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/*
* Copyright (C) 2017 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <android/set_abort_message.h>
#include <async_safe/log.h>
#include <bionic/set_abort_message_internal.h>
#include <bits/stdatomic.h>
#include <pthread.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#include "private/bionic_defs.h"
#include "private/bionic_globals.h"
#include "private/ScopedPthreadMutexLocker.h"
struct abort_msg_t {
size_t size;
char msg[0];
};
static_assert(
offsetof(abort_msg_t, msg) == sizeof(size_t),
"The in-memory layout of abort_msg_t is not consistent with what libdebuggerd expects.");
struct magic_abort_msg_t {
uint64_t magic1;
uint64_t magic2;
abort_msg_t msg;
};
static_assert(offsetof(magic_abort_msg_t, msg) == 2 * sizeof(uint64_t),
"The in-memory layout of magic_abort_msg_t is not consistent with what automated "
"tools expect.");
static _Atomic(crash_detail_t*) free_head = nullptr;
[[clang::optnone]]
static void fill_abort_message_magic(magic_abort_msg_t* new_magic_abort_message) {
// 128-bit magic for the abort message. Chosen by fair dice roll.
// This function is intentionally deoptimized to avoid the magic to be present
// in the final binary. This causes clang to only use instructions where parts
// of the magic are encoded into immediate arguments for the instructions in
// all supported architectures.
new_magic_abort_message->magic1 = 0xb18e40886ac388f0ULL;
new_magic_abort_message->magic2 = 0xc6dfba755a1de0b5ULL;
}
__BIONIC_WEAK_FOR_NATIVE_BRIDGE
void android_set_abort_message(const char* msg) {
ScopedPthreadMutexLocker locker(&__libc_shared_globals()->abort_msg_lock);
if (__libc_shared_globals()->abort_msg != nullptr) {
// We already have an abort message.
// Assume that the first crash is the one most worth reporting.
return;
}
if (msg == nullptr) {
msg = "(null)";
}
size_t size = sizeof(magic_abort_msg_t) + strlen(msg) + 1;
void* map = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
if (map == MAP_FAILED) {
return;
}
// Name the abort message mapping to make it easier for tools to find the
// mapping.
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, map, size, "abort message");
magic_abort_msg_t* new_magic_abort_message = reinterpret_cast<magic_abort_msg_t*>(map);
fill_abort_message_magic(new_magic_abort_message);
new_magic_abort_message->msg.size = size;
strcpy(new_magic_abort_message->msg.msg, msg);
__libc_shared_globals()->abort_msg = &new_magic_abort_message->msg;
}
__BIONIC_WEAK_FOR_NATIVE_BRIDGE
crash_detail_t* android_register_crash_detail(const void* name, size_t name_size, const void* data,
size_t data_size) {
auto populate_crash_detail = [&](crash_detail_t* result) {
result->name = reinterpret_cast<const char*>(name);
result->name_size = name_size;
result->data = reinterpret_cast<const char*>(data);
result->data_size = data_size;
};
// This is a atomic fast-path for RAII use-cases where the app keeps creating and deleting
// crash details for short periods of time to capture detailed scopes.
if (crash_detail_t* head = atomic_load(&free_head)) {
while (head != nullptr && !atomic_compare_exchange_strong(&free_head, &head, head->prev_free)) {
// intentionally left blank.
}
if (head) {
head->prev_free = nullptr;
populate_crash_detail(head);
return head;
}
}
ScopedPthreadMutexLocker locker(&__libc_shared_globals()->crash_detail_page_lock);
struct crash_detail_page_t* prev = nullptr;
struct crash_detail_page_t* page = __libc_shared_globals()->crash_detail_page;
if (page != nullptr && page->used == kNumCrashDetails) {
prev = page;
page = nullptr;
}
if (page == nullptr) {
size_t size = sizeof(crash_detail_page_t);
void* map = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
if (map == MAP_FAILED) {
async_safe_format_log(ANDROID_LOG_ERROR, "libc", "failed to allocate crash_detail_page: %m");
return nullptr;
}
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, map, size, "crash details");
page = reinterpret_cast<struct crash_detail_page_t*>(map);
page->prev = prev;
__libc_shared_globals()->crash_detail_page = page;
}
crash_detail_t* result = &page->crash_details[page->used];
populate_crash_detail(result);
page->used++;
return result;
}
__BIONIC_WEAK_FOR_NATIVE_BRIDGE
void android_unregister_crash_detail(crash_detail_t* crash_detail) {
if (crash_detail) {
if (crash_detail->prev_free) {
// removing already removed would mess up the free-list by creating a circle.
return;
}
crash_detail->data = nullptr;
crash_detail->name = nullptr;
crash_detail_t* prev = atomic_load(&free_head);
do {
crash_detail->prev_free = prev;
} while (!atomic_compare_exchange_strong(&free_head, &prev, crash_detail));
}
}
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