void gdt_install(void)
{
gdt_ptr.limit = sizeof(gdt) - 1;
gdt_ptr.base = (unsigned int)&gdt;
memset(gdt, 0, sizeof(gdt));
// Kernel space
gdt_set_gate(&gdt[GDT_KERNEL_CS].memseg, 0, 0xFFFFF, 0, 1);
gdt_set_gate(&gdt[GDT_KERNEL_DS].memseg, 0, 0xFFFFF, 0, 0);
// User space
gdt_set_gate(&gdt[GDT_USER_CS].memseg, 0, 0xFFFFF, 3, 1);
gdt_set_gate(&gdt[GDT_USER_DS].memseg, 0, 0xFFFFF, 3, 0);
// IRQ, faults, thread
gdt_set_tss(&gdt[GDT_HW_INT_TSS].tss, &kernel_tasks.tss_for_hw_int);
gdt_set_tss(&gdt[GDT_PAGE_FAULT_TSS].tss, &kernel_tasks.tss_for_page_fault);
gdt_set_tss(&gdt[GDT_DOUBLE_FAULT_TSS].tss, &kernel_tasks.tss_for_double_fault);
gdt_set_tss(&gdt[GDT_ACTIVE_THREAD_TSS].tss, &kernel_tasks.tss_for_active_thread);
asm_gdt_flush(&gdt_ptr);
asm_set_tr(8 * GDT_ACTIVE_THREAD_TSS);
}
/* This one get's called from the architecture-specific interrupt
* handlers, which do fiddling like EOIs (i386).
*/
isf_t* __attribute__((fastcall)) interrupts_callback(uint32_t intr, isf_t* regs) {
struct interrupt_reg reg = interrupt_handlers[intr];
task_t* task = scheduler_get_current();
#ifdef INTERRUPTS_DEBUG
debug("state before:\n");
dump_isf(LOG_DEBUG, regs);
#endif
if(reg.handler) {
if(reg.can_reent) {
interrupts_enable();
}
reg.handler(regs);
}
#ifdef ENABLE_PICOTCP
if(intr == IRQ(0)) {
net_tick();
}
#endif
// Run scheduler every 100th tick, or when task yields
if((intr == IRQ(0) && !(timer_get_tick() % 100)) || (task && task->interrupt_yield)) {
if((task && task->interrupt_yield)) {
task->interrupt_yield = false;
}
task_t* new_task = scheduler_select(regs);
if(new_task && new_task->state) {
#ifdef INTERRUPTS_DEBUG
debug("state after (task selection):\n");
dump_isf(LOG_DEBUG, new_task->state);
#endif
gdt_set_tss(new_task->kernel_stack + PAGE_SIZE);
return new_task->state;
}
}
#ifdef INTERRUPTS_DEBUG
debug("state after:\n");
dump_isf(LOG_DEBUG, regs);
#endif
return regs;
}
void gdt_init()
{
memset(&gdt_entries, 0, sizeof(gdt_entries));
gdt_set_gate(0, 0, 0, 0, 0); // 0x0 Null segment
gdt_set_gate(1, 0, 0xFFFF, 0x98, 0x20); // 0x8 Kernel Code segment
gdt_set_gate(2, 0, 0xFFFF, 0x90, 0x00); // 0x10 Kernel Data segment
gdt_set_gate(3, 0, 0xFFFF, 0xF8, 0x20); // 0x18 User mode code segment
gdt_set_gate(4, 0, 0xFFFF, 0xF0, 0x00); // 0x20 User mode data segment
gdt_set_tss(); // 0x28 TSS64
gdt_ptr.limit = sizeof(gdt_entries) - 1;
gdt_ptr.base = (u64)&gdt_entries;
gdt_flush(&gdt_ptr);
tss_flush();
}