svn commit: r236567 - in head/sys/cddl/dev/dtrace: amd64 i386

[George V. Neville-Neil]

Author: gnn
Date: Mon Jun  4 16:15:40 2012
New Revision: 236567
URL: http://svn.freebsd.org/changeset/base/236567

Log:
  Integrate a fix for a very odd signal delivery problem found
  by Bryan Cantril and others in the Solaris/Illumos version of DTrace.
  
  Obtained from: https://www.illumos.org/issues/789
  MFC after:	2 weeks

Modified:
  head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c
  head/sys/cddl/dev/dtrace/i386/dtrace_subr.c

Modified: head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c
==============================================================================
--- head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c	Mon Jun  4 16:04:01 2012	(r236566)
+++ head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c	Mon Jun  4 16:15:40 2012	(r236567)
@@ -27,6 +27,10 @@
  * Use is subject to license terms.
  */
 
+/*
+ * Copyright (c) 2011, Joyent, Inc. All rights reserved.
+ */
+
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/types.h>
@@ -297,14 +301,15 @@ dtrace_safe_defer_signal(void)
 	}
 
 	/*
-	 * If we've executed the original instruction, but haven't performed
-	 * the jmp back to t->t_dtrace_npc or the clean up of any registers
-	 * used to emulate %rip-relative instructions in 64-bit mode, do that
-	 * here and take the signal right away. We detect this condition by
-	 * seeing if the program counter is the range [scrpc + isz, astpc).
+	 * If we have executed the original instruction, but we have performed
+	 * neither the jmp back to t->t_dtrace_npc nor the clean up of any
+	 * registers used to emulate %rip-relative instructions in 64-bit mode,
+	 * we'll save ourselves some effort by doing that here and taking the
+	 * signal right away.  We detect this condition by seeing if the program
+	 * counter is the range [scrpc + isz, astpc).
 	 */
-	if (t->t_dtrace_astpc - rp->r_pc <
-	    t->t_dtrace_astpc - t->t_dtrace_scrpc - isz) {
+	if (rp->r_pc >= t->t_dtrace_scrpc + isz &&
+	    rp->r_pc < t->t_dtrace_astpc) {
 #ifdef __amd64
 		/*
 		 * If there is a scratch register and we're on the

Modified: head/sys/cddl/dev/dtrace/i386/dtrace_subr.c
==============================================================================
--- head/sys/cddl/dev/dtrace/i386/dtrace_subr.c	Mon Jun  4 16:04:01 2012	(r236566)
+++ head/sys/cddl/dev/dtrace/i386/dtrace_subr.c	Mon Jun  4 16:15:40 2012	(r236567)
@@ -27,6 +27,10 @@
  * Use is subject to license terms.
  */
 
+/*
+ * Copyright (c) 2011, Joyent, Inc. All rights reserved.
+ */
+
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/types.h>
@@ -298,14 +302,15 @@ dtrace_safe_defer_signal(void)
 	}
 
 	/*
-	 * If we've executed the original instruction, but haven't performed
-	 * the jmp back to t->t_dtrace_npc or the clean up of any registers
-	 * used to emulate %rip-relative instructions in 64-bit mode, do that
-	 * here and take the signal right away. We detect this condition by
-	 * seeing if the program counter is the range [scrpc + isz, astpc).
+	 * If we have executed the original instruction, but we have performed
+	 * neither the jmp back to t->t_dtrace_npc nor the clean up of any
+	 * registers used to emulate %rip-relative instructions in 64-bit mode,
+	 * we'll save ourselves some effort by doing that here and taking the
+	 * signal right away.  We detect this condition by seeing if the program
+	 * counter is the range [scrpc + isz, astpc).
 	 */
-	if (t->t_dtrace_astpc - rp->r_pc <
-	    t->t_dtrace_astpc - t->t_dtrace_scrpc - isz) {
+	if (rp->r_pc >= t->t_dtrace_scrpc + isz &&
+	    rp->r_pc < t->t_dtrace_astpc) {
 #ifdef __amd64
 		/*
 		 * If there is a scratch register and we're on the