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feature: kalloc_frame and demo in the main

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This commit is contained in:
0x35c 2024-09-19 17:04:35 +02:00
parent 8fd17276b2
commit f559e71433
4 changed files with 57 additions and 23 deletions
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1
boot/linker.ld
View File

@ -24,5 +24,6 @@ SECTIONS
{
*(COMMON)
*(.bss)
end_kernel = .;
}
}

30
headers/memory.h
View File

@ -2,28 +2,12 @@
#include <stdint.h>
#define NOT_PRESENT (1 << 0)
#define RW (1 << 1)
#define SUPERVISOR (0 << 2)
#define INIT_FLAGS (NOT_PRESENT | RW | SUPERVISOR)
struct page_directory_entry {
uint32_t present : 1;
uint32_t rw : 1;
uint32_t user : 1;
uint32_t page_size : 1;
uint32_t unused : 8;
uint32_t frame : 20;
};
struct page_table_entry {
uint32_t present : 1;
uint32_t rw : 1;
uint32_t user : 1;
uint32_t accessed : 1;
uint32_t dirty : 1;
uint32_t unused : 7;
uint32_t frame : 20;
};
#define PRESENT (1 << 0)
#define RW (1 << 1)
#define SUPERVISOR (0 << 2)
#define ACCESSED (1 << 4)
#define INIT_FLAGS (PRESENT | RW | SUPERVISOR)
#define PAGE_SIZE 4096
void init_memory(void);
uintptr_t kalloc_frame(uint32_t nb_frames);

5
src/kernel.c
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@ -1,6 +1,8 @@
#include "gdt.h"
#include "kprintf.h"
#include "memory.h"
#include "shell.h"
#include "string.h"
#include "terminal.h"
#include <stdbool.h>
@ -23,5 +25,8 @@ void kernel_main(void)
terminal_initialize();
init_gdt();
init_memory();
char *str = (char *)kalloc_frame(1);
memcpy(str, "Hello world!\n", 15);
kprintf(KERN_INFO, "%s", str);
shell_init();
}

44
src/memory/frame.c Normal file
View File

@ -0,0 +1,44 @@
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include "kprintf.h"
#include "memory.h"
#define MAX_FRAMES 1048319
#define CEIL(x, y) (((x) + (y) - 1) / (y))
#define GET_FRAME(i) (frame_table[i / 8] & (1 << (i % 8)))
#define SET_FRAME(i, used) \
do { \
if (used) \
frame_table[i / 8] |= (1 << (i % 8)); \
else \
frame_table[i / 8] &= ~(1 << (i % 8)); \
} while (0)
extern uint32_t end_kernel;
static uint8_t frame_table[CEIL(MAX_FRAMES, 8)];
uintptr_t kalloc_frame(uint32_t nb_frames)
{
if (nb_frames > MAX_FRAMES)
kprintf(KERN_CRIT, "Not enough frames (max: %d)\n", MAX_FRAMES);
size_t i = 0;
while (i < MAX_FRAMES) {
size_t free_frames = 1;
while (!GET_FRAME(i + free_frames) && free_frames < nb_frames)
free_frames++;
if (free_frames == nb_frames)
goto end;
i += free_frames;
}
end:
if (i != MAX_FRAMES) {
for (size_t j = 0; j < nb_frames; j++)
SET_FRAME(j + i, 1);
return (uintptr_t)&end_kernel + i * PAGE_SIZE;
}
kprintf(KERN_WARNING, "Not enough frames available\n", MAX_FRAMES);
return 0;
}