83b330bf2b
There were a few lingering bugs due to places where 510/511 were hard-coded as the kernel-space PML4 entries. These are now constants defined in kernel_memory.h instead. Tags: boot memory paging
45 lines
1.2 KiB
C++
45 lines
1.2 KiB
C++
#pragma once
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/// \file kernel_memory.h
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/// Constants related to the kernel's memory layout
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#include <stddef.h>
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#include <stdint.h>
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namespace memory {
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/// Size of a single page frame.
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constexpr size_t frame_size = 0x1000;
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/// Start of kernel memory.
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constexpr uintptr_t kernel_offset = 0xffff800000000000;
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/// Offset from physical where page tables are mapped.
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constexpr uintptr_t page_offset = 0xffffc00000000000;
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/// Initial process thread's stack address
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constexpr uintptr_t initial_stack = 0x0000800000000000;
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/// Initial process thread's stack size, in pages
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constexpr unsigned initial_stack_pages = 1;
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/// Max size of the kernel heap
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constexpr size_t kernel_max_heap = 0x8000000000; // 512GiB
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/// Start of the kernel heap
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constexpr uintptr_t heap_start = page_offset - kernel_max_heap;
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/// First kernel space PML4 entry
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constexpr unsigned pml4e_kernel = 256;
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/// First offset-mapped space PML4 entry
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constexpr unsigned pml4e_offset = 384;
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/// Number of page_table entries
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constexpr unsigned table_entries = 512;
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/// Helper to determine if a physical address can be accessed
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/// through the page_offset area.
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inline bool page_mappable(uintptr_t a) { return (a & page_offset) == 0; }
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} // namespace memory
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