281 lines
6.8 KiB
C++
281 lines
6.8 KiB
C++
/*
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* \brief Kernel backend for protection domains
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* \author Martin Stein
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* \author Stefan Kalkowski
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* \date 2012-11-30
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*/
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/*
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* Copyright (C) 2012-2013 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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#ifndef _KERNEL__PD_H_
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#define _KERNEL__PD_H_
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/* Genode includes */
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#include <cpu/atomic.h>
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/* core includes */
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#include <kernel/configuration.h>
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#include <kernel/object.h>
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#include <kernel/processor.h>
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#include <translation_table.h>
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#include <assert.h>
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#include <page_slab.h>
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/* structure of the mode transition */
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extern int _mt_begin;
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extern int _mt_end;
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extern int _mt_user_entry_pic;
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extern int _mt_vm_entry_pic;
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extern Genode::addr_t _mt_client_context_ptr;
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extern Genode::addr_t _mt_master_context_begin;
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extern Genode::addr_t _mt_master_context_end;
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namespace Kernel
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{
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/**
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* Lock that enables synchronization inside the kernel
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*/
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class Lock;
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}
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class Kernel::Lock
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{
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private:
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int volatile _locked;
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/**
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* Finish all previously started memory transactions
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*/
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void _memory_barrier() { asm volatile ("" : : : "memory"); }
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public:
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Lock() : _locked(0) { }
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/**
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* Request the lock
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*/
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void lock() { while (!Genode::cmpxchg(&_locked, 0, 1)); }
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/**
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* Free the lock
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*/
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void unlock()
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{
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_memory_barrier();
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_locked = 0;
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}
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/**
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* Provide guard semantic for this type of lock
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*/
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typedef Genode::Lock_guard<Kernel::Lock> Guard;
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};
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namespace Kernel
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{
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/**
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* Controls the mode-transition page
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*
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* The mode transition page is a small memory region that is mapped by
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* every PD to the same virtual address. It contains code that acts as a
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* link between high privileged CPU mode (often called kernel) and low
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* privileged CPU mode (often called userland). The mode transition
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* control provides a simple interface to access the code from within
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* the kernel.
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*/
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struct Mode_transition_control;
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/**
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* Return the system wide mode-transition control
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*/
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Mode_transition_control * mtc();
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/**
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* Kernel backend of protection domains
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*/
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class Pd;
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class Pd_ids : public Id_allocator<MAX_PDS> { };
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typedef Object_pool<Pd> Pd_pool;
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Pd_ids * pd_ids();
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Pd_pool * pd_pool();
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Lock & data_lock();
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}
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class Kernel::Mode_transition_control
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{
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friend class Pd;
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private:
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typedef Genode::Cpu_state_modes Cpu_state_modes;
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typedef Genode::Page_flags Page_flags;
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addr_t const _virt_user_entry;
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/**
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* Continue execution of client context
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*
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* \param context targeted client processor-context
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* \param processor_id kernel name of targeted processor
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* \param entry_raw raw pointer to assembly entry-code
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*/
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void _continue_client(void * const context, unsigned const processor_id,
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addr_t const entry_raw)
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{
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/* override client-context pointer of the executing processor */
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addr_t const context_ptr_base = (addr_t)&_mt_client_context_ptr;
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size_t const context_ptr_offset = processor_id * sizeof(context);
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addr_t const context_ptr = context_ptr_base + context_ptr_offset;
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*(void * *)context_ptr = context;
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/* unlock kernel data */
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data_lock().unlock();
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/* call assembly code that applies the virtual-machine context */
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typedef void (* Entry)();
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Entry __attribute__((noreturn)) const entry = (Entry)entry_raw;
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entry();
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}
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public:
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enum {
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SIZE_LOG2 = Genode::Translation_table::MIN_PAGE_SIZE_LOG2,
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SIZE = 1 << SIZE_LOG2,
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VIRT_BASE = Processor::EXCEPTION_ENTRY,
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VIRT_END = VIRT_BASE + SIZE,
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ALIGNM_LOG2 = SIZE_LOG2,
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};
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/**
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* Constructor
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*
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* \param c CPU context for kernel mode entry
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*/
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Mode_transition_control(Processor::Context * const c)
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:
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_virt_user_entry(VIRT_BASE + ((addr_t)&_mt_user_entry_pic -
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(addr_t)&_mt_begin))
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{
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/* check if mode transition fits into aligned region */
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addr_t const mt_begin = (addr_t)&_mt_begin;
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addr_t const mt_end = (addr_t)&_mt_end;
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size_t const mt_size = mt_end - mt_begin;
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assert(mt_size <= SIZE);
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/* check if kernel context fits into the mode transition */
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addr_t const kc_begin = (addr_t)&_mt_master_context_begin;
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addr_t const kc_end = (addr_t)&_mt_master_context_end;
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size_t const kc_size = kc_end - kc_begin;
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assert(sizeof(Processor::Context) <= kc_size);
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/* fetch kernel-mode context */
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Genode::memcpy(&_mt_master_context_begin, c,
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sizeof(Processor::Context));
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}
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/**
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* Map the mode transition page to a virtual address space
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*
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* \param tt translation buffer of the address space
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* \param ram RAM donation for mapping (first try without)
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*/
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void map(Genode::Translation_table * tt,
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Genode::Page_slab * alloc)
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{
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try {
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addr_t const phys_base = (addr_t)&_mt_begin;
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tt->insert_translation(VIRT_BASE, phys_base, SIZE,
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Page_flags::mode_transition(), alloc);
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} catch(...) {
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PERR("Inserting exception vector in page table failed!"); }
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}
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/**
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* Continue execution of userland context
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*
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* \param context targeted userland context
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* \param processor_id kernel name of targeted processor
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*/
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void continue_user(Processor::Context * const context,
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unsigned const processor_id)
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{
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_continue_client(context, processor_id, _virt_user_entry);
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}
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/**
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* Continue execution of virtual machine
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*
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* \param context targeted virtual-machine context
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* \param processor_id kernel name of targeted processor
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*/
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void continue_vm(Cpu_state_modes * const context,
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unsigned const processor_id)
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{
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_continue_client(context, processor_id, _mt_vm_entry_pic);
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}
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};
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class Kernel::Pd : public Object<Pd, MAX_PDS, Pd_ids, pd_ids, pd_pool>
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{
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private:
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Genode::Translation_table * const _tt;
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Platform_pd * const _platform_pd;
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/* keep ready memory for size-aligned extra costs at construction */
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enum {
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EXTRA_RAM_SIZE = 2 * Genode::Translation_table::MAX_COSTS_PER_TRANSLATION
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};
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char _extra_ram[EXTRA_RAM_SIZE];
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public:
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/**
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* Constructor
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*
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* \param tt translation lookaside buffer of the PD
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* \param platform_pd core object of the PD
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*/
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Pd(Genode::Translation_table * const tt,
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Platform_pd * const platform_pd)
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: _tt(tt), _platform_pd(platform_pd) { }
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/**
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* Destructor
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*/
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~Pd() { }
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/**
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* Let the CPU context 'c' join the PD
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*/
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void admit(Processor::Context * const c)
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{
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c->protection_domain(id());
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c->translation_table((addr_t)translation_table());
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}
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/***************
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** Accessors **
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***************/
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Platform_pd * platform_pd() const { return _platform_pd; }
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Genode::Translation_table * translation_table() const {
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return _tt; }
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};
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#endif /* _KERNEL__PD_H_ */
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