os/kernel/cpu/i386/tasking_helpers_c.c
2020-07-23 11:50:23 -05:00

62 lines
1.5 KiB
C

#include "../../tasking.h"
#include "../paging.h"
#include "../tasking_helpers.h"
#include "../../pmem.h"
#include <stddef.h>
static void** kstacks=(void*)0xC8000000;
static char kstack_bmap[(218*1024)/8]={0};
static char get_bmap_bit(size_t index) {
size_t byte=index/8;
size_t bit=index%8;
char entry=kstack_bmap[byte];
return (entry&(1<<bit))>0;
}
static void set_bmap_bit(size_t index) {
size_t byte=index/8;
size_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;
}
}
if (num==-1) {
return -1;
}
set_bmap_bit(num);
map_pages(((char*)kstacks+num*0x1000),pmem_alloc(1),1,1,1);
return num;
}
void setup_kstack(Thread* thread,void* param1,void* param2,char kmode,void* eip) {
void* old_cr3=get_cr3();
size_t kstack_num=new_kstack();
load_address_space(thread->cr3);
if (kmode) {
size_t top_idx=(1024*(kstack_num+1));
thread->kernel_esp=((void*)(&kstacks[top_idx-5]));
thread->kernel_esp_top=thread->kernel_esp;
kstacks[top_idx-1]=(void*)eip;
} else {
size_t top_idx=(1024*(kstack_num+1));
thread->kernel_esp=((void*)(&kstacks[top_idx-7]));
thread->kernel_esp_top=thread->kernel_esp;
void** user_stack=(void**)(((char*)alloc_pages(2))+0x2000);
user_stack-=2;
user_stack[0]=param1;
user_stack[1]=param2;
kstacks[top_idx-3]=(void*)task_init;
kstacks[top_idx-2]=(void*)user_stack;
kstacks[top_idx-1]=(void*)eip;
}
load_address_space(old_cr3);
}