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#include "paging.h"
#include "kheap.h"
#include "../system.h"
#include "../lib/lib.h"
#include "../io/io.h"
page_directory_t *kernel_directory = 0;
page_directory_t *current_directory = 0;
uint32_t *frames;
uint32_t nframes;
extern uint32_t placement_address;
extern heap_t *kheap;
#define INDEX_FROM_BIT(a) (a/(8*4))
#define OFFSET_FROM_BIT(a) (a%(8*4))
static void set_frame(uint32_t frame_addr) {
uint32_t frame = frame_addr / 0x1000;
uint32_t idx = INDEX_FROM_BIT(frame);
uint32_t off = OFFSET_FROM_BIT(frame);
frames[idx] |= (0x1 << off);
}
static void clear_frame(uint32_t frame_addr) {
uint32_t frame = frame_addr / 0x1000;
uint32_t idx = INDEX_FROM_BIT(frame);
uint32_t off = OFFSET_FROM_BIT(frame);
frames[idx] &= ~(0x1 << off);
}
/*static uint32_t test_frame(uint32_t frame_addr) {
uint32_t frame = frame_addr / 0x1000;
uint32_t idx = INDEX_FROM_BIT(frame);
uint32_t off = OFFSET_FROM_BIT(frame);
return (frames[idx] & (0x1 << off));
}*/
static uint32_t first_frame() {
uint32_t i, j;
for (i = 0; i < INDEX_FROM_BIT(nframes); i++) {
if (frames[i] != 0xFFFFFFFF) {
for (j = 0; j < 32; j++) {
uint32_t toTest = 0x1 << j;
if (!(frames[i] & toTest)) {
return i * 4 * 8 + j;
}
}
}
}
return -1;
}
void alloc_frame(page_t *page, int is_kernel, int is_writeable) {
if (page->frame != 0) {
return;
} else {
uint32_t idx = first_frame();
if (idx == (uint32_t) -1) panic("No free frames!");
set_frame(idx * 0x1000);
page->present = 1;
page->rw = (is_writeable == 1) ? 1 : 0;
page->user = (is_kernel == 1) ? 0 : 1;
page->frame = idx;
}
}
void free_frame(page_t *page) {
uint32_t frame;
if (!(frame = page->frame)) {
return;
} else {
clear_frame(frame);
page->frame = 0x0;
}
}
void initialise_paging() {
uint32_t mem_end_page = 0x1000000;
nframes = mem_end_page / 0x1000;
frames = (uint32_t *) kmalloc(INDEX_FROM_BIT(nframes));
memory_set(frames, 0, INDEX_FROM_BIT(nframes));
kernel_directory = (page_directory_t *) kmalloc_a(sizeof(page_directory_t));
memory_set(kernel_directory, 0, sizeof(page_directory_t));
kernel_directory->physicalAddr = (uint32_t) kernel_directory->tablesPhysical;
unsigned int i = 0;
for (i = KHEAP_START; i < KHEAP_START + KHEAP_INITIAL_SIZE; i += 0x1000)
get_page(i, 1, kernel_directory);
i = 0;
while (i < 0x400000) {
alloc_frame(get_page(i, 1, kernel_directory), 0, 0);
i += 0x1000;
}
for (i = KHEAP_START; i < KHEAP_START + KHEAP_INITIAL_SIZE; i += 0x1000)
alloc_frame(get_page(i, 1, kernel_directory), 0, 0);
irq_install_handler(14, page_fault);
switch_page_directory(kernel_directory);
kheap = create_heap(KHEAP_START, KHEAP_START + KHEAP_INITIAL_SIZE, 0xCFFFF000, 0, 0);
current_directory = clone_directory(kernel_directory);
switch_page_directory(current_directory);
}
void disable_paging() {
uint32_t cr0;
asm volatile("mov %%cr0, %0": "=r"(cr0));
cr0 &= 0x7fffffff;
asm volatile("mov %0, %%cr0"::"r"(cr0));
}
void enable_paging() {
switch_page_directory(kernel_directory);
switch_page_directory(current_directory);
}
void switch_page_directory(page_directory_t *dir) {
current_directory = dir;
asm volatile("mov %0, %%cr3"::"r"(dir->physicalAddr));
uint32_t cr0;
asm volatile("mov %%cr0, %0": "=r"(cr0));
cr0 |= 0x80000000;
asm volatile("mov %0, %%cr0"::"r"(cr0));
}
page_t *get_page(uint32_t address, int make, page_directory_t *dir) {
address /= 0x1000;
uint32_t table_idx = address / 1024;
if (dir->tables[table_idx]) {
return &dir->tables[table_idx]->pages[address % 1024];
} else if (make) {
uint32_t tmp;
dir->tables[table_idx] = (page_table_t *) kmalloc_ap(sizeof(page_table_t), &tmp);
memory_set(dir->tables[table_idx], 0, 0x1000);
dir->tablesPhysical[table_idx] = tmp | 0x7;
return &dir->tables[table_idx]->pages[address % 1024];
} else {
return 0;
}
}
void page_fault(struct regs *r) {
uint32_t faulting_address;
asm volatile("mov %%cr2, %0" : "=r" (faulting_address));
int present = !(r->err_code & 0x1);
int rw = r->err_code & 0x2;
int us = r->err_code & 0x4;
int reserved = r->err_code & 0x8;
// int id = r->err_code & 0x10;
serial_write("Page fault! ( ");
if (present) serial_write("present ");
if (rw) serial_write("read-only ");
if (us) serial_write("user-mode ");
if (reserved) serial_write("reserved ");
serial_write(") at 0x");
serial_write_hex(faulting_address);
serial_write(" - EIP: ");
serial_write_hex(r->eip);
serial_write("\n");
panic("Page fault");
}
static page_table_t *clone_table(page_table_t *src, uint32_t *physAddr) {
page_table_t *table = (page_table_t *) kmalloc_ap(sizeof(page_table_t), physAddr);
memory_set(table, 0, sizeof(page_directory_t));
int i;
for (i = 0; i < 1024; i++) {
if (!src->pages[i].frame)
continue;
alloc_frame(&table->pages[i], 0, 0);
if (src->pages[i].present) table->pages[i].present = 1;
if (src->pages[i].rw) table->pages[i].rw = 1;
if (src->pages[i].user) table->pages[i].user = 1;
if (src->pages[i].accessed)table->pages[i].accessed = 1;
if (src->pages[i].dirty) table->pages[i].dirty = 1;
extern void copy_page_physical(int a, int b);
copy_page_physical(src->pages[i].frame * 0x1000, table->pages[i].frame * 0x1000);
}
return table;
}
page_directory_t *clone_directory(page_directory_t *src) {
uint32_t phys;
page_directory_t *dir = (page_directory_t *) kmalloc_ap(sizeof(page_directory_t), &phys);
memory_set(dir, 0, sizeof(page_directory_t));
uint32_t offset = (uint32_t) dir->tablesPhysical - (uint32_t) dir;
dir->physicalAddr = phys + offset;
for (int i = 0; i < 1024; i++) {
if (!src->tables[i])
continue;
if (kernel_directory->tables[i] == src->tables[i]) {
dir->tables[i] = src->tables[i];
dir->tablesPhysical[i] = src->tablesPhysical[i];
} else {
uint32_t phys;
dir->tables[i] = clone_table(src->tables[i], &phys);
dir->tablesPhysical[i] = phys | 0x07;
}
}
return dir;
}
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