[src/trunk]: src/sys/arch/i386/i386 handle IDT-less case just as linux does

[itojun <itojun%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/40e40da872a2
branches:  trunk
changeset: 533207:40e40da872a2
user:      itojun <itojun%NetBSD.org@localhost>
date:      Mon Jun 24 10:10:17 2002 +0000

description:
handle IDT-less case just as linux does

diffstat:

 sys/arch/i386/i386/vm86.c |  21 +++++++++++++--------
 1 files changed, 13 insertions(+), 8 deletions(-)

diffs (49 lines):

diff -r 31f14ddf241c -r 40e40da872a2 sys/arch/i386/i386/vm86.c
--- a/sys/arch/i386/i386/vm86.c Mon Jun 24 10:10:16 2002 +0000
+++ b/sys/arch/i386/i386/vm86.c Mon Jun 24 10:10:17 2002 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vm86.c,v 1.26 2002/03/29 17:07:06 christos Exp $       */
+/*     $NetBSD: vm86.c,v 1.27 2002/06/24 10:10:17 itojun Exp $ */
 
 /*-
  * Copyright (c) 1996 The NetBSD Foundation, Inc.
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vm86.c,v 1.26 2002/03/29 17:07:06 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vm86.c,v 1.27 2002/06/24 10:10:17 itojun Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -158,8 +158,17 @@
         * Fetch intr handler info from "real-mode" IDT based at addr 0 in
         * the user address space.
         */
-       if (copyin((caddr_t)(intrno * sizeof(ihand)), &ihand, sizeof(ihand)))
-               goto bad;
+       if (copyin((caddr_t)(intrno * sizeof(ihand)), &ihand, sizeof(ihand))) {
+               /*
+                * No IDT!  What Linux does here is simply call back into
+                * userspace with the VM86_INTx arg as if it was a revectored
+                * int.  Some applications rely on this (i.e. dynamically
+                * emulate an IDT), and those that don't will crash in a
+                * spectacular way, I suppose.
+                *      --thorpej%netbsd.org@localhost
+                */
+               goto vector;
+       }
 
        /*
         * Otherwise, push flags, cs, eip, and jump to handler to
@@ -181,10 +190,6 @@
 vector:
        vm86_return(p, VM86_MAKEVAL(VM86_INTx, intrno));
        return;
-
-bad:
-       vm86_return(p, VM86_UNKNOWN);
-       return;
 }
 
 void