89 lines
2.3 KiB
C++
89 lines
2.3 KiB
C++
/*
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* \brief Context-allocator implementation for the Genode Thread API
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* \author Norman Feske
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* \author Martin Stein
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* \date 2014-01-26
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*/
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/*
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* Copyright (C) 2010-2014 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 General Public License version 2.
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*/
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/* Genode includes */
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#include <base/thread.h>
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using namespace Genode;
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Thread_base::Context *Thread_base::Context_allocator::base_to_context(addr_t base)
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{
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addr_t result = base + Native_config::context_virtual_size()
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- sizeof(Context);
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return reinterpret_cast<Context *>(result);
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}
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addr_t Thread_base::Context_allocator::addr_to_base(void *addr)
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{
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return ((addr_t)addr) & ~(Native_config::context_virtual_size() - 1);
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}
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size_t Thread_base::Context_allocator::base_to_idx(addr_t base)
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{
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/* the first context isn't managed through the indices */
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return ((base - Native_config::context_area_virtual_base()) /
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Native_config::context_virtual_size()) - 1;
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}
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addr_t Thread_base::Context_allocator::idx_to_base(size_t idx)
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{
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/* the first context isn't managed through the indices */
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return Native_config::context_area_virtual_base() +
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(idx + 1) * Native_config::context_virtual_size();
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}
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Thread_base::Context *
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Thread_base::Context_allocator::alloc(Thread_base *thread_base, bool main_thread)
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{
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Lock::Guard _lock_guard(_threads_lock);
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try {
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addr_t base;
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if (main_thread) {
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/* the main-thread context isn't managed by '_alloc' */
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base = Native_config::context_area_virtual_base();
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} else {
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/* contexts besides main-thread context are managed by '_alloc' */
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base = idx_to_base(_alloc.alloc());
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}
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return base_to_context(base);
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} catch(Bit_allocator<MAX_THREADS>::Out_of_indices) {
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return 0;
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}
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}
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void Thread_base::Context_allocator::free(Context *context)
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{
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Lock::Guard _lock_guard(_threads_lock);
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addr_t const base = addr_to_base(context);
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/* the main-thread context isn't managed by '_alloc' */
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if (base == Native_config::context_area_virtual_base()) { return; }
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/* contexts besides main-thread context are managed by '_alloc' */
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_alloc.free(base_to_idx(base));
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}
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Thread_base::Context_allocator *Thread_base::_context_allocator()
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{
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static Context_allocator context_allocator_inst;
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return &context_allocator_inst;
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}
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