349 lines
9.8 KiB
C++
349 lines
9.8 KiB
C++
/*
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* \brief Virtual-memory space
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* \author Norman Feske
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* \date 2015-05-04
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*/
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/*
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* Copyright (C) 2015 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 _CORE__INCLUDE__VM_SPACE_H_
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#define _CORE__INCLUDE__VM_SPACE_H_
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/* Genode includes */
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#include <util/bit_allocator.h>
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#include <util/volatile_object.h>
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#include <base/thread.h>
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/* core includes */
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#include <page_table_registry.h>
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#include <cnode.h>
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#include <cap_sel_alloc.h>
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#include <core_cspace.h>
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#include <reentrant_lock.h>
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namespace Genode { class Vm_space; }
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class Genode::Vm_space
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{
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private:
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Cap_sel_alloc &_cap_sel_alloc;
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Page_table_registry &_page_table_registry;
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unsigned const _id;
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Cap_sel const _pd_sel;
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Range_allocator &_phys_alloc;
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enum {
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/**
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* Number of entries of 3rd-level VM CNode ('_vm_3rd_cnode')
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*/
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VM_3RD_CNODE_SIZE_LOG2 = 8,
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/**
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* Number of entries of each leaf CNodes
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*/
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LEAF_CNODE_SIZE_LOG2 = 8UL,
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LEAF_CNODE_SIZE = 1UL << LEAF_CNODE_SIZE_LOG2,
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/**
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* Number of leaf CNodes
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*/
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NUM_LEAF_CNODES_LOG2 = 4UL,
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NUM_LEAF_CNODES = 1UL << NUM_LEAF_CNODES_LOG2,
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/**
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* Maximum number of page tables and page frames for the VM space
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*/
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NUM_VM_SEL_LOG2 = LEAF_CNODE_SIZE_LOG2 + NUM_LEAF_CNODES_LOG2,
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/**
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* Number of entries of the VM padding CNode ('_vm_pad_cnode')
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*/
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VM_PAD_CNODE_SIZE_LOG2 = 32 - Core_cspace::NUM_TOP_SEL_LOG2
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- VM_3RD_CNODE_SIZE_LOG2 - LEAF_CNODE_SIZE_LOG2,
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};
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Cnode &_top_level_cnode;
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Cnode &_phys_cnode;
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/**
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* 2nd-level CNode for aligning '_vm_cnode' with the LSB of the CSpace
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*/
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Cnode _vm_pad_cnode;
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/**
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* 3rd-level CNode that hosts the leaf CNodes
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*/
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Cnode _vm_3rd_cnode;
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/***
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* 4th-level CNode for storing page-table and page-frame capabilities
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*/
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class Leaf_cnode
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{
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private:
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/*
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* We leave the CNode unconstructed at the time of its
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* instantiation to be able to create an array of 'Leaf_cnode'
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* objects (where we cannot pass any arguments to the
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* constructors of the individual objects).
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*/
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Lazy_volatile_object<Cnode> _cnode;
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public:
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void construct(Cap_sel_alloc &cap_sel_alloc,
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Cap_sel core_cnode_sel,
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Range_allocator &phys_alloc)
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{
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_cnode.construct(core_cnode_sel, cap_sel_alloc.alloc(),
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LEAF_CNODE_SIZE_LOG2, phys_alloc);
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}
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void destruct(Cap_sel_alloc &cap_sel_alloc)
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{
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cap_sel_alloc.free(_cnode->sel());
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}
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Cnode &cnode() { return *_cnode; }
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};
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Leaf_cnode _vm_cnodes[NUM_LEAF_CNODES];
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/**
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* Allocator for the selectors within '_vm_cnodes'
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*/
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Bit_allocator<1UL << NUM_VM_SEL_LOG2> _sel_alloc;
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/**
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* Return leaf CNode that contains an index allocated from '_sel_alloc'
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*/
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Cnode &_leaf_cnode(unsigned idx)
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{
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return _vm_cnodes[idx >> LEAF_CNODE_SIZE_LOG2].cnode();
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}
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/**
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* Return entry within leaf cnode
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*/
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Cnode_index _leaf_cnode_entry(unsigned idx) const
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{
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return Cnode_index(idx & (LEAF_CNODE_SIZE - 1));
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}
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/*
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* We have to use a reentrant lock here to account for the fact that
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* 'map_local' may be called recursively in some circumstances.
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*
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* For example, to zero-out physical memory pages, the '_clear_ds'
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* method needs to locally map the pages within core's local address
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* space by calling 'map_local'. The 'map_local' function populates
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* core's VM space and performs the required book keeping via the
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* page-table registry embedded within core's 'Vm_space' object.
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* Internally, the page-table registry maintains metadata via slab
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* allocators. In the corner case where a new slab block needs to be
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* allocated as a side effect of adding metadata for a new page or page
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* table, the slab allocator needs to make another physical memory
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* range visible within core, which eventually leads to a nested call
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* of 'map_local'.
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*/
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Reentrant_lock _lock;
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/**
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* Return selector for a capability slot within '_vm_cnodes'
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*/
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unsigned _idx_to_sel(unsigned idx) const { return (_id << 20) | idx; }
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void _map_page(addr_t from_phys, addr_t to_virt)
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{
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/* allocate page-table entry selector */
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unsigned pte_idx = _sel_alloc.alloc();
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/*
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* Copy page-frame selector to pte_sel
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*
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* This is needed because each page-frame selector can be
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* inserted into only a single page table.
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*/
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_leaf_cnode(pte_idx).copy(_phys_cnode,
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Cnode_index(from_phys >> get_page_size_log2()),
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Cnode_index(_leaf_cnode_entry(pte_idx)));
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/* remember relationship between pte_sel and the virtual address */
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_page_table_registry.insert_page_table_entry(to_virt, pte_idx);
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/*
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* Insert copy of page-frame selector into page table
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*/
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{
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seL4_IA32_Page const service = _idx_to_sel(pte_idx);
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seL4_IA32_PageDirectory const pd = _pd_sel.value();
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seL4_Word const vaddr = to_virt;
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seL4_CapRights const rights = seL4_AllRights;
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seL4_IA32_VMAttributes const attr = seL4_IA32_Default_VMAttributes;
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int const ret = seL4_IA32_Page_Map(service, pd, vaddr, rights, attr);
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if (ret != 0)
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PERR("seL4_IA32_Page_Map to 0x%lx returned %d",
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(unsigned long)vaddr, ret);
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}
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}
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void _unmap_page(addr_t virt)
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{
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/* delete copy of the mapping's page-frame selector */
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_page_table_registry.apply(virt, [&] (unsigned idx) {
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_leaf_cnode(idx).remove(_leaf_cnode_entry(idx));
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_sel_alloc.free(idx);
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});
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/* release meta data about the mapping */
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_page_table_registry.forget_page_table_entry(virt);
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}
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void _map_page_table(Cap_sel pt_sel, addr_t to_virt)
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{
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seL4_IA32_PageTable const service = pt_sel.value();
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seL4_IA32_PageDirectory const pd = _pd_sel.value();
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seL4_Word const vaddr = to_virt;
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seL4_IA32_VMAttributes const attr = seL4_IA32_Default_VMAttributes;
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PDBG("map page table 0x%lx to virt 0x%lx, pdir sel %lu",
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pt_sel.value(), to_virt, _pd_sel.value());
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int const ret = seL4_IA32_PageTable_Map(service, pd, vaddr, attr);
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if (ret != 0)
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PDBG("seL4_IA32_PageTable_Map returned %d", ret);
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}
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class Alloc_page_table_failed : Exception { };
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/**
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* Allocate and install page table at given virtual address
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*
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* \throw Alloc_page_table_failed
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*/
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void _alloc_and_map_page_table(addr_t to_virt)
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{
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/* allocate page-table selector */
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unsigned const pt_idx = _sel_alloc.alloc();
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/* XXX account the consumed backing store */
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try {
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create<Page_table_kobj>(_phys_alloc,
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_leaf_cnode(pt_idx).sel(),
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_leaf_cnode_entry(pt_idx));
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} catch (...) { throw Alloc_page_table_failed(); }
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Cap_sel const pt_sel(_idx_to_sel(pt_idx));
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_page_table_registry.insert_page_table(to_virt, pt_sel);
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_map_page_table(pt_sel, to_virt);
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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 pd_sel selector for page directory
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* \param cap_sel_alloc capability-selector allocator used for
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* VM CNodes
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* \param phys_alloc backing store for the CNodes
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* \param top_level_cnode top-level CNode to insert 'vm_pad_cnode_sel'
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* \param id ID used as index in 'top_level_cnode'
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* \param page_table_registry association of VM CNode selectors with
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* with virtual addresses
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*/
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Vm_space(Cap_sel pd_sel,
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Cap_sel_alloc &cap_sel_alloc,
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Range_allocator &phys_alloc,
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Cnode &top_level_cnode,
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Cnode &core_cnode,
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Cnode &phys_cnode,
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unsigned id,
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Page_table_registry &page_table_registry)
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:
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_cap_sel_alloc(cap_sel_alloc),
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_page_table_registry(page_table_registry),
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_id(id), _pd_sel(pd_sel),
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_phys_alloc(phys_alloc),
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_top_level_cnode(top_level_cnode),
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_phys_cnode(phys_cnode),
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_vm_pad_cnode(core_cnode.sel(),
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Cnode_index(_cap_sel_alloc.alloc().value()),
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VM_PAD_CNODE_SIZE_LOG2, phys_alloc),
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_vm_3rd_cnode(core_cnode.sel(),
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Cnode_index(_cap_sel_alloc.alloc().value()),
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VM_3RD_CNODE_SIZE_LOG2, phys_alloc)
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{
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Cnode_base const cspace(Cap_sel(seL4_CapInitThreadCNode), 32);
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for (unsigned i = 0; i < NUM_LEAF_CNODES; i++) {
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/* init leaf VM CNode */
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_vm_cnodes[i].construct(_cap_sel_alloc, core_cnode.sel(), phys_alloc);
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/* insert leaf VM CNode into 3nd-level VM CNode */
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_vm_3rd_cnode.copy(cspace, _vm_cnodes[i].cnode().sel(), Cnode_index(i));
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}
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/* insert 3rd-level VM CNode into 2nd-level VM-pad CNode */
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_vm_pad_cnode.copy(cspace, _vm_3rd_cnode.sel(), Cnode_index(0));
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/* insert 2nd-level VM-pad CNode into 1st-level CNode */
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_top_level_cnode.copy(cspace, _vm_pad_cnode.sel(), Cnode_index(id));
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}
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~Vm_space()
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{
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_cap_sel_alloc.free(_vm_pad_cnode.sel());
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_cap_sel_alloc.free(_vm_3rd_cnode.sel());
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for (unsigned i = 0; i < NUM_LEAF_CNODES; i++)
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_vm_cnodes[i].destruct(_cap_sel_alloc);
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}
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void map(addr_t from_phys, addr_t to_virt, size_t num_pages)
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{
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Reentrant_lock::Guard guard(_lock);
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/* check if we need to add a page table to core's VM space */
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if (!_page_table_registry.has_page_table_at(to_virt))
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_alloc_and_map_page_table(to_virt);
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for (size_t i = 0; i < num_pages; i++) {
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off_t const offset = i << get_page_size_log2();
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_map_page(from_phys + offset, to_virt + offset);
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}
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}
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void unmap(addr_t virt, size_t num_pages)
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{
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Reentrant_lock::Guard guard(_lock);
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for (size_t i = 0; i < num_pages; i++) {
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off_t const offset = i << get_page_size_log2();
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_unmap_page(virt + offset);
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}
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}
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};
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#endif /* _CORE__INCLUDE__VM_SPACE_H_ */
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