139 lines
2.8 KiB
C
139 lines
2.8 KiB
C
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// vmm.c
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// Author: Josh Holtrop
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// Date: 09/30/03
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PageDirectory *vmm_PDBR = 0;
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dword vmm_first_virtual_address = 0;
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void vmm_init()
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{
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if (!(vmm_PDBR = mm_palloc(1, PID_KERNEL)))
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{
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printf("ERROR! COULD NOT ALLOCATE PAGE FOR INITIAL PAGE DIRECTORY!!\n");
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halt();
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}
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vmm_init_pagetable((dword)vmm_PDBR);
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if (mm_totalmem % 4096)
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vmm_first_virtual_address = mm_totalmem + (4096 - (mm_totalmem % 4096));
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else
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vmm_first_virtual_address = mm_totalmem;
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if (vmm_mapn(0, 0, 0x03, mm_totalmem/4096+1))
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{
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printf("Could not page in all physical RAM!\n");
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halt();
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}
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//we also need to map in the video framebuffer memory:
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if (video_mode.PhysBasePtr > 0 && video_mode.BitsPerPixel > 0)
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{
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if (vmm_mapn(video_mode.PhysBasePtr, video_mode.PhysBasePtr, 0x03, (video_mode.BitsPerPixel/8 * video_mode.XResolution * video_mode.YResolution)/4096+1))
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{
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printf("Could not page in video memory at 0x%x!\n", video_mode.PhysBasePtr);
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halt();
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}
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}
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}
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void vmm_enable_paging()
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{
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write_cr3((dword)vmm_PDBR);
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write_cr0(0x80000000|read_cr0());
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}
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int vmm_map1(dword virtual, dword physical, dword flags)
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{
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if (virtual & 0x00000FFF)
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return 1; // ERROR 1: address not page-aligned
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if (physical & 0x00000FFF)
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return 1; // ERROR 1: address not page-aligned
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int pde = (virtual & 0xFFC00000) >> 22;
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int pte = (virtual & 0x003FF000) >> 12;
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if (!(vmm_PDBR->pageTables[pde] & 0x01))
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{
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vmm_PDBR->pageTables[pde] = (dword)mm_palloc(1, PID_KERNEL) | 0x7; //user, r/w, present
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vmm_init_pagetable(vmm_PDBR->pageTables[pde] & 0xFFFFF000);
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if (vmm_PDBR->pageTables[pde] == 0x07)
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return 2; // ERROR 2: page table could not be created
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}
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PageTable *ptp = (PageTable *)(vmm_PDBR->pageTables[pde] & 0xFFFFF000);
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if (ptp->page[pte] & 0x01)
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return 3; // ERROR 3: page table entry already exists
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ptp->page[pte] = physical | flags;
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return 0;
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}
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int vmm_mapn(dword virtual, dword physical, dword flags, dword n)
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{
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int mapped;
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int result = 0;
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dword va = virtual;
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dword pa = physical;
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for (mapped = 0; mapped < n; mapped++)
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{
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result = vmm_map1(va, pa, flags);
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if (result != 0)
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{
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if (mapped > 0)
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vmm_unmapn(virtual, mapped);
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return result;
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}
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va += 4096;
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pa += 4096;
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}
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}
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int vmm_unmap1(dword virtual)
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{
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int pde = (virtual & 0xFFC00000) >> 22;
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int pte = (virtual & 0x003FF000) >> 12;
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if (virtual & 0x00000FFF)
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return 1; // ERROR 1: address not page-aligned
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PageTable *ptp = (PageTable *)(vmm_PDBR->pageTables[pde] & 0xFFFFF000);
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}
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int vmm_unmapn(dword virtual, dword n)
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{
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}
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void vmm_init_pagetable(dword address)
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{
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PageTable *ptp = (PageTable *)address;
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int n;
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for (n = 0; n < 1024; n++)
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ptp->page[n] = 0;
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}
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void *malloc(dword bytes)
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{
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}
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int free(void *ptr)
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{
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}
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