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#include "types.h"
#include "defs.h"
#include "param.h"
#include "mmu.h"
#include "proc.h"
#include "x86.h"
#include "traps.h"
#include "spinlock.h"
// Interrupt descriptor table (shared by all CPUs).
struct gatedesc idt[256];
extern uint vectors[]; // in vectors.S: array of 256 entry pointers
struct spinlock tickslock;
int ticks;
void
tvinit(void)
{
int i;
for(i = 0; i < 256; i++)
SETGATE(idt[i], 0, SEG_KCODE<<3, vectors[i], 0);
SETGATE(idt[T_SYSCALL], 0, SEG_KCODE<<3, vectors[T_SYSCALL], DPL_USER);
initlock(&tickslock, "time");
}
void
idtinit(void)
{
lidt(idt, sizeof(idt));
}
void
trap(struct trapframe *tf)
{
if(tf->trapno == T_SYSCALL){
if(cp->killed)
exit();
cp->tf = tf;
syscall();
if(cp->killed)
exit();
return;
}
// Increment nlock to make sure interrupts stay off
// during interrupt handler. Decrement before returning.
cpus[cpu()].nlock++;
switch(tf->trapno){
case IRQ_OFFSET + IRQ_TIMER:
if(cpu() == 0){
acquire(&tickslock);
ticks++;
wakeup(&ticks);
release(&tickslock);
}
lapic_eoi();
break;
case IRQ_OFFSET + IRQ_IDE:
ide_intr();
lapic_eoi();
break;
case IRQ_OFFSET + IRQ_KBD:
kbd_intr();
lapic_eoi();
break;
case IRQ_OFFSET + IRQ_SPURIOUS:
cprintf("spurious interrupt from cpu %d eip %x\n", cpu(), tf->eip);
lapic_eoi();
break;
default:
if(cp == 0){
// Otherwise it's our mistake.
cprintf("unexpected trap %d from cpu %d eip %x\n",
tf->trapno, cpu(), tf->eip);
panic("trap");
}
// Assume process divided by zero or dereferenced null, etc.
cprintf("pid %d %s: trap %d err %d on cpu %d eip %x -- kill proc\n",
cp->pid, cp->name, tf->trapno, tf->err, cpu(), tf->eip);
cp->killed = 1;
}
cpus[cpu()].nlock--;
// Force process exit if it has been killed and is in user space.
// (If it is still executing in the kernel, let it keep running
// until it gets to the regular system call return.)
if(cp && cp->killed && (tf->cs&3) == DPL_USER)
exit();
// Force process to give up CPU on clock tick.
// If interrupts were on while locks held, would need to check nlock.
if(cp && cp->state == RUNNING && tf->trapno == IRQ_OFFSET+IRQ_TIMER)
yield();
}
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