Initial Commit
This commit is contained in:
kaguya
+295
@@ -0,0 +1,295 @@
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#include "vmm.h"
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#include "pmm.h"
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#include "memory.h"
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#include "stdio.h"
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struct pagemap *kernel_pagemap = NULL;
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__attribute__((used, section(".limine_requests")))
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volatile struct limine_hhdm_request hhdm_request = {
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.id = LIMINE_HHDM_REQUEST_ID, .revision = 0
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};
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__attribute__((used, section(".limine_requests")))
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volatile struct limine_executable_address_request kernel_address_request = {
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.id = LIMINE_EXECUTABLE_ADDRESS_REQUEST_ID, .revision = 0
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};
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__attribute__((used, section(".limine_requests")))
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volatile struct limine_paging_mode_request paging_mode_request = {
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.id = LIMINE_PAGING_MODE_REQUEST_ID, .revision = 0, .mode = LIMINE_PAGING_MODE_X86_64_4LVL
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};
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static uint64_t *get_next_level(uint64_t *top_level, size_t idx, bool allocate) {
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if (top_level[idx] & 1)
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return (uint64_t *)((top_level[idx] & ~0xFFFULL) + MEM_PHYS_OFFSET);
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if (!allocate) return NULL;
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void *next = pmm_allocz(1);
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if (!next) return NULL;
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top_level[idx] = (uint64_t)next | 0b111;
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return (uint64_t *)((uintptr_t)next + MEM_PHYS_OFFSET);
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}
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void vmm_init(struct limine_memmap_entry **memmap, size_t memmapentries) {
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if (!hhdm_request.response) {
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printf("PRAISE BE TO LIMINE WE DON'T HAE HHDM RESP");
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}
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size_t memmap_entries = memmapentries - 1;
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kernel_pagemap = kmalloc(sizeof(struct pagemap));
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if (!kernel_pagemap) {
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printf("VMM: OOm allocating kernel_pagemap\n");
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while(1) asm volatile ("hlt");
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}
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spinlock_init(&kernel_pagemap->lock);
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kernel_pagemap->top_level = (uint64_t *)((uintptr_t)pmm_allocz(1) + MEM_PHYS_OFFSET);
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if (!kernel_pagemap->top_level) {
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printf("VMM: OOM allocating PML4\n");
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while (1) asm volatile ("hlt");
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}
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// Identity map lower half + HHDM
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for (uint64_t p = 256; p < 512; p++)
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get_next_level(kernel_pagemap->top_level, p, true);
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// Map all physical memory (HHDM)
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for (uint64_t p = 0; p < 0x8000000000ULL; p += 0x200000) // 2 MiB pages up to 256 GiB
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vmm_map_page(kernel_pagemap, p + MEM_PHYS_OFFSET, p, PAGE_READ | PAGE_WRITE, Size2MiB);
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// Map kernel sections with correct permissions
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extern char __text_start_addr[], __text_end_addr[];
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extern char __rodata_start_addr[], __rodata_end_addr[];
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extern char __data_start_addr[], __data_end_addr[];
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extern char __bss_start_addr[], __bss_end_addr[];
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uintptr_t text_start = ALIGN_DOWN((uintptr_t)__text_start_addr, PAGE_SIZE);
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uintptr_t text_end = ALIGN_UP((uintptr_t)__text_end_addr, PAGE_SIZE);
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uintptr_t rodata_start = ALIGN_DOWN((uintptr_t)__rodata_start_addr, PAGE_SIZE);
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uintptr_t rodata_end = ALIGN_UP((uintptr_t)__rodata_end_addr, PAGE_SIZE);
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uintptr_t data_start = ALIGN_DOWN((uintptr_t)__data_start_addr, PAGE_SIZE);
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uintptr_t data_end = ALIGN_UP((uintptr_t)__data_end_addr, PAGE_SIZE);
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uintptr_t bss_start = ALIGN_DOWN((uintptr_t)__bss_start_addr, PAGE_SIZE);
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uintptr_t bss_end = ALIGN_UP((uintptr_t)__bss_end_addr, PAGE_SIZE);
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uint64_t paddr = kernel_address_request.response->physical_base;
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uint64_t vaddr = kernel_address_request.response->virtual_base;
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// Map everything from kernel load address up to .text (this is the requests section)
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for (uintptr_t va = vaddr; va < text_start; va += PAGE_SIZE) {
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uint64_t pa = va - vaddr + paddr;
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vmm_map_page(kernel_pagemap, va, pa,
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PAGE_READ | PAGE_WRITE | PAGE_NO_EXECUTE, Size4KiB);
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}
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for (uintptr_t va = text_start; va < text_end; va += PAGE_SIZE) {
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uint64_t pa = va - vaddr + paddr;
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vmm_map_page(kernel_pagemap, va, pa, PAGE_READ, Size4KiB);
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}
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// .rodata : R-- + NX
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for (uintptr_t va = rodata_start; va < rodata_end; va += PAGE_SIZE) {
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uint64_t pa = va - vaddr + paddr;
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vmm_map_page(kernel_pagemap, va, pa, PAGE_READ | PAGE_NO_EXECUTE, Size4KiB);
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}
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// .data : RW- + NX
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for (uintptr_t va = data_start; va < data_end; va += PAGE_SIZE) {
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uint64_t pa = va - vaddr + paddr;
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vmm_map_page(kernel_pagemap, va, pa, PAGE_READ | PAGE_WRITE | PAGE_NO_EXECUTE, Size4KiB);
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}
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// .bss : RW- + NX (stack lives here)
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for (uintptr_t va = bss_start; va < bss_end; va += PAGE_SIZE) {
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uint64_t pa = va - vaddr + paddr;
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vmm_map_page(kernel_pagemap, va, pa, PAGE_READ | PAGE_WRITE | PAGE_NO_EXECUTE, Size4KiB);
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}
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vmm_switch_pagemap(kernel_pagemap);
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printf("VMM: switched to new kernel pagemap\n");
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}
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void vmm_switch_pagemap(struct pagemap *pagemap) {
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uint64_t phys_cr3 = (uintptr_t)pagemap->top_level - MEM_PHYS_OFFSET;
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printf("VMM: loading CR3 with PML4 @ 0x%lx\n", phys_cr3);
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asm volatile("mov %0, %%cr3" : : "r"((uint64_t)pagemap->top_level - MEM_PHYS_OFFSET) : "memory");
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printf("rah");
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}
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bool vmm_map_page(struct pagemap *pagemap, uint64_t virt, uint64_t phys,
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uint64_t flags, enum page_size pg_size) {
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spinlock_acquire_or_wait(&pagemap->lock);
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// Calculate the indices in the various tables using the virtual address
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size_t pml5_entry = (virt & ((uint64_t)0x1FF << 48)) >> 48;
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size_t pml4_entry = (virt & ((uint64_t)0x1FF << 39)) >> 39;
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size_t pml3_entry = (virt & ((uint64_t)0x1FF << 30)) >> 30;
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size_t pml2_entry = (virt & ((uint64_t)0x1FF << 21)) >> 21;
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size_t pml1_entry = (virt & ((uint64_t)0x1FF << 12)) >> 12;
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uint64_t *pml5, *pml4, *pml3, *pml2, *pml1;
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if (paging_mode_request.response->mode == LIMINE_PAGING_MODE_X86_64_5LVL) {
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pml5 = pagemap->top_level;
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goto level5;
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} else {
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pml4 = pagemap->top_level;
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goto level4;
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}
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level5:
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pml4 = get_next_level(pml5, pml5_entry, true);
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if (pml4 == NULL) {
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goto die;
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}
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level4:
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pml3 = get_next_level(pml4, pml4_entry, true);
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if (pml3 == NULL) {
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goto die;
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}
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pml2 = get_next_level(pml3, pml3_entry, true);
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if (pml2 == NULL) {
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goto die;
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}
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if (pg_size == Size2MiB) {
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pml2[pml2_entry] = phys | flags | (1 << 7);
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spinlock_drop(&pagemap->lock);
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return true;
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}
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pml1 = get_next_level(pml2, pml2_entry, true);
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if (pml1 == NULL) {
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die:
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spinlock_drop(&pagemap->lock);
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return false;
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}
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pml1[pml1_entry] = phys | flags;
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spinlock_drop(&pagemap->lock);
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return true; // simplified for this response
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}
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bool vmm_unmap_page(struct pagemap *pagemap, uintptr_t virt, bool locked) {
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if (!locked) {
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spinlock_acquire_or_wait(&pagemap->lock);
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}
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size_t pml5_entry = (virt & ((uint64_t)0x1FF << 48)) >> 48;
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size_t pml4_entry = (virt & ((uint64_t)0x1FF << 39)) >> 39;
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size_t pml3_entry = (virt & ((uint64_t)0x1FF << 30)) >> 30;
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size_t pml2_entry = (virt & ((uint64_t)0x1FF << 21)) >> 21;
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size_t pml1_entry = (virt & ((uint64_t)0x1FF << 12)) >> 12;
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uint64_t *pml5, *pml4, *pml3, *pml2, *pml1;
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if (paging_mode_request.response->mode == LIMINE_PAGING_MODE_X86_64_5LVL) {
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pml5 = pagemap->top_level;
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goto level5;
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} else {
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pml4 = pagemap->top_level;
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goto level4;
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}
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level5:
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pml4 = get_next_level(pml5, pml5_entry, false);
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if (pml4 == NULL) {
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goto die;
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}
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level4:
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pml3 = get_next_level(pml4, pml4_entry, false);
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if (pml3 == NULL) {
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goto die;
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}
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pml2 = get_next_level(pml3, pml3_entry, false);
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if (pml2 == NULL) {
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goto die;
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}
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pml1 = get_next_level(pml2, pml2_entry, false);
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if (pml1 == NULL) {
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goto die;
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}
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if ((pml1[pml1_entry] & 1) == 0) {
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die:
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if (!locked) {
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spinlock_drop(&pagemap->lock);
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}
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return false;
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}
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pml1[pml1_entry] = 0;
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asm volatile("invlpg (%0)" : : "r"(virt) : "memory");
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if (!locked) {
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spinlock_drop(&pagemap->lock);
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}
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return true;
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}
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uint64_t *vmm_virt_to_pte(struct pagemap *pagemap, uintptr_t virt_addr,
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bool allocate) {
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// spinlock_acquire_or_wait(&pagemap->lock);
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size_t pml5_entry = (virt_addr & ((uint64_t)0x1FF << 48)) >> 48;
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size_t pml4_entry = (virt_addr & ((uint64_t)0x1FF << 39)) >> 39;
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size_t pml3_entry = (virt_addr & ((uint64_t)0x1FF << 30)) >> 30;
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size_t pml2_entry = (virt_addr & ((uint64_t)0x1FF << 21)) >> 21;
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size_t pml1_entry = (virt_addr & ((uint64_t)0x1FF << 12)) >> 12;
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uint64_t *pml5, *pml4, *pml3, *pml2, *pml1;
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if (paging_mode_request.response->mode == LIMINE_PAGING_MODE_X86_64_5LVL) {
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pml5 = pagemap->top_level;
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goto level5;
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} else {
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pml4 = pagemap->top_level;
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goto level4;
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}
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level5:
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pml4 = get_next_level(pml5, pml5_entry, allocate);
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if (pml4 == NULL) {
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goto die;
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}
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level4:
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pml3 = get_next_level(pml4, pml4_entry, allocate);
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if (pml3 == NULL) {
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goto die;
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}
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pml2 = get_next_level(pml3, pml3_entry, allocate);
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if (pml2 == NULL) {
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goto die;
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}
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pml1 = get_next_level(pml2, pml2_entry, allocate);
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if (pml1 == NULL) {
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die:
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spinlock_drop(&pagemap->lock);
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return NULL;
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}
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// spinlock_drop(&pagemap->lock);
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return &pml1[pml1_entry];
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}
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uint64_t vmm_virt_to_phys(struct pagemap *pagemap, uint64_t virt) {
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spinlock_acquire_or_wait(&pagemap->lock);
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uint64_t *pte = vmm_virt_to_pte(pagemap, virt, false);
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spinlock_drop(&pagemap->lock);
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if (pte == NULL || (((*pte) & ~0xffffffffff000) & 1) == 0)
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return INVALID_PHYS;
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return ((*pte) & 0xffffffffff000);
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}
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