69 lines
2.0 KiB
C
69 lines
2.0 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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#define MAX_FRAMES 1048319
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#define CEIL(x, y) (((x) + (y) - 1) / (y))
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#define GET_FRAME(i) (frame_table[i / 8] & (1 << (i % 8)))
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#define SET_FRAME(i, used) \
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do { \
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if (used) \
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frame_table[i / 8] |= (1 << (i % 8)); \
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else \
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frame_table[i / 8] &= ~(1 << (i % 8)); \
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} while (0)
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extern uint32_t end_kernel;
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static uint8_t frame_table[CEIL(MAX_FRAMES, 8)];
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static uint32_t remaining_frames = MAX_FRAMES;
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void *kalloc_frame(uint32_t nb_frames)
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{
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if (nb_frames > remaining_frames) {
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kprintf(KERN_CRIT "Not enough frames (max: %d)\n", MAX_FRAMES);
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return NULL;
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}
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size_t i = 0;
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while (i < MAX_FRAMES) {
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size_t free_frames = 1;
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while (!GET_FRAME(i + free_frames) && free_frames < nb_frames &&
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i + free_frames < remaining_frames)
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free_frames++;
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if (free_frames == nb_frames)
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goto end;
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i += free_frames;
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}
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end:
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if (i != MAX_FRAMES) {
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for (size_t j = 0; j < nb_frames; j++)
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SET_FRAME(j + i, 1);
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remaining_frames -= nb_frames;
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return &end_kernel + i * PAGE_SIZE;
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}
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kprintf(KERN_WARNING "Not enough frames available\n", MAX_FRAMES);
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return NULL;
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}
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void kfree_frame(void *frame, uint32_t nb_frames)
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{
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const uint32_t start = (frame - (void *)&end_kernel) / PAGE_SIZE;
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if (start > MAX_FRAMES || frame < (void *)&end_kernel) {
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kprintf(KERN_WARNING "Address out of range\n");
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return;
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} else if ((uint32_t)frame % PAGE_SIZE) {
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kprintf(KERN_WARNING "Invalid address\n");
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return;
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} else if (start + nb_frames > MAX_FRAMES) {
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kprintf(KERN_WARNING "Invalid number of frames\n");
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return;
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}
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for (size_t i = start; i < start + nb_frames; i++)
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SET_FRAME(i, 0);
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remaining_frames += nb_frames;
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}
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