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#include "paging.h"
#include "lib/bitset.h"
#include "lib/stdlib.h"
#include "monitor.h"
#include "mem.h"
#include "sys.h"
static struct bitset frames;
struct page_directory *kernel_pagedir, *current_pagedir;
/* ACCESSOR FUNCTIONS FOR STATIC BITSET */
uint32_t frame_alloc() {
uint32_t free = bitset_firstFree(&frames);
bitset_set(&frames, free);
return free;
}
void frame_free(uint32_t id) {
bitset_clear(&frames, id);
}
void paging_init(size_t totalRam) {
uint32_t i;
frames.size = totalRam / 0x1000;
frames.bits = kmalloc(INDEX_FROM_BIT(frames.size));
kernel_pagedir = kmalloc(sizeof(struct page_directory));
kernel_pagedir->tablesPhysical = kmalloc_page(&kernel_pagedir->physicalAddr);
for (i = 0; i < 1024; i++) {
kernel_pagedir->tables[i] = 0;
kernel_pagedir->tablesPhysical[i] = 0;
}
for (i = 0xE0000000; i < mem_placementAddr; i += 0x1000) {
page_map(pagedir_getPage(kernel_pagedir, i, 1), frame_alloc(), 0, 0);
}
for (i = 0; i < (mem_placementAddr - 0xE0000000) / 0x100000; i++) {
kernel_pagedir->tablesPhysical[i] = kernel_pagedir->tablesPhysical[i + 896];
kernel_pagedir->tables[i] = kernel_pagedir->tables[i + 896];
}
monitor_write("Page dir is at: ");
monitor_writeHex(kernel_pagedir->physicalAddr);
pagedir_switch(kernel_pagedir);
monitor_write("\nPaging started\n");
}
void paging_cleanup() {
uint32_t i;
for (i = 0; i < (mem_placementAddr - 0xE0000000) / 0x100000; i++) {
kernel_pagedir->tablesPhysical[i] = 9;
kernel_pagedir->tables[i] = 0;
}
monitor_write("Pages cleaned up\n");
}
void pagedir_switch(struct page_directory *pd) {
current_pagedir = pd;
asm volatile("mov %0, %%cr3" : : "r"(pd->physicalAddr));
uint32_t cr0;
asm volatile("mov %%cr0, %0" : "=r"(cr0));
cr0 |= 0x80000000;
asm volatile("mov %0, %%cr0" : : "r"(cr0));
}
uint32_t paging_fault(struct registers *regs) {
size_t addr;
asm volatile("mov %%cr2, %0" : "=r"(addr));
monitor_write("PageFault ");
if (regs->err_code & 0x1) monitor_write("present ");
if (regs->err_code & 0x2) monitor_write("write ");
if (regs->err_code & 0x4) monitor_write("user ");
if (regs->err_code & 0x8) monitor_write("rsvd ");
if (regs->err_code & 0x10) monitor_write("instructionfetch ");
monitor_write("@"); monitor_writeHex(addr); monitor_write("\n");
PANIC("Page fault");
return 0;
}
struct page *pagedir_getPage(struct page_directory *pd, uint32_t address, int make) {
address /= 0x1000;
uint32_t table_idx = address / 1024;
if (pd->tables[table_idx]) {
return &pd->tables[table_idx]->pages[address % 1024];
} else if (make) {
pd->tables[table_idx] = kmalloc_page(pd->tablesPhysical + table_idx);
memset((uint8_t*)pd->tables[table_idx], 0, 0x1000);
pd->tablesPhysical[table_idx] |= 0x07;
return &pd->tables[table_idx]->pages[address % 1024];
} else {
return 0;
}
}
void page_map(struct page *page, uint32_t frame, uint32_t user, uint32_t rw) {
if (page != 0 && page->frame == 0 && page->present == 0) {
page->present = 1;
page->rw = (rw ? 1 : 0);
page->user = (user ? 1 : 0);
page->frame = frame;
}
}
void page_unmap(struct page *page) {
if (page != 0) {
page->frame = 0;
page->present = 0;
}
}
void page_unmapFree(struct page *page) {
if (page != 0) {
if (page->frame != 0) frame_free(page->frame);
page->frame = 0;
page->present = 0;
}
}
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