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6317e3ad00
The page_tree struct was doing a lot of bit manipulation to keep its base, level, and flags in a single uint64_t. But since this is such a large structure anyway, another word doesn't change it much and greatly simplifies both the code and reasoning about it.
49 lines
1.8 KiB
C++
49 lines
1.8 KiB
C++
#pragma once
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/// \file page_tree.h
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/// Definition of mapped page tracking structure and related definitions
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#include <stdint.h>
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/// A radix tree node that tracks mapped pages
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class page_tree
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{
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public:
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/// Get the physical address of the page at the given offset.
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/// \arg root The root node of the tree
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/// \arg offset Offset into the VMA, in bytes
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/// \arg page [out] Receives the page physical address, if found
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/// \returns True if a page was found
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static bool find(const page_tree *root, uint64_t offset, uintptr_t &page);
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/// Get the physical address of the page at the given offset. If one does
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/// not exist yet, allocate a page, insert it, and return that.
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/// \arg root [inout] The root node of the tree. This pointer may be updated.
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/// \arg offset Offset into the VMA, in bytes
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/// \arg page [out] Receives the page physical address, if found
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/// \returns True if a page was found
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static bool find_or_add(page_tree * &root, uint64_t offset, uintptr_t &page);
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private:
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page_tree(uint64_t base, uint8_t level);
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/// Check if this node should contain the given virtual address
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/// \arg offset The offset into the VMA, in bytes
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/// \arg index [out] If found, what entry index should contain addr
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/// \returns True if the address is contained
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bool contains(uintptr_t offset, uint8_t &index) const;
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/// Stores the page offset of the start of this node's pages virtual addresses
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uint64_t m_base;
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/// Level of this node: 0 maps actual physical pages. Other levels N point to
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/// nodes of level N-1.
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uint8_t m_level;
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/// For a level 0 node, the entries area all physical page addresses.
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/// Other nodes contain pointers to child tree nodes.
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union {
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uintptr_t entry;
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page_tree *child;
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} m_entries[64];
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};
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