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/*
* Copyright (C) 2008 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 "libc_init_common.h"
#include "private/KernelArgumentBlock.h"
#include "private/bionic_arc4random.h"
#include "private/bionic_auxv.h"
#include "private/bionic_globals.h"
#include "private/bionic_ssp.h"
#include "pthread_internal.h"
extern "C" int __set_tls(void* ptr);
extern "C" int __set_tid_address(int* tid_address);
// Declared in "private/bionic_ssp.h".
uintptr_t __stack_chk_guard = 0;
void __libc_init_global_stack_chk_guard(KernelArgumentBlock& args) {
__libc_safe_arc4random_buf(&__stack_chk_guard, sizeof(__stack_chk_guard), args);
}
// Setup for the main thread. For dynamic executables, this is called by the
// linker _before_ libc is mapped in memory. This means that all writes to
// globals from this function will apply to linker-private copies and will not
// be visible from libc later on.
//
// Note: this function creates a pthread_internal_t for the initial thread and
// stores the pointer in TLS, but does not add it to pthread's thread list. This
// has to be done later from libc itself (see __libc_init_common).
//
// This is in a file by itself because it needs to be built with
// -fno-stack-protector because it's responsible for setting up the main
// thread's TLS (which stack protector relies on).
void __libc_init_main_thread(KernelArgumentBlock& args) {
__libc_auxv = args.auxv;
#if defined(__i386__)
__libc_init_sysinfo(args);
#endif
static pthread_internal_t main_thread;
// The -fstack-protector implementation uses TLS, so make sure that's
// set up before we call any function that might get a stack check inserted.
// TLS also needs to be set up before errno (and therefore syscalls) can be used.
__set_tls(main_thread.tls);
if (!__init_tls(&main_thread)) async_safe_fatal("failed to initialize TLS: %s", strerror(errno));
// Tell the kernel to clear our tid field when we exit, so we're like any other pthread.
// As a side-effect, this tells us our pid (which is the same as the main thread's tid).
main_thread.tid = __set_tid_address(&main_thread.tid);
main_thread.set_cached_pid(main_thread.tid);
// We don't want to free the main thread's stack even when the main thread exits
// because things like environment variables with global scope live on it.
// We also can't free the pthread_internal_t itself, since that lives on the main
// thread's stack rather than on the heap.
// The main thread has no mmap allocated space for stack or pthread_internal_t.
main_thread.mmap_size = 0;
pthread_attr_init(&main_thread.attr);
main_thread.attr.guard_size = 0; // The main thread has no guard page.
main_thread.attr.stack_size = 0; // User code should never see this; we'll compute it when asked.
// TODO: the main thread's sched_policy and sched_priority need to be queried.
// The TLS stack guard is set from the global, so ensure that we've initialized the global
// before we initialize the TLS. Dynamic executables will initialize their copy of the global
// stack protector from the one in the main thread's TLS.
__libc_init_global_stack_chk_guard(args);
__init_thread_stack_guard(&main_thread);
__init_thread(&main_thread);
// Store a pointer to the kernel argument block in a TLS slot to be
// picked up by the libc constructor.
main_thread.tls[TLS_SLOT_BIONIC_PREINIT] = &args;
__init_alternate_signal_stack(&main_thread);
}
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