Module Name: src
Committed By: maxv
Date: Wed Jun 14 17:21:04 UTC 2017
Modified Files:
src/sys/arch/i386/i386: i386_trap.S
Log Message:
Disable interrupts for T_NMI (inline calltrap). Note that there's still a
way to evade the NMI mode here, if a segment register faults in
INTRFASTEXIT; but we don't care. I didn't test this change, but it seems
fine enough.
To generate a diff of this commit:
cvs rdiff -u -r1.7 -r1.8 src/sys/arch/i386/i386/i386_trap.S
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/i386/i386/i386_trap.S
diff -u src/sys/arch/i386/i386/i386_trap.S:1.7 src/sys/arch/i386/i386/i386_trap.S:1.8
--- src/sys/arch/i386/i386/i386_trap.S:1.7 Wed Jun 14 17:02:16 2017
+++ src/sys/arch/i386/i386/i386_trap.S Wed Jun 14 17:21:04 2017
@@ -1,4 +1,4 @@
-/* $NetBSD: i386_trap.S,v 1.7 2017/06/14 17:02:16 maxv Exp $ */
+/* $NetBSD: i386_trap.S,v 1.8 2017/06/14 17:21:04 maxv Exp $ */
/*
* Copyright 2002 (c) Wasabi Systems, Inc.
@@ -66,7 +66,7 @@
#if 0
#include <machine/asm.h>
-__KERNEL_RCSID(0, "$NetBSD: i386_trap.S,v 1.7 2017/06/14 17:02:16 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: i386_trap.S,v 1.8 2017/06/14 17:21:04 maxv Exp $");
#endif
/*
@@ -98,11 +98,26 @@ IDTVEC(trap01)
BPTTRAP(T_TRCTRAP)
IDTVEC_END(trap01)
+/*
+ * Non Maskable Interrupts are a special case: they can be triggered even
+ * with interrupts disabled, and once triggered they block further NMIs
+ * until an 'iret' instruction is executed.
+ *
+ * Therefore we don't enable interrupts, because the CPU could switch to
+ * another LWP, call 'iret' and unintentionally leave the NMI mode.
+ */
IDTVEC(trap02)
pushl $0
pushl $(T_NMI)
INTRENTRY
- jmp _C_LABEL(calltrap)
+
+ addl $1,CPUVAR(NTRAP) /* statistical info */
+ adcl $0,CPUVAR(NTRAP)+4
+ pushl %esp
+ call _C_LABEL(trap)
+ addl $4,%esp
+
+ INTRFASTEXIT
IDTVEC_END(trap02)
IDTVEC(trap03)
