os/kernel/cpu/i386/paging.c

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#include "../../pmem.h"
#include "../../vga_err.h"
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#include "../halt.h"
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#include "../paging.h"
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#include "arch_consts.h"
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#include "paging_helpers.h"
#include <klog.h>
#include <stdint.h>
#include <stdlib.h>
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static uint32_t page_directory[1024] __attribute__((aligned(4096)));
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static uint32_t kern_page_tables[NUM_KERN_FRAMES] __attribute__((aligned(4096)));
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static uint32_t kstack_page_tables[218*1024] __attribute__((aligned(4096)));
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static uint32_t kmalloc_page_tables[4*1024] __attribute__((aligned(4096)));
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static uint32_t smap_page_tables[2048] __attribute__((aligned(4096)));
static uint32_t* smap=(uint32_t*)0xFF800000;
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static uint32_t kstack_bmap[(218*1024)/8];
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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;
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}
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void map_pages(void* virt_addr_ptr,void* phys_addr_ptr,int num_pages,char usr,char wr) {
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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++) {
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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;
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table_entry++;
if (table_entry==1024) {
table_entry=0;
dir_entry++;
}
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phys_addr+=0x1000;
}
}
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static char get_bmap_bit(uint32_t index) {
uint32_t byte=index/8;
uint32_t bit=index%8;
char entry=kstack_bmap[byte];
return (entry&(1<<bit))>0;
}
static void set_bmap_bit(uint32_t index) {
uint32_t byte=index/8;
uint32_t bit=index%8;
kstack_bmap[byte]=kstack_bmap[byte]|(1<<bit);
}
static void clear_bmap_bit(uint32_t index) {
uint32_t byte=index/8;
uint32_t bit=index%8;
kstack_bmap[byte]=kstack_bmap[byte]&(~(1<<bit));
}
int new_kstack() {
int num=-1;
for (int i=0;i<(218*1024);i++) {
if (get_bmap_bit(i)==0) {
num=i;
break;
}
}
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if (num==-1) {
return -1;
}
set_bmap_bit(num);
if (!(kstack_page_tables[num]&0x1)) {
kstack_page_tables[num]=(uint32_t)pmem_alloc(1)|0x3;
}
return num;
}
void* find_free_pages(int num_pages) {
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uint32_t bmap_index;
uint32_t remaining_blks;
for(uint32_t i=1;i<131072;i++) {
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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");
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halt();
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}
return (void*)(bmap_index<<12);
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}
void* alloc_pages(int num_pages) {
void* phys_addr=pmem_alloc(num_pages);
void* addr=find_free_pages(num_pages);
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map_pages(addr,phys_addr,num_pages,1,1);
return addr;
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}
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void* virt_to_phys(void* virt_addr_arg) {
uint32_t virt_addr=(uint32_t)virt_addr_arg;
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int offset=virt_addr&0x3FF;
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virt_addr=virt_addr&0xFFFFFC00;
if (!is_page_present(virt_addr>>12)) return NULL;
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int dir_idx=(virt_addr&0xFFC00000)>>22;
int tbl_idx=(virt_addr&0x3FFC00)>>12;
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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);
}
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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);
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}
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void invl_page(void* addr) {
asm volatile("invlpg (%0)"::"r"(addr):"memory");
}
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void* paging_new_address_space() {
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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;
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invl_page(smap);
for (uint32_t i=0;i<1024;i++) {
smap[i]=page_directory[i];
}
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smap_page_tables[0]=cr3|0x3;
invl_page(smap);
return dir;
}
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void load_address_space(void* cr3) {
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load_smap(cr3);
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load_page_directory((uint32_t*)cr3);
}
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void load_smap(void* cr3) {
smap_page_tables[0]=(uint32_t)cr3|0x3;
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invl_page(&smap[0]);
for (uint32_t i=1;i<2048;i++) {
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invl_page(&smap[i*1024]);
smap_page_tables[i]=0;
}
}
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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;
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for (uint32_t i=0;i<=num_pages;i++) {
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if (smap[dir_entry]&0x1) {
smap_page_tables[dir_entry+1]=(smap[dir_entry]&0xFFFFFC00)|0x3;
smap[(1024+(1024*dir_entry))+table_entry]=0;
invl_page(start_virt+(i*1024));
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table_entry++;
if (table_entry==1024) {
dir_entry++;
table_entry=0;
}
}
}
}
char make_protector(int page) {
int table=page>>10;
if (is_page_present(page)) return 0;
page=page&0x3FF;
smap_page_tables[table+1]=(smap[table]&0xFFFFFC00)|0x3;
uint32_t page_val=smap[(1024+(1024*table))+page];
page_val=page_val&(~0x6);
page_val=page_val|0x800;
smap[(1024+(1024*table))+page]=page_val;
return 1;
}
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char is_in_protector(void* addr) {
int page=((uint32_t)addr)>>12;
if (is_page_present(page)) return 0;
int table=page>>10;
page=page&0x3FF;
smap_page_tables[table+1]=(smap[table]&0xFFFFFC00)|0x3;
return smap[(1024+(1024*table))+page]&0x800;
return 1;
}
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void paging_init() {
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for (uint32_t i=0;i<NUM_KERN_FRAMES;i++) {
kern_page_tables[i]=(i<<12)|0x3;
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}
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for (uint32_t i=0;i<218*1024;i++) {
kstack_page_tables[i]=0;
}
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for (uint32_t i=0;i<4*1024;i++) {
kmalloc_page_tables[i]=(uint32_t)pmem_alloc(1)|0x3;
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}
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smap_page_tables[0]=(((uint32_t)&(page_directory))-0xC0000000)|0x3;
for (uint32_t i=1;i<2048;i++) {
smap_page_tables[i]=0;
}
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for (uint32_t i=0;i<NUM_KERN_FRAMES/1024;i++) {
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uint32_t entry_virt=(uint32_t)&(kern_page_tables[i*1024]);
page_directory[i+768]=(entry_virt-0xC0000000)|0x3;
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}
page_directory[985]=(uint32_t)(pmem_alloc(1024))|0x83;
for (uint32_t i=0;i<218;i++) {
uint32_t entry_virt=(uint32_t)&(kstack_page_tables[i*1024]);
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page_directory[i+800]=(entry_virt-0xC0000000)|0x3;
}
for (uint32_t i=0;i<(218*1024)/8;i++) {
kstack_bmap[i]=0;
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}
for (uint32_t i=0;i<4;i++) {
uint32_t entry_virt=(uint32_t)&(kmalloc_page_tables[i*1024]);
page_directory[i+1018]=(entry_virt-0xC0000000)|0x3;
}
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// page_directory[1018,1021]=(((uint32_t)kmalloc_page_tables)-0xC0000000)|0x3;
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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;
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}
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load_page_directory((uint32_t*)((uint32_t)page_directory-0xC0000000));
}
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void* get_cr3() {
void* cr3;
asm volatile("movl %%cr3, %%eax; movl %%eax, %0;":"=m"(cr3)::"%eax");
return cr3;
}