os/kernel/kernel.c

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C
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#include <grub/text_fb_info.h>
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#include <stdlib.h>
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#include <tasking.h>
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#include <string.h>
#include <memory.h>
#include <grub/multiboot2.h>
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#include <stdint.h>
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#include "cpu/cpu_init.h"
#include "vga_err.h"
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#include <elf.h>
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typedef struct {
char filename[100];
char mode[8];
char uid[8];
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char gid[8];
char size[12];
char mtime[12];
char chksum[8];
char typeflag[1];
} tar_header;
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static long initrd_sz;
static char* initrd;
typedef int (*func_ptr)();
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static struct multiboot_boot_header_tag* tags;
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static void read_initrd(struct multiboot_boot_header_tag* tags) {
struct multiboot_tag* tag=(struct multiboot_tag*)(tags+1);
while (tag->type!=0) {
switch (tag->type) {
case MULTIBOOT_TAG_TYPE_MODULE: {
struct multiboot_tag_module* mod=(struct multiboot_tag_module*) tag;
initrd=malloc(sizeof(char)*(mod->mod_end-mod->mod_start));
initrd_sz=mod->mod_end-mod->mod_start;
memcpy(initrd,(void*)(mod->mod_start+0xC0000000),mod->mod_end-mod->mod_start);
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}
}
tag=(struct multiboot_tag*)((char*)tag+((tag->size+7)&0xFFFFFFF8));
}
}
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uint32_t getsize(const char *in) {
uint32_t size=0;
uint32_t j;
uint32_t count=1;
for (j=11;j>0;j--,count*=8) {
size+=((in[j-1]-'0')*count);
}
return size;
}
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void kmain(struct multiboot_boot_header_tag* hdr) {
tags=hdr;
cpu_init(tags);
vga_init((char*)0xC00B8000);
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read_initrd(tags);
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int pos=0;
uint32_t datapos;
tar_header* tar_hdr;
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for (int i=0;;i++) {
tar_hdr=(tar_header*)&initrd[pos];
if (tar_hdr->filename[0]=='\0') break;
uint32_t size=getsize(tar_hdr->size);
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pos+=512;
if (strcmp(&tar_hdr->filename[0],"init")==0) {
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datapos=pos;
break;
}
pos+=size;
if (pos%512!=0) {
pos+=512-(pos%512);
}
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}
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elf_header header;
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pos=datapos;
char* hdr_ptr=(char*)&header;
for (size_t i=0;i<sizeof(elf_header);i++) {
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hdr_ptr[i]=initrd[pos];
pos++;
}
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if (header.magic!=ELF_MAGIC) {
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vga_write_string("[INFO] Invalid magic number for prog.elf\n");
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} else {
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void* cr3=new_address_space();
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for (int i=0;i<header.pheader_ent_nm;i++) {
elf_pheader pheader;
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pos=(header.prog_hdr)+(header.pheader_ent_sz*i)+datapos;
char* phdr_ptr=(char*)&pheader;
for (size_t i=0;i<sizeof(elf_pheader);i++) {
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phdr_ptr[i]=initrd[pos];
pos++;
}
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char* ptr=alloc_memory(((pheader.memsz)/4096)+1);
memset(ptr,0,pheader.memsz);
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if (pheader.filesz>0) {
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pos=pheader.offset+datapos;
for (size_t i=0;i<pheader.filesz;i++) {
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ptr[i]=initrd[pos];
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pos++;
}
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}
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copy_data(cr3,ptr,pheader.memsz,(void*)pheader.vaddr);
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}
char* initrd2=alloc_memory((initrd_sz/4096)+1);
memcpy(initrd2,initrd,initrd_sz);
initrd2=put_data(cr3,initrd2,initrd_sz);
createTaskCr3Param((void*)header.entry,cr3,(uint32_t)initrd2,initrd_sz);
exit(0);
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}
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}