116 lines
3.1 KiB
C
116 lines
3.1 KiB
C
#include <stdint.h>
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#include <stdlib.h>
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#include "paging_helpers.h"
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#include "paging.h"
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#include "pmem.h"
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#include <klog.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_DIRS*1024] __attribute__((aligned(4096)));
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static uint32_t smap_page_tables[2048] __attribute__((aligned(4096)));
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static uint32_t* smap=(uint32_t*)0xFF800000;
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static char is_page_present(int page) {
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int table=page>>10;
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page=page&0x3FF;
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if ((smap[table]&0x1)==0) {
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return 0;
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}
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smap_page_tables[table+1]=(smap[table]&0xFFFFFC00)|0x3;
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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;
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uint32_t phys_addr=(uint32_t)phys_addr_ptr;
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int dir_entry=(virt_addr&0xFFC00000)>>22;
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int table_entry=(virt_addr&0x3FF000)>>12;
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for (int i=0;i<=num_pages;i++) {
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if (!(smap[dir_entry]&0x1)) {
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int flags=1;
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flags=flags|((wr&1)<<1);
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flags=flags|((usr&1)<<2);
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smap[dir_entry]=(uint32_t)pmem_alloc(1)|flags;
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}
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smap_page_tables[dir_entry+1]=(smap[dir_entry]&0xFFFFFC00)|0x3;
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int flags=1;
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flags=flags|((wr&1)<<1);
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flags=flags|((usr&1)<<2);
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smap[(1024+(1024*dir_entry))+table_entry]=phys_addr|flags;
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table_entry++;
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phys_addr+=0x1000;
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}
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}
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void* alloc_pages(int num_pages) {
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void* phys_addr=pmem_alloc(num_pages);
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uint32_t bmap_index;
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uint32_t remaining_blks;
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for(uint32_t i=0;i<131072;i++) {
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char got_0=0;
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remaining_blks=num_pages;
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uint32_t old_j;
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for (uint32_t j=i*8;;j++) {
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char bit=is_page_present(j);
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if (got_0) {
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if (bit) {
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if (remaining_blks==0) {
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bmap_index=old_j;
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break;
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} else {
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i+=j/8;
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i--;
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break;
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}
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} else {
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remaining_blks--;
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}
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} else {
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if (!bit) {
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got_0=1;
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old_j=j;
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remaining_blks--;
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}
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}
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if (remaining_blks==0) {
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bmap_index=old_j;
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break;
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}
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}
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if (remaining_blks==0) {
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break;
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}
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}
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if (remaining_blks!=0) {
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klog("PANIC","Out of memory");
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}
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void* addr=(void*)(bmap_index<<12);
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map_pages(addr,phys_addr,num_pages,1,1);
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return addr;
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}
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void alloc_pages_virt(int num_pages,void* addr) {
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void* phys_addr=pmem_alloc(num_pages);
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map_pages(addr,phys_addr,num_pages,1,1);
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}
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void paging_init() {
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for (uint32_t i=0;i<NUM_KERN_DIRS*1024;i++) {
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kern_page_tables[i]=(i<<12)|0x7;
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}
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smap_page_tables[0]=(((uint32_t)&(page_directory))-0xC0000000)|0x3;
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for (uint32_t i=1;i<2048;i++) {
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smap_page_tables[i]=0;
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}
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for (uint32_t i=0;i<NUM_KERN_DIRS;i++) {
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uint32_t entry_virt=(uint32_t)&(kern_page_tables[i*1024]);
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page_directory[i+768]=(entry_virt-0xC0000000)|0x7;
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}
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for (uint32_t i=0;i<2;i++) {
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uint32_t entry_virt=(uint32_t)&(smap_page_tables[i*1024]);
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page_directory[i+1022]=(entry_virt-0xC0000000)|0x7;
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}
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load_page_directory((uint32_t*)((uint32_t)page_directory-0xC0000000));
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}
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