genode/base-fiasco/src/core/platform_pd.cc

/*
 * \brief   Fiasco protection domain facility
 * \author  Christian Helmuth
 * \date    2006-04-11
 *
 * On Fiasco, the pd class has several duties:
 *
 * - It is an allocator for L4 tasks and cares for versioning and recycling. We
 *   do this with "static class members".
 * - L4 threads are tied to L4 tasks and there are only 128 per L4 task. So
 *   each pd object is an allocator for its threads.
 */

/*
 * Copyright (C) 2006-2012 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 <base/native_types.h>

/* core includes */
#include <util.h>
#include <platform_pd.h>

/* Fiasco includes */
namespace Fiasco {
#include <l4/sys/syscalls.h>
}

using namespace Fiasco;
using namespace Genode;


static const bool verbose = false;


/**************************
 ** Static class members **
 **************************/

static bool _init = false;


void Platform_pd::init()
{
	if (_init) return;

	unsigned i;
	Pd_alloc reserved(true, true, 0);
	Pd_alloc free(false, true, 0);

	/* mark reserved protection domains */
	for (i = 0; i < PD_FIRST; ++i) _pds()[i] = reserved;
	/* init remainder */
	for ( ; i < PD_MAX; ++i) _pds()[i] = free;

	_init = true;
}


/****************************
 ** Private object members **
 ****************************/

void Platform_pd::_create_pd(bool syscall)
{
	l4_threadid_t l4t   = l4_myself();
	l4t.id.task         = _pd_id;
	l4t.id.lthread      = 0;
	l4t.id.version_low  = _version;

	l4_taskid_t nt;
	if (syscall)
		nt = l4_task_new(l4t, 0, 0, 0, l4t);
	else
		nt = l4t;

	if (l4_is_nil_id(nt))
		panic("pd creation failed");

	_l4_task_id = nt;
}


void Platform_pd::_destroy_pd()
{
	l4_threadid_t l4t = _l4_task_id;

	/* L4 task deletion is: make inactive with myself as chief in 2nd parameter */
	l4_taskid_t nt = l4_task_new(l4t, convert_native_thread_id_to_badge(l4_myself()),
	                             0, 0, L4_NIL_ID);

	if (l4_is_nil_id(nt))
		panic("pd destruction failed");

	_l4_task_id = L4_INVALID_ID;
}


int Platform_pd::_alloc_pd(signed pd_id)
{
	if (pd_id == PD_INVALID) {
		unsigned i;

		for (i = PD_FIRST; i < PD_MAX; i++)
			if (_pds()[i].free) break;

		/* no free protection domains available */
		if (i == PD_MAX) return -1;

		pd_id = i;
	} else {
		if (!_pds()[pd_id].reserved || !_pds()[pd_id].free)
			return -1;
	}

	_pds()[pd_id].free = 0;

	_pd_id   = pd_id;
	_version = _pds()[pd_id].version;

	return pd_id;
}


void Platform_pd::_free_pd()
{
	unsigned t = _pd_id;

	/* XXX check and log double-free? */
	if (_pds()[t].free) return;

	/* maximum reuse count reached leave non-free */
	if (_pds()[t].version == PD_VERSION_MAX) return;

	_pds()[t].free = 1;
	++_pds()[t].version;
}


void Platform_pd::_init_threads()
{
	unsigned i;

	for (i = 0; i < THREAD_MAX; ++i)
		_threads[i] = 0;
}


Platform_thread* Platform_pd::_next_thread()
{
	unsigned i;

	/* look for bound thread */
	for (i = 0; i < THREAD_MAX; ++i)
		if (_threads[i]) break;

	/* no bound threads */
	if (i == THREAD_MAX) return 0;

	return _threads[i];
}


int Platform_pd::_alloc_thread(int thread_id, Platform_thread *thread)
{
	int i = thread_id;

	/* look for free thread */
	if (thread_id == Platform_thread::THREAD_INVALID) {
		for (i = 0; i < THREAD_MAX; ++i)
			if (!_threads[i]) break;

		/* no free threads available */
		if (i == THREAD_MAX) return -1;
	} else {
		if (_threads[i]) return -2;
	}

	_threads[i] = thread;

	return i;
}


void Platform_pd::_free_thread(int thread_id)
{
	if (!_threads[thread_id])
		PWRN("double-free of thread %x.%x detected", _pd_id, thread_id);

	_threads[thread_id] = 0;
}


/***************************
 ** Public object members **
 ***************************/

int Platform_pd::bind_thread(Platform_thread *thread)
{
	/* thread_id is THREAD_INVALID by default - only core is the special case */
	int thread_id = thread->thread_id();
	l4_threadid_t l4_thread_id;

	int t = _alloc_thread(thread_id, thread);
	if (t < 0) {
		PERR("Thread alloc failed");
		return -1;
	}
	thread_id = t;

	l4_thread_id = _l4_task_id;
	l4_thread_id.id.lthread = thread_id;

	/* finally inform thread about binding */
	thread->bind(thread_id, l4_thread_id, this);

	if (verbose) _debug_log_threads();
	return 0;
}


void Platform_pd::unbind_thread(Platform_thread *thread)
{
	int thread_id = thread->thread_id();

	/* unbind thread before proceeding */
	thread->unbind();

	_free_thread(thread_id);

	if (verbose) _debug_log_threads();
}


Platform_pd::Platform_pd(signed pd_id, bool create)
{
	/* check correct init */
	if (!_init)
		panic("init pd facility via Platform_pd::init() before using it!");

	/* init threads */
	_init_threads();

	int ret = _alloc_pd(pd_id);
	if (ret < 0) {
		_debug_log_pds();
		panic("pd alloc failed");
	}

	_create_pd(create);
}


Platform_pd::~Platform_pd()
{
	/* unbind all threads */
	while (Platform_thread *t = _next_thread()) unbind_thread(t);

	_destroy_pd();
	_free_pd();
}


/***********************
 ** Debugging support **
 ***********************/

void Platform_pd::_debug_log_threads()
{
	int i;
	printf("[%02x] ", _pd_id);
	for (i = 0; i < THREAD_MAX; ++i) {
		printf("%c", !_threads[i] ? '.' : 'X');
		if (i == 63) printf("\n     ");
	}
	printf("\n");
}


void Platform_pd::_debug_log_pds()
{
	int i;
	for (i = 0; i < PD_MAX; ++i)
		printf("[%02x] %d %d %d\n", i, _pds()[i].reserved, _pds()[i].free,
		       _pds()[i].version);
}