exception.c

一个简单的操作系统minix的核心代码

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				src/kernel/exception.c	 	 
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07500	/* This file contains a simple exception handler.  Exceptions in user
07501	 * processes are converted to signals.  Exceptions in the kernel, MM and
07502	 * FS cause a panic.
07503	 */
07504	
07505	#include "kernel.h"
07506	#include <signal.h>
07507	#include "proc.h"
07508	
07509	/*==========================================================================*
07510	 *                              exception                                   *
07511	 *==========================================================================*/
07512	PUBLIC void exception(vec_nr)
07513	unsigned vec_nr;
07514	{
07515	/* An exception or unexpected interrupt has occurred. */
07516	
07517	  struct ex_s {
07518	        char *msg;
07519	        int signum;
07520	        int minprocessor;
07521	  };
07522	  static struct ex_s ex_data[] = {
07523	        "Divide error", SIGFPE, 86,
07524	        "Debug exception", SIGTRAP, 86,
07525	        "Nonmaskable interrupt", SIGBUS, 86,
07526	        "Breakpoint", SIGEMT, 86,
07527	        "Overflow", SIGFPE, 86,
07528	        "Bounds check", SIGFPE, 186,
07529	        "Invalid opcode", SIGILL, 186,
07530	        "Coprocessor not available", SIGFPE, 186,
07531	        "Double fault", SIGBUS, 286,
07532	        "Copressor segment overrun", SIGSEGV, 286,
07533	        "Invalid TSS", SIGSEGV, 286,
07534	        "Segment not present", SIGSEGV, 286,
07535	        "Stack exception", SIGSEGV, 286,        /* STACK_FAULT already used */
07536	        "General protection", SIGSEGV, 286,
07537	        "Page fault", SIGSEGV, 386,             /* not close */
07538	        NIL_PTR, SIGILL, 0,                     /* probably software trap */
07539	        "Coprocessor error", SIGFPE, 386,
07540	  };
07541	  register struct ex_s *ep;
07542	  struct proc *saved_proc;
07543	
07544	  saved_proc= proc_ptr; /* Save proc_ptr, because it may be changed by debug 
07545	                         * statements.
07546	                         */
07547	
07548	  ep = &ex_data[vec_nr];
07549	
07550	  if (vec_nr == 2) {            /* spurious NMI on some machines */
07551	        printf("got spurious NMI\n");
07552	        return;
07553	  }
07554	
07555	  if (k_reenter == 0 && isuserp(saved_proc)) {
07556	        unlock();               /* this is protected like sys_call() */
07557	        cause_sig(proc_number(saved_proc), ep->signum);
07558	        return;
07559	  }
07560	
07561	  /* This is not supposed to happen. */
07562	  if (ep->msg == NIL_PTR || processor < ep->minprocessor)
07563	        printf("\nIntel-reserved exception %d\n", vec_nr);
07564	  else
07565	        printf("\n%s\n", ep->msg);
07566	  printf("process number %d, pc = 0x%04x:0x%08x\n",
07567	        proc_number(saved_proc),
07568	        (unsigned) saved_proc->p_reg.cs,
07569	        (unsigned) saved_proc->p_reg.pc);
07570	  panic("exception in system code", NO_NUM);
07571	}