9e6f3be806
This patch updates seL4 from the experimental branch of one year ago to the master branch of version 2.1. The transition has the following implications. In contrast to the experimental branch, the master branch has no way to manually define the allocation of kernel objects within untyped memory ranges. Instead, the kernel maintains a built-in allocation policy. This policy rules out the deallocation of once-used parts of untyped memory. The only way to reuse memory is to revoke the entire untyped memory range. Consequently, we cannot share a large untyped memory range for kernel objects of different protection domains. In order to reuse memory at a reasonably fine granularity, we need to split the initial untyped memory ranges into small chunks that can be individually revoked. Those chunks are called "untyped pages". An untyped page is a 4 KiB untyped memory region. The bootstrapping of core has to employ a two-stage allocation approach now. For creating the initial kernel objects for core, which remain static during the entire lifetime of the system, kernel objects are created directly out of the initial untyped memory regions as reported by the kernel. The so-called "initial untyped pool" keeps track of the consumption of those untyped memory ranges by mimicking the kernel's internal allocation policy. Kernel objects created this way can be of any size. For example the phys CNode, which is used to store page-frame capabilities is 16 MiB in size. Also, core's CSpace uses a relatively large CNode. After the initial setup phase, all remaining untyped memory is turned into untyped pages. From this point on, new created kernel objects cannot exceed 4 KiB in size because one kernel object cannot span multiple untyped memory regions. The capability selectors for untyped pages are organized similarly to those of page-frame capabilities. There is a new 2nd-level CNode (UNTYPED_CORE_CNODE) that is dimensioned according to the maximum amount of physical memory (1M entries, each entry representing 4 KiB). The CNode is organized such that an index into the CNode directly corresponds to the physical frame number of the underlying memory. This way, we can easily determine a untyped page selector for any physical addresses, i.e., for revoking the kernel objects allocated at a specific physical page. The downside is the need for another 16 MiB chunk of meta data. Also, we need to keep in mind that this approach won't scale to 64-bit systems. We will eventually need to replace the PHYS_CORE_CNODE and UNTYPED_CORE_CNODE by CNode hierarchies to model a sparsely populated CNode. The size constrain of kernel objects has the immediate implication that the VM CSpaces of protection domains must be organized via several levels of CNodes. I.e., as the top-level CNode of core has a size of 2^12, the remaining 20 PD-specific CSpace address bits are organized as a 2nd-level 2^4 padding CNode, a 3rd-level 2^8 CNode, and several 4th-level 2^8 leaf CNodes. The latter contain the actual selectors for the page tables and page-table entries of the respective PD. As another slight difference from the experimental branch, the master branch requires the explicit assignment of page directories to an ASID pool. Besides the adjustment to the new seL4 version, the patch introduces a dedicated type for capability selectors. Previously, we just used to represent them as unsigned integer values, which became increasingly confusing. The new type 'Cap_sel' is a PD-local capability selector. The type 'Cnode_index' is an index into a CNode (which is not generally not the entire CSpace of the PD). Fixes #1887
183 lines
4.4 KiB
C++
183 lines
4.4 KiB
C++
/*
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* \brief Protection-domain facility
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* \author Norman Feske
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* \date 2015-05-01
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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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/* Genode includes */
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#include <base/printf.h>
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/* core includes */
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#include <platform_pd.h>
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#include <platform.h>
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#include <util.h>
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#include <core_cspace.h>
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#include <kernel_object.h>
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/* base-internal includes */
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#include <internal/capability_space_sel4.h>
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using namespace Genode;
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/*****************************************
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** Allocator for protection-domain IDs **
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*****************************************/
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struct Pd_id_alloc : Bit_allocator<1024>
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{
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Pd_id_alloc()
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{
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/*
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* Skip 0 because this top-level index is used to address the core
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* CNode.
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*/
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_reserve(0, 1);
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_reserve(Core_cspace::CORE_VM_ID, 1);
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}
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};
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static Pd_id_alloc &pd_id_alloc()
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{
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static Pd_id_alloc inst;
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return inst;
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}
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int Platform_pd::bind_thread(Platform_thread *thread)
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{
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ASSERT(thread);
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thread->_pd = this;
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/*
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* Map IPC buffer
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*
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* XXX The mapping of the IPC buffer could be evicted from the PD's
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* 'Vm_space'. In contrast to mapping that are created as a result of
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* the RM-session's page-fault resolution, the IPC buffer's mapping
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* won't be recoverable once flushed. For this reason, it is important
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* to attach the UTCB as a dataspace to the context-area to make the RM
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* session aware to the mapping. This code is missing.
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*/
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if (thread->_utcb) {
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_vm_space.map(thread->_info.ipc_buffer_phys, thread->_utcb, 1);
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} else {
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_vm_space.map(thread->_info.ipc_buffer_phys, thread->INITIAL_IPC_BUFFER_VIRT, 1);
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}
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return 0;
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}
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void Platform_pd::unbind_thread(Platform_thread *thread)
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{
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PDBG("not implemented");
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}
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int Platform_pd::assign_parent(Native_capability parent)
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{
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Capability_space::Ipc_cap_data const ipc_cap_data =
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Capability_space::ipc_cap_data(parent);
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_parent = parent;
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/*
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* Install parent endpoint selector at the predefined position
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* INITIAL_SEL_PARENT within the PD's CSpace.
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*/
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_cspace_cnode.copy(platform_specific()->core_cnode(),
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Cnode_index(ipc_cap_data.sel),
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Cnode_index(INITIAL_SEL_PARENT));
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return 0;
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}
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addr_t Platform_pd::_init_page_directory()
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{
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PDBG("_init_page_directory at sel %lu", _page_directory_sel.value());
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addr_t const phys =
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create<Page_directory_kobj>(*platform()->ram_alloc(),
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platform_specific()->core_cnode().sel(),
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_page_directory_sel);
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int const ret = seL4_IA32_ASIDPool_Assign(platform_specific()->asid_pool().value(),
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_page_directory_sel.value());
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if (ret != 0)
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PERR("seL4_IA32_ASIDPool_Assign returned %d", ret);
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return phys;
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}
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Cap_sel Platform_pd::alloc_sel()
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{
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Lock::Guard guard(_sel_alloc_lock);
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return Cap_sel(_sel_alloc.alloc());
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}
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void Platform_pd::free_sel(Cap_sel sel)
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{
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Lock::Guard guard(_sel_alloc_lock);
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_sel_alloc.free(sel.value());
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}
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void Platform_pd::install_mapping(Mapping const &mapping)
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{
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_vm_space.map(mapping.from_phys(), mapping.to_virt(), mapping.num_pages());
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}
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void Platform_pd::flush(addr_t virt_addr, size_t size)
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{
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_vm_space.unmap(virt_addr, round_page(size) >> get_page_size_log2());
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}
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Platform_pd::Platform_pd(Allocator * md_alloc, char const *,
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signed pd_id, bool create)
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:
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_id(pd_id_alloc().alloc()),
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_page_table_registry(*md_alloc),
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_page_directory_sel(platform_specific()->core_sel_alloc().alloc()),
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_page_directory(_init_page_directory()),
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_vm_space(_page_directory_sel,
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platform_specific()->core_sel_alloc(),
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*platform()->ram_alloc(),
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platform_specific()->top_cnode(),
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platform_specific()->core_cnode(),
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platform_specific()->phys_cnode(),
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_id,
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_page_table_registry),
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_cspace_cnode_sel(platform_specific()->core_sel_alloc().alloc()),
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_cspace_cnode(platform_specific()->core_cnode().sel(), _cspace_cnode_sel,
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CSPACE_SIZE_LOG2,
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*platform()->ram_alloc())
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{
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/* install CSpace selector at predefined position in the PD's CSpace */
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_cspace_cnode.copy(platform_specific()->core_cnode(),
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_cspace_cnode_sel,
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Cnode_index(INITIAL_SEL_CNODE));
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}
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Platform_pd::~Platform_pd()
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{
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/* invalidate weak pointers to this object */
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Address_space::lock_for_destruction();
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}
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