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96 lines
2.3 KiB
96 lines
2.3 KiB
2 years ago
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#include "paging.h"
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#include "../debug/assert.h"
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#include <stivale2.h>
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extern uint64_t get_cr0(void);
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extern void set_cr0(uint64_t cr0);
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extern void _cr3(uint64_t cr3);
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extern uint64_t get_cr4(void);
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extern void set_cr4(uint64_t cr4);
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#define CR0_PG_BIT (1lu << 31)
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#define CR4_PAE_BIT (1lu << 5)
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/**
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* 4th level table (pde) entry
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*/
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typedef const void* pte;
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/**
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* 3rd level table (pde) entry
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*/
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typedef const pte* pde;
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/**
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* 2nd level table (pdpt) entry
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*
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*/
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typedef const pde* pdpte;
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/**
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* 1st level table (pml4) entry
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*/
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typedef const pdpte* pml4e;
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pml4e pml4_table[512] __attribute__((aligned(4096))) = {0};
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/*
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struct stivale2_struct_tag_memmap {
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struct stivale2_tag tag; // Identifier: 0x2187f79e8612de07
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uint64_t entries; // Count of memory map entries
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struct stivale2_mmap_entry memmap[]; // Array of memory map entries
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};
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struct stivale2_mmap_entry {
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uint64_t base; // Physical address of base of the memory section
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uint64_t length; // Length of the section
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uint32_t type; // Type (described below)
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uint32_t unused;
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};
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enum stivale2_mmap_type : uint32_t {
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USABLE = 1,
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RESERVED = 2,
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ACPI_RECLAIMABLE = 3,
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ACPI_NVS = 4,
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BAD_MEMORY = 5,
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BOOTLOADER_RECLAIMABLE = 0x1000,
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KERNEL_AND_MODULES = 0x1001,
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FRAMEBUFFER = 0x1002
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};
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*/
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void init_paging(const struct stivale2_struct_tag_memmap* memory_map) {
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for(unsigned i = 0; i < memory_map->entries; i++) {
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const struct stivale2_mmap_entry* e = &memory_map->memmap[i];
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kprintf("%0x16x - %0x16x - %d\n", e->base, e->base+e->length, e->type);
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}
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// get the physical address of the pml4 table
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uint64_t lower_half_ptr = ~0xffffffff80000000llu | (uint64_t)&pml4_table;
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// Page level Write Through (PWT) 0
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// Page level Cache Disable (PCD) 0
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// [63:MAXPHYADDR] must be 0!!! as 'lower_half_ptr' is supposed to
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// be a physical address already, it should be the case
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_cr3(lower_half_ptr);
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// enable PAE in cr4
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set_cr4(get_cr4() | CR0_PG_BIT);
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// enable the PG bit
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set_cr0(get_cr0() | CR0_PG_BIT);
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}
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void map_pages(uint64_t physical_addr, uint64_t virtual_addr, size_t count) {
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(void) (physical_addr + virtual_addr + count);
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}
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