91 lines
2.3 KiB
C
91 lines
2.3 KiB
C
#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include "debug.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 MAX_TLB_ENTRIES 32
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static int16_t find_next_block(size_t nb_pages, uint16_t *pd_index_ptr,
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uint32_t **page_table_ptr)
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{
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for (*pd_index_ptr = 1; *pd_index_ptr < 768; (*pd_index_ptr)++) {
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if (page_directory[(*pd_index_ptr)] == 0x02) {
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if (add_page_table(*pd_index_ptr) < 0)
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return -2;
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}
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*page_table_ptr =
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(uint32_t *)GET_PAGE_ADDR(0, *pd_index_ptr + PT_START);
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for (uint16_t i = 0; i + nb_pages < PT_SIZE; i++) {
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uint16_t j;
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for (j = 0; (*page_table_ptr)[i + j] >> 12 == i + j &&
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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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}
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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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uint16_t pd_index;
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uint32_t *page_table;
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const int16_t index = find_next_block(nb_pages, &pd_index, &page_table);
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if (index < 0) {
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kprintf(KERN_CRIT "%d: Not enough pages (max: %d)\n", index,
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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_frame();
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if (!frame) {
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for (size_t j = index; j < i; j++)
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free_frame((void *)(page_table[j] >> 12));
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return NULL;
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}
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page_table[i] = ((uint32_t)frame & PAGE_MASK) | INIT_FLAGS;
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}
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return (void *)GET_PAGE_ADDR(pd_index, index);
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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 page_addr = (uint32_t)page_ptr;
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const uint32_t nb_pages = CEIL(size, PAGE_SIZE);
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const uint32_t page_index = page_addr / PAGE_SIZE;
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const uint32_t pd_index = page_index / PD_SIZE;
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const uint32_t pt_index = page_index % PD_SIZE;
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if ((uint32_t)pd_index > 0x300) {
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kprintf(KERN_WARNING "Address out of range\n");
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return -1;
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} else if (page_addr % PAGE_SIZE) {
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kprintf(KERN_WARNING "Invalid address\n");
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return -1;
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} else if (pt_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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uint32_t *page_table =
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(uint32_t *)GET_PAGE_ADDR(0, PT_START + pd_index);
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for (uint16_t i = pt_index; i < pt_index + nb_pages; i++) {
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if (page_table[i] >> 12 == i) {
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kprintf(KERN_WARNING "Page already free\n");
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return -2;
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}
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free_frame((void *)(page_table[i] & PAGE_MASK));
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page_table[i] = i << 12;
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}
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return 0;
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}
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