Nigel
dea8ab7d71
Added new entries to .gitignore Moved away from source directory as central spot for all source code
127 lines
4.3 KiB
C++
127 lines
4.3 KiB
C++
#include "VirtualMemoryManager.h"
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#define ALIGN(addr, align) (((addr) & ~((align) - 1 )) + (align))
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extern uint32_t boot_page_directory[1024] ; // points to the wrong location
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extern uint32_t boot_page_table[1024];
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void flush_cr3(){
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asm volatile("movl %cr3, %ecx;"
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"movl %ecx, %cr3");
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}
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void AllocatePage(uint32_t vaddr)
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{
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uint32_t page_aligned_address = ALIGN(vaddr, 4096);
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// allocate a page at virtual address
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int PageDirectoryEntryIndex = vaddr >> 22;
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int PageTableEntryIndex = (vaddr >> 12) & 0x1FFF;
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printf("Allocation happening at PDE: %d PTE: %d\n", PageDirectoryEntryIndex, PageTableEntryIndex);
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// check if the page directory entry is marked as present
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if (boot_page_directory[PageDirectoryEntryIndex] & 0x1 )
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{
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printf("Directory entry is marked as present\n");
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uint32_t* page_table = (uint32_t*)((boot_page_directory[PageDirectoryEntryIndex]) & 0xFFFFE000) ;
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//page_table = (uint32_t*) ((uint32_t)page_table + 0xC0000000); // Add kernel offset
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printf("Page table address: 0x%x\n", (uint32_t)&page_table);
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// check if the page table entry is marked as present
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if ( page_table[PageTableEntryIndex] & 0x1 )
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{
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printf("page already present!\n");
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} else{
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printf("Mapping a physical page.\n");
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// Map the entry to a physical page
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page_table[PageTableEntryIndex] = (uint32_t)allocate_block() | 0x3;
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}
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} else {
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printf("Mapping a new page directory entry with a page table\n");
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// mark the page table as present and allocate a physical block for it
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boot_page_directory[PageDirectoryEntryIndex] = (uint32_t)allocate_block() | 0x3;
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}
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asm ("cli; invlpg (%0); sti" :: "r" (vaddr) : "memory" );
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}
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void FreePage(uint32_t vaddr )
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{
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uint32_t page_aligned_address = ALIGN(vaddr, 4096);
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// allocate a page at virtual address
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int PageDirectoryEntryIndex = vaddr >> 22;
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int PageTableEntryIndex = (vaddr >> 12) & 0x1FFF;
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uint32_t* pageTable = (uint32_t*)(boot_page_directory[PageDirectoryEntryIndex] & 0xFFFFE000 + 0xC0000000);
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void* physicalAddressToFree = (void*)(pageTable[PageTableEntryIndex] & 0xFFFFE000 + 0xC0000000);
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free_block(physicalAddressToFree);
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pageTable[PageTableEntryIndex] = 0x0;
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}
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void Immediate_Map ( uint32_t vaddr, uint32_t paddr)
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{
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printf("map 0x%x to 0x%x\n", paddr, vaddr);
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// allocate a page at virtual address
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int PageDirectoryEntryIndex = vaddr >> 22;
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int PageTableEntryIndex = (vaddr >> 12) & 0x1FFF;
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printf("Map address at PDE 0x%x PTE 0x%x\n", PageDirectoryEntryIndex, PageTableEntryIndex);
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if ((boot_page_directory - 0xC0000000)[PageDirectoryEntryIndex] & 0x1 )
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{
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printf("Directory entry is marked as present\n");
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} else {
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printf("Mapping a new page directory entry with a page table\n");
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// mark the page table as present and allocate a physical block for it
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void* new_page_dir = allocate_block();
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printf("New page directory address 0x%x\n", new_page_dir);
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boot_page_directory[PageDirectoryEntryIndex] = (uint32_t)new_page_dir | 0x3;
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}
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printf("PDE found at : 0x%x\n", (uint32_t) &boot_page_directory[PageDirectoryEntryIndex]);
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uint32_t* page_table = (uint32_t*)(boot_page_directory[PageDirectoryEntryIndex] & 0xFFFFE000) ;
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//page_table = (uint32_t*) ((uint32_t)page_table - 0xC0000000); // remove kernel offset
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printf("Page table address: 0x%x\n", (uint32_t)page_table);
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// check if the page table entry is marked as present
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if ( page_table[PageTableEntryIndex] & 0x1 )
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{
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printf("page already present!\n");
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printf("Entry found at addr: 0x%x\n", &(page_table[PageTableEntryIndex]));
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} else{
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printf("Mapping a physical page.\n");
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// Map the entry to a physical page
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page_table[PageTableEntryIndex] = (uint32_t)(paddr | 0x3);
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}
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asm ("cli; invlpg (%0); sti" :: "r" (vaddr) : "memory" );
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}
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void Immediate_Unmap(uint32_t vaddr)
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{
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// NOTE: I will implement lazy unmapping for now
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uint32_t page_aligned_address = ALIGN(vaddr, 4096);
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// allocate a page at virtual address
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int PageDirectoryEntryIndex = vaddr >> 22;
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int PageTableEntryIndex = (vaddr >> 12) & 0x1FFF;
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}
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