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https://github.com/RGBCube/serenity
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e362b56b4f
The kernel and its static data structures are no longer identity-mapped in the bottom 8MB of the address space, but instead move above 3GB. The first 8MB above 3GB are pseudo-identity-mapped to the bottom 8MB of the physical address space. But things don't have to stay this way! Thanks to Jesse who made an earlier attempt at this, it was really easy to get device drivers working once the page tables were in place! :^) Fixes #734.
41 lines
1.3 KiB
C++
41 lines
1.3 KiB
C++
#pragma once
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#include <AK/HashMap.h>
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#include <AK/RefCounted.h>
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#include <AK/RefPtr.h>
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#include <Kernel/VM/PhysicalPage.h>
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#include <Kernel/VM/RangeAllocator.h>
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class Process;
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class PageDirectory : public RefCounted<PageDirectory> {
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friend class MemoryManager;
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public:
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static NonnullRefPtr<PageDirectory> create_for_userspace(Process& process, const RangeAllocator* parent_range_allocator = nullptr)
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{
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return adopt(*new PageDirectory(process, parent_range_allocator));
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}
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static NonnullRefPtr<PageDirectory> create_kernel_page_directory() { return adopt(*new PageDirectory); }
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static RefPtr<PageDirectory> find_by_cr3(u32);
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~PageDirectory();
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u32 cr3() const { return m_directory_table->paddr().get(); }
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PageDirectoryPointerTable& table() { return *reinterpret_cast<PageDirectoryPointerTable*>(0xc0000000 + cr3()); }
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RangeAllocator& range_allocator() { return m_range_allocator; }
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Process* process() { return m_process; }
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const Process* process() const { return m_process; }
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private:
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PageDirectory(Process&, const RangeAllocator* parent_range_allocator);
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PageDirectory();
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Process* m_process { nullptr };
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RangeAllocator m_range_allocator;
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RefPtr<PhysicalPage> m_directory_table;
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RefPtr<PhysicalPage> m_directory_pages[4];
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HashMap<unsigned, RefPtr<PhysicalPage>> m_physical_pages;
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};
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