80 lines
2.6 KiB
C
80 lines
2.6 KiB
C
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/**************************************
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* iceOS Kernel *
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* Developed by Marco 'icebit' Cetica *
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* (c) 2019 *
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* Released under GPLv3 *
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* https://github.com/ice-bit/iceOS *
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***************************************/
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#ifndef PAGING_H
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#define PAGING_H
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#include <stdint.h>
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#include "../drivers/isr.h"
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#define FRAME_SIZE 4096
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#define PAGE_TABLE_SIZE 1024
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#define PAGE_DIRECTORY_SIZE 1024
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#define PAGE_NOT_PRESENT 0
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#define PAGE_PRESENT 1
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#define PAGE_READ_ONLY 0
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#define PAGE_READ_WRITE 1
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#define PAGE_USER 0
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#define PAGE_SUPERVISOR 0
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#define PAGE_SIZE_4KB 0
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#define PAGE_SIZE_4MB 1
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// Frames macros
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#define FRAME_ALLOCATIONS_SECTION_SIZE 32
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#define USED_FRAME_SECTION 0xFFFFFFFF
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#define FREE_FRAME_SECTION 0x00000000
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#define FRAME(addr) (addr/FRAME_SIZE)
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#define FRAME_SECTION(frame) (frame/FRAME_ALLOCATIONS_SECTION_SIZE)
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#define FRAME_OFFSET(frame) (frame%FRAME_ALLOCATIONS_SECTION_SIZE)
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// Set physical memory to 15 MiB
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#define PHYSICAL_MEM_SIZE 0x10000000
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struct page { // Single page structure, from intel's developer manual
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uint8_t pr : 1; // Present: 1 to map 4KB page
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uint8_t rw : 1; // Read/Write mode
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uint8_t us : 1; // if 0, user mode access aren't allowed to the page
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uint8_t pw : 1; // Page-level write through
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uint8_t pc : 1; // Page-level cache disable
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uint8_t ac : 1; // 1 if we have accessed 4kb page
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uint8_t di : 1; // 1 if page has been written(dirty)
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uint8_t pa : 1; // Unused bit
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uint8_t gl : 1; // 1 if page is global
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uint8_t ig : 3; // Unused bit
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uint32_t fr: 20; // Physical address of frame
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} __attribute__((packed));
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typedef struct page page_t;
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typedef struct page_table {
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page_t pages[PAGE_TABLE_SIZE];
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} page_table_t;
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/* Holds 2 arrays for each page directory
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* one holds the physical address, while
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* the other one holds the virtual address
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* (to write/read to it) */
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typedef struct page_directory {
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page_table_t *page_tables_virtual[PAGE_DIRECTORY_SIZE];
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uint32_t page_tables_physical[PAGE_DIRECTORY_SIZE];
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} page_directory_t;
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// Setup environment, page directories and enable paging
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void init_paging();
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// Perform the "enable-paging" operation to the right register
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void enable_paging(page_directory_t *dir);
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// Retrieve a pointer from the given page
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page_t *get_page(uint32_t address, int32_t make, page_directory_t *dir);
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// Identity map(phys = virtual addr) to access it as if paging wasn't enabled
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void identity_map();
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// Delete a frame
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void free_frame(page_t *page);
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// Allocate a new frame
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void alloc_frame(page_t *page, int32_t is_super, int32_t is_write);
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// Page faults handler(ISR recorder)
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void page_fault(registers_t regs);
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#endif
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