137 lines
3.3 KiB
C++
137 lines
3.3 KiB
C++
/*
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* \brief Setup the thread environment of a programs first thread
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* \author Christian Helmuth
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* \author Christian Prochaska
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* \author Martin Stein
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* \date 2013-12-04
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*/
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/*
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* Copyright (C) 2013-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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/* Genode includes */
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#include <util/construct_at.h>
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#include <base/env.h>
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#include <base/thread.h>
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#include <deprecated/env.h>
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/* base-internal includes */
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#include <base/internal/globals.h>
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using namespace Genode;
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addr_t init_main_thread_result;
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extern void init_exception_handling();
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namespace Genode { extern Region_map * env_stack_area_region_map; }
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void prepare_init_main_thread();
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enum { MAIN_THREAD_STACK_SIZE = 1024*sizeof(Genode::addr_t) };
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/**
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* Satisfy crt0.s in static programs, LDSO overrides this symbol
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*/
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extern "C" void init_rtld() __attribute__((weak));
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void init_rtld() { }
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/**
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* Lower bound of the stack, solely used for sanity checking
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*/
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extern unsigned char __initial_stack_base[];
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/**
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* The first thread in a program
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*/
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class Main_thread : public Thread_deprecated<MAIN_THREAD_STACK_SIZE>
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{
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public:
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/**
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* Constructor
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*
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* \param reinit wether this is called for reinitialization
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*/
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Main_thread(bool reinit)
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:
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Thread_deprecated("main", reinit ? REINITIALIZED_MAIN : MAIN)
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{ }
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/**********************
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** Thread interface **
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**********************/
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void entry() override { }
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};
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Main_thread * main_thread()
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{
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static Main_thread s(false);
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return &s;
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}
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/**
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* Create a thread object for the main thread
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*
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* \return stack pointer of the new environment via init_main_thread_result
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*
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* This function must be called only once per program and before the _main
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* function. It can be called as soon as a temporary environment provides
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* some stack space and inter-process communication. At this stage, global
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* static objects are not registered for implicit destruction at program exit.
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*/
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extern "C" void init_main_thread()
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{
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/* do platform specific preparation */
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prepare_init_main_thread();
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/*
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* Explicitly setup program environment at this point to ensure that its
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* destructor won't be registered for the atexit routine.
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*/
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(void*)env_deprecated();
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init_log(*env_deprecated()->parent());
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init_exit(*env_deprecated()->parent());
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/* create a thread object for the main thread */
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main_thread();
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/**
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* The new stack pointer enables the caller to switch from its current
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* environment to the those that the thread object provides.
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*/
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addr_t const sp = reinterpret_cast<addr_t>(main_thread()->stack_top());
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init_main_thread_result = sp;
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/*
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* Sanity check for the usage of the initial stack
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*
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* Because the initial stack is located in the BSS, it is zero-initialized.
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* We check that the stack still contains zeros at its lower boundary after
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* executing all the initialization code.
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*/
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enum { STACK_PAD = 256U };
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for (unsigned i = 0; i < STACK_PAD; i++) {
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if (__initial_stack_base[i] == 0)
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continue;
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error("initial stack overflow detected");
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for (;;);
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}
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}
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/**
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* Reinitialize main-thread object according to a reinitialized environment
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*/
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void reinit_main_thread() { construct_at<Main_thread>(main_thread(), true); }
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