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
190 lines
5.7 KiB
C++
190 lines
5.7 KiB
C++
/*
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* \brief Utilities for creating seL4 kernel objects
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* \author Norman Feske
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* \date 2015-05-08
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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__KERNEL_OBJECT_H_
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#define _CORE__INCLUDE__KERNEL_OBJECT_H_
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/* Genode includes */
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#include <base/exception.h>
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/* core includes */
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#include <untyped_memory.h>
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#include <initial_untyped_pool.h>
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namespace Genode {
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/**
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* Index referring to a slot in a CNode
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*/
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struct Cnode_index : Cap_sel
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{
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explicit Cnode_index(addr_t value) : Cap_sel(value) { }
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Cnode_index(Cap_sel sel) : Cap_sel(sel.value()) { }
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};
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struct Tcb_kobj
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{
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enum { SEL4_TYPE = seL4_TCBObject, SIZE_LOG2 = 12 };
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static char const *name() { return "TCB"; }
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};
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struct Endpoint_kobj
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{
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enum { SEL4_TYPE = seL4_EndpointObject, SIZE_LOG2 = 4 };
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static char const *name() { return "endpoint"; }
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};
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struct Cnode_kobj
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{
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enum { SEL4_TYPE = seL4_CapTableObject, SIZE_LOG2 = 4 };
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static char const *name() { return "cnode"; }
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};
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struct Page_table_kobj
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{
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enum { SEL4_TYPE = seL4_IA32_PageTableObject, SIZE_LOG2 = 12 };
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static char const *name() { return "page table"; }
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};
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struct Page_directory_kobj
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{
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enum { SEL4_TYPE = seL4_IA32_PageDirectoryObject, SIZE_LOG2 = 12 };
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static char const *name() { return "page directory"; }
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};
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struct Retype_untyped_failed : Genode::Exception { };
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/**
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* Create kernel object from untyped memory
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*
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* \param KOBJ kernel-object description
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* \param phys_alloc allocator for untyped memory
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* \param dst_cnode_sel CNode selector where to store the cap pointing to
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* the new kernel object
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* \param dst_idx designated index of cap selector within 'dst_cnode'
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* \param size_log2 size of kernel object in bits, only needed for
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* variable-sized objects like CNodes
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*
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* \return physical address of created kernel object
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*
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* \throw Phys_alloc_failed
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* \throw Retype_untyped_failed
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*
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* The kernel-object description is a policy type that contains enum
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* definitions for 'SEL4_TYPE' and 'SIZE_LOG2', and a static function
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* 'name' that returns the type name as a char const pointer.
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*
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* XXX to be removed
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*/
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template <typename KOBJ>
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static addr_t create(Range_allocator &phys_alloc,
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Cap_sel dst_cnode_sel,
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Cnode_index dst_idx,
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size_t size_log2 = 0)
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{
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/* allocate physical page */
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addr_t phys_addr = Untyped_memory::alloc_page(phys_alloc);
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seL4_Untyped const service = Untyped_memory::untyped_sel(phys_addr).value();
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int const type = KOBJ::SEL4_TYPE;
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int const size_bits = size_log2;
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seL4_CNode const root = dst_cnode_sel.value();
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int const node_index = 0;
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int const node_depth = 0;
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int const node_offset = dst_idx.value();
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int const num_objects = 1;
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int const ret = seL4_Untyped_Retype(service,
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type,
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size_bits,
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root,
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node_index,
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node_depth,
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node_offset,
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num_objects);
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if (ret != 0) {
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PERR("seL4_Untyped_RetypeAtOffset (%s) returned %d",
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KOBJ::name(), ret);
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throw Retype_untyped_failed();
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}
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PLOG("created kernel object '%s' at 0x%lx -> root=%lu index=%lu",
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KOBJ::name(), phys_addr, dst_cnode_sel.value(), dst_idx.value());
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return phys_addr;
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}
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/**
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* Create kernel object from initial untyped memory pool
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*
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* \param KOBJ kernel-object description
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* \param untyped_pool initial untyped memory pool
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* \param dst_cnode_sel CNode selector where to store the cap pointing to
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* the new kernel object
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* \param dst_idx designated index of cap selector within 'dst_cnode'
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* \param size_log2 size of kernel object in bits, only needed for
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* variable-sized objects like CNodes
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*
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* \throw Initial_untyped_pool::Initial_untyped_pool_exhausted
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* \throw Retype_untyped_failed
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*
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* The kernel-object description is a policy type that contains enum
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* definitions for 'SEL4_TYPE' and 'SIZE_LOG2', and a static function
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* 'name' that returns the type name as a char const pointer.
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*/
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template <typename KOBJ>
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static void create(Initial_untyped_pool &untyped_pool,
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Cap_sel dst_cnode_sel,
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Cnode_index dst_idx,
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size_t size_log2 = 0)
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{
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unsigned const sel = untyped_pool.alloc(KOBJ::SIZE_LOG2 + size_log2);
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seL4_Untyped const service = sel;
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int const type = KOBJ::SEL4_TYPE;
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int const size_bits = size_log2;
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seL4_CNode const root = dst_cnode_sel.value();
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int const node_index = 0;
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int const node_depth = 0;
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int const node_offset = dst_idx.value();
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int const num_objects = 1;
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int const ret = seL4_Untyped_Retype(service,
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type,
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size_bits,
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root,
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node_index,
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node_depth,
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node_offset,
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num_objects);
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if (ret != 0) {
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PERR("seL4_Untyped_Retype (%s) returned %d",
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KOBJ::name(), ret);
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throw Retype_untyped_failed();
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}
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}
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};
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#endif /* _CORE__INCLUDE__KERNEL_OBJECT_H_ */
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