73 lines
1.8 KiB
C
73 lines
1.8 KiB
C
#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include "kprintf.h"
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#include "memory.h"
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#include "utils.h"
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#define PT_SIZE 0x300
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#define MAX_TLB_ENTRIES 32
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extern uint32_t page_table_entries[PT_SIZE] __attribute__((aligned(4096)));
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static int16_t find_next_block(size_t nb_pages)
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{
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for (uint16_t i = 0; i < PT_SIZE; i++) {
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uint16_t j;
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for (j = 0;
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page_table_entries[i + j] >> 12 == i + j && j < nb_pages;
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j++)
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;
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if (j == nb_pages)
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return i;
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i += j;
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}
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return -1;
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}
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void *alloc_pages(size_t size)
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{
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const uint32_t nb_pages = CEIL(size, PAGE_SIZE);
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const int16_t index = find_next_block(nb_pages);
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if (index < 0) {
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kprintf(KERN_CRIT "Not enough pages (max: %d)\n", PT_SIZE);
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return NULL;
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}
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for (size_t i = index; i - (size_t)index < nb_pages; i++) {
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void *frame = alloc_frames(PAGE_SIZE);
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if (!frame) {
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for (size_t j = index; j < i; j++)
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free_frames(
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(void *)(page_table_entries[j] >> 12),
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PAGE_SIZE);
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return NULL;
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}
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page_table_entries[i] = (uint32_t)frame << 12 | INIT_FLAGS;
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}
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return (void *)(page_table_entries[index] >> 12);
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}
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int free_pages(void *page_ptr, size_t size)
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{
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const uint32_t nb_pages = CEIL(size, PAGE_SIZE);
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const uint32_t page_index = (uint32_t)page_ptr / PAGE_SIZE;
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if ((uint32_t)page_ptr > PT_SIZE * PAGE_SIZE) {
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kprintf(KERN_WARNING "Address out of range\n");
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return -1;
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} else if ((uint32_t)page_ptr % PAGE_SIZE) {
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kprintf(KERN_WARNING "Invalid address\n");
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return -1;
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} else if (page_index + nb_pages > PT_SIZE) {
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kprintf(KERN_WARNING "Invalid number of frames\n");
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return -1;
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}
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for (size_t i = page_index; i < page_index + nb_pages; i++) {
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free_frames((void *)(page_table_entries[i] >> 12), PAGE_SIZE);
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page_table_entries[i] = (i >> 12) | INIT_FLAGS;
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}
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return 0;
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}
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