Author: kib
Date: Mon Aug 21 15:44:57 2017
New Revision: 322755
URL: https://svnweb.freebsd.org/changeset/base/322755
Log:
MFC r322667,r322706:
Improve i386 #UD low-level kdtrace hook.
Approved by: re (marius)
Modified:
stable/10/sys/i386/i386/exception.s
Directory Properties:
stable/10/ (props changed)
Modified: stable/10/sys/i386/i386/exception.s
==============================================================================
--- stable/10/sys/i386/i386/exception.s Mon Aug 21 15:39:48 2017
(r322754)
+++ stable/10/sys/i386/i386/exception.s Mon Aug 21 15:44:57 2017
(r322755)
@@ -185,21 +185,29 @@ calltrap:
#ifdef KDTRACE_HOOKS
SUPERALIGN_TEXT
IDTVEC(ill)
- /* Check if there is no DTrace hook registered. */
- cmpl $0,dtrace_invop_jump_addr
+ /*
+ * Check if a DTrace hook is registered. The default (data) segment
+ * cannot be used for this since %ds is not known good until we
+ * verify that the entry was from kernel mode.
+ */
+ cmpl $0,%ss:dtrace_invop_jump_addr
je norm_ill
- /* Check if this is a user fault. */
- cmpl $GSEL_KPL, 4(%esp) /* Check the code segment. */
-
- /* If so, just handle it as a normal trap. */
+ /*
+ * Check if this is a user fault. If so, just handle it as a normal
+ * trap.
+ */
+ cmpl $GSEL_KPL, 4(%esp) /* Check the code segment */
jne norm_ill
+ testl $PSL_VM, 8(%esp) /* and vm86 mode. */
+ jnz norm_ill
/*
* This is a kernel instruction fault that might have been caused
* by a DTrace provider.
*/
- pushal /* Push all registers onto the stack. */
+ pushal
+ cld
/*
* Set our jump address for the jump back in the event that
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