genode/repos/base/src/lib/startup/init_main_thread.cc
2016-11-08 15:26:32 +01:00

113 lines
2.6 KiB
C++

/*
* \brief Setup the thread environment of a programs first thread
* \author Christian Helmuth
* \author Christian Prochaska
* \author Martin Stein
* \date 2013-12-04
*/
/*
* Copyright (C) 2013 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
/* Genode includes */
#include <util/construct_at.h>
#include <base/env.h>
#include <base/thread.h>
/* base-internal includes */
#include <base/internal/globals.h>
using namespace Genode;
addr_t init_main_thread_result;
extern void init_exception_handling();
namespace Genode { extern Region_map * env_stack_area_region_map; }
void prepare_init_main_thread();
enum { MAIN_THREAD_STACK_SIZE = 16UL * 1024 * sizeof(Genode::addr_t) };
/**
* Satisfy crt0.s in static programs, LDSO overrides this symbol
*/
extern "C" void init_rtld() __attribute__((weak));
void init_rtld() { }
/**
* The first thread in a program
*/
class Main_thread : public Thread_deprecated<MAIN_THREAD_STACK_SIZE>
{
public:
/**
* Constructor
*
* \param reinit wether this is called for reinitialization
*/
Main_thread(bool reinit)
:
Thread_deprecated("main", reinit ? REINITIALIZED_MAIN : MAIN)
{ }
/**********************
** Thread interface **
**********************/
void entry() { }
};
Main_thread * main_thread()
{
static Main_thread s(false);
return &s;
}
/**
* Create a thread object for the main thread
*
* \return stack pointer of the new environment via init_main_thread_result
*
* This function must be called only once per program and before the _main
* function. It can be called as soon as a temporary environment provides
* some stack space and inter-process communication. At this stage, global
* static objects are not registered for implicit destruction at program exit.
*/
extern "C" void init_main_thread()
{
/* do platform specific preparation */
prepare_init_main_thread();
/*
* Explicitly setup program environment at this point to ensure that its
* destructor won't be registered for the atexit routine.
*/
(void*)env();
init_log();
/* create a thread object for the main thread */
main_thread();
/**
* The new stack pointer enables the caller to switch from its current
* environment to the those that the thread object provides.
*/
addr_t sp = reinterpret_cast<addr_t>(main_thread()->stack_top());
init_main_thread_result = sp;
}
/**
* Reinitialize main-thread object according to a reinitialized environment
*/
void reinit_main_thread() { construct_at<Main_thread>(main_thread(), true); }