42d949ff9d
Exactly which functions get a stack protector is up to the compiler, so let's separate the code that sets up the environment stack protection requires and explicitly build it with -fno-stack-protector. Bug: http://b/26276517 Change-Id: I8719e23ead1f1e81715c32c1335da868f68369b5
85 lines
3.8 KiB
C++
85 lines
3.8 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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#include "libc_init_common.h"
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#include "private/bionic_auxv.h"
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#include "private/bionic_globals.h"
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#include "private/KernelArgumentBlock.h"
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#include "pthread_internal.h"
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extern "C" int __set_tls(void* ptr);
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extern "C" int __set_tid_address(int* tid_address);
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// Setup for the main thread. For dynamic executables, this is called by the
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// linker _before_ libc is mapped in memory. This means that all writes to
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// globals from this function will apply to linker-private copies and will not
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// be visible from libc later on.
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//
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// Note: this function creates a pthread_internal_t for the initial thread and
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// stores the pointer in TLS, but does not add it to pthread's thread list. This
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// has to be done later from libc itself (see __libc_init_common).
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//
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// This is in a file by itself because it needs to be built with
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// -fno-stack-protector because it's responsible for setting up the main
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// thread's TLS (which stack protector relies on).
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void __libc_init_main_thread(KernelArgumentBlock& args) {
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__libc_auxv = args.auxv;
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static pthread_internal_t main_thread;
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// The -fstack-protector implementation uses TLS, so make sure that's
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// set up before we call any function that might get a stack check inserted.
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__set_tls(main_thread.tls);
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// Tell the kernel to clear our tid field when we exit, so we're like any other pthread.
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// As a side-effect, this tells us our pid (which is the same as the main thread's tid).
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main_thread.tid = __set_tid_address(&main_thread.tid);
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main_thread.set_cached_pid(main_thread.tid);
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// We don't want to free the main thread's stack even when the main thread exits
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// because things like environment variables with global scope live on it.
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// We also can't free the pthread_internal_t itself, since that lives on the main
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// thread's stack rather than on the heap.
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// The main thread has no mmap allocated space for stack or pthread_internal_t.
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main_thread.mmap_size = 0;
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pthread_attr_init(&main_thread.attr);
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main_thread.attr.guard_size = 0; // The main thread has no guard page.
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main_thread.attr.stack_size = 0; // User code should never see this; we'll compute it when asked.
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// TODO: the main thread's sched_policy and sched_priority need to be queried.
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__init_thread(&main_thread);
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__init_tls(&main_thread);
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// Store a pointer to the kernel argument block in a TLS slot to be
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// picked up by the libc constructor.
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main_thread.tls[TLS_SLOT_BIONIC_PREINIT] = &args;
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__init_alternate_signal_stack(&main_thread);
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}
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