1 #include "types.h"
2 #include "defs.h"
3 #include "param.h"
4 #include "memlayout.h"
5 #include "mmu.h"
6 #include "proc.h"
7 #include "x86.h"
8 #include "traps.h"
9 #include "spinlock.h"
10
11 // Interrupt descriptor table (shared by all CPUs).
12 struct gatedesc idt[256];
13 extern uint vectors[]; // in vectors.S: array of 256 entry pointers
14 struct spinlock tickslock;
15 uint ticks;
16
17 void
tvinit(void)18 tvinit(void)
19 {
20 int i;
21
22 for(i = 0; i < 256; i++)
23 SETGATE(idt[i], 0, SEG_KCODE<<3, vectors[i], 0);
24 SETGATE(idt[T_SYSCALL], 1, SEG_KCODE<<3, vectors[T_SYSCALL], DPL_USER);
25
26 initlock(&tickslock, "time");
27 }
28
29 void
idtinit(void)30 idtinit(void)
31 {
32 lidt(idt, sizeof(idt));
33 }
34
35 //PAGEBREAK: 41
36 void
trap(struct trapframe * tf)37 trap(struct trapframe *tf)
38 {
39 if(tf->trapno == T_SYSCALL){
40 if(myproc()->killed)
41 exit();
42 myproc()->tf = tf;
43 syscall();
44 if(myproc()->killed)
45 exit();
46 return;
47 }
48
49 switch(tf->trapno){
50 case T_IRQ0 + IRQ_TIMER:
51 if(cpuid() == 0){
52 acquire(&tickslock);
53 ticks++;
54 wakeup(&ticks);
55 release(&tickslock);
56 }
57 lapiceoi();
58 break;
59 case T_IRQ0 + IRQ_IDE:
60 ideintr();
61 lapiceoi();
62 break;
63 case T_IRQ0 + IRQ_IDE+1:
64 // Bochs generates spurious IDE1 interrupts.
65 break;
66 case T_IRQ0 + IRQ_KBD:
67 kbdintr();
68 lapiceoi();
69 break;
70 case T_IRQ0 + IRQ_COM1:
71 uartintr();
72 lapiceoi();
73 break;
74 case T_IRQ0 + 7:
75 case T_IRQ0 + IRQ_SPURIOUS:
76 cprintf("cpu%d: spurious interrupt at %x:%x\n",
77 cpuid(), tf->cs, tf->eip);
78 lapiceoi();
79 break;
80
81 //PAGEBREAK: 13
82 default:
83 if(myproc() == 0 || (tf->cs&3) == 0){
84 // In kernel, it must be our mistake.
85 cprintf("unexpected trap %d from cpu %d eip %x (cr2=0x%x)\n",
86 tf->trapno, cpuid(), tf->eip, rcr2());
87 panic("trap");
88 }
89 // In user space, assume process misbehaved.
90 cprintf("pid %d %s: trap %d err %d on cpu %d "
91 "eip 0x%x addr 0x%x--kill proc\n",
92 myproc()->pid, myproc()->name, tf->trapno,
93 tf->err, cpuid(), tf->eip, rcr2());
94 myproc()->killed = 1;
95 }
96
97 // Force process exit if it has been killed and is in user space.
98 // (If it is still executing in the kernel, let it keep running
99 // until it gets to the regular system call return.)
100 if(myproc() && myproc()->killed && (tf->cs&3) == DPL_USER)
101 exit();
102
103 // Force process to give up CPU on clock tick.
104 // If interrupts were on while locks held, would need to check nlock.
105 if(myproc() && myproc()->state == RUNNING &&
106 tf->trapno == T_IRQ0+IRQ_TIMER)
107 yield();
108
109 // Check if the process has been killed since we yielded
110 if(myproc() && myproc()->killed && (tf->cs&3) == DPL_USER)
111 exit();
112 }
113