os/kernel/cpu/i386/paging.c
2019-05-28 16:05:51 -05:00

195 lines
5.3 KiB
C

#include <stdint.h>
#include <stdlib.h>
#include "paging_helpers.h"
#include "paging.h"
#include "pmem.h"
#include "../..//vga_err.h"
#include <klog.h>
static uint32_t page_directory[1024] __attribute__((aligned(4096)));
static uint32_t kern_page_tables[NUM_KERN_DIRS*1024] __attribute__((aligned(4096)));
static uint32_t kmalloc_page_tables[1024] __attribute__((aligned(4096)));
static uint32_t smap_page_tables[2048] __attribute__((aligned(4096)));
static uint32_t* smap=(uint32_t*)0xFF800000;
static char is_page_present(int page) {
int table=page>>10;
page=page&0x3FF;
if ((smap[table]&0x1)==0) {
return 0;
}
smap_page_tables[table+1]=(smap[table]&0xFFFFFC00)|0x3;
return smap[(1024+(1024*table))+page]&0x1;
}
void map_pages(void* virt_addr_ptr,void* phys_addr_ptr,int num_pages,char usr,char wr) {
uint32_t virt_addr=(uint32_t)virt_addr_ptr;
uint32_t phys_addr=(uint32_t)phys_addr_ptr;
int dir_entry=(virt_addr&0xFFC00000)>>22;
int table_entry=(virt_addr&0x3FF000)>>12;
for (int i=0;i<=num_pages;i++) {
if (!(smap[dir_entry]&0x1)) {
int flags=1;
flags=flags|((wr&1)<<1);
flags=flags|((usr&1)<<2);
smap[dir_entry]=(uint32_t)pmem_alloc(1)|flags;
}
smap_page_tables[dir_entry+1]=(smap[dir_entry]&0xFFFFFC00)|0x3;
int flags=1;
flags=flags|((wr&1)<<1);
flags=flags|((usr&1)<<2);
smap[(1024+(1024*dir_entry))+table_entry]=phys_addr|flags;
table_entry++;
phys_addr+=0x1000;
}
}
uint32_t find_free_pages(int num_pages) {
uint32_t bmap_index;
uint32_t remaining_blks;
for(uint32_t i=1;i<131072;i++) {
char got_0=0;
remaining_blks=num_pages;
uint32_t old_j;
for (uint32_t j=i*8;;j++) {
char bit=is_page_present(j);
if (got_0) {
if (bit) {
if (remaining_blks==0) {
bmap_index=old_j;
break;
} else {
i+=j/8;
i--;
break;
}
} else {
remaining_blks--;
}
} else {
if (!bit) {
got_0=1;
old_j=j;
remaining_blks--;
}
}
if (remaining_blks==0) {
bmap_index=old_j;
break;
}
}
if (remaining_blks==0) {
break;
}
}
if (remaining_blks!=0) {
vga_write_string("[PANIC] Out of memory");
}
return bmap_index;
}
void* alloc_pages(int num_pages) {
void* phys_addr=pmem_alloc(num_pages);
void* addr=(void*)(find_free_pages(num_pages)<<12);
map_pages(addr,phys_addr,num_pages,1,1);
return addr;
}
void* virt_to_phys(void* virt_addr_arg) {
uint32_t virt_addr=(uint32_t)virt_addr_arg;
int offset=virt_addr&0x3FF;
virt_addr=virt_addr&0xFFFFFC00;
if (!is_page_present(virt_addr>>12)) return NULL;
int dir_idx=(virt_addr&0xFFC00000)>>22;
int tbl_idx=(virt_addr&0x3FFC00)>>12;
if ((smap[dir_idx]&0x1)==0) {
return 0;
}
smap_page_tables[dir_idx+1]=(smap[dir_idx]&0xFFFFFC00)|0x3;
return (void*)((smap[(1024+(1024*dir_idx))+tbl_idx]&0xFFFFFC00)+offset);
}
void alloc_pages_virt(int num_pages,void* addr) {
void* phys_addr=pmem_alloc(num_pages);
map_pages(addr,phys_addr,num_pages,1,1);
}
void invl_page(void* addr) {
asm volatile("invlpg (%0)"::"r"(addr):"memory");
}
void* paging_new_address_space() {
uint32_t cr3;
asm volatile("movl %%cr3, %%eax; movl %%eax, %0;":"=m"(cr3)::"%eax");
void* dir=pmem_alloc(1);
smap_page_tables[0]=((uint32_t)dir)|0x3;
invl_page(smap);
for (uint32_t i=0;i<NUM_KERN_DIRS;i++) {
uint32_t entry_virt=(uint32_t)&(kern_page_tables[i*1024]);
smap[i+768]=(entry_virt-0xC0000000)|0x3;
}
smap[1021]=(((uint32_t)kmalloc_page_tables)-0xC0000000)|0x3;
for (uint32_t i=0;i<2;i++) {
uint32_t entry_virt=(uint32_t)&(smap_page_tables[i*1024]);
smap[i+1022]=(entry_virt-0xC0000000)|0x3;
}
smap_page_tables[0]=cr3|0x3;
invl_page(smap);
return dir;
}
void load_address_space(uint32_t cr3) {
load_smap(cr3);
load_page_directory((uint32_t*)cr3);
}
void load_smap(uint32_t cr3) {
smap_page_tables[0]=cr3|0x3;
invl_page(&smap[0]);
for (uint32_t i=1;i<2048;i++) {
invl_page(&smap[i*1024]);
smap_page_tables[i]=0;
}
}
void unmap_pages(void* start_virt,uint32_t num_pages) {
uint32_t virt_addr=(uint32_t)start_virt;
int dir_entry=(virt_addr&0xFFC00000)>>22;
int table_entry=(virt_addr&0x3FF000)>>12;
for (int i=0;i<=num_pages;i++) {
if (smap[dir_entry]&0x1) {
smap_page_tables[dir_entry+1]=(smap[dir_entry]&0xFFFFFC00)|0x3;
smap[(1024+(1024*dir_entry))+table_entry]=0;
table_entry++;
if (table_entry==1024) {
dir_entry++;
table_entry=0;
}
}
}
}
void paging_init() {
for (uint32_t i=0;i<NUM_KERN_DIRS*1024;i++) {
kern_page_tables[i]=(i<<12)|0x3;
}
for (uint32_t i=0;i<1024;i++) {
kmalloc_page_tables[i]=(uint32_t)pmem_alloc(1)|0x3;
}
smap_page_tables[0]=(((uint32_t)&(page_directory))-0xC0000000)|0x3;
for (uint32_t i=1;i<2048;i++) {
smap_page_tables[i]=0;
}
for (uint32_t i=0;i<NUM_KERN_DIRS;i++) {
uint32_t entry_virt=(uint32_t)&(kern_page_tables[i*1024]);
page_directory[i+768]=(entry_virt-0xC0000000)|0x3;
}
page_directory[1021]=(((uint32_t)kmalloc_page_tables)-0xC0000000)|0x3;
for (uint32_t i=0;i<2;i++) {
uint32_t entry_virt=(uint32_t)&(smap_page_tables[i*1024]);
page_directory[i+1022]=(entry_virt-0xC0000000)|0x3;
}
load_page_directory((uint32_t*)((uint32_t)page_directory-0xC0000000));
}