Message-ID: <20170520232011.5d60111f@gandalf.local.home>
Date:   Sat, 20 May 2017 23:20:11 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] tracing: Fixes for 4.12-rc1


Linus,

This fixes a bug caused by not cleaning up the new instance unique triggers
when deleting an instance. It also creates a selftest that triggers that bug.

Fix the delayed optimization happening after kprobes boot up self tests
being removed by freeing of init memory.

Comment kprobes on why the delay optimization is not a problem for removal
of modules, to keep other developers from searching that riddle.

Fix another rcu isn't watching in stack trace tracing.

Naveen N. Rao (4):
      ftrace: Simplify glob handling in unregister_ftrace_function_probe_func()
      ftrace/instances: Clear function triggers when removing instances
      selftests/ftrace: Fix bashisms
      selftests/ftrace: Add test to remove instance with active event triggers

Steven Rostedt (1):
      tracing: Move postpone selftests to core from early_initcall

Steven Rostedt (VMware) (3):
      ftrace: Remove #ifdef from code and add clear_ftrace_function_probes() stub
      kprobes: Document how optimized kprobes are removed from module unload
      tracing: Make sure RCU is watching before calling a stack trace

Thomas Gleixner (1):
      tracing/kprobes: Enforce kprobes teardown after testing


Please pull the latest trace-v4.12-rc1 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
trace-v4.12-rc1

Tag SHA1: 7edb887bbfb5c2b3556dca9274b68be9bb924c3e
Head SHA1: a33d7d94eed92b23fbbc7b0de06a41b2bbaa49e3


Naveen N. Rao (4):
      ftrace: Simplify glob handling in unregister_ftrace_function_probe_func()
      ftrace/instances: Clear function triggers when removing instances
      selftests/ftrace: Fix bashisms
      selftests/ftrace: Add test to remove instance with active event triggers

Steven Rostedt (1):
      tracing: Move postpone selftests to core from early_initcall

Steven Rostedt (VMware) (3):
      ftrace: Remove #ifdef from code and add clear_ftrace_function_probes() stub
      kprobes: Document how optimized kprobes are removed from module unload
      tracing: Make sure RCU is watching before calling a stack trace

Thomas Gleixner (1):
      tracing/kprobes: Enforce kprobes teardown after testing

----
 include/linux/kprobes.h                            |  3 ++
 kernel/kprobes.c                                   |  8 ++++-
 kernel/trace/ftrace.c                              | 12 ++++++--
 kernel/trace/trace.c                               | 34 ++++++++++++++++++++--
 kernel/trace/trace.h                               |  5 ++++
 kernel/trace/trace_kprobe.c                        |  5 ++++
 tools/testing/selftests/ftrace/ftracetest          |  2 +-
 .../ftrace/test.d/ftrace/func_event_triggers.tc    |  2 +-
 tools/testing/selftests/ftrace/test.d/functions    |  4 +--
 .../ftrace/test.d/instances/instance-event.tc      |  8 +++--
 10 files changed, 72 insertions(+), 11 deletions(-)
---------------------------
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 30f90c1a0aaf..541df0b5b815 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -349,6 +349,9 @@ extern int proc_kprobes_optimization_handler(struct ctl_table *table,
 					     int write, void __user *buffer,
 					     size_t *length, loff_t *ppos);
 #endif
+extern void wait_for_kprobe_optimizer(void);
+#else
+static inline void wait_for_kprobe_optimizer(void) { }
 #endif /* CONFIG_OPTPROBES */
 #ifdef CONFIG_KPROBES_ON_FTRACE
 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 7367e0ec6f81..2d2d3a568e4e 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -595,7 +595,7 @@ static void kprobe_optimizer(struct work_struct *work)
 }
 
 /* Wait for completing optimization and unoptimization */
-static void wait_for_kprobe_optimizer(void)
+void wait_for_kprobe_optimizer(void)
 {
 	mutex_lock(&kprobe_mutex);
 
@@ -2183,6 +2183,12 @@ static int kprobes_module_callback(struct notifier_block *nb,
 				 * The vaddr this probe is installed will soon
 				 * be vfreed buy not synced to disk. Hence,
 				 * disarming the breakpoint isn't needed.
+				 *
+				 * Note, this will also move any optimized probes
+				 * that are pending to be removed from their
+				 * corresponding lists to the freeing_list and
+				 * will not be touched by the delayed
+				 * kprobe_optimizer work handler.
 				 */
 				kill_kprobe(p);
 			}
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 39dca4e86a94..74fdfe9ed3db 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4144,9 +4144,9 @@ unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
 	int i, ret = -ENODEV;
 	int size;
 
-	if (glob && (strcmp(glob, "*") == 0 || !strlen(glob)))
+	if (!glob || !strlen(glob) || !strcmp(glob, "*"))
 		func_g.search = NULL;
-	else if (glob) {
+	else {
 		int not;
 
 		func_g.type = filter_parse_regex(glob, strlen(glob),
@@ -4256,6 +4256,14 @@ unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
 	return ret;
 }
 
+void clear_ftrace_function_probes(struct trace_array *tr)
+{
+	struct ftrace_func_probe *probe, *n;
+
+	list_for_each_entry_safe(probe, n, &tr->func_probes, list)
+		unregister_ftrace_function_probe_func(NULL, tr, probe->probe_ops);
+}
+
 static LIST_HEAD(ftrace_commands);
 static DEFINE_MUTEX(ftrace_cmd_mutex);
 
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c4536c449021..1122f151466f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1558,7 +1558,7 @@ static __init int init_trace_selftests(void)
 
 	return 0;
 }
-early_initcall(init_trace_selftests);
+core_initcall(init_trace_selftests);
 #else
 static inline int run_tracer_selftest(struct tracer *type)
 {
@@ -2568,7 +2568,36 @@ static inline void ftrace_trace_stack(struct trace_array *tr,
 void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
 		   int pc)
 {
-	__ftrace_trace_stack(tr->trace_buffer.buffer, flags, skip, pc, NULL);
+	struct ring_buffer *buffer = tr->trace_buffer.buffer;
+
+	if (rcu_is_watching()) {
+		__ftrace_trace_stack(buffer, flags, skip, pc, NULL);
+		return;
+	}
+
+	/*
+	 * When an NMI triggers, RCU is enabled via rcu_nmi_enter(),
+	 * but if the above rcu_is_watching() failed, then the NMI
+	 * triggered someplace critical, and rcu_irq_enter() should
+	 * not be called from NMI.
+	 */
+	if (unlikely(in_nmi()))
+		return;
+
+	/*
+	 * It is possible that a function is being traced in a
+	 * location that RCU is not watching. A call to
+	 * rcu_irq_enter() will make sure that it is, but there's
+	 * a few internal rcu functions that could be traced
+	 * where that wont work either. In those cases, we just
+	 * do nothing.
+	 */
+	if (unlikely(rcu_irq_enter_disabled()))
+		return;
+
+	rcu_irq_enter_irqson();
+	__ftrace_trace_stack(buffer, flags, skip, pc, NULL);
+	rcu_irq_exit_irqson();
 }
 
 /**
@@ -7550,6 +7579,7 @@ static int instance_rmdir(const char *name)
 	}
 
 	tracing_set_nop(tr);
+	clear_ftrace_function_probes(tr);
 	event_trace_del_tracer(tr);
 	ftrace_clear_pids(tr);
 	ftrace_destroy_function_files(tr);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 291a1bca5748..39fd77330aab 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -980,6 +980,7 @@ register_ftrace_function_probe(char *glob, struct trace_array *tr,
 extern int
 unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
 				      struct ftrace_probe_ops *ops);
+extern void clear_ftrace_function_probes(struct trace_array *tr);
 
 int register_ftrace_command(struct ftrace_func_command *cmd);
 int unregister_ftrace_command(struct ftrace_func_command *cmd);
@@ -998,6 +999,10 @@ static inline __init int unregister_ftrace_command(char *cmd_name)
 {
 	return -EINVAL;
 }
+static inline void clear_ftrace_function_probes(struct trace_array *tr)
+{
+}
+
 /*
  * The ops parameter passed in is usually undefined.
  * This must be a macro.
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 8485f6738a87..c129fca6ec99 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1535,6 +1535,11 @@ static __init int kprobe_trace_self_tests_init(void)
 
 end:
 	release_all_trace_kprobes();
+	/*
+	 * Wait for the optimizer work to finish. Otherwise it might fiddle
+	 * with probes in already freed __init text.
+	 */
+	wait_for_kprobe_optimizer();
 	if (warn)
 		pr_cont("NG: Some tests are failed. Please check them.\n");
 	else
diff --git a/tools/testing/selftests/ftrace/ftracetest b/tools/testing/selftests/ftrace/ftracetest
index 32e6211e1c6e..717581145cfc 100755
--- a/tools/testing/selftests/ftrace/ftracetest
+++ b/tools/testing/selftests/ftrace/ftracetest
@@ -58,7 +58,7 @@ parse_opts() { # opts
     ;;
     --verbose|-v|-vv)
       VERBOSE=$((VERBOSE + 1))
-      [ $1 == '-vv' ] && VERBOSE=$((VERBOSE + 1))
+      [ $1 = '-vv' ] && VERBOSE=$((VERBOSE + 1))
       shift 1
     ;;
     --debug|-d)
diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/func_event_triggers.tc b/tools/testing/selftests/ftrace/test.d/ftrace/func_event_triggers.tc
index 07bb3e5930b4..aa31368851c9 100644
--- a/tools/testing/selftests/ftrace/test.d/ftrace/func_event_triggers.tc
+++ b/tools/testing/selftests/ftrace/test.d/ftrace/func_event_triggers.tc
@@ -48,7 +48,7 @@ test_event_enabled() {
     e=`cat $EVENT_ENABLE`
     if [ "$e" != $val ]; then
 	echo "Expected $val but found $e"
-	exit -1
+	exit 1
     fi
 }
 
diff --git a/tools/testing/selftests/ftrace/test.d/functions b/tools/testing/selftests/ftrace/test.d/functions
index 9aec6fcb7729..f2019b37370d 100644
--- a/tools/testing/selftests/ftrace/test.d/functions
+++ b/tools/testing/selftests/ftrace/test.d/functions
@@ -34,10 +34,10 @@ reset_ftrace_filter() { # reset all triggers in set_ftrace_filter
     echo > set_ftrace_filter
     grep -v '^#' set_ftrace_filter | while read t; do
 	tr=`echo $t | cut -d: -f2`
-	if [ "$tr" == "" ]; then
+	if [ "$tr" = "" ]; then
 	    continue
 	fi
-	if [ $tr == "enable_event" -o $tr == "disable_event" ]; then
+	if [ $tr = "enable_event" -o $tr = "disable_event" ]; then
 	    tr=`echo $t | cut -d: -f1-4`
 	    limit=`echo $t | cut -d: -f5`
 	else
diff --git a/tools/testing/selftests/ftrace/test.d/instances/instance-event.tc b/tools/testing/selftests/ftrace/test.d/instances/instance-event.tc
index 4c5a061a5b4e..c73db7863adb 100644
--- a/tools/testing/selftests/ftrace/test.d/instances/instance-event.tc
+++ b/tools/testing/selftests/ftrace/test.d/instances/instance-event.tc
@@ -75,9 +75,13 @@ rmdir foo
 if [ -d foo ]; then
         fail "foo still exists"
 fi
-exit 0
-
 
+mkdir foo
+echo "schedule:enable_event:sched:sched_switch" > foo/set_ftrace_filter
+rmdir foo
+if [ -d foo ]; then
+        fail "foo still exists"
+fi
 
 
 instance_slam() {

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