svn commit: r332939 - in stable/11/sys/cddl: contrib/opensolaris/uts/common/dtrace dev/dtrace

[Mark Johnston]

Author: markj
Date: Tue Apr 24 15:04:07 2018
New Revision: 332939
URL: https://svnweb.freebsd.org/changeset/base/332939

Log:
  MFC r332364:
  Assert that dtrace_probe() doesn't re-enter itself.

Modified:
  stable/11/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
  stable/11/sys/cddl/dev/dtrace/dtrace_cddl.h
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
==============================================================================
--- stable/11/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c	Tue Apr 24 14:55:22 2018	(r332938)
+++ stable/11/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c	Tue Apr 24 15:04:07 2018	(r332939)
@@ -7116,6 +7116,44 @@ dtrace_store_by_ref(dtrace_difo_t *dp, caddr_t tomax, 
 }
 
 /*
+ * Disables interrupts and sets the per-thread inprobe flag. When DEBUG is
+ * defined, we also assert that we are not recursing unless the probe ID is an
+ * error probe.
+ */
+static dtrace_icookie_t
+dtrace_probe_enter(dtrace_id_t id)
+{
+	dtrace_icookie_t cookie;
+
+	cookie = dtrace_interrupt_disable();
+
+	/*
+	 * Unless this is an ERROR probe, we are not allowed to recurse in
+	 * dtrace_probe(). Recursing into DTrace probe usually means that a
+	 * function is instrumented that should not have been instrumented or
+	 * that the ordering guarantee of the records will be violated,
+	 * resulting in unexpected output. If there is an exception to this
+	 * assertion, a new case should be added.
+	 */
+	ASSERT(curthread->t_dtrace_inprobe == 0 ||
+	    id == dtrace_probeid_error);
+	curthread->t_dtrace_inprobe = 1;
+
+	return (cookie);
+}
+
+/*
+ * Disables interrupts and clears the per-thread inprobe flag.
+ */
+static void
+dtrace_probe_exit(dtrace_icookie_t cookie)
+{
+
+	curthread->t_dtrace_inprobe = 0;
+	dtrace_interrupt_enable(cookie);
+}
+
+/*
  * If you're looking for the epicenter of DTrace, you just found it.  This
  * is the function called by the provider to fire a probe -- from which all
  * subsequent probe-context DTrace activity emanates.
@@ -7149,7 +7187,7 @@ dtrace_probe(dtrace_id_t id, uintptr_t arg0, uintptr_t
 		return;
 #endif
 
-	cookie = dtrace_interrupt_disable();
+	cookie = dtrace_probe_enter(id);
 	probe = dtrace_probes[id - 1];
 	cpuid = curcpu;
 	onintr = CPU_ON_INTR(CPU);
@@ -7160,7 +7198,7 @@ dtrace_probe(dtrace_id_t id, uintptr_t arg0, uintptr_t
 		 * We have hit in the predicate cache; we know that
 		 * this predicate would evaluate to be false.
 		 */
-		dtrace_interrupt_enable(cookie);
+		dtrace_probe_exit(cookie);
 		return;
 	}
 
@@ -7172,7 +7210,7 @@ dtrace_probe(dtrace_id_t id, uintptr_t arg0, uintptr_t
 		/*
 		 * We don't trace anything if we're panicking.
 		 */
-		dtrace_interrupt_enable(cookie);
+		dtrace_probe_exit(cookie);
 		return;
 	}
 
@@ -7858,7 +7896,7 @@ dtrace_probe(dtrace_id_t id, uintptr_t arg0, uintptr_t
 	if (vtime)
 		curthread->t_dtrace_start = dtrace_gethrtime();
 
-	dtrace_interrupt_enable(cookie);
+	dtrace_probe_exit(cookie);
 }
 
 /*

Modified: stable/11/sys/cddl/dev/dtrace/dtrace_cddl.h
==============================================================================
--- stable/11/sys/cddl/dev/dtrace/dtrace_cddl.h	Tue Apr 24 14:55:22 2018	(r332938)
+++ stable/11/sys/cddl/dev/dtrace/dtrace_cddl.h	Tue Apr 24 15:04:07 2018	(r332939)
@@ -46,6 +46,7 @@ typedef struct kdtrace_proc {
 typedef struct kdtrace_thread {
 	u_int8_t	td_dtrace_stop;	/* Indicates a DTrace-desired stop */
 	u_int8_t	td_dtrace_sig;	/* Signal sent via DTrace's raise() */
+	u_int8_t	td_dtrace_inprobe; /* Are we in a probe? */
 	u_int		td_predcache;	/* DTrace predicate cache */
 	u_int64_t	td_dtrace_vtime; /* DTrace virtual time */
 	u_int64_t	td_dtrace_start; /* DTrace slice start time */
@@ -97,6 +98,7 @@ typedef struct kdtrace_thread {
 #define	t_dtrace_start	td_dtrace->td_dtrace_start
 #define	t_dtrace_stop	td_dtrace->td_dtrace_stop
 #define	t_dtrace_sig	td_dtrace->td_dtrace_sig
+#define	t_dtrace_inprobe	td_dtrace->td_dtrace_inprobe
 #define	t_predcache	td_dtrace->td_predcache
 #define	t_dtrace_ft	td_dtrace->td_dtrace_ft
 #define	t_dtrace_on	td_dtrace->td_dtrace_on