kernel/exception.c

   1 /* This file contains a simple exception handler.  Exceptions in user
   2  * processes are converted to signals. Exceptions in a kernel task cause
   3  * a panic.
   4  */
   5
   6 #include "kernel.h"
   7 #include <signal.h>
   8 #include "proc.h"
   9
  10 /*===========================================================================*
  11  *                              exception                                    *
  12  *===========================================================================*/
  13 PUBLIC void exception(vec_nr)
  14 unsigned vec_nr;
  15 {
  16 /* An exception or unexpected interrupt has occurred. */
  17
  18   struct ex_s {
  19         char *msg;
  20         int signum;
  21         int minprocessor;
  22   };
  23   static struct ex_s ex_data[] = {
  24         { "Divide error", SIGFPE, 86 },
  25         { "Debug exception", SIGTRAP, 86 },
  26         { "Nonmaskable interrupt", SIGBUS, 86 },
  27         { "Breakpoint", SIGEMT, 86 },
  28         { "Overflow", SIGFPE, 86 },
  29         { "Bounds check", SIGFPE, 186 },
  30         { "Invalid opcode", SIGILL, 186 },
  31         { "Coprocessor not available", SIGFPE, 186 },
  32         { "Double fault", SIGBUS, 286 },
  33         { "Copressor segment overrun", SIGSEGV, 286 },
  34         { "Invalid TSS", SIGSEGV, 286 },
  35         { "Segment not present", SIGSEGV, 286 },
  36         { "Stack exception", SIGSEGV, 286 },    /* STACK_FAULT already used */
  37         { "General protection", SIGSEGV, 286 },
  38         { "Page fault", SIGSEGV, 386 },         /* not close */
  39         { NIL_PTR, SIGILL, 0 },                 /* probably software trap */
  40         { "Coprocessor error", SIGFPE, 386 },
  41   };
  42   register struct ex_s *ep;
  43   struct proc *saved_proc;
  44
  45   /* Save proc_ptr, because it may be changed by debug statements. */
  46   saved_proc = proc_ptr;
  47
  48   ep = &ex_data[vec_nr];
  49
  50   if (vec_nr == 2) {            /* spurious NMI on some machines */
  51         kprintf("got spurious NMI\n");
  52         return;
  53   }
  54
  55   /* If an exception occurs while running a process, the k_reenter variable
  56    * will be zero. Exceptions in interrupt handlers or system traps will make
  57    * k_reenter larger than zero.
  58    */
  59   if (k_reenter == 0 && ! iskernelp(saved_proc)) {
  60         cause_sig(proc_nr(saved_proc), ep->signum);
  61         return;
  62   }
  63
  64   /* Exception in system code. This is not supposed to happen. */
  65   if (ep->msg == NIL_PTR || machine.processor < ep->minprocessor)
  66         kprintf("\nIntel-reserved exception %d\n", vec_nr);
  67   else
  68         kprintf("\n%s\n", ep->msg);
  69   kprintf("k_reenter = %d ", k_reenter);
  70   kprintf("process %d (%s), ", proc_nr(saved_proc), saved_proc->p_name);
  71   kprintf("pc = %u:0x%x", (unsigned) saved_proc->p_reg.cs,
  72   (unsigned) saved_proc->p_reg.pc);
  73
  74   panic("exception in a kernel task", NO_NUM);
  75 }
  76