void install_tss(ULONG idx, UWORD kernelSS, UWORD kernelESP)
{
kprintf("TSS", "Installing TSS\n");
// install TSS descriptor
ULONG base = (ULONG)&TSS;
// install descriptor
gdt_set_descriptor(idx, base, base + sizeof(struct tss_entry),
I86_GDT_DESC_ACCESS | I86_GDT_DESC_EXEC_CODE | I86_GDT_DESC_DPL | I86_GDT_DESC_MEMORY,
0);
// initialize TSS
memset((void*)&TSS, 0, sizeof(struct tss_entry));
// set stack and segments
TSS.ss0 = kernelSS;
TSS.esp0 = kernelESP;
TSS.cs = 0x0b;
TSS.ss = 0x13;
TSS.es = 0x13;
TSS.ds = 0x13;
TSS.fs = 0x13;
TSS.gs = 0x13;
// flush tss
flush_tss(idx * sizeof(struct gdt_descriptor));
}
void init_gdt()
{
gdt_desc.limit = (sizeof(struct s_gdt_entry) * 6) - 1;
gdt_desc.base = (unsigned int)&gdt;
/* Null segment */
init_segment(0, 0, 0, 0, 0);
/*Ring 0*/
/* Code segment */
init_segment(1, BASE, LIMIT, 0xC, 0x9A);
/* Data segment */
init_segment(2, BASE, LIMIT, 0xC, 0x92);
/*Ring 3*/
/* Code segment */
init_segment(3, BASE, LIMIT, 0xC, 0xFA);
/* Data segment */
init_segment(4, BASE, LIMIT, 0xC, 0xF2);
/*TSS*/
write_tss(5, 0x10, 0);
flush_gdt();
flush_tss();
}
void install_tss (uint32_t idx, uint16_t kernelSS, uint16_t kernelESP) {
//! install TSS descriptor
uint32_t base = (uint32_t) &TSS;
//! install descriptor
gdt_set_descriptor (idx, base, base + sizeof (tss_entry),
I86_GDT_DESC_ACCESS|I86_GDT_DESC_EXEC_CODE|I86_GDT_DESC_DPL|I86_GDT_DESC_MEMORY,
0);
//! initialize TSS
memset ((void*) &TSS, 0, sizeof (tss_entry));
//! set stack and segments
TSS.ss0 = kernelSS;
TSS.esp0 = kernelESP;
TSS.cs=0x0b;
TSS.ss = 0x13;
TSS.es = 0x13;
TSS.ds = 0x13;
TSS.fs = 0x13;
TSS.gs = 0x13;
//! flush tss
flush_tss (idx * sizeof (gdt_descriptor));
}
void sched_initialize()
{
list_head.prev = &list_head;
list_head.next = &list_head;
flush_tss();
pic_register_isr(IRQ0, sched_timer);
}
void scheduler()
{
for (;;)
{
struct process *proc =
current_proc ? current_proc->next : list_head.next;
/* Find a runnable process */
while (proc == &list_head || proc->state != PROC_STATE_RUNNING)
{
if (proc != &list_head && proc->state == PROC_STATE_DEAD)
{
/* Release the dead process */
struct process *dead = proc;
proc = proc->next;
sched_remove(dead);
proc_free(dead);
}
else
{
proc = proc->next;
}
}
close_int();
current_proc = proc;
/* Update TSS */
tss.ss0 = KERNEL_DATA_SELECTOR;
tss.esp0 = proc->kernel_stack;
flush_tss();
/* Change to process virtual address space */
set_cr3(CAST_VIRTUAL_TO_PHYSICAL(proc->page_dir));
if (!proc->context)
init_context(proc);
switch_kcontext(&sched_context, proc->context);
/* Call schedule task */
if (sched_task)
{
sched_task(current_proc);
sched_task = NULL;
}
}
}
void install_tss() {
uint32_t base = (uint32_t) &tss;
gdt_set_entry(5, base, base + sizeof(tss_t), 0xE9);
memset((void *) base, 0, sizeof(tss_t));
tss.esp0 = 0;
tss.ss0 = 0x10;
tss.cs = 0x0B;
tss.ss = 0x13;
tss.es = 0x13;
tss.ds = 0x13;
tss.fs = 0x13;
tss.gs = 0x13;
flush_tss();
}
static void init_gdt(){
gdt_ptr.limit = (sizeof(gdt_entry_t) * 7) - 1;
gdt_ptr.base = (unsigned int) &gdt_entries;
gdt_set_gate(0, 0, 0, 0, 0);
gdt_set_gate(1, 0, 0xFFFFFFFF, 0x9A, 0xCF);
gdt_set_gate(2, 0, 0xFFFFFFFF, 0x92, 0xCF);
gdt_set_gate(3, 0, 0xFFFFFFFF, 0xFA, 0xCF);
gdt_set_gate(4, 0, 0xFFFFFFFF, 0xF2, 0xCF);
write_tss(5, 0x10, stack_hold);
gdt_set_gate(6, 0, 0xFFFFF, 0x92, 0x0);
gdt_set_gate(7, 0, 0xFFFFF, 0x9A, 0x0);
gdt_flush((unsigned int) &gdt_ptr);
flush_tss();
}
