Merge tag 'trace-v4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "This includes two new updates for the ftrace infrastructure.

   - With the changing of the code for filtering events by pid, from a
     list of pids to a bitmask, we can now easily implement following
     forks.  With a new tracing option "event-fork" which, when set,
     will have tasks with pids in set_event_pid, when they fork, to have
     their child pids added to set_event_pid and the child will be
     traced as well.

     Note, if "event-fork" is set and a task with its pid in
     set_event_pid exits, its pid will be removed from set_event_pid

   - The addition of Tom Zanussi's hist triggers.  This includes a very
     thorough documentatino on how to use the hist triggers with events.
     This introduces a quick and easy way to get histogram data from
     events and their fields.

  Some other cleanups and updates were added as well.  Like Masami
  Hiramatsu added test cases for the event trigger and hist triggers.
  Also I added a speed up of filtering by using a temp buffer when
  filters are set"

* tag 'trace-v4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (45 commits)
  tracing: Use temp buffer when filtering events
  tracing: Remove TRACE_EVENT_FL_USE_CALL_FILTER logic
  tracing: Remove unused function trace_current_buffer_lock_reserve()
  tracing: Remove one use of trace_current_buffer_lock_reserve()
  tracing: Have trace_buffer_unlock_commit() call the _regs version with NULL
  tracing: Remove unused function trace_current_buffer_discard_commit()
  tracing: Move trace_buffer_unlock_commit{_regs}() to local header
  tracing: Fold filter_check_discard() into its only user
  tracing: Make filter_check_discard() local
  tracing: Move event_trigger_unlock_commit{_regs}() to local header
  tracing: Don't use the address of the buffer array name in copy_from_user
  tracing: Handle tracing_map_alloc_elts() error path correctly
  tracing: Add check for NULL event field when creating hist field
  tracing: checking for NULL instead of IS_ERR()
  tracing: Do not inherit event-fork option for instances
  tracing: Fix unsigned comparison to zero in hist trigger code
  kselftests/ftrace: Add a test for log2 modifier of hist trigger
  tracing: Add hist trigger 'log2' modifier
  kselftests/ftrace: Add hist trigger testcases
  kselftests/ftrace : Add event trigger testcases
  ...

10 files changed, 3930 insertions, 284 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index e45db6b0d878..fafeaf803bd0 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -528,6 +528,32 @@ config MMIOTRACE
 	  See Documentation/trace/mmiotrace.txt.
 	  If you are not helping to develop drivers, say N.
 
+config TRACING_MAP
+	bool
+	depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
+	help
+	  tracing_map is a special-purpose lock-free map for tracing,
+	  separated out as a stand-alone facility in order to allow it
+	  to be shared between multiple tracers.  It isn't meant to be
+	  generally used outside of that context, and is normally
+	  selected by tracers that use it.
+
+config HIST_TRIGGERS
+	bool "Histogram triggers"
+	depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
+	select TRACING_MAP
+	default n
+	help
+	  Hist triggers allow one or more arbitrary trace event fields
+	  to be aggregated into hash tables and dumped to stdout by
+	  reading a debugfs/tracefs file.  They're useful for
+	  gathering quick and dirty (though precise) summaries of
+	  event activity as an initial guide for further investigation
+	  using more advanced tools.
+
+	  See Documentation/trace/events.txt.
+	  If in doubt, say N.
+
 config MMIOTRACE_TEST
 	tristate "Test module for mmiotrace"
 	depends on MMIOTRACE && m
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 9b1044e936a6..979e7bfbde7a 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -31,6 +31,7 @@ obj-$(CONFIG_TRACING) += trace_output.o
 obj-$(CONFIG_TRACING) += trace_seq.o
 obj-$(CONFIG_TRACING) += trace_stat.o
 obj-$(CONFIG_TRACING) += trace_printk.o
+obj-$(CONFIG_TRACING_MAP) += tracing_map.o
 obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
 obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
 obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
@@ -53,6 +54,7 @@ obj-$(CONFIG_EVENT_TRACING) += trace_event_perf.o
 endif
 obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
 obj-$(CONFIG_EVENT_TRACING) += trace_events_trigger.o
+obj-$(CONFIG_HIST_TRIGGERS) += trace_events_hist.o
 obj-$(CONFIG_BPF_EVENTS) += bpf_trace.o
 obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
 obj-$(CONFIG_TRACEPOINTS) += power-traces.o
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a2f0b9f33e9b..8a4bd6b68a0b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -253,6 +253,9 @@ unsigned long long ns2usecs(cycle_t nsec)
 #define TOP_LEVEL_TRACE_FLAGS (TRACE_ITER_PRINTK |			\
 	       TRACE_ITER_PRINTK_MSGONLY | TRACE_ITER_RECORD_CMD)
 
+/* trace_flags that are default zero for instances */
+#define ZEROED_TRACE_FLAGS \
+	TRACE_ITER_EVENT_FORK
 
 /*
  * The global_trace is the descriptor that holds the tracing
@@ -303,33 +306,18 @@ void trace_array_put(struct trace_array *this_tr)
 	mutex_unlock(&trace_types_lock);
 }
 
-int filter_check_discard(struct trace_event_file *file, void *rec,
-			 struct ring_buffer *buffer,
-			 struct ring_buffer_event *event)
-{
-	if (unlikely(file->flags & EVENT_FILE_FL_FILTERED) &&
-	    !filter_match_preds(file->filter, rec)) {
-		ring_buffer_discard_commit(buffer, event);
-		return 1;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(filter_check_discard);
-
 int call_filter_check_discard(struct trace_event_call *call, void *rec,
 			      struct ring_buffer *buffer,
 			      struct ring_buffer_event *event)
 {
 	if (unlikely(call->flags & TRACE_EVENT_FL_FILTERED) &&
 	    !filter_match_preds(call->filter, rec)) {
-		ring_buffer_discard_commit(buffer, event);
+		__trace_event_discard_commit(buffer, event);
 		return 1;
 	}
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(call_filter_check_discard);
 
 static cycle_t buffer_ftrace_now(struct trace_buffer *buf, int cpu)
 {
@@ -1672,6 +1660,16 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
 }
 EXPORT_SYMBOL_GPL(tracing_generic_entry_update);
 
+static __always_inline void
+trace_event_setup(struct ring_buffer_event *event,
+		  int type, unsigned long flags, int pc)
+{
+	struct trace_entry *ent = ring_buffer_event_data(event);
+
+	tracing_generic_entry_update(ent, flags, pc);
+	ent->type = type;
+}
+
 struct ring_buffer_event *
 trace_buffer_lock_reserve(struct ring_buffer *buffer,
 			  int type,
@@ -1681,34 +1679,137 @@ trace_buffer_lock_reserve(struct ring_buffer *buffer,
 	struct ring_buffer_event *event;
 
 	event = ring_buffer_lock_reserve(buffer, len);
-	if (event != NULL) {
-		struct trace_entry *ent = ring_buffer_event_data(event);
+	if (event != NULL)
+		trace_event_setup(event, type, flags, pc);
+
+	return event;
+}
+
+DEFINE_PER_CPU(struct ring_buffer_event *, trace_buffered_event);
+DEFINE_PER_CPU(int, trace_buffered_event_cnt);
+static int trace_buffered_event_ref;
+
+/**
+ * trace_buffered_event_enable - enable buffering events
+ *
+ * When events are being filtered, it is quicker to use a temporary
+ * buffer to write the event data into if there's a likely chance
+ * that it will not be committed. The discard of the ring buffer
+ * is not as fast as committing, and is much slower than copying
+ * a commit.
+ *
+ * When an event is to be filtered, allocate per cpu buffers to
+ * write the event data into, and if the event is filtered and discarded
+ * it is simply dropped, otherwise, the entire data is to be committed
+ * in one shot.
+ */
+void trace_buffered_event_enable(void)
+{
+	struct ring_buffer_event *event;
+	struct page *page;
+	int cpu;
 
-		tracing_generic_entry_update(ent, flags, pc);
-		ent->type = type;
+	WARN_ON_ONCE(!mutex_is_locked(&event_mutex));
+
+	if (trace_buffered_event_ref++)
+		return;
+
+	for_each_tracing_cpu(cpu) {
+		page = alloc_pages_node(cpu_to_node(cpu),
+					GFP_KERNEL | __GFP_NORETRY, 0);
+		if (!page)
+			goto failed;
+
+		event = page_address(page);
+		memset(event, 0, sizeof(*event));
+
+		per_cpu(trace_buffered_event, cpu) = event;
+
+		preempt_disable();
+		if (cpu == smp_processor_id() &&
+		    this_cpu_read(trace_buffered_event) !=
+		    per_cpu(trace_buffered_event, cpu))
+			WARN_ON_ONCE(1);
+		preempt_enable();
 	}
 
-	return event;
+	return;
+ failed:
+	trace_buffered_event_disable();
 }
 
-void
-__buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
+static void enable_trace_buffered_event(void *data)
 {
-	__this_cpu_write(trace_cmdline_save, true);
-	ring_buffer_unlock_commit(buffer, event);
+	/* Probably not needed, but do it anyway */
+	smp_rmb();
+	this_cpu_dec(trace_buffered_event_cnt);
 }
 
-void trace_buffer_unlock_commit(struct trace_array *tr,
-				struct ring_buffer *buffer,
-				struct ring_buffer_event *event,
-				unsigned long flags, int pc)
+static void disable_trace_buffered_event(void *data)
 {
-	__buffer_unlock_commit(buffer, event);
+	this_cpu_inc(trace_buffered_event_cnt);
+}
 
-	ftrace_trace_stack(tr, buffer, flags, 6, pc, NULL);
-	ftrace_trace_userstack(buffer, flags, pc);
+/**
+ * trace_buffered_event_disable - disable buffering events
+ *
+ * When a filter is removed, it is faster to not use the buffered
+ * events, and to commit directly into the ring buffer. Free up
+ * the temp buffers when there are no more users. This requires
+ * special synchronization with current events.
+ */
+void trace_buffered_event_disable(void)
+{
+	int cpu;
+
+	WARN_ON_ONCE(!mutex_is_locked(&event_mutex));
+
+	if (WARN_ON_ONCE(!trace_buffered_event_ref))
+		return;
+
+	if (--trace_buffered_event_ref)
+		return;
+
+	preempt_disable();
+	/* For each CPU, set the buffer as used. */
+	smp_call_function_many(tracing_buffer_mask,
+			       disable_trace_buffered_event, NULL, 1);
+	preempt_enable();
+
+	/* Wait for all current users to finish */
+	synchronize_sched();
+
+	for_each_tracing_cpu(cpu) {
+		free_page((unsigned long)per_cpu(trace_buffered_event, cpu));
+		per_cpu(trace_buffered_event, cpu) = NULL;
+	}
+	/*
+	 * Make sure trace_buffered_event is NULL before clearing
+	 * trace_buffered_event_cnt.
+	 */
+	smp_wmb();
+
+	preempt_disable();
+	/* Do the work on each cpu */
+	smp_call_function_many(tracing_buffer_mask,
+			       enable_trace_buffered_event, NULL, 1);
+	preempt_enable();
+}
+
+void
+__buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
+{
+	__this_cpu_write(trace_cmdline_save, true);
+
+	/* If this is the temp buffer, we need to commit fully */
+	if (this_cpu_read(trace_buffered_event) == event) {
+		/* Length is in event->array[0] */
+		ring_buffer_write(buffer, event->array[0], &event->array[1]);
+		/* Release the temp buffer */
+		this_cpu_dec(trace_buffered_event_cnt);
+	} else
+		ring_buffer_unlock_commit(buffer, event);
 }
-EXPORT_SYMBOL_GPL(trace_buffer_unlock_commit);
 
 static struct ring_buffer *temp_buffer;
 
@@ -1719,8 +1820,23 @@ trace_event_buffer_lock_reserve(struct ring_buffer **current_rb,
 			  unsigned long flags, int pc)
 {
 	struct ring_buffer_event *entry;
+	int val;
 
 	*current_rb = trace_file->tr->trace_buffer.buffer;
+
+	if ((trace_file->flags &
+	     (EVENT_FILE_FL_SOFT_DISABLED | EVENT_FILE_FL_FILTERED)) &&
+	    (entry = this_cpu_read(trace_buffered_event))) {
+		/* Try to use the per cpu buffer first */
+		val = this_cpu_inc_return(trace_buffered_event_cnt);
+		if (val == 1) {
+			trace_event_setup(entry, type, flags, pc);
+			entry->array[0] = len;
+			return entry;
+		}
+		this_cpu_dec(trace_buffered_event_cnt);
+	}
+
 	entry = trace_buffer_lock_reserve(*current_rb,
 					 type, len, flags, pc);
 	/*
@@ -1738,17 +1854,6 @@ trace_event_buffer_lock_reserve(struct ring_buffer **current_rb,
 }
 EXPORT_SYMBOL_GPL(trace_event_buffer_lock_reserve);
 
-struct ring_buffer_event *
-trace_current_buffer_lock_reserve(struct ring_buffer **current_rb,
-				  int type, unsigned long len,
-				  unsigned long flags, int pc)
-{
-	*current_rb = global_trace.trace_buffer.buffer;
-	return trace_buffer_lock_reserve(*current_rb,
-					 type, len, flags, pc);
-}
-EXPORT_SYMBOL_GPL(trace_current_buffer_lock_reserve);
-
 void trace_buffer_unlock_commit_regs(struct trace_array *tr,
 				     struct ring_buffer *buffer,
 				     struct ring_buffer_event *event,
@@ -1760,14 +1865,6 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr,
 	ftrace_trace_stack(tr, buffer, flags, 0, pc, regs);
 	ftrace_trace_userstack(buffer, flags, pc);
 }
-EXPORT_SYMBOL_GPL(trace_buffer_unlock_commit_regs);
-
-void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
-					 struct ring_buffer_event *event)
-{
-	ring_buffer_discard_commit(buffer, event);
-}
-EXPORT_SYMBOL_GPL(trace_current_buffer_discard_commit);
 
 void
 trace_function(struct trace_array *tr,
@@ -3571,6 +3668,9 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
 	if (mask == TRACE_ITER_RECORD_CMD)
 		trace_event_enable_cmd_record(enabled);
 
+	if (mask == TRACE_ITER_EVENT_FORK)
+		trace_event_follow_fork(tr, enabled);
+
 	if (mask == TRACE_ITER_OVERWRITE) {
 		ring_buffer_change_overwrite(tr->trace_buffer.buffer, enabled);
 #ifdef CONFIG_TRACER_MAX_TRACE
@@ -3658,7 +3758,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 	if (cnt >= sizeof(buf))
 		return -EINVAL;
 
-	if (copy_from_user(&buf, ubuf, cnt))
+	if (copy_from_user(buf, ubuf, cnt))
 		return -EFAULT;
 
 	buf[cnt] = 0;
@@ -3804,12 +3904,19 @@ static const char readme_msg[] =
 	"\t   trigger: traceon, traceoff\n"
 	"\t            enable_event:<system>:<event>\n"
 	"\t            disable_event:<system>:<event>\n"
+#ifdef CONFIG_HIST_TRIGGERS
+	"\t            enable_hist:<system>:<event>\n"
+	"\t            disable_hist:<system>:<event>\n"
+#endif
 #ifdef CONFIG_STACKTRACE
 	"\t\t    stacktrace\n"
 #endif
 #ifdef CONFIG_TRACER_SNAPSHOT
 	"\t\t    snapshot\n"
 #endif
+#ifdef CONFIG_HIST_TRIGGERS
+	"\t\t    hist (see below)\n"
+#endif
 	"\t   example: echo traceoff > events/block/block_unplug/trigger\n"
 	"\t            echo traceoff:3 > events/block/block_unplug/trigger\n"
 	"\t            echo 'enable_event:kmem:kmalloc:3 if nr_rq > 1' > \\\n"
@@ -3825,6 +3932,56 @@ static const char readme_msg[] =
 	"\t   To remove a trigger with a count:\n"
 	"\t     echo '!<trigger>:0 > <system>/<event>/trigger\n"
 	"\t   Filters can be ignored when removing a trigger.\n"
+#ifdef CONFIG_HIST_TRIGGERS
+	"      hist trigger\t- If set, event hits are aggregated into a hash table\n"
+	"\t    Format: hist:keys=<field1[,field2,...]>\n"
+	"\t            [:values=<field1[,field2,...]>]\n"
+	"\t            [:sort=<field1[,field2,...]>]\n"
+	"\t            [:size=#entries]\n"
+	"\t            [:pause][:continue][:clear]\n"
+	"\t            [:name=histname1]\n"
+	"\t            [if <filter>]\n\n"
+	"\t    When a matching event is hit, an entry is added to a hash\n"
+	"\t    table using the key(s) and value(s) named, and the value of a\n"
+	"\t    sum called 'hitcount' is incremented.  Keys and values\n"
+	"\t    correspond to fields in the event's format description.  Keys\n"
+	"\t    can be any field, or the special string 'stacktrace'.\n"
+	"\t    Compound keys consisting of up to two fields can be specified\n"
+	"\t    by the 'keys' keyword.  Values must correspond to numeric\n"
+	"\t    fields.  Sort keys consisting of up to two fields can be\n"
+	"\t    specified using the 'sort' keyword.  The sort direction can\n"
+	"\t    be modified by appending '.descending' or '.ascending' to a\n"
+	"\t    sort field.  The 'size' parameter can be used to specify more\n"
+	"\t    or fewer than the default 2048 entries for the hashtable size.\n"
+	"\t    If a hist trigger is given a name using the 'name' parameter,\n"
+	"\t    its histogram data will be shared with other triggers of the\n"
+	"\t    same name, and trigger hits will update this common data.\n\n"
+	"\t    Reading the 'hist' file for the event will dump the hash\n"
+	"\t    table in its entirety to stdout.  If there are multiple hist\n"
+	"\t    triggers attached to an event, there will be a table for each\n"
+	"\t    trigger in the output.  The table displayed for a named\n"
+	"\t    trigger will be the same as any other instance having the\n"
+	"\t    same name.  The default format used to display a given field\n"
+	"\t    can be modified by appending any of the following modifiers\n"
+	"\t    to the field name, as applicable:\n\n"
+	"\t            .hex        display a number as a hex value\n"
+	"\t            .sym        display an address as a symbol\n"
+	"\t            .sym-offset display an address as a symbol and offset\n"
+	"\t            .execname   display a common_pid as a program name\n"
+	"\t            .syscall    display a syscall id as a syscall name\n\n"
+	"\t            .log2       display log2 value rather than raw number\n\n"
+	"\t    The 'pause' parameter can be used to pause an existing hist\n"
+	"\t    trigger or to start a hist trigger but not log any events\n"
+	"\t    until told to do so.  'continue' can be used to start or\n"
+	"\t    restart a paused hist trigger.\n\n"
+	"\t    The 'clear' parameter will clear the contents of a running\n"
+	"\t    hist trigger and leave its current paused/active state\n"
+	"\t    unchanged.\n\n"
+	"\t    The enable_hist and disable_hist triggers can be used to\n"
+	"\t    have one event conditionally start and stop another event's\n"
+	"\t    already-attached hist trigger.  The syntax is analagous to\n"
+	"\t    the enable_event and disable_event triggers.\n"
+#endif
 ;
 
 static ssize_t
@@ -4474,7 +4631,7 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
 	if (cnt > MAX_TRACER_SIZE)
 		cnt = MAX_TRACER_SIZE;
 
-	if (copy_from_user(&buf, ubuf, cnt))
+	if (copy_from_user(buf, ubuf, cnt))
 		return -EFAULT;
 
 	buf[cnt] = 0;
@@ -5264,7 +5421,7 @@ static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
 	if (cnt >= sizeof(buf))
 		return -EINVAL;
 
-	if (copy_from_user(&buf, ubuf, cnt))
+	if (copy_from_user(buf, ubuf, cnt))
 		return -EFAULT;
 
 	buf[cnt] = 0;
@@ -6650,7 +6807,7 @@ static int instance_mkdir(const char *name)
 	if (!alloc_cpumask_var(&tr->tracing_cpumask, GFP_KERNEL))
 		goto out_free_tr;
 
-	tr->trace_flags = global_trace.trace_flags;
+	tr->trace_flags = global_trace.trace_flags & ~ZEROED_TRACE_FLAGS;
 
 	cpumask_copy(tr->tracing_cpumask, cpu_all_mask);
 
@@ -6724,6 +6881,12 @@ static int instance_rmdir(const char *name)
 
 	list_del(&tr->list);
 
+	/* Disable all the flags that were enabled coming in */
+	for (i = 0; i < TRACE_FLAGS_MAX_SIZE; i++) {
+		if ((1 << i) & ZEROED_TRACE_FLAGS)
+			set_tracer_flag(tr, 1 << i, 0);
+	}
+
 	tracing_set_nop(tr);
 	event_trace_del_tracer(tr);
 	ftrace_destroy_function_files(tr);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 3fff4adfd431..5167c366d6b7 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -177,9 +177,8 @@ struct trace_options {
 };
 
 struct trace_pid_list {
-	unsigned int			nr_pids;
-	int				order;
-	pid_t				*pids;
+	int				pid_max;
+	unsigned long			*pids;
 };
 
 /*
@@ -656,6 +655,7 @@ static inline void __trace_stack(struct trace_array *tr, unsigned long flags,
 extern cycle_t ftrace_now(int cpu);
 
 extern void trace_find_cmdline(int pid, char comm[]);
+extern void trace_event_follow_fork(struct trace_array *tr, bool enable);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 extern unsigned long ftrace_update_tot_cnt;
@@ -967,6 +967,7 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
 		C(STOP_ON_FREE,		"disable_on_free"),	\
 		C(IRQ_INFO,		"irq-info"),		\
 		C(MARKERS,		"markers"),		\
+		C(EVENT_FORK,		"event-fork"),		\
 		FUNCTION_FLAGS					\
 		FGRAPH_FLAGS					\
 		STACK_FLAGS					\
@@ -1064,6 +1065,137 @@ struct trace_subsystem_dir {
 	int				nr_events;
 };
 
+extern int call_filter_check_discard(struct trace_event_call *call, void *rec,
+				     struct ring_buffer *buffer,
+				     struct ring_buffer_event *event);
+
+void trace_buffer_unlock_commit_regs(struct trace_array *tr,
+				     struct ring_buffer *buffer,
+				     struct ring_buffer_event *event,
+				     unsigned long flags, int pc,
+				     struct pt_regs *regs);
+
+static inline void trace_buffer_unlock_commit(struct trace_array *tr,
+					      struct ring_buffer *buffer,
+					      struct ring_buffer_event *event,
+					      unsigned long flags, int pc)
+{
+	trace_buffer_unlock_commit_regs(tr, buffer, event, flags, pc, NULL);
+}
+
+DECLARE_PER_CPU(struct ring_buffer_event *, trace_buffered_event);
+DECLARE_PER_CPU(int, trace_buffered_event_cnt);
+void trace_buffered_event_disable(void);
+void trace_buffered_event_enable(void);
+
+static inline void
+__trace_event_discard_commit(struct ring_buffer *buffer,
+			     struct ring_buffer_event *event)
+{
+	if (this_cpu_read(trace_buffered_event) == event) {
+		/* Simply release the temp buffer */
+		this_cpu_dec(trace_buffered_event_cnt);
+		return;
+	}
+	ring_buffer_discard_commit(buffer, event);
+}
+
+/*
+ * Helper function for event_trigger_unlock_commit{_regs}().
+ * If there are event triggers attached to this event that requires
+ * filtering against its fields, then they wil be called as the
+ * entry already holds the field information of the current event.
+ *
+ * It also checks if the event should be discarded or not.
+ * It is to be discarded if the event is soft disabled and the
+ * event was only recorded to process triggers, or if the event
+ * filter is active and this event did not match the filters.
+ *
+ * Returns true if the event is discarded, false otherwise.
+ */
+static inline bool
+__event_trigger_test_discard(struct trace_event_file *file,
+			     struct ring_buffer *buffer,
+			     struct ring_buffer_event *event,
+			     void *entry,
+			     enum event_trigger_type *tt)
+{
+	unsigned long eflags = file->flags;
+
+	if (eflags & EVENT_FILE_FL_TRIGGER_COND)
+		*tt = event_triggers_call(file, entry);
+
+	if (test_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags) ||
+	    (unlikely(file->flags & EVENT_FILE_FL_FILTERED) &&
+	     !filter_match_preds(file->filter, entry))) {
+		__trace_event_discard_commit(buffer, event);
+		return true;
+	}
+
+	return false;
+}
+
+/**
+ * event_trigger_unlock_commit - handle triggers and finish event commit
+ * @file: The file pointer assoctiated to the event
+ * @buffer: The ring buffer that the event is being written to
+ * @event: The event meta data in the ring buffer
+ * @entry: The event itself
+ * @irq_flags: The state of the interrupts at the start of the event
+ * @pc: The state of the preempt count at the start of the event.
+ *
+ * This is a helper function to handle triggers that require data
+ * from the event itself. It also tests the event against filters and
+ * if the event is soft disabled and should be discarded.
+ */
+static inline void
+event_trigger_unlock_commit(struct trace_event_file *file,
+			    struct ring_buffer *buffer,
+			    struct ring_buffer_event *event,
+			    void *entry, unsigned long irq_flags, int pc)
+{
+	enum event_trigger_type tt = ETT_NONE;
+
+	if (!__event_trigger_test_discard(file, buffer, event, entry, &tt))
+		trace_buffer_unlock_commit(file->tr, buffer, event, irq_flags, pc);
+
+	if (tt)
+		event_triggers_post_call(file, tt, entry);
+}
+
+/**
+ * event_trigger_unlock_commit_regs - handle triggers and finish event commit
+ * @file: The file pointer assoctiated to the event
+ * @buffer: The ring buffer that the event is being written to
+ * @event: The event meta data in the ring buffer
+ * @entry: The event itself
+ * @irq_flags: The state of the interrupts at the start of the event
+ * @pc: The state of the preempt count at the start of the event.
+ *
+ * This is a helper function to handle triggers that require data
+ * from the event itself. It also tests the event against filters and
+ * if the event is soft disabled and should be discarded.
+ *
+ * Same as event_trigger_unlock_commit() but calls
+ * trace_buffer_unlock_commit_regs() instead of trace_buffer_unlock_commit().
+ */
+static inline void
+event_trigger_unlock_commit_regs(struct trace_event_file *file,
+				 struct ring_buffer *buffer,
+				 struct ring_buffer_event *event,
+				 void *entry, unsigned long irq_flags, int pc,
+				 struct pt_regs *regs)
+{
+	enum event_trigger_type tt = ETT_NONE;
+
+	if (!__event_trigger_test_discard(file, buffer, event, entry, &tt))
+		trace_buffer_unlock_commit_regs(file->tr, buffer, event,
+						irq_flags, pc, regs);
+
+	if (tt)
+		event_triggers_post_call(file, tt, entry);
+}
+
 #define FILTER_PRED_INVALID	((unsigned short)-1)
 #define FILTER_PRED_IS_RIGHT	(1 << 15)
 #define FILTER_PRED_FOLD	(1 << 15)
@@ -1161,6 +1293,15 @@ extern struct mutex event_mutex;
 extern struct list_head ftrace_events;
 
 extern const struct file_operations event_trigger_fops;
+extern const struct file_operations event_hist_fops;
+
+#ifdef CONFIG_HIST_TRIGGERS
+extern int register_trigger_hist_cmd(void);
+extern int register_trigger_hist_enable_disable_cmds(void);
+#else
+static inline int register_trigger_hist_cmd(void) { return 0; }
+static inline int register_trigger_hist_enable_disable_cmds(void) { return 0; }
+#endif
 
 extern int register_trigger_cmds(void);
 extern void clear_event_triggers(struct trace_array *tr);
@@ -1174,9 +1315,41 @@ struct event_trigger_data {
 	char				*filter_str;
 	void				*private_data;
 	bool				paused;
+	bool				paused_tmp;
 	struct list_head		list;
+	char				*name;
+	struct list_head		named_list;
+	struct event_trigger_data	*named_data;
+};
+
+/* Avoid typos */
+#define ENABLE_EVENT_STR	"enable_event"
+#define DISABLE_EVENT_STR	"disable_event"
+#define ENABLE_HIST_STR		"enable_hist"
+#define DISABLE_HIST_STR	"disable_hist"
+
+struct enable_trigger_data {
+	struct trace_event_file		*file;
+	bool				enable;
+	bool				hist;
 };
 
+extern int event_enable_trigger_print(struct seq_file *m,
+				      struct event_trigger_ops *ops,
+				      struct event_trigger_data *data);
+extern void event_enable_trigger_free(struct event_trigger_ops *ops,
+				      struct event_trigger_data *data);
+extern int event_enable_trigger_func(struct event_command *cmd_ops,
+				     struct trace_event_file *file,
+				     char *glob, char *cmd, char *param);
+extern int event_enable_register_trigger(char *glob,
+					 struct event_trigger_ops *ops,
+					 struct event_trigger_data *data,
+					 struct trace_event_file *file);
+extern void event_enable_unregister_trigger(char *glob,
+					    struct event_trigger_ops *ops,
+					    struct event_trigger_data *test,
+					    struct trace_event_file *file);
 extern void trigger_data_free(struct event_trigger_data *data);
 extern int event_trigger_init(struct event_trigger_ops *ops,
 			      struct event_trigger_data *data);
@@ -1189,7 +1362,18 @@ extern void unregister_trigger(char *glob, struct event_trigger_ops *ops,
 extern int set_trigger_filter(char *filter_str,
 			      struct event_trigger_data *trigger_data,
 			      struct trace_event_file *file);
+extern struct event_trigger_data *find_named_trigger(const char *name);
+extern bool is_named_trigger(struct event_trigger_data *test);
+extern int save_named_trigger(const char *name,
+			      struct event_trigger_data *data);
+extern void del_named_trigger(struct event_trigger_data *data);
+extern void pause_named_trigger(struct event_trigger_data *data);
+extern void unpause_named_trigger(struct event_trigger_data *data);
+extern void set_named_trigger_data(struct event_trigger_data *data,
+				   struct event_trigger_data *named_data);
 extern int register_event_command(struct event_command *cmd);
+extern int unregister_event_command(struct event_command *cmd);
+extern int register_trigger_hist_enable_disable_cmds(void);
 
 /**
  * struct event_trigger_ops - callbacks for trace event triggers
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index b7b0760ba6ee..3d4155892a1e 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -15,7 +15,7 @@
 #include <linux/kthread.h>
 #include <linux/tracefs.h>
 #include <linux/uaccess.h>
-#include <linux/bsearch.h>
+#include <linux/vmalloc.h>
 #include <linux/module.h>
 #include <linux/ctype.h>
 #include <linux/sort.h>
@@ -381,6 +381,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 {
 	struct trace_event_call *call = file->event_call;
 	struct trace_array *tr = file->tr;
+	unsigned long file_flags = file->flags;
 	int ret = 0;
 	int disable;
 
@@ -463,6 +464,15 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
 		break;
 	}
 
+	/* Enable or disable use of trace_buffered_event */
+	if ((file_flags & EVENT_FILE_FL_SOFT_DISABLED) !=
+	    (file->flags & EVENT_FILE_FL_SOFT_DISABLED)) {
+		if (file->flags & EVENT_FILE_FL_SOFT_DISABLED)
+			trace_buffered_event_enable();
+		else
+			trace_buffered_event_disable();
+	}
+
 	return ret;
 }
 
@@ -489,24 +499,26 @@ static void ftrace_clear_events(struct trace_array *tr)
 	mutex_unlock(&event_mutex);
 }
 
-static int cmp_pid(const void *key, const void *elt)
+/* Shouldn't this be in a header? */
+extern int pid_max;
+
+/* Returns true if found in filter */
+static bool
+find_filtered_pid(struct trace_pid_list *filtered_pids, pid_t search_pid)
 {
-	const pid_t *search_pid = key;
-	const pid_t *pid = elt;
+	/*
+	 * If pid_max changed after filtered_pids was created, we
+	 * by default ignore all pids greater than the previous pid_max.
+	 */
+	if (search_pid >= filtered_pids->pid_max)
+		return false;
 
-	if (*search_pid == *pid)
-		return 0;
-	if (*search_pid < *pid)
-		return -1;
-	return 1;
+	return test_bit(search_pid, filtered_pids->pids);
 }
 
 static bool
-check_ignore_pid(struct trace_pid_list *filtered_pids, struct task_struct *task)
+ignore_this_task(struct trace_pid_list *filtered_pids, struct task_struct *task)
 {
-	pid_t search_pid;
-	pid_t *pid;
-
 	/*
 	 * Return false, because if filtered_pids does not exist,
 	 * all pids are good to trace.
@@ -514,15 +526,68 @@ check_ignore_pid(struct trace_pid_list *filtered_pids, struct task_struct *task)
 	if (!filtered_pids)
 		return false;
 
-	search_pid = task->pid;
+	return !find_filtered_pid(filtered_pids, task->pid);
+}
+
+static void filter_add_remove_task(struct trace_pid_list *pid_list,
+				   struct task_struct *self,
+				   struct task_struct *task)
+{
+	if (!pid_list)
+		return;
+
+	/* For forks, we only add if the forking task is listed */
+	if (self) {
+		if (!find_filtered_pid(pid_list, self->pid))
+			return;
+	}
 
-	pid = bsearch(&search_pid, filtered_pids->pids,
-		      filtered_pids->nr_pids, sizeof(pid_t),
-		      cmp_pid);
-	if (!pid)
-		return true;
+	/* Sorry, but we don't support pid_max changing after setting */
+	if (task->pid >= pid_list->pid_max)
+		return;
 
-	return false;
+	/* "self" is set for forks, and NULL for exits */
+	if (self)
+		set_bit(task->pid, pid_list->pids);
+	else
+		clear_bit(task->pid, pid_list->pids);
+}
+
+static void
+event_filter_pid_sched_process_exit(void *data, struct task_struct *task)
+{
+	struct trace_pid_list *pid_list;
+	struct trace_array *tr = data;
+
+	pid_list = rcu_dereference_sched(tr->filtered_pids);
+	filter_add_remove_task(pid_list, NULL, task);
+}
+
+static void
+event_filter_pid_sched_process_fork(void *data,
+				    struct task_struct *self,
+				    struct task_struct *task)
+{
+	struct trace_pid_list *pid_list;
+	struct trace_array *tr = data;
+
+	pid_list = rcu_dereference_sched(tr->filtered_pids);
+	filter_add_remove_task(pid_list, self, task);
+}
+
+void trace_event_follow_fork(struct trace_array *tr, bool enable)
+{
+	if (enable) {
+		register_trace_prio_sched_process_fork(event_filter_pid_sched_process_fork,
+						       tr, INT_MIN);
+		register_trace_prio_sched_process_exit(event_filter_pid_sched_process_exit,
+						       tr, INT_MAX);
+	} else {
+		unregister_trace_sched_process_fork(event_filter_pid_sched_process_fork,
+						    tr);
+		unregister_trace_sched_process_exit(event_filter_pid_sched_process_exit,
+						    tr);
+	}
 }
 
 static void
@@ -535,8 +600,8 @@ event_filter_pid_sched_switch_probe_pre(void *data, bool preempt,
 	pid_list = rcu_dereference_sched(tr->filtered_pids);
 
 	this_cpu_write(tr->trace_buffer.data->ignore_pid,
-		       check_ignore_pid(pid_list, prev) &&
-		       check_ignore_pid(pid_list, next));
+		       ignore_this_task(pid_list, prev) &&
+		       ignore_this_task(pid_list, next));
 }
 
 static void
@@ -549,7 +614,7 @@ event_filter_pid_sched_switch_probe_post(void *data, bool preempt,
 	pid_list = rcu_dereference_sched(tr->filtered_pids);
 
 	this_cpu_write(tr->trace_buffer.data->ignore_pid,
-		       check_ignore_pid(pid_list, next));
+		       ignore_this_task(pid_list, next));
 }
 
 static void
@@ -565,7 +630,7 @@ event_filter_pid_sched_wakeup_probe_pre(void *data, struct task_struct *task)
 	pid_list = rcu_dereference_sched(tr->filtered_pids);
 
 	this_cpu_write(tr->trace_buffer.data->ignore_pid,
-		       check_ignore_pid(pid_list, task));
+		       ignore_this_task(pid_list, task));
 }
 
 static void
@@ -582,7 +647,7 @@ event_filter_pid_sched_wakeup_probe_post(void *data, struct task_struct *task)
 
 	/* Set tracing if current is enabled */
 	this_cpu_write(tr->trace_buffer.data->ignore_pid,
-		       check_ignore_pid(pid_list, current));
+		       ignore_this_task(pid_list, current));
 }
 
 static void __ftrace_clear_event_pids(struct trace_array *tr)
@@ -620,7 +685,7 @@ static void __ftrace_clear_event_pids(struct trace_array *tr)
 	/* Wait till all users are no longer using pid filtering */
 	synchronize_sched();
 
-	free_pages((unsigned long)pid_list->pids, pid_list->order);
+	vfree(pid_list->pids);
 	kfree(pid_list);
 }
 
@@ -964,11 +1029,32 @@ static void t_stop(struct seq_file *m, void *p)
 	mutex_unlock(&event_mutex);
 }
 
+static void *
+p_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct trace_array *tr = m->private;
+	struct trace_pid_list *pid_list = rcu_dereference_sched(tr->filtered_pids);
+	unsigned long pid = (unsigned long)v;
+
+	(*pos)++;
+
+	/* pid already is +1 of the actual prevous bit */
+	pid = find_next_bit(pid_list->pids, pid_list->pid_max, pid);
+
+	/* Return pid + 1 to allow zero to be represented */
+	if (pid < pid_list->pid_max)
+		return (void *)(pid + 1);
+
+	return NULL;
+}
+
 static void *p_start(struct seq_file *m, loff_t *pos)
 	__acquires(RCU)
 {
 	struct trace_pid_list *pid_list;
 	struct trace_array *tr = m->private;
+	unsigned long pid;
+	loff_t l = 0;
 
 	/*
 	 * Grab the mutex, to keep calls to p_next() having the same
@@ -981,10 +1067,18 @@ static void *p_start(struct seq_file *m, loff_t *pos)
 
 	pid_list = rcu_dereference_sched(tr->filtered_pids);
 
-	if (!pid_list || *pos >= pid_list->nr_pids)
+	if (!pid_list)
+		return NULL;
+
+	pid = find_first_bit(pid_list->pids, pid_list->pid_max);
+	if (pid >= pid_list->pid_max)
 		return NULL;
 
-	return (void *)&pid_list->pids[*pos];
+	/* Return pid + 1 so that zero can be the exit value */
+	for (pid++; pid && l < *pos;
+	     pid = (unsigned long)p_next(m, (void *)pid, &l))
+		;
+	return (void *)pid;
 }
 
 static void p_stop(struct seq_file *m, void *p)
@@ -994,25 +1088,11 @@ static void p_stop(struct seq_file *m, void *p)
 	mutex_unlock(&event_mutex);
 }
 
-static void *
-p_next(struct seq_file *m, void *v, loff_t *pos)
-{
-	struct trace_array *tr = m->private;
-	struct trace_pid_list *pid_list = rcu_dereference_sched(tr->filtered_pids);
-
-	(*pos)++;
-
-	if (*pos >= pid_list->nr_pids)
-		return NULL;
-
-	return (void *)&pid_list->pids[*pos];
-}
-
 static int p_show(struct seq_file *m, void *v)
 {
-	pid_t *pid = v;
+	unsigned long pid = (unsigned long)v - 1;
 
-	seq_printf(m, "%d\n", *pid);
+	seq_printf(m, "%lu\n", pid);
 	return 0;
 }
 
@@ -1561,11 +1641,6 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 	return r;
 }
 
-static int max_pids(struct trace_pid_list *pid_list)
-{
-	return (PAGE_SIZE << pid_list->order) / sizeof(pid_t);
-}
-
 static void ignore_task_cpu(void *data)
 {
 	struct trace_array *tr = data;
@@ -1579,7 +1654,7 @@ static void ignore_task_cpu(void *data)
 					     mutex_is_locked(&event_mutex));
 
 	this_cpu_write(tr->trace_buffer.data->ignore_pid,
-		       check_ignore_pid(pid_list, current));
+		       ignore_this_task(pid_list, current));
 }
 
 static ssize_t
@@ -1589,7 +1664,7 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
 	struct seq_file *m = filp->private_data;
 	struct trace_array *tr = m->private;
 	struct trace_pid_list *filtered_pids = NULL;
-	struct trace_pid_list *pid_list = NULL;
+	struct trace_pid_list *pid_list;
 	struct trace_event_file *file;
 	struct trace_parser parser;
 	unsigned long val;
@@ -1597,7 +1672,7 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
 	ssize_t read = 0;
 	ssize_t ret = 0;
 	pid_t pid;
-	int i;
+	int nr_pids = 0;
 
 	if (!cnt)
 		return 0;
@@ -1610,10 +1685,43 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
 		return -ENOMEM;
 
 	mutex_lock(&event_mutex);
+	filtered_pids = rcu_dereference_protected(tr->filtered_pids,
+					     lockdep_is_held(&event_mutex));
+
 	/*
-	 * Load as many pids into the array before doing a
-	 * swap from the tr->filtered_pids to the new list.
+	 * Always recreate a new array. The write is an all or nothing
+	 * operation. Always create a new array when adding new pids by
+	 * the user. If the operation fails, then the current list is
+	 * not modified.
 	 */
+	pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL);
+	if (!pid_list) {
+		read = -ENOMEM;
+		goto out;
+	}
+	pid_list->pid_max = READ_ONCE(pid_max);
+	/* Only truncating will shrink pid_max */
+	if (filtered_pids && filtered_pids->pid_max > pid_list->pid_max)
+		pid_list->pid_max = filtered_pids->pid_max;
+	pid_list->pids = vzalloc((pid_list->pid_max + 7) >> 3);
+	if (!pid_list->pids) {
+		kfree(pid_list);
+		read = -ENOMEM;
+		goto out;
+	}
+	if (filtered_pids) {
+		/* copy the current bits to the new max */
+		pid = find_first_bit(filtered_pids->pids,
+				     filtered_pids->pid_max);
+		while (pid < filtered_pids->pid_max) {
+			set_bit(pid, pid_list->pids);
+			pid = find_next_bit(filtered_pids->pids,
+					    filtered_pids->pid_max,
+					    pid + 1);
+			nr_pids++;
+		}
+	}
+
 	while (cnt > 0) {
 
 		this_pos = 0;
@@ -1631,92 +1739,35 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
 		ret = -EINVAL;
 		if (kstrtoul(parser.buffer, 0, &val))
 			break;
-		if (val > INT_MAX)
+		if (val >= pid_list->pid_max)
 			break;
 
 		pid = (pid_t)val;
 
-		ret = -ENOMEM;
-		if (!pid_list) {
-			pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL);
-			if (!pid_list)
-				break;
+		set_bit(pid, pid_list->pids);
+		nr_pids++;
 
-			filtered_pids = rcu_dereference_protected(tr->filtered_pids,
-							lockdep_is_held(&event_mutex));
-			if (filtered_pids)
-				pid_list->order = filtered_pids->order;
-			else
-				pid_list->order = 0;
-
-			pid_list->pids = (void *)__get_free_pages(GFP_KERNEL,
-								  pid_list->order);
-			if (!pid_list->pids)
-				break;
-
-			if (filtered_pids) {
-				pid_list->nr_pids = filtered_pids->nr_pids;
-				memcpy(pid_list->pids, filtered_pids->pids,
-				       pid_list->nr_pids * sizeof(pid_t));
-			} else
-				pid_list->nr_pids = 0;
-		}
-
-		if (pid_list->nr_pids >= max_pids(pid_list)) {
-			pid_t *pid_page;
-
-			pid_page = (void *)__get_free_pages(GFP_KERNEL,
-							    pid_list->order + 1);
-			if (!pid_page)
-				break;
-			memcpy(pid_page, pid_list->pids,
-			       pid_list->nr_pids * sizeof(pid_t));
-			free_pages((unsigned long)pid_list->pids, pid_list->order);
-
-			pid_list->order++;
-			pid_list->pids = pid_page;
-		}
-
-		pid_list->pids[pid_list->nr_pids++] = pid;
 		trace_parser_clear(&parser);
 		ret = 0;
 	}
 	trace_parser_put(&parser);
 
 	if (ret < 0) {
-		if (pid_list)
-			free_pages((unsigned long)pid_list->pids, pid_list->order);
+		vfree(pid_list->pids);
 		kfree(pid_list);
-		mutex_unlock(&event_mutex);
-		return ret;
-	}
-
-	if (!pid_list) {
-		mutex_unlock(&event_mutex);
-		return ret;
+		read = ret;
+		goto out;
 	}
 
-	sort(pid_list->pids, pid_list->nr_pids, sizeof(pid_t), cmp_pid, NULL);
-
-	/* Remove duplicates */
-	for (i = 1; i < pid_list->nr_pids; i++) {
-		int start = i;
-
-		while (i < pid_list->nr_pids &&
-		       pid_list->pids[i - 1] == pid_list->pids[i])
-			i++;
-
-		if (start != i) {
-			if (i < pid_list->nr_pids) {
-				memmove(&pid_list->pids[start], &pid_list->pids[i],
-					(pid_list->nr_pids - i) * sizeof(pid_t));
-				pid_list->nr_pids -= i - start;
-				i = start;
-			} else
-				pid_list->nr_pids = start;
-		}
+	if (!nr_pids) {
+		/* Cleared the list of pids */
+		vfree(pid_list->pids);
+		kfree(pid_list);
+		read = ret;
+		if (!filtered_pids)
+			goto out;
+		pid_list = NULL;
 	}
-
 	rcu_assign_pointer(tr->filtered_pids, pid_list);
 
 	list_for_each_entry(file, &tr->events, list) {
@@ -1726,7 +1777,7 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
 	if (filtered_pids) {
 		synchronize_sched();
 
-		free_pages((unsigned long)filtered_pids->pids, filtered_pids->order);
+		vfree(filtered_pids->pids);
 		kfree(filtered_pids);
 	} else {
 		/*
@@ -1763,10 +1814,12 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
 	 */
 	on_each_cpu(ignore_task_cpu, tr, 1);
 
+ out:
 	mutex_unlock(&event_mutex);
 
 	ret = read;
-	*ppos += read;
+	if (read > 0)
+		*ppos += read;
 
 	return ret;
 }
@@ -2121,6 +2174,10 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file)
 		trace_create_file("trigger", 0644, file->dir, file,
 				  &event_trigger_fops);
 
+#ifdef CONFIG_HIST_TRIGGERS
+	trace_create_file("hist", 0444, file->dir, file,
+			  &event_hist_fops);
+#endif
 	trace_create_file("format", 0444, file->dir, call,
 			  &ftrace_event_format_fops);
 
@@ -3368,7 +3425,7 @@ static __init void event_trace_self_tests(void)
 
 static DEFINE_PER_CPU(atomic_t, ftrace_test_event_disable);
 
-static struct trace_array *event_tr;
+static struct trace_event_file event_trace_file __initdata;
 
 static void __init
 function_test_events_call(unsigned long ip, unsigned long parent_ip,
@@ -3392,17 +3449,17 @@ function_test_events_call(unsigned long ip, unsigned long parent_ip,
 
 	local_save_flags(flags);
 
-	event = trace_current_buffer_lock_reserve(&buffer,
-						  TRACE_FN, sizeof(*entry),
-						  flags, pc);
+	event = trace_event_buffer_lock_reserve(&buffer, &event_trace_file,
+						TRACE_FN, sizeof(*entry),
+						flags, pc);
 	if (!event)
 		goto out;
 	entry	= ring_buffer_event_data(event);
 	entry->ip			= ip;
 	entry->parent_ip		= parent_ip;
 
-	trace_buffer_unlock_commit(event_tr, buffer, event, flags, pc);
-
+	event_trigger_unlock_commit(&event_trace_file, buffer, event,
+				    entry, flags, pc);
  out:
 	atomic_dec(&per_cpu(ftrace_test_event_disable, cpu));
 	preempt_enable_notrace();
@@ -3417,9 +3474,11 @@ static struct ftrace_ops trace_ops __initdata  =
 static __init void event_trace_self_test_with_function(void)
 {
 	int ret;
-	event_tr = top_trace_array();
-	if (WARN_ON(!event_tr))
+
+	event_trace_file.tr = top_trace_array();
+	if (WARN_ON(!event_trace_file.tr))
 		return;
+
 	ret = register_ftrace_function(&trace_ops);
 	if (WARN_ON(ret < 0)) {
 		pr_info("Failed to enable function tracer for event tests\n");
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index b3f5051cd4e9..9daa9b3bc6d9 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -689,10 +689,7 @@ static void append_filter_err(struct filter_parse_state *ps,
 
 static inline struct event_filter *event_filter(struct trace_event_file *file)
 {
-	if (file->event_call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
-		return file->event_call->filter;
-	else
-		return file->filter;
+	return file->filter;
 }
 
 /* caller must hold event_mutex */
@@ -826,12 +823,12 @@ static void __free_preds(struct event_filter *filter)
 
 static void filter_disable(struct trace_event_file *file)
 {
-	struct trace_event_call *call = file->event_call;
+	unsigned long old_flags = file->flags;
 
-	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
-		call->flags &= ~TRACE_EVENT_FL_FILTERED;
-	else
-		file->flags &= ~EVENT_FILE_FL_FILTERED;
+	file->flags &= ~EVENT_FILE_FL_FILTERED;
+
+	if (old_flags != file->flags)
+		trace_buffered_event_disable();
 }
 
 static void __free_filter(struct event_filter *filter)
@@ -883,13 +880,8 @@ static int __alloc_preds(struct event_filter *filter, int n_preds)
 
 static inline void __remove_filter(struct trace_event_file *file)
 {
-	struct trace_event_call *call = file->event_call;
-
 	filter_disable(file);
-	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
-		remove_filter_string(call->filter);
-	else
-		remove_filter_string(file->filter);
+	remove_filter_string(file->filter);
 }
 
 static void filter_free_subsystem_preds(struct trace_subsystem_dir *dir,
@@ -906,15 +898,8 @@ static void filter_free_subsystem_preds(struct trace_subsystem_dir *dir,
 
 static inline void __free_subsystem_filter(struct trace_event_file *file)
 {
-	struct trace_event_call *call = file->event_call;
-
-	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER) {
-		__free_filter(call->filter);
-		call->filter = NULL;
-	} else {
-		__free_filter(file->filter);
-		file->filter = NULL;
-	}
+	__free_filter(file->filter);
+	file->filter = NULL;
 }
 
 static void filter_free_subsystem_filters(struct trace_subsystem_dir *dir,
@@ -1718,69 +1703,43 @@ fail:
 
 static inline void event_set_filtered_flag(struct trace_event_file *file)
 {
-	struct trace_event_call *call = file->event_call;
+	unsigned long old_flags = file->flags;
 
-	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
-		call->flags |= TRACE_EVENT_FL_FILTERED;
-	else
-		file->flags |= EVENT_FILE_FL_FILTERED;
+	file->flags |= EVENT_FILE_FL_FILTERED;
+
+	if (old_flags != file->flags)
+		trace_buffered_event_enable();
 }
 
 static inline void event_set_filter(struct trace_event_file *file,
 				    struct event_filter *filter)
 {
-	struct trace_event_call *call = file->event_call;
-
-	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
-		rcu_assign_pointer(call->filter, filter);
-	else
-		rcu_assign_pointer(file->filter, filter);
+	rcu_assign_pointer(file->filter, filter);
 }
 
 static inline void event_clear_filter(struct trace_event_file *file)
 {
-	struct trace_event_call *call = file->event_call;
-
-	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
-		RCU_INIT_POINTER(call->filter, NULL);
-	else
-		RCU_INIT_POINTER(file->filter, NULL);
+	RCU_INIT_POINTER(file->filter, NULL);
 }
 
 static inline void
 event_set_no_set_filter_flag(struct trace_event_file *file)
 {
-	struct trace_event_call *call = file->event_call;
-
-	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
-		call->flags |= TRACE_EVENT_FL_NO_SET_FILTER;
-	else
-		file->flags |= EVENT_FILE_FL_NO_SET_FILTER;
+	file->flags |= EVENT_FILE_FL_NO_SET_FILTER;
 }
 
 static inline void
 event_clear_no_set_filter_flag(struct trace_event_file *file)
 {
-	struct trace_event_call *call = file->event_call;
-
-	if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
-		call->flags &= ~TRACE_EVENT_FL_NO_SET_FILTER;
-	else
-		file->flags &= ~EVENT_FILE_FL_NO_SET_FILTER;
+	file->flags &= ~EVENT_FILE_FL_NO_SET_FILTER;
 }
 
 static inline bool
 event_no_set_filter_flag(struct trace_event_file *file)
 {
-	struct trace_event_call *call = file->event_call;
-
 	if (file->flags & EVENT_FILE_FL_NO_SET_FILTER)
 		return true;
 
-	if ((call->flags & TRACE_EVENT_FL_USE_CALL_FILTER) &&
-	    (call->flags & TRACE_EVENT_FL_NO_SET_FILTER))
-		return true;
-
 	return false;
 }
 
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
new file mode 100644
index 000000000000..0c05b8a99806
--- /dev/null
+++ b/kernel/trace/trace_events_hist.c
@@ -0,0 +1,1755 @@
+/*
+ * trace_events_hist - trace event hist triggers
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Copyright (C) 2015 Tom Zanussi <tom.zanussi@linux.intel.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kallsyms.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/stacktrace.h>
+
+#include "tracing_map.h"
+#include "trace.h"
+
+struct hist_field;
+
+typedef u64 (*hist_field_fn_t) (struct hist_field *field, void *event);
+
+struct hist_field {
+	struct ftrace_event_field	*field;
+	unsigned long			flags;
+	hist_field_fn_t			fn;
+	unsigned int			size;
+	unsigned int			offset;
+};
+
+static u64 hist_field_none(struct hist_field *field, void *event)
+{
+	return 0;
+}
+
+static u64 hist_field_counter(struct hist_field *field, void *event)
+{
+	return 1;
+}
+
+static u64 hist_field_string(struct hist_field *hist_field, void *event)
+{
+	char *addr = (char *)(event + hist_field->field->offset);
+
+	return (u64)(unsigned long)addr;
+}
+
+static u64 hist_field_dynstring(struct hist_field *hist_field, void *event)
+{
+	u32 str_item = *(u32 *)(event + hist_field->field->offset);
+	int str_loc = str_item & 0xffff;
+	char *addr = (char *)(event + str_loc);
+
+	return (u64)(unsigned long)addr;
+}
+
+static u64 hist_field_pstring(struct hist_field *hist_field, void *event)
+{
+	char **addr = (char **)(event + hist_field->field->offset);
+
+	return (u64)(unsigned long)*addr;
+}
+
+static u64 hist_field_log2(struct hist_field *hist_field, void *event)
+{
+	u64 val = *(u64 *)(event + hist_field->field->offset);
+
+	return (u64) ilog2(roundup_pow_of_two(val));
+}
+
+#define DEFINE_HIST_FIELD_FN(type)					\
+static u64 hist_field_##type(struct hist_field *hist_field, void *event)\
+{									\
+	type *addr = (type *)(event + hist_field->field->offset);	\
+									\
+	return (u64)(unsigned long)*addr;				\
+}
+
+DEFINE_HIST_FIELD_FN(s64);
+DEFINE_HIST_FIELD_FN(u64);
+DEFINE_HIST_FIELD_FN(s32);
+DEFINE_HIST_FIELD_FN(u32);
+DEFINE_HIST_FIELD_FN(s16);
+DEFINE_HIST_FIELD_FN(u16);
+DEFINE_HIST_FIELD_FN(s8);
+DEFINE_HIST_FIELD_FN(u8);
+
+#define for_each_hist_field(i, hist_data)	\
+	for ((i) = 0; (i) < (hist_data)->n_fields; (i)++)
+
+#define for_each_hist_val_field(i, hist_data)	\
+	for ((i) = 0; (i) < (hist_data)->n_vals; (i)++)
+
+#define for_each_hist_key_field(i, hist_data)	\
+	for ((i) = (hist_data)->n_vals; (i) < (hist_data)->n_fields; (i)++)
+
+#define HIST_STACKTRACE_DEPTH	16
+#define HIST_STACKTRACE_SIZE	(HIST_STACKTRACE_DEPTH * sizeof(unsigned long))
+#define HIST_STACKTRACE_SKIP	5
+
+#define HITCOUNT_IDX		0
+#define HIST_KEY_SIZE_MAX	(MAX_FILTER_STR_VAL + HIST_STACKTRACE_SIZE)
+
+enum hist_field_flags {
+	HIST_FIELD_FL_HITCOUNT		= 1,
+	HIST_FIELD_FL_KEY		= 2,
+	HIST_FIELD_FL_STRING		= 4,
+	HIST_FIELD_FL_HEX		= 8,
+	HIST_FIELD_FL_SYM		= 16,
+	HIST_FIELD_FL_SYM_OFFSET	= 32,
+	HIST_FIELD_FL_EXECNAME		= 64,
+	HIST_FIELD_FL_SYSCALL		= 128,
+	HIST_FIELD_FL_STACKTRACE	= 256,
+	HIST_FIELD_FL_LOG2		= 512,
+};
+
+struct hist_trigger_attrs {
+	char		*keys_str;
+	char		*vals_str;
+	char		*sort_key_str;
+	char		*name;
+	bool		pause;
+	bool		cont;
+	bool		clear;
+	unsigned int	map_bits;
+};
+
+struct hist_trigger_data {
+	struct hist_field               *fields[TRACING_MAP_FIELDS_MAX];
+	unsigned int			n_vals;
+	unsigned int			n_keys;
+	unsigned int			n_fields;
+	unsigned int			key_size;
+	struct tracing_map_sort_key	sort_keys[TRACING_MAP_SORT_KEYS_MAX];
+	unsigned int			n_sort_keys;
+	struct trace_event_file		*event_file;
+	struct hist_trigger_attrs	*attrs;
+	struct tracing_map		*map;
+};
+
+static hist_field_fn_t select_value_fn(int field_size, int field_is_signed)
+{
+	hist_field_fn_t fn = NULL;
+
+	switch (field_size) {
+	case 8:
+		if (field_is_signed)
+			fn = hist_field_s64;
+		else
+			fn = hist_field_u64;
+		break;
+	case 4:
+		if (field_is_signed)
+			fn = hist_field_s32;
+		else
+			fn = hist_field_u32;
+		break;
+	case 2:
+		if (field_is_signed)
+			fn = hist_field_s16;
+		else
+			fn = hist_field_u16;
+		break;
+	case 1:
+		if (field_is_signed)
+			fn = hist_field_s8;
+		else
+			fn = hist_field_u8;
+		break;
+	}
+
+	return fn;
+}
+
+static int parse_map_size(char *str)
+{
+	unsigned long size, map_bits;
+	int ret;
+
+	strsep(&str, "=");
+	if (!str) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = kstrtoul(str, 0, &size);
+	if (ret)
+		goto out;
+
+	map_bits = ilog2(roundup_pow_of_two(size));
+	if (map_bits < TRACING_MAP_BITS_MIN ||
+	    map_bits > TRACING_MAP_BITS_MAX)
+		ret = -EINVAL;
+	else
+		ret = map_bits;
+ out:
+	return ret;
+}
+
+static void destroy_hist_trigger_attrs(struct hist_trigger_attrs *attrs)
+{
+	if (!attrs)
+		return;
+
+	kfree(attrs->name);
+	kfree(attrs->sort_key_str);
+	kfree(attrs->keys_str);
+	kfree(attrs->vals_str);
+	kfree(attrs);
+}
+
+static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str)
+{
+	struct hist_trigger_attrs *attrs;
+	int ret = 0;
+
+	attrs = kzalloc(sizeof(*attrs), GFP_KERNEL);
+	if (!attrs)
+		return ERR_PTR(-ENOMEM);
+
+	while (trigger_str) {
+		char *str = strsep(&trigger_str, ":");
+
+		if ((strncmp(str, "key=", strlen("key=")) == 0) ||
+		    (strncmp(str, "keys=", strlen("keys=")) == 0))
+			attrs->keys_str = kstrdup(str, GFP_KERNEL);
+		else if ((strncmp(str, "val=", strlen("val=")) == 0) ||
+			 (strncmp(str, "vals=", strlen("vals=")) == 0) ||
+			 (strncmp(str, "values=", strlen("values=")) == 0))
+			attrs->vals_str = kstrdup(str, GFP_KERNEL);
+		else if (strncmp(str, "sort=", strlen("sort=")) == 0)
+			attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
+		else if (strncmp(str, "name=", strlen("name=")) == 0)
+			attrs->name = kstrdup(str, GFP_KERNEL);
+		else if (strcmp(str, "pause") == 0)
+			attrs->pause = true;
+		else if ((strcmp(str, "cont") == 0) ||
+			 (strcmp(str, "continue") == 0))
+			attrs->cont = true;
+		else if (strcmp(str, "clear") == 0)
+			attrs->clear = true;
+		else if (strncmp(str, "size=", strlen("size=")) == 0) {
+			int map_bits = parse_map_size(str);
+
+			if (map_bits < 0) {
+				ret = map_bits;
+				goto free;
+			}
+			attrs->map_bits = map_bits;
+		} else {
+			ret = -EINVAL;
+			goto free;
+		}
+	}
+
+	if (!attrs->keys_str) {
+		ret = -EINVAL;
+		goto free;
+	}
+
+	return attrs;
+ free:
+	destroy_hist_trigger_attrs(attrs);
+
+	return ERR_PTR(ret);
+}
+
+static inline void save_comm(char *comm, struct task_struct *task)
+{
+	if (!task->pid) {
+		strcpy(comm, "<idle>");
+		return;
+	}
+
+	if (WARN_ON_ONCE(task->pid < 0)) {
+		strcpy(comm, "<XXX>");
+		return;
+	}
+
+	memcpy(comm, task->comm, TASK_COMM_LEN);
+}
+
+static void hist_trigger_elt_comm_free(struct tracing_map_elt *elt)
+{
+	kfree((char *)elt->private_data);
+}
+
+static int hist_trigger_elt_comm_alloc(struct tracing_map_elt *elt)
+{
+	struct hist_trigger_data *hist_data = elt->map->private_data;
+	struct hist_field *key_field;
+	unsigned int i;
+
+	for_each_hist_key_field(i, hist_data) {
+		key_field = hist_data->fields[i];
+
+		if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
+			unsigned int size = TASK_COMM_LEN + 1;
+
+			elt->private_data = kzalloc(size, GFP_KERNEL);
+			if (!elt->private_data)
+				return -ENOMEM;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static void hist_trigger_elt_comm_copy(struct tracing_map_elt *to,
+				       struct tracing_map_elt *from)
+{
+	char *comm_from = from->private_data;
+	char *comm_to = to->private_data;
+
+	if (comm_from)
+		memcpy(comm_to, comm_from, TASK_COMM_LEN + 1);
+}
+
+static void hist_trigger_elt_comm_init(struct tracing_map_elt *elt)
+{
+	char *comm = elt->private_data;
+
+	if (comm)
+		save_comm(comm, current);
+}
+
+static const struct tracing_map_ops hist_trigger_elt_comm_ops = {
+	.elt_alloc	= hist_trigger_elt_comm_alloc,
+	.elt_copy	= hist_trigger_elt_comm_copy,
+	.elt_free	= hist_trigger_elt_comm_free,
+	.elt_init	= hist_trigger_elt_comm_init,
+};
+
+static void destroy_hist_field(struct hist_field *hist_field)
+{
+	kfree(hist_field);
+}
+
+static struct hist_field *create_hist_field(struct ftrace_event_field *field,
+					    unsigned long flags)
+{
+	struct hist_field *hist_field;
+
+	if (field && is_function_field(field))
+		return NULL;
+
+	hist_field = kzalloc(sizeof(struct hist_field), GFP_KERNEL);
+	if (!hist_field)
+		return NULL;
+
+	if (flags & HIST_FIELD_FL_HITCOUNT) {
+		hist_field->fn = hist_field_counter;
+		goto out;
+	}
+
+	if (flags & HIST_FIELD_FL_STACKTRACE) {
+		hist_field->fn = hist_field_none;
+		goto out;
+	}
+
+	if (flags & HIST_FIELD_FL_LOG2) {
+		hist_field->fn = hist_field_log2;
+		goto out;
+	}
+
+	if (WARN_ON_ONCE(!field))
+		goto out;
+
+	if (is_string_field(field)) {
+		flags |= HIST_FIELD_FL_STRING;
+
+		if (field->filter_type == FILTER_STATIC_STRING)
+			hist_field->fn = hist_field_string;
+		else if (field->filter_type == FILTER_DYN_STRING)
+			hist_field->fn = hist_field_dynstring;
+		else
+			hist_field->fn = hist_field_pstring;
+	} else {
+		hist_field->fn = select_value_fn(field->size,
+						 field->is_signed);
+		if (!hist_field->fn) {
+			destroy_hist_field(hist_field);
+			return NULL;
+		}
+	}
+ out:
+	hist_field->field = field;
+	hist_field->flags = flags;
+
+	return hist_field;
+}
+
+static void destroy_hist_fields(struct hist_trigger_data *hist_data)
+{
+	unsigned int i;
+
+	for (i = 0; i < TRACING_MAP_FIELDS_MAX; i++) {
+		if (hist_data->fields[i]) {
+			destroy_hist_field(hist_data->fields[i]);
+			hist_data->fields[i] = NULL;
+		}
+	}
+}
+
+static int create_hitcount_val(struct hist_trigger_data *hist_data)
+{
+	hist_data->fields[HITCOUNT_IDX] =
+		create_hist_field(NULL, HIST_FIELD_FL_HITCOUNT);
+	if (!hist_data->fields[HITCOUNT_IDX])
+		return -ENOMEM;
+
+	hist_data->n_vals++;
+
+	if (WARN_ON(hist_data->n_vals > TRACING_MAP_VALS_MAX))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int create_val_field(struct hist_trigger_data *hist_data,
+			    unsigned int val_idx,
+			    struct trace_event_file *file,
+			    char *field_str)
+{
+	struct ftrace_event_field *field = NULL;
+	unsigned long flags = 0;
+	char *field_name;
+	int ret = 0;
+
+	if (WARN_ON(val_idx >= TRACING_MAP_VALS_MAX))
+		return -EINVAL;
+
+	field_name = strsep(&field_str, ".");
+	if (field_str) {
+		if (strcmp(field_str, "hex") == 0)
+			flags |= HIST_FIELD_FL_HEX;
+		else {
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+	field = trace_find_event_field(file->event_call, field_name);
+	if (!field) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	hist_data->fields[val_idx] = create_hist_field(field, flags);
+	if (!hist_data->fields[val_idx]) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	++hist_data->n_vals;
+
+	if (WARN_ON(hist_data->n_vals > TRACING_MAP_VALS_MAX))
+		ret = -EINVAL;
+ out:
+	return ret;
+}
+
+static int create_val_fields(struct hist_trigger_data *hist_data,
+			     struct trace_event_file *file)
+{
+	char *fields_str, *field_str;
+	unsigned int i, j;
+	int ret;
+
+	ret = create_hitcount_val(hist_data);
+	if (ret)
+		goto out;
+
+	fields_str = hist_data->attrs->vals_str;
+	if (!fields_str)
+		goto out;
+
+	strsep(&fields_str, "=");
+	if (!fields_str)
+		goto out;
+
+	for (i = 0, j = 1; i < TRACING_MAP_VALS_MAX &&
+		     j < TRACING_MAP_VALS_MAX; i++) {
+		field_str = strsep(&fields_str, ",");
+		if (!field_str)
+			break;
+		if (strcmp(field_str, "hitcount") == 0)
+			continue;
+		ret = create_val_field(hist_data, j++, file, field_str);
+		if (ret)
+			goto out;
+	}
+	if (fields_str && (strcmp(fields_str, "hitcount") != 0))
+		ret = -EINVAL;
+ out:
+	return ret;
+}
+
+static int create_key_field(struct hist_trigger_data *hist_data,
+			    unsigned int key_idx,
+			    unsigned int key_offset,
+			    struct trace_event_file *file,
+			    char *field_str)
+{
+	struct ftrace_event_field *field = NULL;
+	unsigned long flags = 0;
+	unsigned int key_size;
+	int ret = 0;
+
+	if (WARN_ON(key_idx >= TRACING_MAP_FIELDS_MAX))
+		return -EINVAL;
+
+	flags |= HIST_FIELD_FL_KEY;
+
+	if (strcmp(field_str, "stacktrace") == 0) {
+		flags |= HIST_FIELD_FL_STACKTRACE;
+		key_size = sizeof(unsigned long) * HIST_STACKTRACE_DEPTH;
+	} else {
+		char *field_name = strsep(&field_str, ".");
+
+		if (field_str) {
+			if (strcmp(field_str, "hex") == 0)
+				flags |= HIST_FIELD_FL_HEX;
+			else if (strcmp(field_str, "sym") == 0)
+				flags |= HIST_FIELD_FL_SYM;
+			else if (strcmp(field_str, "sym-offset") == 0)
+				flags |= HIST_FIELD_FL_SYM_OFFSET;
+			else if ((strcmp(field_str, "execname") == 0) &&
+				 (strcmp(field_name, "common_pid") == 0))
+				flags |= HIST_FIELD_FL_EXECNAME;
+			else if (strcmp(field_str, "syscall") == 0)
+				flags |= HIST_FIELD_FL_SYSCALL;
+			else if (strcmp(field_str, "log2") == 0)
+				flags |= HIST_FIELD_FL_LOG2;
+			else {
+				ret = -EINVAL;
+				goto out;
+			}
+		}
+
+		field = trace_find_event_field(file->event_call, field_name);
+		if (!field) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (is_string_field(field))
+			key_size = MAX_FILTER_STR_VAL;
+		else
+			key_size = field->size;
+	}
+
+	hist_data->fields[key_idx] = create_hist_field(field, flags);
+	if (!hist_data->fields[key_idx]) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	key_size = ALIGN(key_size, sizeof(u64));
+	hist_data->fields[key_idx]->size = key_size;
+	hist_data->fields[key_idx]->offset = key_offset;
+	hist_data->key_size += key_size;
+	if (hist_data->key_size > HIST_KEY_SIZE_MAX) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	hist_data->n_keys++;
+
+	if (WARN_ON(hist_data->n_keys > TRACING_MAP_KEYS_MAX))
+		return -EINVAL;
+
+	ret = key_size;
+ out:
+	return ret;
+}
+
+static int create_key_fields(struct hist_trigger_data *hist_data,
+			     struct trace_event_file *file)
+{
+	unsigned int i, key_offset = 0, n_vals = hist_data->n_vals;
+	char *fields_str, *field_str;
+	int ret = -EINVAL;
+
+	fields_str = hist_data->attrs->keys_str;
+	if (!fields_str)
+		goto out;
+
+	strsep(&fields_str, "=");
+	if (!fields_str)
+		goto out;
+
+	for (i = n_vals; i < n_vals + TRACING_MAP_KEYS_MAX; i++) {
+		field_str = strsep(&fields_str, ",");
+		if (!field_str)
+			break;
+		ret = create_key_field(hist_data, i, key_offset,
+				       file, field_str);
+		if (ret < 0)
+			goto out;
+		key_offset += ret;
+	}
+	if (fields_str) {
+		ret = -EINVAL;
+		goto out;
+	}
+	ret = 0;
+ out:
+	return ret;
+}
+
+static int create_hist_fields(struct hist_trigger_data *hist_data,
+			      struct trace_event_file *file)
+{
+	int ret;
+
+	ret = create_val_fields(hist_data, file);
+	if (ret)
+		goto out;
+
+	ret = create_key_fields(hist_data, file);
+	if (ret)
+		goto out;
+
+	hist_data->n_fields = hist_data->n_vals + hist_data->n_keys;
+ out:
+	return ret;
+}
+
+static int is_descending(const char *str)
+{
+	if (!str)
+		return 0;
+
+	if (strcmp(str, "descending") == 0)
+		return 1;
+
+	if (strcmp(str, "ascending") == 0)
+		return 0;
+
+	return -EINVAL;
+}
+
+static int create_sort_keys(struct hist_trigger_data *hist_data)
+{
+	char *fields_str = hist_data->attrs->sort_key_str;
+	struct ftrace_event_field *field = NULL;
+	struct tracing_map_sort_key *sort_key;
+	int descending, ret = 0;
+	unsigned int i, j;
+
+	hist_data->n_sort_keys = 1; /* we always have at least one, hitcount */
+
+	if (!fields_str)
+		goto out;
+
+	strsep(&fields_str, "=");
+	if (!fields_str) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	for (i = 0; i < TRACING_MAP_SORT_KEYS_MAX; i++) {
+		char *field_str, *field_name;
+
+		sort_key = &hist_data->sort_keys[i];
+
+		field_str = strsep(&fields_str, ",");
+		if (!field_str) {
+			if (i == 0)
+				ret = -EINVAL;
+			break;
+		}
+
+		if ((i == TRACING_MAP_SORT_KEYS_MAX - 1) && fields_str) {
+			ret = -EINVAL;
+			break;
+		}
+
+		field_name = strsep(&field_str, ".");
+		if (!field_name) {
+			ret = -EINVAL;
+			break;
+		}
+
+		if (strcmp(field_name, "hitcount") == 0) {
+			descending = is_descending(field_str);
+			if (descending < 0) {
+				ret = descending;
+				break;
+			}
+			sort_key->descending = descending;
+			continue;
+		}
+
+		for (j = 1; j < hist_data->n_fields; j++) {
+			field = hist_data->fields[j]->field;
+			if (field && (strcmp(field_name, field->name) == 0)) {
+				sort_key->field_idx = j;
+				descending = is_descending(field_str);
+				if (descending < 0) {
+					ret = descending;
+					goto out;
+				}
+				sort_key->descending = descending;
+				break;
+			}
+		}
+		if (j == hist_data->n_fields) {
+			ret = -EINVAL;
+			break;
+		}
+	}
+	hist_data->n_sort_keys = i;
+ out:
+	return ret;
+}
+
+static void destroy_hist_data(struct hist_trigger_data *hist_data)
+{
+	destroy_hist_trigger_attrs(hist_data->attrs);
+	destroy_hist_fields(hist_data);
+	tracing_map_destroy(hist_data->map);
+	kfree(hist_data);
+}
+
+static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
+{
+	struct tracing_map *map = hist_data->map;
+	struct ftrace_event_field *field;
+	struct hist_field *hist_field;
+	int i, idx;
+
+	for_each_hist_field(i, hist_data) {
+		hist_field = hist_data->fields[i];
+		if (hist_field->flags & HIST_FIELD_FL_KEY) {
+			tracing_map_cmp_fn_t cmp_fn;
+
+			field = hist_field->field;
+
+			if (hist_field->flags & HIST_FIELD_FL_STACKTRACE)
+				cmp_fn = tracing_map_cmp_none;
+			else if (is_string_field(field))
+				cmp_fn = tracing_map_cmp_string;
+			else
+				cmp_fn = tracing_map_cmp_num(field->size,
+							     field->is_signed);
+			idx = tracing_map_add_key_field(map,
+							hist_field->offset,
+							cmp_fn);
+
+		} else
+			idx = tracing_map_add_sum_field(map);
+
+		if (idx < 0)
+			return idx;
+	}
+
+	return 0;
+}
+
+static bool need_tracing_map_ops(struct hist_trigger_data *hist_data)
+{
+	struct hist_field *key_field;
+	unsigned int i;
+
+	for_each_hist_key_field(i, hist_data) {
+		key_field = hist_data->fields[i];
+
+		if (key_field->flags & HIST_FIELD_FL_EXECNAME)
+			return true;
+	}
+
+	return false;
+}
+
+static struct hist_trigger_data *
+create_hist_data(unsigned int map_bits,
+		 struct hist_trigger_attrs *attrs,
+		 struct trace_event_file *file)
+{
+	const struct tracing_map_ops *map_ops = NULL;
+	struct hist_trigger_data *hist_data;
+	int ret = 0;
+
+	hist_data = kzalloc(sizeof(*hist_data), GFP_KERNEL);
+	if (!hist_data)
+		return ERR_PTR(-ENOMEM);
+
+	hist_data->attrs = attrs;
+
+	ret = create_hist_fields(hist_data, file);
+	if (ret)
+		goto free;
+
+	ret = create_sort_keys(hist_data);
+	if (ret)
+		goto free;
+
+	if (need_tracing_map_ops(hist_data))
+		map_ops = &hist_trigger_elt_comm_ops;
+
+	hist_data->map = tracing_map_create(map_bits, hist_data->key_size,
+					    map_ops, hist_data);
+	if (IS_ERR(hist_data->map)) {
+		ret = PTR_ERR(hist_data->map);
+		hist_data->map = NULL;
+		goto free;
+	}
+
+	ret = create_tracing_map_fields(hist_data);
+	if (ret)
+		goto free;
+
+	ret = tracing_map_init(hist_data->map);
+	if (ret)
+		goto free;
+
+	hist_data->event_file = file;
+ out:
+	return hist_data;
+ free:
+	hist_data->attrs = NULL;
+
+	destroy_hist_data(hist_data);
+
+	hist_data = ERR_PTR(ret);
+
+	goto out;
+}
+
+static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
+				    struct tracing_map_elt *elt,
+				    void *rec)
+{
+	struct hist_field *hist_field;
+	unsigned int i;
+	u64 hist_val;
+
+	for_each_hist_val_field(i, hist_data) {
+		hist_field = hist_data->fields[i];
+		hist_val = hist_field->fn(hist_field, rec);
+		tracing_map_update_sum(elt, i, hist_val);
+	}
+}
+
+static inline void add_to_key(char *compound_key, void *key,
+			      struct hist_field *key_field, void *rec)
+{
+	size_t size = key_field->size;
+
+	if (key_field->flags & HIST_FIELD_FL_STRING) {
+		struct ftrace_event_field *field;
+
+		field = key_field->field;
+		if (field->filter_type == FILTER_DYN_STRING)
+			size = *(u32 *)(rec + field->offset) >> 16;
+		else if (field->filter_type == FILTER_PTR_STRING)
+			size = strlen(key);
+		else if (field->filter_type == FILTER_STATIC_STRING)
+			size = field->size;
+
+		/* ensure NULL-termination */
+		if (size > key_field->size - 1)
+			size = key_field->size - 1;
+	}
+
+	memcpy(compound_key + key_field->offset, key, size);
+}
+
+static void event_hist_trigger(struct event_trigger_data *data, void *rec)
+{
+	struct hist_trigger_data *hist_data = data->private_data;
+	bool use_compound_key = (hist_data->n_keys > 1);
+	unsigned long entries[HIST_STACKTRACE_DEPTH];
+	char compound_key[HIST_KEY_SIZE_MAX];
+	struct stack_trace stacktrace;
+	struct hist_field *key_field;
+	struct tracing_map_elt *elt;
+	u64 field_contents;
+	void *key = NULL;
+	unsigned int i;
+
+	memset(compound_key, 0, hist_data->key_size);
+
+	for_each_hist_key_field(i, hist_data) {
+		key_field = hist_data->fields[i];
+
+		if (key_field->flags & HIST_FIELD_FL_STACKTRACE) {
+			stacktrace.max_entries = HIST_STACKTRACE_DEPTH;
+			stacktrace.entries = entries;
+			stacktrace.nr_entries = 0;
+			stacktrace.skip = HIST_STACKTRACE_SKIP;
+
+			memset(stacktrace.entries, 0, HIST_STACKTRACE_SIZE);
+			save_stack_trace(&stacktrace);
+
+			key = entries;
+		} else {
+			field_contents = key_field->fn(key_field, rec);
+			if (key_field->flags & HIST_FIELD_FL_STRING) {
+				key = (void *)(unsigned long)field_contents;
+				use_compound_key = true;
+			} else
+				key = (void *)&field_contents;
+		}
+
+		if (use_compound_key)
+			add_to_key(compound_key, key, key_field, rec);
+	}
+
+	if (use_compound_key)
+		key = compound_key;
+
+	elt = tracing_map_insert(hist_data->map, key);
+	if (elt)
+		hist_trigger_elt_update(hist_data, elt, rec);
+}
+
+static void hist_trigger_stacktrace_print(struct seq_file *m,
+					  unsigned long *stacktrace_entries,
+					  unsigned int max_entries)
+{
+	char str[KSYM_SYMBOL_LEN];
+	unsigned int spaces = 8;
+	unsigned int i;
+
+	for (i = 0; i < max_entries; i++) {
+		if (stacktrace_entries[i] == ULONG_MAX)
+			return;
+
+		seq_printf(m, "%*c", 1 + spaces, ' ');
+		sprint_symbol(str, stacktrace_entries[i]);
+		seq_printf(m, "%s\n", str);
+	}
+}
+
+static void
+hist_trigger_entry_print(struct seq_file *m,
+			 struct hist_trigger_data *hist_data, void *key,
+			 struct tracing_map_elt *elt)
+{
+	struct hist_field *key_field;
+	char str[KSYM_SYMBOL_LEN];
+	bool multiline = false;
+	unsigned int i;
+	u64 uval;
+
+	seq_puts(m, "{ ");
+
+	for_each_hist_key_field(i, hist_data) {
+		key_field = hist_data->fields[i];
+
+		if (i > hist_data->n_vals)
+			seq_puts(m, ", ");
+
+		if (key_field->flags & HIST_FIELD_FL_HEX) {
+			uval = *(u64 *)(key + key_field->offset);
+			seq_printf(m, "%s: %llx",
+				   key_field->field->name, uval);
+		} else if (key_field->flags & HIST_FIELD_FL_SYM) {
+			uval = *(u64 *)(key + key_field->offset);
+			sprint_symbol_no_offset(str, uval);
+			seq_printf(m, "%s: [%llx] %-45s",
+				   key_field->field->name, uval, str);
+		} else if (key_field->flags & HIST_FIELD_FL_SYM_OFFSET) {
+			uval = *(u64 *)(key + key_field->offset);
+			sprint_symbol(str, uval);
+			seq_printf(m, "%s: [%llx] %-55s",
+				   key_field->field->name, uval, str);
+		} else if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
+			char *comm = elt->private_data;
+
+			uval = *(u64 *)(key + key_field->offset);
+			seq_printf(m, "%s: %-16s[%10llu]",
+				   key_field->field->name, comm, uval);
+		} else if (key_field->flags & HIST_FIELD_FL_SYSCALL) {
+			const char *syscall_name;
+
+			uval = *(u64 *)(key + key_field->offset);
+			syscall_name = get_syscall_name(uval);
+			if (!syscall_name)
+				syscall_name = "unknown_syscall";
+
+			seq_printf(m, "%s: %-30s[%3llu]",
+				   key_field->field->name, syscall_name, uval);
+		} else if (key_field->flags & HIST_FIELD_FL_STACKTRACE) {
+			seq_puts(m, "stacktrace:\n");
+			hist_trigger_stacktrace_print(m,
+						      key + key_field->offset,
+						      HIST_STACKTRACE_DEPTH);
+			multiline = true;
+		} else if (key_field->flags & HIST_FIELD_FL_LOG2) {
+			seq_printf(m, "%s: ~ 2^%-2llu", key_field->field->name,
+				   *(u64 *)(key + key_field->offset));
+		} else if (key_field->flags & HIST_FIELD_FL_STRING) {
+			seq_printf(m, "%s: %-50s", key_field->field->name,
+				   (char *)(key + key_field->offset));
+		} else {
+			uval = *(u64 *)(key + key_field->offset);
+			seq_printf(m, "%s: %10llu", key_field->field->name,
+				   uval);
+		}
+	}
+
+	if (!multiline)
+		seq_puts(m, " ");
+
+	seq_puts(m, "}");
+
+	seq_printf(m, " hitcount: %10llu",
+		   tracing_map_read_sum(elt, HITCOUNT_IDX));
+
+	for (i = 1; i < hist_data->n_vals; i++) {
+		if (hist_data->fields[i]->flags & HIST_FIELD_FL_HEX) {
+			seq_printf(m, "  %s: %10llx",
+				   hist_data->fields[i]->field->name,
+				   tracing_map_read_sum(elt, i));
+		} else {
+			seq_printf(m, "  %s: %10llu",
+				   hist_data->fields[i]->field->name,
+				   tracing_map_read_sum(elt, i));
+		}
+	}
+
+	seq_puts(m, "\n");
+}
+
+static int print_entries(struct seq_file *m,
+			 struct hist_trigger_data *hist_data)
+{
+	struct tracing_map_sort_entry **sort_entries = NULL;
+	struct tracing_map *map = hist_data->map;
+	int i, n_entries;
+
+	n_entries = tracing_map_sort_entries(map, hist_data->sort_keys,
+					     hist_data->n_sort_keys,
+					     &sort_entries);
+	if (n_entries < 0)
+		return n_entries;
+
+	for (i = 0; i < n_entries; i++)
+		hist_trigger_entry_print(m, hist_data,
+					 sort_entries[i]->key,
+					 sort_entries[i]->elt);
+
+	tracing_map_destroy_sort_entries(sort_entries, n_entries);
+
+	return n_entries;
+}
+
+static void hist_trigger_show(struct seq_file *m,
+			      struct event_trigger_data *data, int n)
+{
+	struct hist_trigger_data *hist_data;
+	int n_entries, ret = 0;
+
+	if (n > 0)
+		seq_puts(m, "\n\n");
+
+	seq_puts(m, "# event histogram\n#\n# trigger info: ");
+	data->ops->print(m, data->ops, data);
+	seq_puts(m, "#\n\n");
+
+	hist_data = data->private_data;
+	n_entries = print_entries(m, hist_data);
+	if (n_entries < 0) {
+		ret = n_entries;
+		n_entries = 0;
+	}
+
+	seq_printf(m, "\nTotals:\n    Hits: %llu\n    Entries: %u\n    Dropped: %llu\n",
+		   (u64)atomic64_read(&hist_data->map->hits),
+		   n_entries, (u64)atomic64_read(&hist_data->map->drops));
+}
+
+static int hist_show(struct seq_file *m, void *v)
+{
+	struct event_trigger_data *data;
+	struct trace_event_file *event_file;
+	int n = 0, ret = 0;
+
+	mutex_lock(&event_mutex);
+
+	event_file = event_file_data(m->private);
+	if (unlikely(!event_file)) {
+		ret = -ENODEV;
+		goto out_unlock;
+	}
+
+	list_for_each_entry_rcu(data, &event_file->triggers, list) {
+		if (data->cmd_ops->trigger_type == ETT_EVENT_HIST)
+			hist_trigger_show(m, data, n++);
+	}
+
+ out_unlock:
+	mutex_unlock(&event_mutex);
+
+	return ret;
+}
+
+static int event_hist_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, hist_show, file);
+}
+
+const struct file_operations event_hist_fops = {
+	.open = event_hist_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static const char *get_hist_field_flags(struct hist_field *hist_field)
+{
+	const char *flags_str = NULL;
+
+	if (hist_field->flags & HIST_FIELD_FL_HEX)
+		flags_str = "hex";
+	else if (hist_field->flags & HIST_FIELD_FL_SYM)
+		flags_str = "sym";
+	else if (hist_field->flags & HIST_FIELD_FL_SYM_OFFSET)
+		flags_str = "sym-offset";
+	else if (hist_field->flags & HIST_FIELD_FL_EXECNAME)
+		flags_str = "execname";
+	else if (hist_field->flags & HIST_FIELD_FL_SYSCALL)
+		flags_str = "syscall";
+	else if (hist_field->flags & HIST_FIELD_FL_LOG2)
+		flags_str = "log2";
+
+	return flags_str;
+}
+
+static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
+{
+	seq_printf(m, "%s", hist_field->field->name);
+	if (hist_field->flags) {
+		const char *flags_str = get_hist_field_flags(hist_field);
+
+		if (flags_str)
+			seq_printf(m, ".%s", flags_str);
+	}
+}
+
+static int event_hist_trigger_print(struct seq_file *m,
+				    struct event_trigger_ops *ops,
+				    struct event_trigger_data *data)
+{
+	struct hist_trigger_data *hist_data = data->private_data;
+	struct hist_field *key_field;
+	unsigned int i;
+
+	seq_puts(m, "hist:");
+
+	if (data->name)
+		seq_printf(m, "%s:", data->name);
+
+	seq_puts(m, "keys=");
+
+	for_each_hist_key_field(i, hist_data) {
+		key_field = hist_data->fields[i];
+
+		if (i > hist_data->n_vals)
+			seq_puts(m, ",");
+
+		if (key_field->flags & HIST_FIELD_FL_STACKTRACE)
+			seq_puts(m, "stacktrace");
+		else
+			hist_field_print(m, key_field);
+	}
+
+	seq_puts(m, ":vals=");
+
+	for_each_hist_val_field(i, hist_data) {
+		if (i == HITCOUNT_IDX)
+			seq_puts(m, "hitcount");
+		else {
+			seq_puts(m, ",");
+			hist_field_print(m, hist_data->fields[i]);
+		}
+	}
+
+	seq_puts(m, ":sort=");
+
+	for (i = 0; i < hist_data->n_sort_keys; i++) {
+		struct tracing_map_sort_key *sort_key;
+
+		sort_key = &hist_data->sort_keys[i];
+
+		if (i > 0)
+			seq_puts(m, ",");
+
+		if (sort_key->field_idx == HITCOUNT_IDX)
+			seq_puts(m, "hitcount");
+		else {
+			unsigned int idx = sort_key->field_idx;
+
+			if (WARN_ON(idx >= TRACING_MAP_FIELDS_MAX))
+				return -EINVAL;
+
+			hist_field_print(m, hist_data->fields[idx]);
+		}
+
+		if (sort_key->descending)
+			seq_puts(m, ".descending");
+	}
+
+	seq_printf(m, ":size=%u", (1 << hist_data->map->map_bits));
+
+	if (data->filter_str)
+		seq_printf(m, " if %s", data->filter_str);
+
+	if (data->paused)
+		seq_puts(m, " [paused]");
+	else
+		seq_puts(m, " [active]");
+
+	seq_putc(m, '\n');
+
+	return 0;
+}
+
+static int event_hist_trigger_init(struct event_trigger_ops *ops,
+				   struct event_trigger_data *data)
+{
+	struct hist_trigger_data *hist_data = data->private_data;
+
+	if (!data->ref && hist_data->attrs->name)
+		save_named_trigger(hist_data->attrs->name, data);
+
+	data->ref++;
+
+	return 0;
+}
+
+static void event_hist_trigger_free(struct event_trigger_ops *ops,
+				    struct event_trigger_data *data)
+{
+	struct hist_trigger_data *hist_data = data->private_data;
+
+	if (WARN_ON_ONCE(data->ref <= 0))
+		return;
+
+	data->ref--;
+	if (!data->ref) {
+		if (data->name)
+			del_named_trigger(data);
+		trigger_data_free(data);
+		destroy_hist_data(hist_data);
+	}
+}
+
+static struct event_trigger_ops event_hist_trigger_ops = {
+	.func			= event_hist_trigger,
+	.print			= event_hist_trigger_print,
+	.init			= event_hist_trigger_init,
+	.free			= event_hist_trigger_free,
+};
+
+static int event_hist_trigger_named_init(struct event_trigger_ops *ops,
+					 struct event_trigger_data *data)
+{
+	data->ref++;
+
+	save_named_trigger(data->named_data->name, data);
+
+	event_hist_trigger_init(ops, data->named_data);
+
+	return 0;
+}
+
+static void event_hist_trigger_named_free(struct event_trigger_ops *ops,
+					  struct event_trigger_data *data)
+{
+	if (WARN_ON_ONCE(data->ref <= 0))
+		return;
+
+	event_hist_trigger_free(ops, data->named_data);
+
+	data->ref--;
+	if (!data->ref) {
+		del_named_trigger(data);
+		trigger_data_free(data);
+	}
+}
+
+static struct event_trigger_ops event_hist_trigger_named_ops = {
+	.func			= event_hist_trigger,
+	.print			= event_hist_trigger_print,
+	.init			= event_hist_trigger_named_init,
+	.free			= event_hist_trigger_named_free,
+};
+
+static struct event_trigger_ops *event_hist_get_trigger_ops(char *cmd,
+							    char *param)
+{
+	return &event_hist_trigger_ops;
+}
+
+static void hist_clear(struct event_trigger_data *data)
+{
+	struct hist_trigger_data *hist_data = data->private_data;
+
+	if (data->name)
+		pause_named_trigger(data);
+
+	synchronize_sched();
+
+	tracing_map_clear(hist_data->map);
+
+	if (data->name)
+		unpause_named_trigger(data);
+}
+
+static bool compatible_field(struct ftrace_event_field *field,
+			     struct ftrace_event_field *test_field)
+{
+	if (field == test_field)
+		return true;
+	if (field == NULL || test_field == NULL)
+		return false;
+	if (strcmp(field->name, test_field->name) != 0)
+		return false;
+	if (strcmp(field->type, test_field->type) != 0)
+		return false;
+	if (field->size != test_field->size)
+		return false;
+	if (field->is_signed != test_field->is_signed)
+		return false;
+
+	return true;
+}
+
+static bool hist_trigger_match(struct event_trigger_data *data,
+			       struct event_trigger_data *data_test,
+			       struct event_trigger_data *named_data,
+			       bool ignore_filter)
+{
+	struct tracing_map_sort_key *sort_key, *sort_key_test;
+	struct hist_trigger_data *hist_data, *hist_data_test;
+	struct hist_field *key_field, *key_field_test;
+	unsigned int i;
+
+	if (named_data && (named_data != data_test) &&
+	    (named_data != data_test->named_data))
+		return false;
+
+	if (!named_data && is_named_trigger(data_test))
+		return false;
+
+	hist_data = data->private_data;
+	hist_data_test = data_test->private_data;
+
+	if (hist_data->n_vals != hist_data_test->n_vals ||
+	    hist_data->n_fields != hist_data_test->n_fields ||
+	    hist_data->n_sort_keys != hist_data_test->n_sort_keys)
+		return false;
+
+	if (!ignore_filter) {
+		if ((data->filter_str && !data_test->filter_str) ||
+		   (!data->filter_str && data_test->filter_str))
+			return false;
+	}
+
+	for_each_hist_field(i, hist_data) {
+		key_field = hist_data->fields[i];
+		key_field_test = hist_data_test->fields[i];
+
+		if (key_field->flags != key_field_test->flags)
+			return false;
+		if (!compatible_field(key_field->field, key_field_test->field))
+			return false;
+		if (key_field->offset != key_field_test->offset)
+			return false;
+	}
+
+	for (i = 0; i < hist_data->n_sort_keys; i++) {
+		sort_key = &hist_data->sort_keys[i];
+		sort_key_test = &hist_data_test->sort_keys[i];
+
+		if (sort_key->field_idx != sort_key_test->field_idx ||
+		    sort_key->descending != sort_key_test->descending)
+			return false;
+	}
+
+	if (!ignore_filter && data->filter_str &&
+	    (strcmp(data->filter_str, data_test->filter_str) != 0))
+		return false;
+
+	return true;
+}
+
+static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
+				 struct event_trigger_data *data,
+				 struct trace_event_file *file)
+{
+	struct hist_trigger_data *hist_data = data->private_data;
+	struct event_trigger_data *test, *named_data = NULL;
+	int ret = 0;
+
+	if (hist_data->attrs->name) {
+		named_data = find_named_trigger(hist_data->attrs->name);
+		if (named_data) {
+			if (!hist_trigger_match(data, named_data, named_data,
+						true)) {
+				ret = -EINVAL;
+				goto out;
+			}
+		}
+	}
+
+	if (hist_data->attrs->name && !named_data)
+		goto new;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			if (!hist_trigger_match(data, test, named_data, false))
+				continue;
+			if (hist_data->attrs->pause)
+				test->paused = true;
+			else if (hist_data->attrs->cont)
+				test->paused = false;
+			else if (hist_data->attrs->clear)
+				hist_clear(test);
+			else
+				ret = -EEXIST;
+			goto out;
+		}
+	}
+ new:
+	if (hist_data->attrs->cont || hist_data->attrs->clear) {
+		ret = -ENOENT;
+		goto out;
+	}
+
+	if (named_data) {
+		destroy_hist_data(data->private_data);
+		data->private_data = named_data->private_data;
+		set_named_trigger_data(data, named_data);
+		data->ops = &event_hist_trigger_named_ops;
+	}
+
+	if (hist_data->attrs->pause)
+		data->paused = true;
+
+	if (data->ops->init) {
+		ret = data->ops->init(data->ops, data);
+		if (ret < 0)
+			goto out;
+	}
+
+	list_add_rcu(&data->list, &file->triggers);
+	ret++;
+
+	update_cond_flag(file);
+
+	if (trace_event_trigger_enable_disable(file, 1) < 0) {
+		list_del_rcu(&data->list);
+		update_cond_flag(file);
+		ret--;
+	}
+ out:
+	return ret;
+}
+
+static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,
+				    struct event_trigger_data *data,
+				    struct trace_event_file *file)
+{
+	struct hist_trigger_data *hist_data = data->private_data;
+	struct event_trigger_data *test, *named_data = NULL;
+	bool unregistered = false;
+
+	if (hist_data->attrs->name)
+		named_data = find_named_trigger(hist_data->attrs->name);
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			if (!hist_trigger_match(data, test, named_data, false))
+				continue;
+			unregistered = true;
+			list_del_rcu(&test->list);
+			trace_event_trigger_enable_disable(file, 0);
+			update_cond_flag(file);
+			break;
+		}
+	}
+
+	if (unregistered && test->ops->free)
+		test->ops->free(test->ops, test);
+}
+
+static void hist_unreg_all(struct trace_event_file *file)
+{
+	struct event_trigger_data *test;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			list_del_rcu(&test->list);
+			trace_event_trigger_enable_disable(file, 0);
+			update_cond_flag(file);
+			if (test->ops->free)
+				test->ops->free(test->ops, test);
+		}
+	}
+}
+
+static int event_hist_trigger_func(struct event_command *cmd_ops,
+				   struct trace_event_file *file,
+				   char *glob, char *cmd, char *param)
+{
+	unsigned int hist_trigger_bits = TRACING_MAP_BITS_DEFAULT;
+	struct event_trigger_data *trigger_data;
+	struct hist_trigger_attrs *attrs;
+	struct event_trigger_ops *trigger_ops;
+	struct hist_trigger_data *hist_data;
+	char *trigger;
+	int ret = 0;
+
+	if (!param)
+		return -EINVAL;
+
+	/* separate the trigger from the filter (k:v [if filter]) */
+	trigger = strsep(&param, " \t");
+	if (!trigger)
+		return -EINVAL;
+
+	attrs = parse_hist_trigger_attrs(trigger);
+	if (IS_ERR(attrs))
+		return PTR_ERR(attrs);
+
+	if (attrs->map_bits)
+		hist_trigger_bits = attrs->map_bits;
+
+	hist_data = create_hist_data(hist_trigger_bits, attrs, file);
+	if (IS_ERR(hist_data)) {
+		destroy_hist_trigger_attrs(attrs);
+		return PTR_ERR(hist_data);
+	}
+
+	trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
+
+	ret = -ENOMEM;
+	trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
+	if (!trigger_data)
+		goto out_free;
+
+	trigger_data->count = -1;
+	trigger_data->ops = trigger_ops;
+	trigger_data->cmd_ops = cmd_ops;
+
+	INIT_LIST_HEAD(&trigger_data->list);
+	RCU_INIT_POINTER(trigger_data->filter, NULL);
+
+	trigger_data->private_data = hist_data;
+
+	/* if param is non-empty, it's supposed to be a filter */
+	if (param && cmd_ops->set_filter) {
+		ret = cmd_ops->set_filter(param, trigger_data, file);
+		if (ret < 0)
+			goto out_free;
+	}
+
+	if (glob[0] == '!') {
+		cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
+		ret = 0;
+		goto out_free;
+	}
+
+	ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
+	/*
+	 * The above returns on success the # of triggers registered,
+	 * but if it didn't register any it returns zero.  Consider no
+	 * triggers registered a failure too.
+	 */
+	if (!ret) {
+		if (!(attrs->pause || attrs->cont || attrs->clear))
+			ret = -ENOENT;
+		goto out_free;
+	} else if (ret < 0)
+		goto out_free;
+	/* Just return zero, not the number of registered triggers */
+	ret = 0;
+ out:
+	return ret;
+ out_free:
+	if (cmd_ops->set_filter)
+		cmd_ops->set_filter(NULL, trigger_data, NULL);
+
+	kfree(trigger_data);
+
+	destroy_hist_data(hist_data);
+	goto out;
+}
+
+static struct event_command trigger_hist_cmd = {
+	.name			= "hist",
+	.trigger_type		= ETT_EVENT_HIST,
+	.flags			= EVENT_CMD_FL_NEEDS_REC,
+	.func			= event_hist_trigger_func,
+	.reg			= hist_register_trigger,
+	.unreg			= hist_unregister_trigger,
+	.unreg_all		= hist_unreg_all,
+	.get_trigger_ops	= event_hist_get_trigger_ops,
+	.set_filter		= set_trigger_filter,
+};
+
+__init int register_trigger_hist_cmd(void)
+{
+	int ret;
+
+	ret = register_event_command(&trigger_hist_cmd);
+	WARN_ON(ret < 0);
+
+	return ret;
+}
+
+static void
+hist_enable_trigger(struct event_trigger_data *data, void *rec)
+{
+	struct enable_trigger_data *enable_data = data->private_data;
+	struct event_trigger_data *test;
+
+	list_for_each_entry_rcu(test, &enable_data->file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+			if (enable_data->enable)
+				test->paused = false;
+			else
+				test->paused = true;
+		}
+	}
+}
+
+static void
+hist_enable_count_trigger(struct event_trigger_data *data, void *rec)
+{
+	if (!data->count)
+		return;
+
+	if (data->count != -1)
+		(data->count)--;
+
+	hist_enable_trigger(data, rec);
+}
+
+static struct event_trigger_ops hist_enable_trigger_ops = {
+	.func			= hist_enable_trigger,
+	.print			= event_enable_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_enable_trigger_free,
+};
+
+static struct event_trigger_ops hist_enable_count_trigger_ops = {
+	.func			= hist_enable_count_trigger,
+	.print			= event_enable_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_enable_trigger_free,
+};
+
+static struct event_trigger_ops hist_disable_trigger_ops = {
+	.func			= hist_enable_trigger,
+	.print			= event_enable_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_enable_trigger_free,
+};
+
+static struct event_trigger_ops hist_disable_count_trigger_ops = {
+	.func			= hist_enable_count_trigger,
+	.print			= event_enable_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_enable_trigger_free,
+};
+
+static struct event_trigger_ops *
+hist_enable_get_trigger_ops(char *cmd, char *param)
+{
+	struct event_trigger_ops *ops;
+	bool enable;
+
+	enable = (strcmp(cmd, ENABLE_HIST_STR) == 0);
+
+	if (enable)
+		ops = param ? &hist_enable_count_trigger_ops :
+			&hist_enable_trigger_ops;
+	else
+		ops = param ? &hist_disable_count_trigger_ops :
+			&hist_disable_trigger_ops;
+
+	return ops;
+}
+
+static void hist_enable_unreg_all(struct trace_event_file *file)
+{
+	struct event_trigger_data *test;
+
+	list_for_each_entry_rcu(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == ETT_HIST_ENABLE) {
+			list_del_rcu(&test->list);
+			update_cond_flag(file);
+			trace_event_trigger_enable_disable(file, 0);
+			if (test->ops->free)
+				test->ops->free(test->ops, test);
+		}
+	}
+}
+
+static struct event_command trigger_hist_enable_cmd = {
+	.name			= ENABLE_HIST_STR,
+	.trigger_type		= ETT_HIST_ENABLE,
+	.func			= event_enable_trigger_func,
+	.reg			= event_enable_register_trigger,
+	.unreg			= event_enable_unregister_trigger,
+	.unreg_all		= hist_enable_unreg_all,
+	.get_trigger_ops	= hist_enable_get_trigger_ops,
+	.set_filter		= set_trigger_filter,
+};
+
+static struct event_command trigger_hist_disable_cmd = {
+	.name			= DISABLE_HIST_STR,
+	.trigger_type		= ETT_HIST_ENABLE,
+	.func			= event_enable_trigger_func,
+	.reg			= event_enable_register_trigger,
+	.unreg			= event_enable_unregister_trigger,
+	.unreg_all		= hist_enable_unreg_all,
+	.get_trigger_ops	= hist_enable_get_trigger_ops,
+	.set_filter		= set_trigger_filter,
+};
+
+static __init void unregister_trigger_hist_enable_disable_cmds(void)
+{
+	unregister_event_command(&trigger_hist_enable_cmd);
+	unregister_event_command(&trigger_hist_disable_cmd);
+}
+
+__init int register_trigger_hist_enable_disable_cmds(void)
+{
+	int ret;
+
+	ret = register_event_command(&trigger_hist_enable_cmd);
+	if (WARN_ON(ret < 0))
+		return ret;
+	ret = register_event_command(&trigger_hist_disable_cmd);
+	if (WARN_ON(ret < 0))
+		unregister_trigger_hist_enable_disable_cmds();
+
+	return ret;
+}
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index d67992f3bb0e..a975571cde24 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -347,7 +347,7 @@ __init int register_event_command(struct event_command *cmd)
  * Currently we only unregister event commands from __init, so mark
  * this __init too.
  */
-static __init int unregister_event_command(struct event_command *cmd)
+__init int unregister_event_command(struct event_command *cmd)
 {
 	struct event_command *p, *n;
 	int ret = -ENODEV;
@@ -641,6 +641,7 @@ event_trigger_callback(struct event_command *cmd_ops,
 	trigger_data->ops = trigger_ops;
 	trigger_data->cmd_ops = cmd_ops;
 	INIT_LIST_HEAD(&trigger_data->list);
+	INIT_LIST_HEAD(&trigger_data->named_list);
 
 	if (glob[0] == '!') {
 		cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
@@ -764,6 +765,148 @@ int set_trigger_filter(char *filter_str,
 	return ret;
 }
 
+static LIST_HEAD(named_triggers);
+
+/**
+ * find_named_trigger - Find the common named trigger associated with @name
+ * @name: The name of the set of named triggers to find the common data for
+ *
+ * Named triggers are sets of triggers that share a common set of
+ * trigger data.  The first named trigger registered with a given name
+ * owns the common trigger data that the others subsequently
+ * registered with the same name will reference.  This function
+ * returns the common trigger data associated with that first
+ * registered instance.
+ *
+ * Return: the common trigger data for the given named trigger on
+ * success, NULL otherwise.
+ */
+struct event_trigger_data *find_named_trigger(const char *name)
+{
+	struct event_trigger_data *data;
+
+	if (!name)
+		return NULL;
+
+	list_for_each_entry(data, &named_triggers, named_list) {
+		if (data->named_data)
+			continue;
+		if (strcmp(data->name, name) == 0)
+			return data;
+	}
+
+	return NULL;
+}
+
+/**
+ * is_named_trigger - determine if a given trigger is a named trigger
+ * @test: The trigger data to test
+ *
+ * Return: true if 'test' is a named trigger, false otherwise.
+ */
+bool is_named_trigger(struct event_trigger_data *test)
+{
+	struct event_trigger_data *data;
+
+	list_for_each_entry(data, &named_triggers, named_list) {
+		if (test == data)
+			return true;
+	}
+
+	return false;
+}
+
+/**
+ * save_named_trigger - save the trigger in the named trigger list
+ * @name: The name of the named trigger set
+ * @data: The trigger data to save
+ *
+ * Return: 0 if successful, negative error otherwise.
+ */
+int save_named_trigger(const char *name, struct event_trigger_data *data)
+{
+	data->name = kstrdup(name, GFP_KERNEL);
+	if (!data->name)
+		return -ENOMEM;
+
+	list_add(&data->named_list, &named_triggers);
+
+	return 0;
+}
+
+/**
+ * del_named_trigger - delete a trigger from the named trigger list
+ * @data: The trigger data to delete
+ */
+void del_named_trigger(struct event_trigger_data *data)
+{
+	kfree(data->name);
+	data->name = NULL;
+
+	list_del(&data->named_list);
+}
+
+static void __pause_named_trigger(struct event_trigger_data *data, bool pause)
+{
+	struct event_trigger_data *test;
+
+	list_for_each_entry(test, &named_triggers, named_list) {
+		if (strcmp(test->name, data->name) == 0) {
+			if (pause) {
+				test->paused_tmp = test->paused;
+				test->paused = true;
+			} else {
+				test->paused = test->paused_tmp;
+			}
+		}
+	}
+}
+
+/**
+ * pause_named_trigger - Pause all named triggers with the same name
+ * @data: The trigger data of a named trigger to pause
+ *
+ * Pauses a named trigger along with all other triggers having the
+ * same name.  Because named triggers share a common set of data,
+ * pausing only one is meaningless, so pausing one named trigger needs
+ * to pause all triggers with the same name.
+ */
+void pause_named_trigger(struct event_trigger_data *data)
+{
+	__pause_named_trigger(data, true);
+}
+
+/**
+ * unpause_named_trigger - Un-pause all named triggers with the same name
+ * @data: The trigger data of a named trigger to unpause
+ *
+ * Un-pauses a named trigger along with all other triggers having the
+ * same name.  Because named triggers share a common set of data,
+ * unpausing only one is meaningless, so unpausing one named trigger
+ * needs to unpause all triggers with the same name.
+ */
+void unpause_named_trigger(struct event_trigger_data *data)
+{
+	__pause_named_trigger(data, false);
+}
+
+/**
+ * set_named_trigger_data - Associate common named trigger data
+ * @data: The trigger data of a named trigger to unpause
+ *
+ * Named triggers are sets of triggers that share a common set of
+ * trigger data.  The first named trigger registered with a given name
+ * owns the common trigger data that the others subsequently
+ * registered with the same name will reference.  This function
+ * associates the common trigger data from the first trigger with the
+ * given trigger.
+ */
+void set_named_trigger_data(struct event_trigger_data *data,
+			    struct event_trigger_data *named_data)
+{
+	data->named_data = named_data;
+}
+
 static void
 traceon_trigger(struct event_trigger_data *data, void *rec)
 {
@@ -1062,15 +1205,6 @@ static __init void unregister_trigger_traceon_traceoff_cmds(void)
 	unregister_event_command(&trigger_traceoff_cmd);
 }
 
-/* Avoid typos */
-#define ENABLE_EVENT_STR	"enable_event"
-#define DISABLE_EVENT_STR	"disable_event"
-
-struct enable_trigger_data {
-	struct trace_event_file		*file;
-	bool				enable;
-};
-
 static void
 event_enable_trigger(struct event_trigger_data *data, void *rec)
 {
@@ -1100,14 +1234,16 @@ event_enable_count_trigger(struct event_trigger_data *data, void *rec)
 	event_enable_trigger(data, rec);
 }
 
-static int
-event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
-			   struct event_trigger_data *data)
+int event_enable_trigger_print(struct seq_file *m,
+			       struct event_trigger_ops *ops,
+			       struct event_trigger_data *data)
 {
 	struct enable_trigger_data *enable_data = data->private_data;
 
 	seq_printf(m, "%s:%s:%s",
-		   enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
+		   enable_data->hist ?
+		   (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
+		   (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
 		   enable_data->file->event_call->class->system,
 		   trace_event_name(enable_data->file->event_call));
 
@@ -1124,9 +1260,8 @@ event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
 	return 0;
 }
 
-static void
-event_enable_trigger_free(struct event_trigger_ops *ops,
-			  struct event_trigger_data *data)
+void event_enable_trigger_free(struct event_trigger_ops *ops,
+			       struct event_trigger_data *data)
 {
 	struct enable_trigger_data *enable_data = data->private_data;
 
@@ -1171,10 +1306,9 @@ static struct event_trigger_ops event_disable_count_trigger_ops = {
 	.free			= event_enable_trigger_free,
 };
 
-static int
-event_enable_trigger_func(struct event_command *cmd_ops,
-			  struct trace_event_file *file,
-			  char *glob, char *cmd, char *param)
+int event_enable_trigger_func(struct event_command *cmd_ops,
+			      struct trace_event_file *file,
+			      char *glob, char *cmd, char *param)
 {
 	struct trace_event_file *event_enable_file;
 	struct enable_trigger_data *enable_data;
@@ -1183,6 +1317,7 @@ event_enable_trigger_func(struct event_command *cmd_ops,
 	struct trace_array *tr = file->tr;
 	const char *system;
 	const char *event;
+	bool hist = false;
 	char *trigger;
 	char *number;
 	bool enable;
@@ -1207,8 +1342,15 @@ event_enable_trigger_func(struct event_command *cmd_ops,
 	if (!event_enable_file)
 		goto out;
 
-	enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
+#ifdef CONFIG_HIST_TRIGGERS
+	hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
+		(strcmp(cmd, DISABLE_HIST_STR) == 0));
 
+	enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
+		  (strcmp(cmd, ENABLE_HIST_STR) == 0));
+#else
+	enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
+#endif
 	trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
 
 	ret = -ENOMEM;
@@ -1228,6 +1370,7 @@ event_enable_trigger_func(struct event_command *cmd_ops,
 	INIT_LIST_HEAD(&trigger_data->list);
 	RCU_INIT_POINTER(trigger_data->filter, NULL);
 
+	enable_data->hist = hist;
 	enable_data->enable = enable;
 	enable_data->file = event_enable_file;
 	trigger_data->private_data = enable_data;
@@ -1305,10 +1448,10 @@ event_enable_trigger_func(struct event_command *cmd_ops,
 	goto out;
 }
 
-static int event_enable_register_trigger(char *glob,
-					 struct event_trigger_ops *ops,
-					 struct event_trigger_data *data,
-					 struct trace_event_file *file)
+int event_enable_register_trigger(char *glob,
+				  struct event_trigger_ops *ops,
+				  struct event_trigger_data *data,
+				  struct trace_event_file *file)
 {
 	struct enable_trigger_data *enable_data = data->private_data;
 	struct enable_trigger_data *test_enable_data;
@@ -1318,6 +1461,8 @@ static int event_enable_register_trigger(char *glob,
 	list_for_each_entry_rcu(test, &file->triggers, list) {
 		test_enable_data = test->private_data;
 		if (test_enable_data &&
+		    (test->cmd_ops->trigger_type ==
+		     data->cmd_ops->trigger_type) &&
 		    (test_enable_data->file == enable_data->file)) {
 			ret = -EEXIST;
 			goto out;
@@ -1343,10 +1488,10 @@ out:
 	return ret;
 }
 
-static void event_enable_unregister_trigger(char *glob,
-					    struct event_trigger_ops *ops,
-					    struct event_trigger_data *test,
-					    struct trace_event_file *file)
+void event_enable_unregister_trigger(char *glob,
+				     struct event_trigger_ops *ops,
+				     struct event_trigger_data *test,
+				     struct trace_event_file *file)
 {
 	struct enable_trigger_data *test_enable_data = test->private_data;
 	struct enable_trigger_data *enable_data;
@@ -1356,6 +1501,8 @@ static void event_enable_unregister_trigger(char *glob,
 	list_for_each_entry_rcu(data, &file->triggers, list) {
 		enable_data = data->private_data;
 		if (enable_data &&
+		    (data->cmd_ops->trigger_type ==
+		     test->cmd_ops->trigger_type) &&
 		    (enable_data->file == test_enable_data->file)) {
 			unregistered = true;
 			list_del_rcu(&data->list);
@@ -1375,8 +1522,12 @@ event_enable_get_trigger_ops(char *cmd, char *param)
 	struct event_trigger_ops *ops;
 	bool enable;
 
+#ifdef CONFIG_HIST_TRIGGERS
+	enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
+		  (strcmp(cmd, ENABLE_HIST_STR) == 0));
+#else
 	enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
-
+#endif
 	if (enable)
 		ops = param ? &event_enable_count_trigger_ops :
 			&event_enable_trigger_ops;
@@ -1447,6 +1598,8 @@ __init int register_trigger_cmds(void)
 	register_trigger_snapshot_cmd();
 	register_trigger_stacktrace_cmd();
 	register_trigger_enable_disable_cmds();
+	register_trigger_hist_enable_disable_cmds();
+	register_trigger_hist_cmd();
 
 	return 0;
 }
diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c
new file mode 100644
index 000000000000..0a689bbb78ef
--- /dev/null
+++ b/kernel/trace/tracing_map.c
@@ -0,0 +1,1062 @@
+/*
+ * tracing_map - lock-free map for tracing
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Copyright (C) 2015 Tom Zanussi <tom.zanussi@linux.intel.com>
+ *
+ * tracing_map implementation inspired by lock-free map algorithms
+ * originated by Dr. Cliff Click:
+ *
+ * http://www.azulsystems.com/blog/cliff/2007-03-26-non-blocking-hashtable
+ * http://www.azulsystems.com/events/javaone_2007/2007_LockFreeHash.pdf
+ */
+
+#include <linux/vmalloc.h>
+#include <linux/jhash.h>
+#include <linux/slab.h>
+#include <linux/sort.h>
+
+#include "tracing_map.h"
+#include "trace.h"
+
+/*
+ * NOTE: For a detailed description of the data structures used by
+ * these functions (such as tracing_map_elt) please see the overview
+ * of tracing_map data structures at the beginning of tracing_map.h.
+ */
+
+/**
+ * tracing_map_update_sum - Add a value to a tracing_map_elt's sum field
+ * @elt: The tracing_map_elt
+ * @i: The index of the given sum associated with the tracing_map_elt
+ * @n: The value to add to the sum
+ *
+ * Add n to sum i associated with the specified tracing_map_elt
+ * instance.  The index i is the index returned by the call to
+ * tracing_map_add_sum_field() when the tracing map was set up.
+ */
+void tracing_map_update_sum(struct tracing_map_elt *elt, unsigned int i, u64 n)
+{
+	atomic64_add(n, &elt->fields[i].sum);
+}
+
+/**
+ * tracing_map_read_sum - Return the value of a tracing_map_elt's sum field
+ * @elt: The tracing_map_elt
+ * @i: The index of the given sum associated with the tracing_map_elt
+ *
+ * Retrieve the value of the sum i associated with the specified
+ * tracing_map_elt instance.  The index i is the index returned by the
+ * call to tracing_map_add_sum_field() when the tracing map was set
+ * up.
+ *
+ * Return: The sum associated with field i for elt.
+ */
+u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i)
+{
+	return (u64)atomic64_read(&elt->fields[i].sum);
+}
+
+int tracing_map_cmp_string(void *val_a, void *val_b)
+{
+	char *a = val_a;
+	char *b = val_b;
+
+	return strcmp(a, b);
+}
+
+int tracing_map_cmp_none(void *val_a, void *val_b)
+{
+	return 0;
+}
+
+static int tracing_map_cmp_atomic64(void *val_a, void *val_b)
+{
+	u64 a = atomic64_read((atomic64_t *)val_a);
+	u64 b = atomic64_read((atomic64_t *)val_b);
+
+	return (a > b) ? 1 : ((a < b) ? -1 : 0);
+}
+
+#define DEFINE_TRACING_MAP_CMP_FN(type)					\
+static int tracing_map_cmp_##type(void *val_a, void *val_b)		\
+{									\
+	type a = *(type *)val_a;					\
+	type b = *(type *)val_b;					\
+									\
+	return (a > b) ? 1 : ((a < b) ? -1 : 0);			\
+}
+
+DEFINE_TRACING_MAP_CMP_FN(s64);
+DEFINE_TRACING_MAP_CMP_FN(u64);
+DEFINE_TRACING_MAP_CMP_FN(s32);
+DEFINE_TRACING_MAP_CMP_FN(u32);
+DEFINE_TRACING_MAP_CMP_FN(s16);
+DEFINE_TRACING_MAP_CMP_FN(u16);
+DEFINE_TRACING_MAP_CMP_FN(s8);
+DEFINE_TRACING_MAP_CMP_FN(u8);
+
+tracing_map_cmp_fn_t tracing_map_cmp_num(int field_size,
+					 int field_is_signed)
+{
+	tracing_map_cmp_fn_t fn = tracing_map_cmp_none;
+
+	switch (field_size) {
+	case 8:
+		if (field_is_signed)
+			fn = tracing_map_cmp_s64;
+		else
+			fn = tracing_map_cmp_u64;
+		break;
+	case 4:
+		if (field_is_signed)
+			fn = tracing_map_cmp_s32;
+		else
+			fn = tracing_map_cmp_u32;
+		break;
+	case 2:
+		if (field_is_signed)
+			fn = tracing_map_cmp_s16;
+		else
+			fn = tracing_map_cmp_u16;
+		break;
+	case 1:
+		if (field_is_signed)
+			fn = tracing_map_cmp_s8;
+		else
+			fn = tracing_map_cmp_u8;
+		break;
+	}
+
+	return fn;
+}
+
+static int tracing_map_add_field(struct tracing_map *map,
+				 tracing_map_cmp_fn_t cmp_fn)
+{
+	int ret = -EINVAL;
+
+	if (map->n_fields < TRACING_MAP_FIELDS_MAX) {
+		ret = map->n_fields;
+		map->fields[map->n_fields++].cmp_fn = cmp_fn;
+	}
+
+	return ret;
+}
+
+/**
+ * tracing_map_add_sum_field - Add a field describing a tracing_map sum
+ * @map: The tracing_map
+ *
+ * Add a sum field to the key and return the index identifying it in
+ * the map and associated tracing_map_elts.  This is the index used
+ * for instance to update a sum for a particular tracing_map_elt using
+ * tracing_map_update_sum() or reading it via tracing_map_read_sum().
+ *
+ * Return: The index identifying the field in the map and associated
+ * tracing_map_elts, or -EINVAL on error.
+ */
+int tracing_map_add_sum_field(struct tracing_map *map)
+{
+	return tracing_map_add_field(map, tracing_map_cmp_atomic64);
+}
+
+/**
+ * tracing_map_add_key_field - Add a field describing a tracing_map key
+ * @map: The tracing_map
+ * @offset: The offset within the key
+ * @cmp_fn: The comparison function that will be used to sort on the key
+ *
+ * Let the map know there is a key and that if it's used as a sort key
+ * to use cmp_fn.
+ *
+ * A key can be a subset of a compound key; for that purpose, the
+ * offset param is used to describe where within the the compound key
+ * the key referenced by this key field resides.
+ *
+ * Return: The index identifying the field in the map and associated
+ * tracing_map_elts, or -EINVAL on error.
+ */
+int tracing_map_add_key_field(struct tracing_map *map,
+			      unsigned int offset,
+			      tracing_map_cmp_fn_t cmp_fn)
+
+{
+	int idx = tracing_map_add_field(map, cmp_fn);
+
+	if (idx < 0)
+		return idx;
+
+	map->fields[idx].offset = offset;
+
+	map->key_idx[map->n_keys++] = idx;
+
+	return idx;
+}
+
+void tracing_map_array_clear(struct tracing_map_array *a)
+{
+	unsigned int i;
+
+	if (!a->pages)
+		return;
+
+	for (i = 0; i < a->n_pages; i++)
+		memset(a->pages[i], 0, PAGE_SIZE);
+}
+
+void tracing_map_array_free(struct tracing_map_array *a)
+{
+	unsigned int i;
+
+	if (!a)
+		return;
+
+	if (!a->pages) {
+		kfree(a);
+		return;
+	}
+
+	for (i = 0; i < a->n_pages; i++) {
+		if (!a->pages[i])
+			break;
+		free_page((unsigned long)a->pages[i]);
+	}
+}
+
+struct tracing_map_array *tracing_map_array_alloc(unsigned int n_elts,
+						  unsigned int entry_size)
+{
+	struct tracing_map_array *a;
+	unsigned int i;
+
+	a = kzalloc(sizeof(*a), GFP_KERNEL);
+	if (!a)
+		return NULL;
+
+	a->entry_size_shift = fls(roundup_pow_of_two(entry_size) - 1);
+	a->entries_per_page = PAGE_SIZE / (1 << a->entry_size_shift);
+	a->n_pages = n_elts / a->entries_per_page;
+	if (!a->n_pages)
+		a->n_pages = 1;
+	a->entry_shift = fls(a->entries_per_page) - 1;
+	a->entry_mask = (1 << a->entry_shift) - 1;
+
+	a->pages = kcalloc(a->n_pages, sizeof(void *), GFP_KERNEL);
+	if (!a->pages)
+		goto free;
+
+	for (i = 0; i < a->n_pages; i++) {
+		a->pages[i] = (void *)get_zeroed_page(GFP_KERNEL);
+		if (!a->pages[i])
+			goto free;
+	}
+ out:
+	return a;
+ free:
+	tracing_map_array_free(a);
+	a = NULL;
+
+	goto out;
+}
+
+static void tracing_map_elt_clear(struct tracing_map_elt *elt)
+{
+	unsigned i;
+
+	for (i = 0; i < elt->map->n_fields; i++)
+		if (elt->fields[i].cmp_fn == tracing_map_cmp_atomic64)
+			atomic64_set(&elt->fields[i].sum, 0);
+
+	if (elt->map->ops && elt->map->ops->elt_clear)
+		elt->map->ops->elt_clear(elt);
+}
+
+static void tracing_map_elt_init_fields(struct tracing_map_elt *elt)
+{
+	unsigned int i;
+
+	tracing_map_elt_clear(elt);
+
+	for (i = 0; i < elt->map->n_fields; i++) {
+		elt->fields[i].cmp_fn = elt->map->fields[i].cmp_fn;
+
+		if (elt->fields[i].cmp_fn != tracing_map_cmp_atomic64)
+			elt->fields[i].offset = elt->map->fields[i].offset;
+	}
+}
+
+static void tracing_map_elt_free(struct tracing_map_elt *elt)
+{
+	if (!elt)
+		return;
+
+	if (elt->map->ops && elt->map->ops->elt_free)
+		elt->map->ops->elt_free(elt);
+	kfree(elt->fields);
+	kfree(elt->key);
+	kfree(elt);
+}
+
+static struct tracing_map_elt *tracing_map_elt_alloc(struct tracing_map *map)
+{
+	struct tracing_map_elt *elt;
+	int err = 0;
+
+	elt = kzalloc(sizeof(*elt), GFP_KERNEL);
+	if (!elt)
+		return ERR_PTR(-ENOMEM);
+
+	elt->map = map;
+
+	elt->key = kzalloc(map->key_size, GFP_KERNEL);
+	if (!elt->key) {
+		err = -ENOMEM;
+		goto free;
+	}
+
+	elt->fields = kcalloc(map->n_fields, sizeof(*elt->fields), GFP_KERNEL);
+	if (!elt->fields) {
+		err = -ENOMEM;
+		goto free;
+	}
+
+	tracing_map_elt_init_fields(elt);
+
+	if (map->ops && map->ops->elt_alloc) {
+		err = map->ops->elt_alloc(elt);
+		if (err)
+			goto free;
+	}
+	return elt;
+ free:
+	tracing_map_elt_free(elt);
+
+	return ERR_PTR(err);
+}
+
+static struct tracing_map_elt *get_free_elt(struct tracing_map *map)
+{
+	struct tracing_map_elt *elt = NULL;
+	int idx;
+
+	idx = atomic_inc_return(&map->next_elt);
+	if (idx < map->max_elts) {
+		elt = *(TRACING_MAP_ELT(map->elts, idx));
+		if (map->ops && map->ops->elt_init)
+			map->ops->elt_init(elt);
+	}
+
+	return elt;
+}
+
+static void tracing_map_free_elts(struct tracing_map *map)
+{
+	unsigned int i;
+
+	if (!map->elts)
+		return;
+
+	for (i = 0; i < map->max_elts; i++) {
+		tracing_map_elt_free(*(TRACING_MAP_ELT(map->elts, i)));
+		*(TRACING_MAP_ELT(map->elts, i)) = NULL;
+	}
+
+	tracing_map_array_free(map->elts);
+	map->elts = NULL;
+}
+
+static int tracing_map_alloc_elts(struct tracing_map *map)
+{
+	unsigned int i;
+
+	map->elts = tracing_map_array_alloc(map->max_elts,
+					    sizeof(struct tracing_map_elt *));
+	if (!map->elts)
+		return -ENOMEM;
+
+	for (i = 0; i < map->max_elts; i++) {
+		*(TRACING_MAP_ELT(map->elts, i)) = tracing_map_elt_alloc(map);
+		if (IS_ERR(*(TRACING_MAP_ELT(map->elts, i)))) {
+			*(TRACING_MAP_ELT(map->elts, i)) = NULL;
+			tracing_map_free_elts(map);
+
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
+static inline bool keys_match(void *key, void *test_key, unsigned key_size)
+{
+	bool match = true;
+
+	if (memcmp(key, test_key, key_size))
+		match = false;
+
+	return match;
+}
+
+static inline struct tracing_map_elt *
+__tracing_map_insert(struct tracing_map *map, void *key, bool lookup_only)
+{
+	u32 idx, key_hash, test_key;
+	struct tracing_map_entry *entry;
+
+	key_hash = jhash(key, map->key_size, 0);
+	if (key_hash == 0)
+		key_hash = 1;
+	idx = key_hash >> (32 - (map->map_bits + 1));
+
+	while (1) {
+		idx &= (map->map_size - 1);
+		entry = TRACING_MAP_ENTRY(map->map, idx);
+		test_key = entry->key;
+
+		if (test_key && test_key == key_hash && entry->val &&
+		    keys_match(key, entry->val->key, map->key_size)) {
+			atomic64_inc(&map->hits);
+			return entry->val;
+		}
+
+		if (!test_key) {
+			if (lookup_only)
+				break;
+
+			if (!cmpxchg(&entry->key, 0, key_hash)) {
+				struct tracing_map_elt *elt;
+
+				elt = get_free_elt(map);
+				if (!elt) {
+					atomic64_inc(&map->drops);
+					entry->key = 0;
+					break;
+				}
+
+				memcpy(elt->key, key, map->key_size);
+				entry->val = elt;
+				atomic64_inc(&map->hits);
+
+				return entry->val;
+			}
+		}
+
+		idx++;
+	}
+
+	return NULL;
+}
+
+/**
+ * tracing_map_insert - Insert key and/or retrieve val from a tracing_map
+ * @map: The tracing_map to insert into
+ * @key: The key to insert
+ *
+ * Inserts a key into a tracing_map and creates and returns a new
+ * tracing_map_elt for it, or if the key has already been inserted by
+ * a previous call, returns the tracing_map_elt already associated
+ * with it.  When the map was created, the number of elements to be
+ * allocated for the map was specified (internally maintained as
+ * 'max_elts' in struct tracing_map), and that number of
+ * tracing_map_elts was created by tracing_map_init().  This is the
+ * pre-allocated pool of tracing_map_elts that tracing_map_insert()
+ * will allocate from when adding new keys.  Once that pool is
+ * exhausted, tracing_map_insert() is useless and will return NULL to
+ * signal that state.  There are two user-visible tracing_map
+ * variables, 'hits' and 'drops', which are updated by this function.
+ * Every time an element is either successfully inserted or retrieved,
+ * the 'hits' value is incrememented.  Every time an element insertion
+ * fails, the 'drops' value is incremented.
+ *
+ * This is a lock-free tracing map insertion function implementing a
+ * modified form of Cliff Click's basic insertion algorithm.  It
+ * requires the table size be a power of two.  To prevent any
+ * possibility of an infinite loop we always make the internal table
+ * size double the size of the requested table size (max_elts * 2).
+ * Likewise, we never reuse a slot or resize or delete elements - when
+ * we've reached max_elts entries, we simply return NULL once we've
+ * run out of entries.  Readers can at any point in time traverse the
+ * tracing map and safely access the key/val pairs.
+ *
+ * Return: the tracing_map_elt pointer val associated with the key.
+ * If this was a newly inserted key, the val will be a newly allocated
+ * and associated tracing_map_elt pointer val.  If the key wasn't
+ * found and the pool of tracing_map_elts has been exhausted, NULL is
+ * returned and no further insertions will succeed.
+ */
+struct tracing_map_elt *tracing_map_insert(struct tracing_map *map, void *key)
+{
+	return __tracing_map_insert(map, key, false);
+}
+
+/**
+ * tracing_map_lookup - Retrieve val from a tracing_map
+ * @map: The tracing_map to perform the lookup on
+ * @key: The key to look up
+ *
+ * Looks up key in tracing_map and if found returns the matching
+ * tracing_map_elt.  This is a lock-free lookup; see
+ * tracing_map_insert() for details on tracing_map and how it works.
+ * Every time an element is retrieved, the 'hits' value is
+ * incrememented.  There is one user-visible tracing_map variable,
+ * 'hits', which is updated by this function.  Every time an element
+ * is successfully retrieved, the 'hits' value is incrememented.  The
+ * 'drops' value is never updated by this function.
+ *
+ * Return: the tracing_map_elt pointer val associated with the key.
+ * If the key wasn't found, NULL is returned.
+ */
+struct tracing_map_elt *tracing_map_lookup(struct tracing_map *map, void *key)
+{
+	return __tracing_map_insert(map, key, true);
+}
+
+/**
+ * tracing_map_destroy - Destroy a tracing_map
+ * @map: The tracing_map to destroy
+ *
+ * Frees a tracing_map along with its associated array of
+ * tracing_map_elts.
+ *
+ * Callers should make sure there are no readers or writers actively
+ * reading or inserting into the map before calling this.
+ */
+void tracing_map_destroy(struct tracing_map *map)
+{
+	if (!map)
+		return;
+
+	tracing_map_free_elts(map);
+
+	tracing_map_array_free(map->map);
+	kfree(map);
+}
+
+/**
+ * tracing_map_clear - Clear a tracing_map
+ * @map: The tracing_map to clear
+ *
+ * Resets the tracing map to a cleared or initial state.  The
+ * tracing_map_elts are all cleared, and the array of struct
+ * tracing_map_entry is reset to an initialized state.
+ *
+ * Callers should make sure there are no writers actively inserting
+ * into the map before calling this.
+ */
+void tracing_map_clear(struct tracing_map *map)
+{
+	unsigned int i;
+
+	atomic_set(&map->next_elt, -1);
+	atomic64_set(&map->hits, 0);
+	atomic64_set(&map->drops, 0);
+
+	tracing_map_array_clear(map->map);
+
+	for (i = 0; i < map->max_elts; i++)
+		tracing_map_elt_clear(*(TRACING_MAP_ELT(map->elts, i)));
+}
+
+static void set_sort_key(struct tracing_map *map,
+			 struct tracing_map_sort_key *sort_key)
+{
+	map->sort_key = *sort_key;
+}
+
+/**
+ * tracing_map_create - Create a lock-free map and element pool
+ * @map_bits: The size of the map (2 ** map_bits)
+ * @key_size: The size of the key for the map in bytes
+ * @ops: Optional client-defined tracing_map_ops instance
+ * @private_data: Client data associated with the map
+ *
+ * Creates and sets up a map to contain 2 ** map_bits number of
+ * elements (internally maintained as 'max_elts' in struct
+ * tracing_map).  Before using, map fields should be added to the map
+ * with tracing_map_add_sum_field() and tracing_map_add_key_field().
+ * tracing_map_init() should then be called to allocate the array of
+ * tracing_map_elts, in order to avoid allocating anything in the map
+ * insertion path.  The user-specified map size reflects the maximum
+ * number of elements that can be contained in the table requested by
+ * the user - internally we double that in order to keep the table
+ * sparse and keep collisions manageable.
+ *
+ * A tracing_map is a special-purpose map designed to aggregate or
+ * 'sum' one or more values associated with a specific object of type
+ * tracing_map_elt, which is attached by the map to a given key.
+ *
+ * tracing_map_create() sets up the map itself, and provides
+ * operations for inserting tracing_map_elts, but doesn't allocate the
+ * tracing_map_elts themselves, or provide a means for describing the
+ * keys or sums associated with the tracing_map_elts.  All
+ * tracing_map_elts for a given map have the same set of sums and
+ * keys, which are defined by the client using the functions
+ * tracing_map_add_key_field() and tracing_map_add_sum_field().  Once
+ * the fields are defined, the pool of elements allocated for the map
+ * can be created, which occurs when the client code calls
+ * tracing_map_init().
+ *
+ * When tracing_map_init() returns, tracing_map_elt elements can be
+ * inserted into the map using tracing_map_insert().  When called,
+ * tracing_map_insert() grabs a free tracing_map_elt from the pool, or
+ * finds an existing match in the map and in either case returns it.
+ * The client can then use tracing_map_update_sum() and
+ * tracing_map_read_sum() to update or read a given sum field for the
+ * tracing_map_elt.
+ *
+ * The client can at any point retrieve and traverse the current set
+ * of inserted tracing_map_elts in a tracing_map, via
+ * tracing_map_sort_entries().  Sorting can be done on any field,
+ * including keys.
+ *
+ * See tracing_map.h for a description of tracing_map_ops.
+ *
+ * Return: the tracing_map pointer if successful, ERR_PTR if not.
+ */
+struct tracing_map *tracing_map_create(unsigned int map_bits,
+				       unsigned int key_size,
+				       const struct tracing_map_ops *ops,
+				       void *private_data)
+{
+	struct tracing_map *map;
+	unsigned int i;
+
+	if (map_bits < TRACING_MAP_BITS_MIN ||
+	    map_bits > TRACING_MAP_BITS_MAX)
+		return ERR_PTR(-EINVAL);
+
+	map = kzalloc(sizeof(*map), GFP_KERNEL);
+	if (!map)
+		return ERR_PTR(-ENOMEM);
+
+	map->map_bits = map_bits;
+	map->max_elts = (1 << map_bits);
+	atomic_set(&map->next_elt, -1);
+
+	map->map_size = (1 << (map_bits + 1));
+	map->ops = ops;
+
+	map->private_data = private_data;
+
+	map->map = tracing_map_array_alloc(map->map_size,
+					   sizeof(struct tracing_map_entry));
+	if (!map->map)
+		goto free;
+
+	map->key_size = key_size;
+	for (i = 0; i < TRACING_MAP_KEYS_MAX; i++)
+		map->key_idx[i] = -1;
+ out:
+	return map;
+ free:
+	tracing_map_destroy(map);
+	map = ERR_PTR(-ENOMEM);
+
+	goto out;
+}
+
+/**
+ * tracing_map_init - Allocate and clear a map's tracing_map_elts
+ * @map: The tracing_map to initialize
+ *
+ * Allocates a clears a pool of tracing_map_elts equal to the
+ * user-specified size of 2 ** map_bits (internally maintained as
+ * 'max_elts' in struct tracing_map).  Before using, the map fields
+ * should be added to the map with tracing_map_add_sum_field() and
+ * tracing_map_add_key_field().  tracing_map_init() should then be
+ * called to allocate the array of tracing_map_elts, in order to avoid
+ * allocating anything in the map insertion path.  The user-specified
+ * map size reflects the max number of elements requested by the user
+ * - internally we double that in order to keep the table sparse and
+ * keep collisions manageable.
+ *
+ * See tracing_map.h for a description of tracing_map_ops.
+ *
+ * Return: the tracing_map pointer if successful, ERR_PTR if not.
+ */
+int tracing_map_init(struct tracing_map *map)
+{
+	int err;
+
+	if (map->n_fields < 2)
+		return -EINVAL; /* need at least 1 key and 1 val */
+
+	err = tracing_map_alloc_elts(map);
+	if (err)
+		return err;
+
+	tracing_map_clear(map);
+
+	return err;
+}
+
+static int cmp_entries_dup(const struct tracing_map_sort_entry **a,
+			   const struct tracing_map_sort_entry **b)
+{
+	int ret = 0;
+
+	if (memcmp((*a)->key, (*b)->key, (*a)->elt->map->key_size))
+		ret = 1;
+
+	return ret;
+}
+
+static int cmp_entries_sum(const struct tracing_map_sort_entry **a,
+			   const struct tracing_map_sort_entry **b)
+{
+	const struct tracing_map_elt *elt_a, *elt_b;
+	struct tracing_map_sort_key *sort_key;
+	struct tracing_map_field *field;
+	tracing_map_cmp_fn_t cmp_fn;
+	void *val_a, *val_b;
+	int ret = 0;
+
+	elt_a = (*a)->elt;
+	elt_b = (*b)->elt;
+
+	sort_key = &elt_a->map->sort_key;
+
+	field = &elt_a->fields[sort_key->field_idx];
+	cmp_fn = field->cmp_fn;
+
+	val_a = &elt_a->fields[sort_key->field_idx].sum;
+	val_b = &elt_b->fields[sort_key->field_idx].sum;
+
+	ret = cmp_fn(val_a, val_b);
+	if (sort_key->descending)
+		ret = -ret;
+
+	return ret;
+}
+
+static int cmp_entries_key(const struct tracing_map_sort_entry **a,
+			   const struct tracing_map_sort_entry **b)
+{
+	const struct tracing_map_elt *elt_a, *elt_b;
+	struct tracing_map_sort_key *sort_key;
+	struct tracing_map_field *field;
+	tracing_map_cmp_fn_t cmp_fn;
+	void *val_a, *val_b;
+	int ret = 0;
+
+	elt_a = (*a)->elt;
+	elt_b = (*b)->elt;
+
+	sort_key = &elt_a->map->sort_key;
+
+	field = &elt_a->fields[sort_key->field_idx];
+
+	cmp_fn = field->cmp_fn;
+
+	val_a = elt_a->key + field->offset;
+	val_b = elt_b->key + field->offset;
+
+	ret = cmp_fn(val_a, val_b);
+	if (sort_key->descending)
+		ret = -ret;
+
+	return ret;
+}
+
+static void destroy_sort_entry(struct tracing_map_sort_entry *entry)
+{
+	if (!entry)
+		return;
+
+	if (entry->elt_copied)
+		tracing_map_elt_free(entry->elt);
+
+	kfree(entry);
+}
+
+/**
+ * tracing_map_destroy_sort_entries - Destroy an array of sort entries
+ * @entries: The entries to destroy
+ * @n_entries: The number of entries in the array
+ *
+ * Destroy the elements returned by a tracing_map_sort_entries() call.
+ */
+void tracing_map_destroy_sort_entries(struct tracing_map_sort_entry **entries,
+				      unsigned int n_entries)
+{
+	unsigned int i;
+
+	for (i = 0; i < n_entries; i++)
+		destroy_sort_entry(entries[i]);
+
+	vfree(entries);
+}
+
+static struct tracing_map_sort_entry *
+create_sort_entry(void *key, struct tracing_map_elt *elt)
+{
+	struct tracing_map_sort_entry *sort_entry;
+
+	sort_entry = kzalloc(sizeof(*sort_entry), GFP_KERNEL);
+	if (!sort_entry)
+		return NULL;
+
+	sort_entry->key = key;
+	sort_entry->elt = elt;
+
+	return sort_entry;
+}
+
+static struct tracing_map_elt *copy_elt(struct tracing_map_elt *elt)
+{
+	struct tracing_map_elt *dup_elt;
+	unsigned int i;
+
+	dup_elt = tracing_map_elt_alloc(elt->map);
+	if (IS_ERR(dup_elt))
+		return NULL;
+
+	if (elt->map->ops && elt->map->ops->elt_copy)
+		elt->map->ops->elt_copy(dup_elt, elt);
+
+	dup_elt->private_data = elt->private_data;
+	memcpy(dup_elt->key, elt->key, elt->map->key_size);
+
+	for (i = 0; i < elt->map->n_fields; i++) {
+		atomic64_set(&dup_elt->fields[i].sum,
+			     atomic64_read(&elt->fields[i].sum));
+		dup_elt->fields[i].cmp_fn = elt->fields[i].cmp_fn;
+	}
+
+	return dup_elt;
+}
+
+static int merge_dup(struct tracing_map_sort_entry **sort_entries,
+		     unsigned int target, unsigned int dup)
+{
+	struct tracing_map_elt *target_elt, *elt;
+	bool first_dup = (target - dup) == 1;
+	int i;
+
+	if (first_dup) {
+		elt = sort_entries[target]->elt;
+		target_elt = copy_elt(elt);
+		if (!target_elt)
+			return -ENOMEM;
+		sort_entries[target]->elt = target_elt;
+		sort_entries[target]->elt_copied = true;
+	} else
+		target_elt = sort_entries[target]->elt;
+
+	elt = sort_entries[dup]->elt;
+
+	for (i = 0; i < elt->map->n_fields; i++)
+		atomic64_add(atomic64_read(&elt->fields[i].sum),
+			     &target_elt->fields[i].sum);
+
+	sort_entries[dup]->dup = true;
+
+	return 0;
+}
+
+static int merge_dups(struct tracing_map_sort_entry **sort_entries,
+		      int n_entries, unsigned int key_size)
+{
+	unsigned int dups = 0, total_dups = 0;
+	int err, i, j;
+	void *key;
+
+	if (n_entries < 2)
+		return total_dups;
+
+	sort(sort_entries, n_entries, sizeof(struct tracing_map_sort_entry *),
+	     (int (*)(const void *, const void *))cmp_entries_dup, NULL);
+
+	key = sort_entries[0]->key;
+	for (i = 1; i < n_entries; i++) {
+		if (!memcmp(sort_entries[i]->key, key, key_size)) {
+			dups++; total_dups++;
+			err = merge_dup(sort_entries, i - dups, i);
+			if (err)
+				return err;
+			continue;
+		}
+		key = sort_entries[i]->key;
+		dups = 0;
+	}
+
+	if (!total_dups)
+		return total_dups;
+
+	for (i = 0, j = 0; i < n_entries; i++) {
+		if (!sort_entries[i]->dup) {
+			sort_entries[j] = sort_entries[i];
+			if (j++ != i)
+				sort_entries[i] = NULL;
+		} else {
+			destroy_sort_entry(sort_entries[i]);
+			sort_entries[i] = NULL;
+		}
+	}
+
+	return total_dups;
+}
+
+static bool is_key(struct tracing_map *map, unsigned int field_idx)
+{
+	unsigned int i;
+
+	for (i = 0; i < map->n_keys; i++)
+		if (map->key_idx[i] == field_idx)
+			return true;
+	return false;
+}
+
+static void sort_secondary(struct tracing_map *map,
+			   const struct tracing_map_sort_entry **entries,
+			   unsigned int n_entries,
+			   struct tracing_map_sort_key *primary_key,
+			   struct tracing_map_sort_key *secondary_key)
+{
+	int (*primary_fn)(const struct tracing_map_sort_entry **,
+			  const struct tracing_map_sort_entry **);
+	int (*secondary_fn)(const struct tracing_map_sort_entry **,
+			    const struct tracing_map_sort_entry **);
+	unsigned i, start = 0, n_sub = 1;
+
+	if (is_key(map, primary_key->field_idx))
+		primary_fn = cmp_entries_key;
+	else
+		primary_fn = cmp_entries_sum;
+
+	if (is_key(map, secondary_key->field_idx))
+		secondary_fn = cmp_entries_key;
+	else
+		secondary_fn = cmp_entries_sum;
+
+	for (i = 0; i < n_entries - 1; i++) {
+		const struct tracing_map_sort_entry **a = &entries[i];
+		const struct tracing_map_sort_entry **b = &entries[i + 1];
+
+		if (primary_fn(a, b) == 0) {
+			n_sub++;
+			if (i < n_entries - 2)
+				continue;
+		}
+
+		if (n_sub < 2) {
+			start = i + 1;
+			n_sub = 1;
+			continue;
+		}
+
+		set_sort_key(map, secondary_key);
+		sort(&entries[start], n_sub,
+		     sizeof(struct tracing_map_sort_entry *),
+		     (int (*)(const void *, const void *))secondary_fn, NULL);
+		set_sort_key(map, primary_key);
+
+		start = i + 1;
+		n_sub = 1;
+	}
+}
+
+/**
+ * tracing_map_sort_entries - Sort the current set of tracing_map_elts in a map
+ * @map: The tracing_map
+ * @sort_key: The sort key to use for sorting
+ * @sort_entries: outval: pointer to allocated and sorted array of entries
+ *
+ * tracing_map_sort_entries() sorts the current set of entries in the
+ * map and returns the list of tracing_map_sort_entries containing
+ * them to the client in the sort_entries param.  The client can
+ * access the struct tracing_map_elt element of interest directly as
+ * the 'elt' field of a returned struct tracing_map_sort_entry object.
+ *
+ * The sort_key has only two fields: idx and descending.  'idx' refers
+ * to the index of the field added via tracing_map_add_sum_field() or
+ * tracing_map_add_key_field() when the tracing_map was initialized.
+ * 'descending' is a flag that if set reverses the sort order, which
+ * by default is ascending.
+ *
+ * The client should not hold on to the returned array but should use
+ * it and call tracing_map_destroy_sort_entries() when done.
+ *
+ * Return: the number of sort_entries in the struct tracing_map_sort_entry
+ * array, negative on error
+ */
+int tracing_map_sort_entries(struct tracing_map *map,
+			     struct tracing_map_sort_key *sort_keys,
+			     unsigned int n_sort_keys,
+			     struct tracing_map_sort_entry ***sort_entries)
+{
+	int (*cmp_entries_fn)(const struct tracing_map_sort_entry **,
+			      const struct tracing_map_sort_entry **);
+	struct tracing_map_sort_entry *sort_entry, **entries;
+	int i, n_entries, ret;
+
+	entries = vmalloc(map->max_elts * sizeof(sort_entry));
+	if (!entries)
+		return -ENOMEM;
+
+	for (i = 0, n_entries = 0; i < map->map_size; i++) {
+		struct tracing_map_entry *entry;
+
+		entry = TRACING_MAP_ENTRY(map->map, i);
+
+		if (!entry->key || !entry->val)
+			continue;
+
+		entries[n_entries] = create_sort_entry(entry->val->key,
+						       entry->val);
+		if (!entries[n_entries++]) {
+			ret = -ENOMEM;
+			goto free;
+		}
+	}
+
+	if (n_entries == 0) {
+		ret = 0;
+		goto free;
+	}
+
+	if (n_entries == 1) {
+		*sort_entries = entries;
+		return 1;
+	}
+
+	ret = merge_dups(entries, n_entries, map->key_size);
+	if (ret < 0)
+		goto free;
+	n_entries -= ret;
+
+	if (is_key(map, sort_keys[0].field_idx))
+		cmp_entries_fn = cmp_entries_key;
+	else
+		cmp_entries_fn = cmp_entries_sum;
+
+	set_sort_key(map, &sort_keys[0]);
+
+	sort(entries, n_entries, sizeof(struct tracing_map_sort_entry *),
+	     (int (*)(const void *, const void *))cmp_entries_fn, NULL);
+
+	if (n_sort_keys > 1)
+		sort_secondary(map,
+			       (const struct tracing_map_sort_entry **)entries,
+			       n_entries,
+			       &sort_keys[0],
+			       &sort_keys[1]);
+
+	*sort_entries = entries;
+
+	return n_entries;
+ free:
+	tracing_map_destroy_sort_entries(entries, n_entries);
+
+	return ret;
+}
diff --git a/kernel/trace/tracing_map.h b/kernel/trace/tracing_map.h
new file mode 100644
index 000000000000..618838f5f30a
--- /dev/null
+++ b/kernel/trace/tracing_map.h
@@ -0,0 +1,283 @@
+#ifndef __TRACING_MAP_H
+#define __TRACING_MAP_H
+
+#define TRACING_MAP_BITS_DEFAULT	11
+#define TRACING_MAP_BITS_MAX		17
+#define TRACING_MAP_BITS_MIN		7
+
+#define TRACING_MAP_KEYS_MAX		2
+#define TRACING_MAP_VALS_MAX		3
+#define TRACING_MAP_FIELDS_MAX		(TRACING_MAP_KEYS_MAX + \
+					 TRACING_MAP_VALS_MAX)
+#define TRACING_MAP_SORT_KEYS_MAX	2
+
+typedef int (*tracing_map_cmp_fn_t) (void *val_a, void *val_b);
+
+/*
+ * This is an overview of the tracing_map data structures and how they
+ * relate to the tracing_map API.  The details of the algorithms
+ * aren't discussed here - this is just a general overview of the data
+ * structures and how they interact with the API.
+ *
+ * The central data structure of the tracing_map is an initially
+ * zeroed array of struct tracing_map_entry (stored in the map field
+ * of struct tracing_map).  tracing_map_entry is a very simple data
+ * structure containing only two fields: a 32-bit unsigned 'key'
+ * variable and a pointer named 'val'.  This array of struct
+ * tracing_map_entry is essentially a hash table which will be
+ * modified by a single function, tracing_map_insert(), but which can
+ * be traversed and read by a user at any time (though the user does
+ * this indirectly via an array of tracing_map_sort_entry - see the
+ * explanation of that data structure in the discussion of the
+ * sorting-related data structures below).
+ *
+ * The central function of the tracing_map API is
+ * tracing_map_insert().  tracing_map_insert() hashes the
+ * arbitrarily-sized key passed into it into a 32-bit unsigned key.
+ * It then uses this key, truncated to the array size, as an index
+ * into the array of tracing_map_entries.  If the value of the 'key'
+ * field of the tracing_map_entry found at that location is 0, then
+ * that entry is considered to be free and can be claimed, by
+ * replacing the 0 in the 'key' field of the tracing_map_entry with
+ * the new 32-bit hashed key.  Once claimed, that tracing_map_entry's
+ * 'val' field is then used to store a unique element which will be
+ * forever associated with that 32-bit hashed key in the
+ * tracing_map_entry.
+ *
+ * That unique element now in the tracing_map_entry's 'val' field is
+ * an instance of tracing_map_elt, where 'elt' in the latter part of
+ * that variable name is short for 'element'.  The purpose of a
+ * tracing_map_elt is to hold values specific to the particular
+ * 32-bit hashed key it's assocated with.  Things such as the unique
+ * set of aggregated sums associated with the 32-bit hashed key, along
+ * with a copy of the full key associated with the entry, and which
+ * was used to produce the 32-bit hashed key.
+ *
+ * When tracing_map_create() is called to create the tracing map, the
+ * user specifies (indirectly via the map_bits param, the details are
+ * unimportant for this discussion) the maximum number of elements
+ * that the map can hold (stored in the max_elts field of struct
+ * tracing_map).  This is the maximum possible number of
+ * tracing_map_entries in the tracing_map_entry array which can be
+ * 'claimed' as described in the above discussion, and therefore is
+ * also the maximum number of tracing_map_elts that can be associated
+ * with the tracing_map_entry array in the tracing_map.  Because of
+ * the way the insertion algorithm works, the size of the allocated
+ * tracing_map_entry array is always twice the maximum number of
+ * elements (2 * max_elts).  This value is stored in the map_size
+ * field of struct tracing_map.
+ *
+ * Because tracing_map_insert() needs to work from any context,
+ * including from within the memory allocation functions themselves,
+ * both the tracing_map_entry array and a pool of max_elts
+ * tracing_map_elts are pre-allocated before any call is made to
+ * tracing_map_insert().
+ *
+ * The tracing_map_entry array is allocated as a single block by
+ * tracing_map_create().
+ *
+ * Because the tracing_map_elts are much larger objects and can't
+ * generally be allocated together as a single large array without
+ * failure, they're allocated individually, by tracing_map_init().
+ *
+ * The pool of tracing_map_elts are allocated by tracing_map_init()
+ * rather than by tracing_map_create() because at the time
+ * tracing_map_create() is called, there isn't enough information to
+ * create the tracing_map_elts.  Specifically,the user first needs to
+ * tell the tracing_map implementation how many fields the
+ * tracing_map_elts contain, and which types of fields they are (key
+ * or sum).  The user does this via the tracing_map_add_sum_field()
+ * and tracing_map_add_key_field() functions, following which the user
+ * calls tracing_map_init() to finish up the tracing map setup.  The
+ * array holding the pointers which make up the pre-allocated pool of
+ * tracing_map_elts is allocated as a single block and is stored in
+ * the elts field of struct tracing_map.
+ *
+ * There is also a set of structures used for sorting that might
+ * benefit from some minimal explanation.
+ *
+ * struct tracing_map_sort_key is used to drive the sort at any given
+ * time.  By 'any given time' we mean that a different
+ * tracing_map_sort_key will be used at different times depending on
+ * whether the sort currently being performed is a primary or a
+ * secondary sort.
+ *
+ * The sort key is very simple, consisting of the field index of the
+ * tracing_map_elt field to sort on (which the user saved when adding
+ * the field), and whether the sort should be done in an ascending or
+ * descending order.
+ *
+ * For the convenience of the sorting code, a tracing_map_sort_entry
+ * is created for each tracing_map_elt, again individually allocated
+ * to avoid failures that might be expected if allocated as a single
+ * large array of struct tracing_map_sort_entry.
+ * tracing_map_sort_entry instances are the objects expected by the
+ * various internal sorting functions, and are also what the user
+ * ultimately receives after calling tracing_map_sort_entries().
+ * Because it doesn't make sense for users to access an unordered and
+ * sparsely populated tracing_map directly, the
+ * tracing_map_sort_entries() function is provided so that users can
+ * retrieve a sorted list of all existing elements.  In addition to
+ * the associated tracing_map_elt 'elt' field contained within the
+ * tracing_map_sort_entry, which is the object of interest to the
+ * user, tracing_map_sort_entry objects contain a number of additional
+ * fields which are used for caching and internal purposes and can
+ * safely be ignored.
+*/
+
+struct tracing_map_field {
+	tracing_map_cmp_fn_t		cmp_fn;
+	union {
+		atomic64_t			sum;
+		unsigned int			offset;
+	};
+};
+
+struct tracing_map_elt {
+	struct tracing_map		*map;
+	struct tracing_map_field	*fields;
+	void				*key;
+	void				*private_data;
+};
+
+struct tracing_map_entry {
+	u32				key;
+	struct tracing_map_elt		*val;
+};
+
+struct tracing_map_sort_key {
+	unsigned int			field_idx;
+	bool				descending;
+};
+
+struct tracing_map_sort_entry {
+	void				*key;
+	struct tracing_map_elt		*elt;
+	bool				elt_copied;
+	bool				dup;
+};
+
+struct tracing_map_array {
+	unsigned int entries_per_page;
+	unsigned int entry_size_shift;
+	unsigned int entry_shift;
+	unsigned int entry_mask;
+	unsigned int n_pages;
+	void **pages;
+};
+
+#define TRACING_MAP_ARRAY_ELT(array, idx)				\
+	(array->pages[idx >> array->entry_shift] +			\
+	 ((idx & array->entry_mask) << array->entry_size_shift))
+
+#define TRACING_MAP_ENTRY(array, idx)					\
+	((struct tracing_map_entry *)TRACING_MAP_ARRAY_ELT(array, idx))
+
+#define TRACING_MAP_ELT(array, idx)					\
+	((struct tracing_map_elt **)TRACING_MAP_ARRAY_ELT(array, idx))
+
+struct tracing_map {
+	unsigned int			key_size;
+	unsigned int			map_bits;
+	unsigned int			map_size;
+	unsigned int			max_elts;
+	atomic_t			next_elt;
+	struct tracing_map_array	*elts;
+	struct tracing_map_array	*map;
+	const struct tracing_map_ops	*ops;
+	void				*private_data;
+	struct tracing_map_field	fields[TRACING_MAP_FIELDS_MAX];
+	unsigned int			n_fields;
+	int				key_idx[TRACING_MAP_KEYS_MAX];
+	unsigned int			n_keys;
+	struct tracing_map_sort_key	sort_key;
+	atomic64_t			hits;
+	atomic64_t			drops;
+};
+
+/**
+ * struct tracing_map_ops - callbacks for tracing_map
+ *
+ * The methods in this structure define callback functions for various
+ * operations on a tracing_map or objects related to a tracing_map.
+ *
+ * For a detailed description of tracing_map_elt objects please see
+ * the overview of tracing_map data structures at the beginning of
+ * this file.
+ *
+ * All the methods below are optional.
+ *
+ * @elt_alloc: When a tracing_map_elt is allocated, this function, if
+ *	defined, will be called and gives clients the opportunity to
+ *	allocate additional data and attach it to the element
+ *	(tracing_map_elt->private_data is meant for that purpose).
+ *	Element allocation occurs before tracing begins, when the
+ *	tracing_map_init() call is made by client code.
+ *
+ * @elt_copy: At certain points in the lifetime of an element, it may
+ *	need to be copied.  The copy should include a copy of the
+ *	client-allocated data, which can be copied into the 'to'
+ *	element from the 'from' element.
+ *
+ * @elt_free: When a tracing_map_elt is freed, this function is called
+ *	and allows client-allocated per-element data to be freed.
+ *
+ * @elt_clear: This callback allows per-element client-defined data to
+ *	be cleared, if applicable.
+ *
+ * @elt_init: This callback allows per-element client-defined data to
+ *	be initialized when used i.e. when the element is actually
+ *	claimed by tracing_map_insert() in the context of the map
+ *	insertion.
+ */
+struct tracing_map_ops {
+	int			(*elt_alloc)(struct tracing_map_elt *elt);
+	void			(*elt_copy)(struct tracing_map_elt *to,
+					    struct tracing_map_elt *from);
+	void			(*elt_free)(struct tracing_map_elt *elt);
+	void			(*elt_clear)(struct tracing_map_elt *elt);
+	void			(*elt_init)(struct tracing_map_elt *elt);
+};
+
+extern struct tracing_map *
+tracing_map_create(unsigned int map_bits,
+		   unsigned int key_size,
+		   const struct tracing_map_ops *ops,
+		   void *private_data);
+extern int tracing_map_init(struct tracing_map *map);
+
+extern int tracing_map_add_sum_field(struct tracing_map *map);
+extern int tracing_map_add_key_field(struct tracing_map *map,
+				     unsigned int offset,
+				     tracing_map_cmp_fn_t cmp_fn);
+
+extern void tracing_map_destroy(struct tracing_map *map);
+extern void tracing_map_clear(struct tracing_map *map);
+
+extern struct tracing_map_elt *
+tracing_map_insert(struct tracing_map *map, void *key);
+extern struct tracing_map_elt *
+tracing_map_lookup(struct tracing_map *map, void *key);
+
+extern tracing_map_cmp_fn_t tracing_map_cmp_num(int field_size,
+						int field_is_signed);
+extern int tracing_map_cmp_string(void *val_a, void *val_b);
+extern int tracing_map_cmp_none(void *val_a, void *val_b);
+
+extern void tracing_map_update_sum(struct tracing_map_elt *elt,
+				   unsigned int i, u64 n);
+extern u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i);
+extern void tracing_map_set_field_descr(struct tracing_map *map,
+					unsigned int i,
+					unsigned int key_offset,
+					tracing_map_cmp_fn_t cmp_fn);
+extern int
+tracing_map_sort_entries(struct tracing_map *map,
+			 struct tracing_map_sort_key *sort_keys,
+			 unsigned int n_sort_keys,
+			 struct tracing_map_sort_entry ***sort_entries);
+
+extern void
+tracing_map_destroy_sort_entries(struct tracing_map_sort_entry **entries,
+				 unsigned int n_entries);
+#endif /* __TRACING_MAP_H */