xv6-cs450/trap.c

100 lines
2.2 KiB
C
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#include "types.h"
#include "param.h"
#include "mmu.h"
#include "proc.h"
#include "defs.h"
#include "x86.h"
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#include "traps.h"
#include "syscall.h"
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struct gatedesc idt[256];
extern uint vectors[]; /* vectors.S, array of 256 entry point addresses */
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extern void trapenter(void);
extern void trapenter1(void);
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void
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tvinit(void)
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{
int i;
for(i = 0; i < 256; i++){
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SETGATE(idt[i], 1, SEG_KCODE << 3, vectors[i], 0);
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}
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SETGATE(idt[T_SYSCALL], T_SYSCALL, SEG_KCODE << 3, vectors[48], 3);
}
void
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idtinit(void)
{
lidt(idt, sizeof idt);
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}
void
trap(struct trapframe *tf)
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{
int v = tf->trapno;
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if(v == T_SYSCALL){
struct proc *cp = curproc[cpu()];
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int num = cp->tf->eax;
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if(cp == 0)
panic("syscall with no proc");
if(cp->killed)
proc_exit();
cp->tf = tf;
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syscall();
if(cp != curproc[cpu()])
panic("trap ret wrong curproc");
if(cp->state != RUNNING)
panic("trap ret but not RUNNING");
if(tf != cp->tf)
panic("trap ret wrong tf");
if(cpus[cpu()].nlock){
cprintf("num=%d\n", num);
panic("syscall returning locks held");
}
if((read_eflags() & FL_IF) == 0)
panic("syscall returning but FL_IF clear");
if(read_esp() < (uint)cp->kstack ||
read_esp() >= (uint)cp->kstack + KSTACKSIZE)
panic("trap ret esp wrong");
if(cp->killed)
proc_exit();
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return;
}
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if(v == (IRQ_OFFSET + IRQ_TIMER)){
struct proc *cp = curproc[cpu()];
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lapic_timerintr();
if(cpus[cpu()].nlock)
panic("timer interrupt while holding a lock");
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if((read_eflags() & FL_IF) == 0)
panic("timer interrupt but interrupts now disabled");
if(cp){
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// Force process exit if it has been killed
// and the interrupt came from user space.
// (If the kernel was executing at time of interrupt,
// don't kill the process. Let the process get back
// out to its regular system call return.)
if((tf->cs&3) == 3 && cp->killed)
proc_exit();
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// Force process to give up CPU and let others run.
if(cp->state == RUNNING)
yield();
}
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return;
}
if(v == (IRQ_OFFSET + IRQ_IDE)){
ide_intr();
return;
}
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// XXX probably ought to lgdt on trap return
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return;
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}