mirror of
https://github.com/Tom-on64/kern.git
synced 2026-11-03 18:22:22 +00:00
Implemented paging
This commit is contained in:
+3
-2
@@ -62,8 +62,9 @@ section .data
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align 4096
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global init_pagedir
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init_pagedir:
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dd 0b10000011
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times 768-1 dd 0
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dd 0b10000011 ; Identity map first 4MB
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times 768-1 dd 0
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; Map first 16MB of kernel to 0xC0000000
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dd (0 << 22) | 0b10000011
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dd (1 << 22) | 0b10000011
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dd (2 << 22) | 0b10000011
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+2
-4
@@ -15,8 +15,6 @@ void kmain(void* ptr, uint32_t magic) {
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// Serial console for debugging
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serial_init(COM1);
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// ESC[H moves cursor to (0,0), ESC[J clears from cursor to end of screen
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// ESC[<x>m sets graphics mode, 0 - reset, 36 - cyan
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debugf("\x1b[H\x1b[J\x1b[0mkern. \x1b[36m(serial console)\x1b[0m\n\n");
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// VGA tty thingy
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@@ -24,8 +22,8 @@ void kmain(void* ptr, uint32_t magic) {
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tty_puts("kern.\n\n");
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// Memory manager init
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// pmm_init();
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// vmm_init();
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//pmm_init();
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//vmm_init();
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gdt_init();
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isr_init();
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+199
-1
@@ -1,7 +1,16 @@
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#include <kernel.h>
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#include <string.h>
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#include <pmm.h>
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#include <paging.h>
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#define PAGE_DIR_COUNT 256
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static uint32_t pagedirs[PAGE_DIR_COUNT][1024] __align(4096);
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static uint8_t pagedirUsed[PAGE_DIR_COUNT];
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// TODO: Should this be initialized? If so, to what?
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size_t pag_pageCount;
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// Invalidates the pagedir entry in the CPUs TLB cache
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static inline void invalidate(uint32_t vaddr) {
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__asm__ volatile ("invlpg %0" : : "m"(vaddr));
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@@ -18,10 +27,199 @@ int pag_init(void) {
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* as a pagetab even though it's a pagedir. This maps it to
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* the virtual address 0xFFFFF000.
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*/
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init_pagedir[1023] = ((uint32_t)init_pagedir - 0xC0000000) |
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init_pagedir[1023] = ((uint32_t)init_pagedir - KERNEL_BASE) |
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PAGE_FLAG_PRESENT | PAGE_FLAG_WRITE;
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invalidate(0xFFFFF000);
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memset(pagedirs, 0, PAGE_SIZE * PAGE_DIR_COUNT);
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memset(pagedirUsed, 0, PAGE_DIR_COUNT);
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return 0;
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}
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void pag_mapPage(uint32_t vaddr, uint32_t paddr, uint32_t flags) {
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// Save the pagedir we were in
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uint32_t* prevpd = NULL;
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// Switch to the init pagedir if in kernel memory
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if (vaddr >= KERNEL_BASE) {
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prevpd = pag_getPagedir();
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if (prevpd != init_pagedir) pag_setPagedir(init_pagedir);
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}
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// Extract indecies
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size_t pdi = vaddr >> 22;
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size_t pti = vaddr >> 12 & 0x3FF;
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uint32_t* pagedir = PAGEDIR;
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uint32_t* pagetab = PAGETAB(pdi);
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// Allocate a pagetab if it didn't exist
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if (!(pagedir[pdi] & PAGE_FLAG_PRESENT)) {
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uint32_t tabaddr = (uint32_t)pmm_alloc(1);
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pagedir[pdi] = tabaddr |
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PAGE_FLAG_PRESENT | PAGE_FLAG_WRITE | PAGE_FLAG_OWNER | flags;
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invalidate(vaddr);
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for (size_t i = 0; i < 1024; i++) {
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pagetab[i] = 0;
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}
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}
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// The actuall mapping
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pagetab[pti] = paddr | PAGE_FLAG_PRESENT | flags;
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pag_pageCount++;
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invalidate(vaddr);
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// Do we need to return to the original pagedir?
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if (prevpd != NULL) {
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pag_syncPagedir(); // Sync it to other pagedirs
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if (prevpd != init_pagedir) pag_setPagedir(prevpd);
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}
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}
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uint32_t pag_umapPage(uint32_t vaddr) {
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// Same saving as in pag_mapPage()
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uint32_t* prevpd = NULL;
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if (vaddr >= KERNEL_BASE) {
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prevpd = pag_getPagedir();
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if (prevpd != init_pagedir) pag_setPagedir(init_pagedir);
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}
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// Extract indecies
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size_t pdi = vaddr >> 22;
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size_t pti = vaddr >> 12 & 0x3FF;
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uint32_t* pagedir = PAGEDIR;
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uint32_t* pagetab = PAGETAB(pdi);
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uint32_t pte = pagetab[pti];
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pagetab[pti] = 0;
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pag_pageCount--;
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// Look if we can free the pagetab
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int remove = 1;
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for (size_t i = 0; i < 1024; i++) {
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if (!(pagetab[i] & PAGE_FLAG_PRESENT)) continue;
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remove = 0;
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break;
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}
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// Free the pagetab if possible
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uint32_t pde = pagedir[pdi];
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if (remove && pde & PAGE_FLAG_OWNER) {
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uint32_t tabaddr = PHYS_ADDR(pde);
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pmm_free((void*)tabaddr, 1);
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pagedir[pdi] = 0;
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}
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invalidate(vaddr);
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// Free the page frame
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if (pte & PAGE_FLAG_OWNER) pmm_free((void*)PHYS_ADDR(pte), 1);
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if (prevpd != NULL) {
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pag_syncPagedir(); // Sync it to other pagedirs
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if (prevpd != init_pagedir) pag_setPagedir(prevpd);
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}
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return pte;
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}
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void* pag_virtToPhys(uint32_t vaddr) {
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uint32_t pdi = vaddr >> 22;
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uint32_t pti = vaddr >> 12 & 0x3FF;
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uint32_t* pagetab = PAGETAB(pdi);
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return (void*)((pagetab[pti] & ~0xFFF) + ((uint32_t)vaddr & 0xFFF));
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}
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uint32_t* pag_getPagedir() {
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uint32_t pagedir;
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__asm__ volatile ("mov %%cr3, %0" : "=r"(pagedir));
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pagedir += KERNEL_BASE;
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return (uint32_t*)pagedir;
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}
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void pag_setPagedir(uint32_t* pagedir) {
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pagedir = (uint32_t*)((uint32_t)pagedir - KERNEL_BASE);
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__asm__ volatile (
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"mov %0, %%eax\n"
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"mov %%eax, %%cr3"
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: : "m"(pagedir)
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);
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}
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void pag_syncPagedir() {
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for (size_t i = 0; i < PAGE_DIR_COUNT; i++) {
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if (!pagedirUsed[i]) continue;
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uint32_t* pagedir = pagedirs[i];
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// Sync ONLY the kernel pages so 768 has base at 0xC0000000
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// Also don't sync the recursive mapping in the last page
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for (size_t i = 768; i < 1023; i++) {
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pagedir[i] = init_pagedir[i] & ~PAGE_FLAG_OWNER;
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}
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}
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}
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uint32_t* pag_allocPagedir() {
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// Find the first unused page
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for (size_t i = 0; i < PAGE_DIR_COUNT; i++) {
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if (pagedirUsed[i]) continue;
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pagedirUsed[i] = 1;
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uint32_t* pagedir = pagedirs[i];
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memset(pagedir, 0, PAGE_SIZE);
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// First 768 entries are user pagetabs (3:1 memory split)
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for (size_t i = 0; i < 768; i++) pagedir[i] = 0;
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// Next 255 are kernel space
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for (size_t i = 768; i < 1023; i++) pagedir[i] = init_pagedir[i] & ~PAGE_FLAG_OWNER;
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// Last page is the recursive table mapping
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pagedir[1023] = ((uint32_t)pagedir - KERNEL_BASE) |
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PAGE_FLAG_PRESENT | PAGE_FLAG_WRITE;
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return pagedir;
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}
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// No pages left - out of memory
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return NULL;
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}
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void pag_freePagedir(uint32_t* pagedir) {
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uint32_t* prevpd = pag_getPagedir();
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pag_setPagedir(pagedir);
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uint32_t pdi = (uint32_t)pagedir - (uint32_t)pagedirs;
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pdi /= PAGE_SIZE;
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// Free all allocated page frames & pagetabs
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uint32_t* pd = PAGEDIR;
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for (int i = 0; i < 768; i++) {
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uint32_t pde = pd[i];
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if (pde == 0) continue;
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uint32_t* pagetab = PAGETAB(i);
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for (size_t j = 0; j < 1024; j++) {
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uint32_t pte = pagetab[j];
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if (pte & PAGE_FLAG_OWNER) pmm_free((void*)PHYS_ADDR(pte), 1);
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}
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memset(pagetab, 0, PAGE_SIZE);
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if (pde & PAGE_FLAG_OWNER) pmm_free((void*)PHYS_ADDR(pde), 1);
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pd[i] = 0;
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}
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pagedirUsed[pdi] = 0;
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pag_setPagedir(prevpd);
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}
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