b491a09686
Finish updating the page tables, call UEFI's `set_virtual_address_map` and jump to the kernel!
55 lines
1.7 KiB
C++
55 lines
1.7 KiB
C++
#pragma once
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/// \file paging.h
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/// Page table structure and related definitions
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#include <stdint.h>
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#include <uefi/boot_services.h>
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#include "kernel_args.h"
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namespace boot {
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namespace paging {
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/// Struct to allow easy accessing of a memory page being used as a page table.
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struct page_table
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{
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uint64_t entries[512];
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inline page_table * get(int i, uint16_t *flags = nullptr) const {
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uint64_t entry = entries[i];
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if ((entry & 1) == 0) return nullptr;
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if (flags) *flags = entry & 0xfff;
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return reinterpret_cast<page_table *>(entry & ~0xfffull);
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}
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inline void set(int i, void *p, uint16_t flags) {
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entries[i] = reinterpret_cast<uint64_t>(p) | (flags & 0xfff);
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}
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};
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/// Allocate memory to be used for initial page tables. Initial offset-mapped
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/// page tables are pre-filled. All pages are saved as a module in kernel args
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/// and kernel args' `page_table_cache` and `num_free_tables` are updated with
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/// the leftover space.
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void allocate_tables(
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kernel::args::header *args,
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uefi::boot_services *bs);
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/// Copy existing page table entries to a new page table. Does not do a deep
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/// copy - the new PML4 is updated to point to the existing next-level page
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/// tables in the current PML4.
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void add_current_mappings(page_table *new_pml4);
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/// Map a physical address to a virtual address in the given page tables.
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/// \arg pml4 The root of the set of page tables to be updated
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/// \arg args The kernel args header, used for the page table cache
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/// \arg phys The phyiscal address to map in
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/// \arg virt The virtual address to map in
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/// \arg size The size in bytes of the mapping
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void map_pages(
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page_table *pml4,
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kernel::args::header *args,
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uintptr_t phys, uintptr_t virt,
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size_t bytes);
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} // namespace paging
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} // namespace boot
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