the magic to be present
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// in the final binary. This causes clang to only use instructions where parts
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// of the magic are encoded into immediate arguments for the instructions in
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// all supported architectures.
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new_magic_abort_message->magic1 = 0xb18e40886ac388f0ULL;
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new_magic_abort_message->magic2 = 0xc6dfba755a1de0b5ULL;
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}
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__BIONIC_WEAK_FOR_NATIVE_BRIDGE
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void android_set_abort_message(const char* msg) {
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ScopedPthreadMutexLocker locker(&__libc_shared_globals()->abort_msg_lock);
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if (__libc_shared_globals()->abort_msg != nullptr) {
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// We already have an abort message.
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// Assume that the first crash is the one most worth reporting.
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return;
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}
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size_t size = sizeof(magic_abort_msg_t) + strlen(msg) + 1;
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void* map = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
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if (map == MAP_FAILED) {
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return;
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}
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magic_abort_msg_t* new_magic_abort_message = reinterpret_cast<magic_abort_msg_t*>(map);
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fill_abort_message_magic(new_magic_abort_message);
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new_magic_abort_message->msg.size = size;
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strcpy(new_magic_abort_message->msg.msg, msg);
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__libc_shared_globals()->abort_msg = &new_magic_abort_message->msg;
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}
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