/**
* Install the GDT.
* Set both code and data base address 0, limit 4GB.
*/
void install_gdt() {
_gdtr.limit = sizeof(union gdt_desc) * MAX_DESCRIPTORS;
_gdtr.base = (uint32_t) _gdt;
// null descriptor.
set_gdt_desc(0, 0, 0, 0, 0);
// code descriptor.
set_gdt_desc(1, 0, 0xffffffff, 0b10011010, 0b11001111);
// data descriptor.
set_gdt_desc(2, 0, 0xffffffff, 0b10010010, 0b11001111);
__asm__ volatile ("lgdt _gdtr");
}
void gdt_install(){
// null desc
set_gdt_desc(0, 0, 0, 0, 0);
// code descriptor, full 4 gigs and 4 kilobyte granularity
set_gdt_desc(1, 0, 0xFFFFFFFF, 0x9A, 0xCF);
// data descriptor, same as above
set_gdt_desc(2, 0, 0xFFFFFFFF, 0x92, 0xCF);
// user code and data descriptors
set_gdt_desc(3, 0, 0xFFFFFFFF, 0xFA, 0xCF);
set_gdt_desc(4, 0, 0xFFFFFFFF, 0xF2, 0xCF);
// flush the gdt into memory
flush_gdt();
}
int do_fork(unsigned int esp)
{
struct task_struct *tsk;
struct regs *reg = (struct regs *)(esp + 4);
int pid;
DbgPrint("cs: 0x%x, eip: 0x%x, ds: 0x%x, eax: 0x%x, ebx: 0x%x\n"
"ecx: 0x%x, es: 0x%x, fs: 0x%x, eflags: 0x%x\n"
"ss: 0x%x, esp: 0x%x, orig_eax: 0x%x\n",
reg->orig_cs, reg->orig_eip, reg->ds, reg->eax, reg->ebx,
reg->ecx, reg->es, reg->fs, reg->eflags,
reg->ss, reg->esp, reg->error_code);
pid = get_pid();
if (pid == -1) {
printk("Get new pid failed.\n");
return -1;
}
DbgPrint("Get new pid: %d\n", pid);
tsk = (struct task_struct *)alloc_page(0);
if (!tsk) {
DbgPrint("Alloc tsk page failed.\n");
return -1;
}
printk("Alloc task_struct page at: 0x%x\n", tsk);
*tsk = *current;
tsk->tss.prev_task_link = 0;
tsk->tss.esp0 = (unsigned int)tsk + PAGE_SIZE - 4;
tsk->tss.ss0 = KERNEL_DATA_SEL;
tsk->tss.esp1 = 0;
tsk->tss.ss1 = 0;
tsk->tss.esp2 = 0;
tsk->tss.ss2 = 0;
tsk->tss.eip = reg->orig_eip;
tsk->tss.eflags = reg->eflags;
tsk->tss.eax = 0;
tsk->tss.ebx = reg->ebx;
tsk->tss.ecx = reg->ecx;
tsk->tss.edx = reg->edx;
tsk->tss.esp = reg->esp;
tsk->tss.ebp = reg->ebp;
tsk->tss.esi = reg->esi;
tsk->tss.edi = reg->edi;
tsk->tss.es = reg->es;
tsk->tss.cs = reg->orig_cs;
tsk->tss.ss = reg->ss;
tsk->tss.ds = reg->ds;
tsk->tss.fs = reg->fs;
tsk->tss.gs = USER_DATA_SEL;
tsk->tss.ldt_sel = LDT_SEL(pid);
tsk->tss.io_map = 0x80000000;
tsk->pid = pid;
tsk->tss_sel = TSS_SEL(pid);
tsk->ldt_sel = LDT_SEL(pid);
tsk->state = TASK_RUNABLE;
tsk->counter = DEFAULT_COUNTER;
tsk->priority = DEFAULT_PRIORITY;
set_tss_desc(new_gdt, (unsigned int)&(tsk->tss), TSS_LIMIT, TSS_TYPE, TSS_IDX(pid));
set_ldt_desc(new_gdt, (unsigned int)&(tsk->ldt), LDT_LIMIT, LDT_TYPE, LDT_IDX(pid));
set_gdt_desc(tsk->ldt, CODE_BASE, USER_CODE_LIMIT, USER_CODE_TYPE, 1);
set_gdt_desc(tsk->ldt, DATA_BASE, USER_DATA_LIMIT, USER_DATA_TYPE, 2);
//setup_task_pages(tsk);
copy_page_tables(tsk);
list_add_tail(&(tsk->list), &task_list_head);
/*
printk("cs: 0x%x, eip: 0x%x, ds: 0x%x, eax: 0x%x, ebx: 0x%x\n"
"ecx: 0x%x, es: 0x%x, fs: 0x%x, eflags: 0x%x\n"
"ss: 0x%x, esp: 0x%x\n",
tsk->tss.cs, tsk->tss.eip, tsk->tss.ds, tsk->tss.eax, tsk->tss.ebx,
tsk->tss.ecx, tsk->tss.es, tsk->tss.fs, tsk->tss.eflags,
tsk->tss.ss, tsk->tss.esp);
*/
printk("task esp0: 0x%x, esp: 0x%x\n", tsk->tss.esp0, tsk->tss.esp);
return pid;
}
int sys_creat_task(unsigned int eip)
{
struct task_struct *tsk;
int pid;
pid = get_pid();
if (pid == -1) {
DbgPrint("Get pid failed.\n");
return -1;
}
printk("Get new pid: %d\n", pid);
tsk = (struct task_struct *)alloc_page(0);
if (!tsk) {
DbgPrint("Alloc tsk page failed.\n");
return -1;
}
DbgPrint("Alloc tsk page at: 0x%x\n", tsk);
*tsk = *current;
tsk->tss.prev_task_link = 0;
tsk->tss.esp0 = (unsigned int)tsk + PAGE_SIZE;
tsk->tss.ss0 = KERNEL_DATA_SEL;
tsk->tss.esp1 = 0;
tsk->tss.ss1 = 0;
tsk->tss.esp2 = 0;
tsk->tss.ss2 = 0;
tsk->tss.eip = eip;
tsk->tss.eflags = 0x200;
tsk->tss.eax = 0;
tsk->tss.ebx = 0;
tsk->tss.ecx = 0;
tsk->tss.edx = 0;
tsk->tss.esp = (unsigned int)alloc_page(0) + PAGE_SIZE;
DbgPrint("Alloc tsk ring3 stack at 0x%x\n", tsk->tss.esp - PAGE_SIZE);
tsk->tss.ebp = 0;
tsk->tss.esi = 0;
tsk->tss.edi = 0;
tsk->tss.es = USER_DATA_SEL;
tsk->tss.cs = USER_CODE_SEL;
tsk->tss.ss = USER_DATA_SEL;
tsk->tss.ds = USER_DATA_SEL;
tsk->tss.fs = USER_DATA_SEL;
tsk->tss.gs = USER_DATA_SEL;
tsk->tss.ldt_sel = LDT_SEL(pid);
tsk->tss.io_map = 0x80000000;
tsk->pid = pid;
tsk->tss_sel = TSS_SEL(pid);
tsk->ldt_sel = LDT_SEL(pid);
tsk->state = TASK_RUNABLE;
tsk->counter = DEFAULT_COUNTER;
tsk->priority = DEFAULT_PRIORITY;
set_tss_desc(new_gdt, (unsigned int)&(tsk->tss), TSS_LIMIT, TSS_TYPE, TSS_IDX(pid));
set_ldt_desc(new_gdt, (unsigned int)&(tsk->ldt), LDT_LIMIT, LDT_TYPE, LDT_IDX(pid));
set_gdt_desc(tsk->ldt, CODE_BASE, USER_CODE_LIMIT, USER_CODE_TYPE, 1);
set_gdt_desc(tsk->ldt, DATA_BASE, USER_DATA_LIMIT, USER_DATA_TYPE, 2);
setup_task_pages(tsk);
//copy_page_tables(tsk);
list_add_tail(&(tsk->list), &task_list_head);
return 0;
}
