1 files changed, 195 insertions, 28 deletions

diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index f93723ca66bc..1f0e63f5d1f9 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -27,13 +27,28 @@ function_trace_call(unsigned long ip, unsigned long parent_ip,
 static void
 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
 			  struct ftrace_ops *op, struct ftrace_regs *fregs);
+static void
+function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
+			       struct ftrace_ops *op, struct ftrace_regs *fregs);
+static void
+function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
+				     struct ftrace_ops *op,
+				     struct ftrace_regs *fregs);
 static struct tracer_flags func_flags;
 
 /* Our option */
 enum {
-	TRACE_FUNC_OPT_STACK	= 0x1,
+
+	TRACE_FUNC_NO_OPTS		= 0x0, /* No flags set. */
+	TRACE_FUNC_OPT_STACK		= 0x1,
+	TRACE_FUNC_OPT_NO_REPEATS	= 0x2,
+
+	/* Update this to next highest bit. */
+	TRACE_FUNC_OPT_HIGHEST_BIT	= 0x4
 };
 
+#define TRACE_FUNC_OPT_MASK	(TRACE_FUNC_OPT_HIGHEST_BIT - 1)
+
 int ftrace_allocate_ftrace_ops(struct trace_array *tr)
 {
 	struct ftrace_ops *ops;
@@ -86,6 +101,34 @@ void ftrace_destroy_function_files(struct trace_array *tr)
 	ftrace_free_ftrace_ops(tr);
 }
 
+static ftrace_func_t select_trace_function(u32 flags_val)
+{
+	switch (flags_val & TRACE_FUNC_OPT_MASK) {
+	case TRACE_FUNC_NO_OPTS:
+		return function_trace_call;
+	case TRACE_FUNC_OPT_STACK:
+		return function_stack_trace_call;
+	case TRACE_FUNC_OPT_NO_REPEATS:
+		return function_no_repeats_trace_call;
+	case TRACE_FUNC_OPT_STACK | TRACE_FUNC_OPT_NO_REPEATS:
+		return function_stack_no_repeats_trace_call;
+	default:
+		return NULL;
+	}
+}
+
+static bool handle_func_repeats(struct trace_array *tr, u32 flags_val)
+{
+	if (!tr->last_func_repeats &&
+	    (flags_val & TRACE_FUNC_OPT_NO_REPEATS)) {
+		tr->last_func_repeats = alloc_percpu(struct trace_func_repeats);
+		if (!tr->last_func_repeats)
+			return false;
+	}
+
+	return true;
+}
+
 static int function_trace_init(struct trace_array *tr)
 {
 	ftrace_func_t func;
@@ -97,12 +140,12 @@ static int function_trace_init(struct trace_array *tr)
 	if (!tr->ops)
 		return -ENOMEM;
 
-	/* Currently only the global instance can do stack tracing */
-	if (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
-	    func_flags.val & TRACE_FUNC_OPT_STACK)
-		func = function_stack_trace_call;
-	else
-		func = function_trace_call;
+	func = select_trace_function(func_flags.val);
+	if (!func)
+		return -EINVAL;
+
+	if (!handle_func_repeats(tr, func_flags.val))
+		return -ENOMEM;
 
 	ftrace_init_array_ops(tr, func);
 
@@ -205,15 +248,137 @@ function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
 	local_irq_restore(flags);
 }
 
+static inline bool is_repeat_check(struct trace_array *tr,
+				   struct trace_func_repeats *last_info,
+				   unsigned long ip, unsigned long parent_ip)
+{
+	if (last_info->ip == ip &&
+	    last_info->parent_ip == parent_ip &&
+	    last_info->count < U16_MAX) {
+		last_info->ts_last_call =
+			ring_buffer_time_stamp(tr->array_buffer.buffer);
+		last_info->count++;
+		return true;
+	}
+
+	return false;
+}
+
+static inline void process_repeats(struct trace_array *tr,
+				   unsigned long ip, unsigned long parent_ip,
+				   struct trace_func_repeats *last_info,
+				   unsigned int trace_ctx)
+{
+	if (last_info->count) {
+		trace_last_func_repeats(tr, last_info, trace_ctx);
+		last_info->count = 0;
+	}
+
+	last_info->ip = ip;
+	last_info->parent_ip = parent_ip;
+}
+
+static void
+function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
+			       struct ftrace_ops *op,
+			       struct ftrace_regs *fregs)
+{
+	struct trace_func_repeats *last_info;
+	struct trace_array *tr = op->private;
+	struct trace_array_cpu *data;
+	unsigned int trace_ctx;
+	unsigned long flags;
+	int bit;
+	int cpu;
+
+	if (unlikely(!tr->function_enabled))
+		return;
+
+	bit = ftrace_test_recursion_trylock(ip, parent_ip);
+	if (bit < 0)
+		return;
+
+	preempt_disable_notrace();
+
+	cpu = smp_processor_id();
+	data = per_cpu_ptr(tr->array_buffer.data, cpu);
+	if (atomic_read(&data->disabled))
+		goto out;
+
+	/*
+	 * An interrupt may happen at any place here. But as far as I can see,
+	 * the only damage that this can cause is to mess up the repetition
+	 * counter without valuable data being lost.
+	 * TODO: think about a solution that is better than just hoping to be
+	 * lucky.
+	 */
+	last_info = per_cpu_ptr(tr->last_func_repeats, cpu);
+	if (is_repeat_check(tr, last_info, ip, parent_ip))
+		goto out;
+
+	local_save_flags(flags);
+	trace_ctx = tracing_gen_ctx_flags(flags);
+	process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
+
+	trace_function(tr, ip, parent_ip, trace_ctx);
+
+out:
+	ftrace_test_recursion_unlock(bit);
+	preempt_enable_notrace();
+}
+
+static void
+function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
+				     struct ftrace_ops *op,
+				     struct ftrace_regs *fregs)
+{
+	struct trace_func_repeats *last_info;
+	struct trace_array *tr = op->private;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+	long disabled;
+	int cpu;
+	unsigned int trace_ctx;
+
+	if (unlikely(!tr->function_enabled))
+		return;
+
+	/*
+	 * Need to use raw, since this must be called before the
+	 * recursive protection is performed.
+	 */
+	local_irq_save(flags);
+	cpu = raw_smp_processor_id();
+	data = per_cpu_ptr(tr->array_buffer.data, cpu);
+	disabled = atomic_inc_return(&data->disabled);
+
+	if (likely(disabled == 1)) {
+		last_info = per_cpu_ptr(tr->last_func_repeats, cpu);
+		if (is_repeat_check(tr, last_info, ip, parent_ip))
+			goto out;
+
+		trace_ctx = tracing_gen_ctx_flags(flags);
+		process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
+
+		trace_function(tr, ip, parent_ip, trace_ctx);
+		__trace_stack(tr, trace_ctx, STACK_SKIP);
+	}
+
+ out:
+	atomic_dec(&data->disabled);
+	local_irq_restore(flags);
+}
+
 static struct tracer_opt func_opts[] = {
 #ifdef CONFIG_STACKTRACE
 	{ TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
 #endif
+	{ TRACER_OPT(func-no-repeats, TRACE_FUNC_OPT_NO_REPEATS) },
 	{ } /* Always set a last empty entry */
 };
 
 static struct tracer_flags func_flags = {
-	.val = 0, /* By default: all flags disabled */
+	.val = TRACE_FUNC_NO_OPTS, /* By default: all flags disabled */
 	.opts = func_opts
 };
 
@@ -235,30 +400,32 @@ static struct tracer function_trace;
 static int
 func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 {
-	switch (bit) {
-	case TRACE_FUNC_OPT_STACK:
-		/* do nothing if already set */
-		if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
-			break;
-
-		/* We can change this flag when not running. */
-		if (tr->current_trace != &function_trace)
-			break;
+	ftrace_func_t func;
+	u32 new_flags;
 
-		unregister_ftrace_function(tr->ops);
+	/* Do nothing if already set. */
+	if (!!set == !!(func_flags.val & bit))
+		return 0;
 
-		if (set) {
-			tr->ops->func = function_stack_trace_call;
-			register_ftrace_function(tr->ops);
-		} else {
-			tr->ops->func = function_trace_call;
-			register_ftrace_function(tr->ops);
-		}
+	/* We can change this flag only when not running. */
+	if (tr->current_trace != &function_trace)
+		return 0;
 
-		break;
-	default:
+	new_flags = (func_flags.val & ~bit) | (set ? bit : 0);
+	func = select_trace_function(new_flags);
+	if (!func)
 		return -EINVAL;
-	}
+
+	/* Check if there's anything to change. */
+	if (tr->ops->func == func)
+		return 0;
+
+	if (!handle_func_repeats(tr, new_flags))
+		return -ENOMEM;
+
+	unregister_ftrace_function(tr->ops);
+	tr->ops->func = func;
+	register_ftrace_function(tr->ops);
 
 	return 0;
 }