mirror of
https://github.com/SmallPond/MIT6.828_OS.git
synced 2026-04-27 04:09:56 +08:00
149 lines
3.6 KiB
C
149 lines
3.6 KiB
C
#include "types.h"
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#include "defs.h"
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#include "param.h"
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#include "memlayout.h"
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#include "mmu.h"
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#include "proc.h"
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#include "x86.h"
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#include "traps.h"
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#include "spinlock.h"
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// Interrupt descriptor table (shared by all CPUs).
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struct gatedesc idt[256];
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extern uint vectors[]; // in vectors.S: array of 256 entry pointers
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struct spinlock tickslock;
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uint ticks;
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void
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tvinit(void)
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{
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int i;
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for(i = 0; i < 256; i++)
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SETGATE(idt[i], 0, SEG_KCODE<<3, vectors[i], 0);
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SETGATE(idt[T_SYSCALL], 1, SEG_KCODE<<3, vectors[T_SYSCALL], DPL_USER);
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initlock(&tickslock, "time");
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}
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void
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idtinit(void)
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{
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lidt(idt, sizeof(idt));
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}
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//PAGEBREAK: 41
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void
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trap(struct trapframe *tf)
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{
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if(tf->trapno == T_SYSCALL){
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if(myproc()->killed)
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exit();
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myproc()->tf = tf;
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syscall();
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if(myproc()->killed)
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exit();
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return;
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}
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char *mem;
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switch(tf->trapno){
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case T_IRQ0 + IRQ_TIMER:
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if(cpuid() == 0){
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acquire(&tickslock);
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ticks++;
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wakeup(&ticks);
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release(&tickslock);
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}
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if(myproc() != 0 && (tf->cs & 3) == 3){
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myproc()->ticks++;
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// 没有alarm任务的proc, 不会进入以下if,因为alarminterval为0
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if(myproc()->ticks == myproc()->alarminterval) {
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myproc()->ticks = 0;
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// 为什么不能像下面这样调用函数
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//myproc()->alarmhandler();
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tf->esp -= 4;
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// eip压栈
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*(uint *)(tf->esp) = tf->eip;
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tf->eip = (uint)myproc()->alarmhandler;
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}
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}
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lapiceoi();
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break;
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case T_IRQ0 + IRQ_IDE:
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ideintr();
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lapiceoi();
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break;
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case T_IRQ0 + IRQ_IDE+1:
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// Bochs generates spurious IDE1 interrupts.
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break;
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case T_IRQ0 + IRQ_KBD:
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kbdintr();
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lapiceoi();
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break;
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case T_IRQ0 + IRQ_COM1:
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uartintr();
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lapiceoi();
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break;
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case T_IRQ0 + 7:
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case T_IRQ0 + IRQ_SPURIOUS:
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cprintf("cpu%d: spurious interrupt at %x:%x\n",
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cpuid(), tf->cs, tf->eip);
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lapiceoi();
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break;
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// T_PGFLT = 14
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case T_PGFLT:
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// kallo或mappages执行失败，则继续执行下面的default.
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// In user space, assume process misbehaved.
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// cr2包含发生页面错误时的线性地址.
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mem = kalloc();
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if(mem != 0){
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uint va = PGROUNDDOWN(rcr2());
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memset(mem, 0, PGSIZE);
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extern int mappages(pde_t *pgdir, void *va, uint size, uint pa, int perm);
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if(mappages(myproc()->pgdir,(void *)va, PGSIZE, V2P(mem), PTE_W|PTE_U) >= 0) {
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// 全部执行成功才break;
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break;
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}
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}
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//PAGEBREAK: 13
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default:
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// tf->cs&3 不明白
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if(myproc() == 0 || (tf->cs&3) == 0){
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// In kernel, it must be our mistake.
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cprintf("unexpected trap %d from cpu %d eip %x (cr2=0x%x)\n",
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tf->trapno, cpuid(), tf->eip, rcr2());
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panic("trap");
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}
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// In user space, assume process misbehaved.
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cprintf("pid %d %s: trap %d err %d on cpu %d "
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"eip 0x%x addr 0x%x--kill proc\n",
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myproc()->pid, myproc()->name, tf->trapno,
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tf->err, cpuid(), tf->eip, rcr2());
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myproc()->killed = 1;
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}
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// Force process exit if it has been killed and is in user space.
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// (If it is still executing in the kernel, let it keep running
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// until it gets to the regular system call return.)
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if(myproc() && myproc()->killed && (tf->cs&3) == DPL_USER)
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exit();
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// Force process to give up CPU on clock tick.
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// If interrupts were on while locks held, would need to check nlock.
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if(myproc() && myproc()->state == RUNNING &&
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tf->trapno == T_IRQ0+IRQ_TIMER)
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yield();
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// Check if the process has been killed since we yielded
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if(myproc() && myproc()->killed && (tf->cs&3) == DPL_USER)
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exit();
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}
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