Initial revision

kernel/exception.c

@@ -0,0 +1,88 @@
+/* This file contains a simple exception handler.  Exceptions in user
+ * processes are converted to signals.  Exceptions in the kernel, MM and
+ * FS cause a panic.
+ *
+ * Changes:
+ *   Sep 28, 2004:	skip_stop_sequence on exceptions in system processes
+ */
+
+#include "kernel.h"
+#include <signal.h>
+#include "proc.h"
+
+/*==========================================================================*
+ *				exception				    *
+ *==========================================================================*/
+PUBLIC void exception(vec_nr)
+unsigned vec_nr;
+{
+/* An exception or unexpected interrupt has occurred. */
+
+  struct ex_s {
+	char *msg;
+	int signum;
+	int minprocessor;
+  };
+  static struct ex_s ex_data[] = {
+	"Divide error", SIGFPE, 86,
+	"Debug exception", SIGTRAP, 86,
+	"Nonmaskable interrupt", SIGBUS, 86,
+	"Breakpoint", SIGEMT, 86,
+	"Overflow", SIGFPE, 86,
+	"Bounds check", SIGFPE, 186,
+	"Invalid opcode", SIGILL, 186,
+	"Coprocessor not available", SIGFPE, 186,
+	"Double fault", SIGBUS, 286,
+	"Copressor segment overrun", SIGSEGV, 286,
+	"Invalid TSS", SIGSEGV, 286,
+	"Segment not present", SIGSEGV, 286,
+	"Stack exception", SIGSEGV, 286,	/* STACK_FAULT already used */
+	"General protection", SIGSEGV, 286,
+	"Page fault", SIGSEGV, 386,		/* not close */
+	NIL_PTR, SIGILL, 0,			/* probably software trap */
+	"Coprocessor error", SIGFPE, 386,
+  };
+  register struct ex_s *ep;
+  struct proc *saved_proc;
+
+  /* Save proc_ptr, because it may be changed by debug statements. */
+  saved_proc = proc_ptr;	
+
+  ep = &ex_data[vec_nr];
+
+  if (vec_nr == 2) {		/* spurious NMI on some machines */
+	kprintf("got spurious NMI\n",NO_ARG);
+	return;
+  }
+
+  if (k_reenter == 0 && isuserp(saved_proc)) {
+	unlock();		/* this is protected like sys_call() */
+	cause_sig(proc_number(saved_proc), ep->signum);
+	return;
+  }
+
+  /* Exception in system code. This is not supposed to happen. */
+  if (ep->msg == NIL_PTR || processor < ep->minprocessor)
+	kprintf("\nIntel-reserved exception %d\n", vec_nr);
+  else
+	kprintf("\n%s\n", karg(ep->msg));
+  kprintf("process number %d", proc_number(saved_proc));
+  kprintf("pc = %d:",  (unsigned) saved_proc->p_reg.cs);
+  kprintf("%d\n", (unsigned) saved_proc->p_reg.pc);
+
+  /* If the exception originates in the kernel, shut down MINIX. Otherwise,
+   * kill the process that caused it. If MINIX is shut down and the stop 
+   * sequence is skipped, the kprintf() output cannot be flushed by the TTY
+   * driver. This leaves the user with a hanging system without proper 
+   * notification ...   
+   */
+  if (istaskp(saved_proc)) {			/* serious problem */
+  	skip_stop_sequence = TRUE;		/* directly shutdown */
+  	panic("exception in a kernel task", NO_NUM);
+  } else {
+  	clear_proc(saved_proc->p_nr);
+  	kprintf("%s was killed by MINIX due to an exception", 
+  		karg(saved_proc->p_name)); 
+  }
+}
+