Merge tag 'trace-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:

 - Add function names as a way to filter function addresses

 - Add sample module to test ftrace ops and dynamic trampolines

 - Allow stack traces to be passed from beginning event to end event for
   synthetic events. This will allow seeing the stack trace of when a
   task is scheduled out and recorded when it gets scheduled back in.

 - Add trace event helper __get_buf() to use as a temporary buffer when
   printing out trace event output.

 - Add kernel command line to create trace instances on boot up.

 - Add enabling of events to instances created at boot up.

 - Add trace_array_puts() to write into instances.

 - Allow boot instances to take a snapshot at the end of boot up.

 - Allow live patch modules to include trace events

 - Minor fixes and clean ups

* tag 'trace-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (31 commits)
  tracing: Remove unnecessary NULL assignment
  tracepoint: Allow livepatch module add trace event
  tracing: Always use canonical ftrace path
  tracing/histogram: Fix stacktrace histogram Documententation
  tracing/histogram: Fix stacktrace key
  tracing/histogram: Fix a few problems with stacktrace variable printing
  tracing: Add BUILD_BUG() to make sure stacktrace fits in strings
  tracing/histogram: Don't use strlen to find length of stacktrace variables
  tracing: Allow boot instances to have snapshot buffers
  tracing: Add trace_array_puts() to write into instance
  tracing: Add enabling of events to boot instances
  tracing: Add creation of instances at boot command line
  tracing: Fix trace_event_raw_event_synth() if else statement
  samples: ftrace: Make some global variables static
  ftrace: sample: avoid open-coded 64-bit division
  samples: ftrace: Include the nospec-branch.h only for x86
  tracing: Acquire buffer from temparary trace sequence
  tracing/histogram: Wrap remaining shell snippets in code blocks
  tracing/osnoise: No need for schedule_hrtimeout range
  bpf/tracing: Use stage6 of tracing to not duplicate macros
  ...

Documentation/admin-guide/kernel-parameters.txt

@@ -1509,6 +1509,15 @@
 			boot up that is likely to be overridden by user space
 			start up functionality.
 
+			Optionally, the snapshot can also be defined for a tracing
+			instance that was created by the trace_instance= command
+			line parameter.
+
+			trace_instance=foo,sched_switch ftrace_boot_snapshot=foo
+
+			The above will cause the "foo" tracing instance to trigger
+			a snapshot at the end of boot up.
+
 	ftrace_dump_on_oops[=orig_cpu]
 			[FTRACE] will dump the trace buffers on oops.
 			If no parameter is passed, ftrace will dump
@@ -6283,6 +6292,26 @@
 			comma-separated list of trace events to enable. See
 			also Documentation/trace/events.rst
 
+	trace_instance=[instance-info]
+			[FTRACE] Create a ring buffer instance early in boot up.
+			This will be listed in:
+
+				/sys/kernel/tracing/instances
+
+			Events can be enabled at the time the instance is created
+			via:
+
+				trace_instance=<name>,<system1>:<event1>,<system2>:<event2>
+
+			Note, the "<system*>:" portion is optional if the event is
+			unique.
+
+				trace_instance=foo,sched:sched_switch,irq_handler_entry,initcall
+
+			will enable the "sched_switch" event (note, the "sched:" is optional, and
+			the same thing would happen if it was left off). The irq_handler_entry
+			event, and all events under the "initcall" system.
+
 	trace_options=[option-list]
 			[FTRACE] Enable or disable tracer options at boot.
 			The option-list is a comma delimited list of options

Documentation/trace/events.rst

@@ -207,6 +207,18 @@ field name::
 As the kernel will have to know how to retrieve the memory that the pointer
 is at from user space.
 
+You can convert any long type to a function address and search by function name::
+
+  call_site.function == security_prepare_creds
+
+The above will filter when the field "call_site" falls on the address within
+"security_prepare_creds". That is, it will compare the value of "call_site" and
+the filter will return true if it is greater than or equal to the start of
+the function "security_prepare_creds" and less than the end of that function.
+
+The ".function" postfix can only be attached to values of size long, and can only
+be compared with "==" or "!=".
+
 5.2 Setting filters
 -------------------
 

include/linux/kernel.h

@@ -297,7 +297,7 @@ bool mac_pton(const char *s, u8 *mac);
  *
  * Use tracing_on/tracing_off when you want to quickly turn on or off
  * tracing. It simply enables or disables the recording of the trace events.
- * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
+ * This also corresponds to the user space /sys/kernel/tracing/tracing_on
  * file, which gives a means for the kernel and userspace to interact.
  * Place a tracing_off() in the kernel where you want tracing to end.
  * From user space, examine the trace, and then echo 1 > tracing_on

include/linux/trace.h

@@ -33,6 +33,18 @@ struct trace_array;
 int register_ftrace_export(struct trace_export *export);
 int unregister_ftrace_export(struct trace_export *export);
 
+/**
+ * trace_array_puts - write a constant string into the trace buffer.
+ * @tr:    The trace array to write to
+ * @str:   The constant string to write
+ */
+#define trace_array_puts(tr, str)					\
+	({								\
+		str ? __trace_array_puts(tr, _THIS_IP_, str, strlen(str)) : -1;	\
+	})
+int __trace_array_puts(struct trace_array *tr, unsigned long ip,
+		       const char *str, int size);
+
 void trace_printk_init_buffers(void);
 __printf(3, 4)
 int trace_array_printk(struct trace_array *tr, unsigned long ip,

include/linux/trace_seq.h

@@ -95,6 +95,7 @@ extern void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
 extern int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str,
 			      int prefix_type, int rowsize, int groupsize,
 			      const void *buf, size_t len, bool ascii);
+char *trace_seq_acquire(struct trace_seq *s, unsigned int len);
 
 #else /* CONFIG_TRACING */
 static inline __printf(2, 3)
@@ -139,6 +140,10 @@ static inline int trace_seq_path(struct trace_seq *s, const struct path *path)
 {
 	return 0;
 }
+static inline char *trace_seq_acquire(struct trace_seq *s, unsigned int len)
+{
+	return NULL;
+}
 #endif /* CONFIG_TRACING */
 
 #endif /* _LINUX_TRACE_SEQ_H */

include/linux/tracepoint.h

@@ -482,7 +482,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
  *	* This is how the trace record is structured and will
  *	* be saved into the ring buffer. These are the fields
  *	* that will be exposed to user-space in
- *	* /sys/kernel/debug/tracing/events/<*>/format.
+ *	* /sys/kernel/tracing/events/<*>/format.
  *	*
  *	* The declared 'local variable' is called '__entry'
  *	*
@@ -542,7 +542,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
  * tracepoint callback (this is used by programmatic plugins and
  * can also by used by generic instrumentation like SystemTap), and
  * it is also used to expose a structured trace record in
- * /sys/kernel/debug/tracing/events/.
+ * /sys/kernel/tracing/events/.
  *
  * A set of (un)registration functions can be passed to the variant
  * TRACE_EVENT_FN to perform any (un)registration work.

include/trace/bpf_probe.h

@@ -4,50 +4,7 @@
 
 #ifdef CONFIG_BPF_EVENTS
 
-#undef __entry
-#define __entry entry
-
-#undef __get_dynamic_array
-#define __get_dynamic_array(field)	\
-		((void *)__entry + (__entry->__data_loc_##field & 0xffff))
-
-#undef __get_dynamic_array_len
-#define __get_dynamic_array_len(field)	\
-		((__entry->__data_loc_##field >> 16) & 0xffff)
-
-#undef __get_str
-#define __get_str(field) ((char *)__get_dynamic_array(field))
-
-#undef __get_bitmask
-#define __get_bitmask(field) (char *)__get_dynamic_array(field)
-
-#undef __get_cpumask
-#define __get_cpumask(field) (char *)__get_dynamic_array(field)
-
-#undef __get_sockaddr
-#define __get_sockaddr(field) ((struct sockaddr *)__get_dynamic_array(field))
-
-#undef __get_rel_dynamic_array
-#define __get_rel_dynamic_array(field)	\
-		((void *)(&__entry->__rel_loc_##field) +	\
-		 sizeof(__entry->__rel_loc_##field) +		\
-		 (__entry->__rel_loc_##field & 0xffff))
-
-#undef __get_rel_dynamic_array_len
-#define __get_rel_dynamic_array_len(field)	\
-		((__entry->__rel_loc_##field >> 16) & 0xffff)
-
-#undef __get_rel_str
-#define __get_rel_str(field) ((char *)__get_rel_dynamic_array(field))
-
-#undef __get_rel_bitmask
-#define __get_rel_bitmask(field) (char *)__get_rel_dynamic_array(field)
-
-#undef __get_rel_cpumask
-#define __get_rel_cpumask(field) (char *)__get_rel_dynamic_array(field)
-
-#undef __get_rel_sockaddr
-#define __get_rel_sockaddr(field) ((struct sockaddr *)__get_rel_dynamic_array(field))
+#include "stages/stage6_event_callback.h"
 
 #undef __perf_count
 #define __perf_count(c)	(c)

include/trace/perf.h

@@ -4,51 +4,7 @@
 
 #ifdef CONFIG_PERF_EVENTS
 
-#undef __entry
-#define __entry entry
-
-#undef __get_dynamic_array
-#define __get_dynamic_array(field)	\
-		((void *)__entry + (__entry->__data_loc_##field & 0xffff))
-
-#undef __get_dynamic_array_len
-#define __get_dynamic_array_len(field)	\
-		((__entry->__data_loc_##field >> 16) & 0xffff)
-
-#undef __get_str
-#define __get_str(field) ((char *)__get_dynamic_array(field))
-
-#undef __get_bitmask
-#define __get_bitmask(field) (char *)__get_dynamic_array(field)
-
-#undef __get_cpumask
-#define __get_cpumask(field) (char *)__get_dynamic_array(field)
-
-#undef __get_sockaddr
-#define __get_sockaddr(field) ((struct sockaddr *)__get_dynamic_array(field))
-
-#undef __get_rel_dynamic_array
-#define __get_rel_dynamic_array(field)	\
-		((void *)__entry +					\
-		 offsetof(typeof(*__entry), __rel_loc_##field) +	\
-		 sizeof(__entry->__rel_loc_##field) +			\
-		 (__entry->__rel_loc_##field & 0xffff))
-
-#undef __get_rel_dynamic_array_len
-#define __get_rel_dynamic_array_len(field)	\
-		((__entry->__rel_loc_##field >> 16) & 0xffff)
-
-#undef __get_rel_str
-#define __get_rel_str(field) ((char *)__get_rel_dynamic_array(field))
-
-#undef __get_rel_bitmask
-#define __get_rel_bitmask(field) (char *)__get_rel_dynamic_array(field)
-
-#undef __get_rel_cpumask
-#define __get_rel_cpumask(field) (char *)__get_rel_dynamic_array(field)
-
-#undef __get_rel_sockaddr
-#define __get_rel_sockaddr(field) ((struct sockaddr *)__get_rel_dynamic_array(field))
+#include "stages/stage6_event_callback.h"
 
 #undef __perf_count
 #define __perf_count(c)	(__count = (c))

include/trace/stages/stage3_trace_output.h

@@ -139,3 +139,6 @@
 		u64 ____val = (u64)(value);		\
 		(u32) do_div(____val, NSEC_PER_SEC);	\
 	})
+
+#undef __get_buf
+#define __get_buf(len)		trace_seq_acquire(p, (len))

include/trace/stages/stage6_event_callback.h

@@ -2,6 +2,9 @@
 
 /* Stage 6 definitions for creating trace events */
 
+/* Reuse some of the stage 3 macros */
+#include "stage3_trace_output.h"
+
 #undef __entry
 #define __entry entry
 

include/trace/stages/stage7_class_define.h

@@ -23,6 +23,7 @@
 #undef __get_rel_sockaddr
 #undef __print_array
 #undef __print_hex_dump
+#undef __get_buf
 
 /*
  * The below is not executed in the kernel. It is only what is

kernel/trace/Kconfig

@@ -242,7 +242,7 @@ config DYNAMIC_FTRACE
 	  enabled, and the functions not enabled will not affect
 	  performance of the system.
 
-	  See the files in /sys/kernel/debug/tracing:
+	  See the files in /sys/kernel/tracing:
 	    available_filter_functions
 	    set_ftrace_filter
 	    set_ftrace_notrace
@@ -306,7 +306,7 @@ config STACK_TRACER
 	select KALLSYMS
 	help
 	  This special tracer records the maximum stack footprint of the
-	  kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
+	  kernel and displays it in /sys/kernel/tracing/stack_trace.
 
 	  This tracer works by hooking into every function call that the
 	  kernel executes, and keeping a maximum stack depth value and
@@ -346,7 +346,7 @@ config IRQSOFF_TRACER
 	  disabled by default and can be runtime (re-)started
 	  via:
 
-	      echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
+	      echo 0 > /sys/kernel/tracing/tracing_max_latency
 
 	  (Note that kernel size and overhead increase with this option
 	  enabled. This option and the preempt-off timing option can be
@@ -370,7 +370,7 @@ config PREEMPT_TRACER
 	  disabled by default and can be runtime (re-)started
 	  via:
 
-	      echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
+	      echo 0 > /sys/kernel/tracing/tracing_max_latency
 
 	  (Note that kernel size and overhead increase with this option
 	  enabled. This option and the irqs-off timing option can be
@@ -522,7 +522,7 @@ config TRACER_SNAPSHOT
 	  Allow tracing users to take snapshot of the current buffer using the
 	  ftrace interface, e.g.:
 
-	      echo 1 > /sys/kernel/debug/tracing/snapshot
+	      echo 1 > /sys/kernel/tracing/snapshot
 	      cat snapshot
 
 config TRACER_SNAPSHOT_PER_CPU_SWAP
@@ -534,7 +534,7 @@ config TRACER_SNAPSHOT_PER_CPU_SWAP
 	  full swap (all buffers). If this is set, then the following is
 	  allowed:
 
-	      echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
+	      echo 1 > /sys/kernel/tracing/per_cpu/cpu2/snapshot
 
 	  After which, only the tracing buffer for CPU 2 was swapped with
 	  the main tracing buffer, and the other CPU buffers remain the same.
@@ -581,7 +581,7 @@ config PROFILE_ANNOTATED_BRANCHES
 	  This tracer profiles all likely and unlikely macros
 	  in the kernel. It will display the results in:
 
-	  /sys/kernel/debug/tracing/trace_stat/branch_annotated
+	  /sys/kernel/tracing/trace_stat/branch_annotated
 
 	  Note: this will add a significant overhead; only turn this
 	  on if you need to profile the system's use of these macros.
@@ -594,7 +594,7 @@ config PROFILE_ALL_BRANCHES
 	  taken in the kernel is recorded whether it hit or miss.
 	  The results will be displayed in:
 
-	  /sys/kernel/debug/tracing/trace_stat/branch_all
+	  /sys/kernel/tracing/trace_stat/branch_all
 
 	  This option also enables the likely/unlikely profiler.
 
@@ -645,8 +645,8 @@ config BLK_DEV_IO_TRACE
 	  Tracing also is possible using the ftrace interface, e.g.:
 
 	    echo 1 > /sys/block/sda/sda1/trace/enable
-	    echo blk > /sys/kernel/debug/tracing/current_tracer
-	    cat /sys/kernel/debug/tracing/trace_pipe
+	    echo blk > /sys/kernel/tracing/current_tracer
+	    cat /sys/kernel/tracing/trace_pipe
 
 	  If unsure, say N.
 

kernel/trace/kprobe_event_gen_test.c

@@ -21,7 +21,7 @@
  * Then:
  *
  * # insmod kernel/trace/kprobe_event_gen_test.ko
- * # cat /sys/kernel/debug/tracing/trace
+ * # cat /sys/kernel/tracing/trace
  *
  * You should see many instances of the "gen_kprobe_test" and
  * "gen_kretprobe_test" events in the trace buffer.

kernel/trace/ring_buffer.c

@@ -2864,7 +2864,7 @@ rb_check_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
 		  sched_clock_stable() ? "" :
 		  "If you just came from a suspend/resume,\n"
 		  "please switch to the trace global clock:\n"
-		  "  echo global > /sys/kernel/debug/tracing/trace_clock\n"
+		  "  echo global > /sys/kernel/tracing/trace_clock\n"
 		  "or add trace_clock=global to the kernel command line\n");
 }
 
@@ -5604,11 +5604,16 @@ EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page);
  */
 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, void *data)
 {
-	struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
+	struct ring_buffer_per_cpu *cpu_buffer;
 	struct buffer_data_page *bpage = data;
 	struct page *page = virt_to_page(bpage);
 	unsigned long flags;
 
+	if (!buffer || !buffer->buffers || !buffer->buffers[cpu])
+		return;
+
+	cpu_buffer = buffer->buffers[cpu];
+
 	/* If the page is still in use someplace else, we can't reuse it */
 	if (page_ref_count(page) > 1)
 		goto out;

kernel/trace/synth_event_gen_test.c

@@ -22,7 +22,7 @@
  * Then:
  *
  * # insmod kernel/trace/synth_event_gen_test.ko
- * # cat /sys/kernel/debug/tracing/trace
+ * # cat /sys/kernel/tracing/trace
  *
  * You should see several events in the trace buffer -
  * "create_synth_test", "empty_synth_test", and several instances of

kernel/trace/trace.c

@@ -49,6 +49,8 @@
 #include <linux/irq_work.h>
 #include <linux/workqueue.h>
 
+#include <asm/setup.h> /* COMMAND_LINE_SIZE */
+
 #include "trace.h"
 #include "trace_output.h"
 
@@ -186,6 +188,12 @@ static char *default_bootup_tracer;
 static bool allocate_snapshot;
 static bool snapshot_at_boot;
 
+static char boot_instance_info[COMMAND_LINE_SIZE] __initdata;
+static int boot_instance_index;
+
+static char boot_snapshot_info[COMMAND_LINE_SIZE] __initdata;
+static int boot_snapshot_index;
+
 static int __init set_cmdline_ftrace(char *str)
 {
 	strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
@@ -222,9 +230,22 @@ __setup("traceoff_on_warning", stop_trace_on_warning);
 
 static int __init boot_alloc_snapshot(char *str)
 {
-	allocate_snapshot = true;
-	/* We also need the main ring buffer expanded */
-	ring_buffer_expanded = true;
+	char *slot = boot_snapshot_info + boot_snapshot_index;
+	int left = sizeof(boot_snapshot_info) - boot_snapshot_index;
+	int ret;
+
+	if (str[0] == '=') {
+		str++;
+		if (strlen(str) >= left)
+			return -1;
+
+		ret = snprintf(slot, left, "%s\t", str);
+		boot_snapshot_index += ret;
+	} else {
+		allocate_snapshot = true;
+		/* We also need the main ring buffer expanded */
+		ring_buffer_expanded = true;
+	}
 	return 1;
 }
 __setup("alloc_snapshot", boot_alloc_snapshot);
@@ -239,6 +260,23 @@ static int __init boot_snapshot(char *str)
 __setup("ftrace_boot_snapshot", boot_snapshot);
 
 
+static int __init boot_instance(char *str)
+{
+	char *slot = boot_instance_info + boot_instance_index;
+	int left = sizeof(boot_instance_info) - boot_instance_index;
+	int ret;
+
+	if (strlen(str) >= left)
+		return -1;
+
+	ret = snprintf(slot, left, "%s\t", str);
+	boot_instance_index += ret;
+
+	return 1;
+}
+__setup("trace_instance=", boot_instance);
+
+
 static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata;
 
 static int __init set_trace_boot_options(char *str)
@@ -1001,13 +1039,8 @@ __buffer_unlock_commit(struct trace_buffer *buffer, struct ring_buffer_event *ev
 		ring_buffer_unlock_commit(buffer);
 }
 
-/**
- * __trace_puts - write a constant string into the trace buffer.
- * @ip:	   The address of the caller
- * @str:   The constant string to write
- * @size:  The size of the string.
- */
-int __trace_puts(unsigned long ip, const char *str, int size)
+int __trace_array_puts(struct trace_array *tr, unsigned long ip,
+		       const char *str, int size)
 {
 	struct ring_buffer_event *event;
 	struct trace_buffer *buffer;
@@ -1015,7 +1048,7 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 	unsigned int trace_ctx;
 	int alloc;
 
-	if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
+	if (!(tr->trace_flags & TRACE_ITER_PRINTK))
 		return 0;
 
 	if (unlikely(tracing_selftest_running || tracing_disabled))
@@ -1024,7 +1057,7 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 	alloc = sizeof(*entry) + size + 2; /* possible \n added */
 
 	trace_ctx = tracing_gen_ctx();
-	buffer = global_trace.array_buffer.buffer;
+	buffer = tr->array_buffer.buffer;
 	ring_buffer_nest_start(buffer);
 	event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, alloc,
 					    trace_ctx);
@@ -1046,11 +1079,23 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 		entry->buf[size] = '\0';
 
 	__buffer_unlock_commit(buffer, event);
-	ftrace_trace_stack(&global_trace, buffer, trace_ctx, 4, NULL);
+	ftrace_trace_stack(tr, buffer, trace_ctx, 4, NULL);
  out:
 	ring_buffer_nest_end(buffer);
 	return size;
 }
+EXPORT_SYMBOL_GPL(__trace_array_puts);
+
+/**
+ * __trace_puts - write a constant string into the trace buffer.
+ * @ip:	   The address of the caller
+ * @str:   The constant string to write
+ * @size:  The size of the string.
+ */
+int __trace_puts(unsigned long ip, const char *str, int size)
+{
+	return __trace_array_puts(&global_trace, ip, str, size);
+}
 EXPORT_SYMBOL_GPL(__trace_puts);
 
 /**
@@ -1142,7 +1187,7 @@ void tracing_snapshot_instance(struct trace_array *tr)
  *
  * Note, make sure to allocate the snapshot with either
  * a tracing_snapshot_alloc(), or by doing it manually
- * with: echo 1 > /sys/kernel/debug/tracing/snapshot
+ * with: echo 1 > /sys/kernel/tracing/snapshot
  *
  * If the snapshot buffer is not allocated, it will stop tracing.
  * Basically making a permanent snapshot.
@@ -5760,7 +5805,7 @@ static const char readme_msg[] =
 #ifdef CONFIG_SYNTH_EVENTS
 	"  events/synthetic_events\t- Create/append/remove/show synthetic events\n"
 	"\t  Write into this file to define/undefine new synthetic events.\n"
-	"\t     example: echo 'myevent u64 lat; char name[]' >> synthetic_events\n"
+	"\t     example: echo 'myevent u64 lat; char name[]; long[] stack' >> synthetic_events\n"
 #endif
 #endif
 ;
@@ -9225,10 +9270,6 @@ static int allocate_trace_buffers(struct trace_array *tr, int size)
 	}
 	tr->allocated_snapshot = allocate_snapshot;
 
-	/*
-	 * Only the top level trace array gets its snapshot allocated
-	 * from the kernel command line.
-	 */
 	allocate_snapshot = false;
 #endif
 
@@ -10144,6 +10185,79 @@ ssize_t trace_parse_run_command(struct file *file, const char __user *buffer,
 	return ret;
 }
 
+#ifdef CONFIG_TRACER_MAX_TRACE
+__init static bool tr_needs_alloc_snapshot(const char *name)
+{
+	char *test;
+	int len = strlen(name);
+	bool ret;
+
+	if (!boot_snapshot_index)
+		return false;
+
+	if (strncmp(name, boot_snapshot_info, len) == 0 &&
+	    boot_snapshot_info[len] == '\t')
+		return true;
+
+	test = kmalloc(strlen(name) + 3, GFP_KERNEL);
+	if (!test)
+		return false;
+
+	sprintf(test, "\t%s\t", name);
+	ret = strstr(boot_snapshot_info, test) == NULL;
+	kfree(test);
+	return ret;
+}
+
+__init static void do_allocate_snapshot(const char *name)
+{
+	if (!tr_needs_alloc_snapshot(name))
+		return;
+
+	/*
+	 * When allocate_snapshot is set, the next call to
+	 * allocate_trace_buffers() (called by trace_array_get_by_name())
+	 * will allocate the snapshot buffer. That will alse clear
+	 * this flag.
+	 */
+	allocate_snapshot = true;
+}
+#else
+static inline void do_allocate_snapshot(const char *name) { }
+#endif
+
+__init static void enable_instances(void)
+{
+	struct trace_array *tr;
+	char *curr_str;
+	char *str;
+	char *tok;
+
+	/* A tab is always appended */
+	boot_instance_info[boot_instance_index - 1] = '\0';
+	str = boot_instance_info;
+
+	while ((curr_str = strsep(&str, "\t"))) {
+
+		tok = strsep(&curr_str, ",");
+
+		if (IS_ENABLED(CONFIG_TRACER_MAX_TRACE))
+			do_allocate_snapshot(tok);
+
+		tr = trace_array_get_by_name(tok);
+		if (!tr) {
+			pr_warn("Failed to create instance buffer %s\n", curr_str);
+			continue;
+		}
+		/* Allow user space to delete it */
+		trace_array_put(tr);
+
+		while ((tok = strsep(&curr_str, ","))) {
+			early_enable_events(tr, tok, true);
+		}
+	}
+}
+
 __init static int tracer_alloc_buffers(void)
 {
 	int ring_buf_size;
@@ -10277,10 +10391,19 @@ __init static int tracer_alloc_buffers(void)
 
 void __init ftrace_boot_snapshot(void)
 {
+	struct trace_array *tr;
+
 	if (snapshot_at_boot) {
 		tracing_snapshot();
 		internal_trace_puts("** Boot snapshot taken **\n");
 	}
+
+	list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+		if (tr == &global_trace)
+			continue;
+		trace_array_puts(tr, "** Boot snapshot taken **\n");
+		tracing_snapshot_instance(tr);
+	}
 }
 
 void __init early_trace_init(void)
@@ -10302,6 +10425,9 @@ void __init early_trace_init(void)
 void __init trace_init(void)
 {
 	trace_event_init();
+
+	if (boot_instance_index)
+		enable_instances();
 }
 
 __init static void clear_boot_tracer(void)

kernel/trace/trace.h

@@ -113,6 +113,10 @@ enum trace_type {
 #define MEM_FAIL(condition, fmt, ...)					\
 	DO_ONCE_LITE_IF(condition, pr_err, "ERROR: " fmt, ##__VA_ARGS__)
 
+#define HIST_STACKTRACE_DEPTH	16
+#define HIST_STACKTRACE_SIZE	(HIST_STACKTRACE_DEPTH * sizeof(unsigned long))
+#define HIST_STACKTRACE_SKIP	5
+
 /*
  * syscalls are special, and need special handling, this is why
  * they are not included in trace_entries.h
@@ -1331,6 +1335,8 @@ DECLARE_PER_CPU(int, trace_buffered_event_cnt);
 void trace_buffered_event_disable(void);
 void trace_buffered_event_enable(void);
 
+void early_enable_events(struct trace_array *tr, char *buf, bool disable_first);
+
 static inline void
 __trace_event_discard_commit(struct trace_buffer *buffer,
 			     struct ring_buffer_event *event)

kernel/trace/trace_events.c

@@ -2281,8 +2281,6 @@ create_new_subsystem(const char *name)
 	if (!system->name)
 		goto out_free;
 
-	system->filter = NULL;
-
 	system->filter = kzalloc(sizeof(struct event_filter), GFP_KERNEL);
 	if (!system->filter)
 		goto out_free;
@@ -2843,7 +2841,7 @@ static __init int setup_trace_triggers(char *str)
 		if (!trigger)
 			break;
 		bootup_triggers[i].event = strsep(&trigger, ".");
-		bootup_triggers[i].trigger = strsep(&trigger, ".");
+		bootup_triggers[i].trigger = trigger;
 		if (!bootup_triggers[i].trigger)
 			break;
 	}
@@ -3771,10 +3769,9 @@ static __init int event_trace_memsetup(void)
 	return 0;
 }
 
-static __init void
-early_enable_events(struct trace_array *tr, bool disable_first)
+__init void
+early_enable_events(struct trace_array *tr, char *buf, bool disable_first)
 {
-	char *buf = bootup_event_buf;
 	char *token;
 	int ret;
 
@@ -3827,7 +3824,7 @@ static __init int event_trace_enable(void)
 	 */
 	__trace_early_add_events(tr);
 
-	early_enable_events(tr, false);
+	early_enable_events(tr, bootup_event_buf, false);
 
 	trace_printk_start_comm();
 
@@ -3855,7 +3852,7 @@ static __init int event_trace_enable_again(void)
 	if (!tr)
 		return -ENODEV;
 
-	early_enable_events(tr, true);
+	early_enable_events(tr, bootup_event_buf, true);
 
 	return 0;
 }

kernel/trace/trace_events_filter.c

@@ -64,6 +64,7 @@ enum filter_pred_fn {
 	FILTER_PRED_FN_PCHAR_USER,
 	FILTER_PRED_FN_PCHAR,
 	FILTER_PRED_FN_CPU,
+	FILTER_PRED_FN_FUNCTION,
 	FILTER_PRED_FN_,
 	FILTER_PRED_TEST_VISITED,
 };
@@ -71,6 +72,7 @@ enum filter_pred_fn {
 struct filter_pred {
 	enum filter_pred_fn 	fn_num;
 	u64 			val;
+	u64 			val2;
 	struct regex		regex;
 	unsigned short		*ops;
 	struct ftrace_event_field *field;
@@ -103,6 +105,7 @@ struct filter_pred {
 	C(INVALID_FILTER,	"Meaningless filter expression"),	\
 	C(IP_FIELD_ONLY,	"Only 'ip' field is supported for function trace"), \
 	C(INVALID_VALUE,	"Invalid value (did you forget quotes)?"), \
+	C(NO_FUNCTION,		"Function not found"),			\
 	C(ERRNO,		"Error"),				\
 	C(NO_FILTER,		"No filter found")
 
@@ -876,6 +879,17 @@ static int filter_pred_comm(struct filter_pred *pred, void *event)
 	return cmp ^ pred->not;
 }
 
+/* Filter predicate for functions. */
+static int filter_pred_function(struct filter_pred *pred, void *event)
+{
+	unsigned long *addr = (unsigned long *)(event + pred->offset);
+	unsigned long start = (unsigned long)pred->val;
+	unsigned long end = (unsigned long)pred->val2;
+	int ret = *addr >= start && *addr < end;
+
+	return pred->op == OP_EQ ? ret : !ret;
+}
+
 /*
  * regex_match_foo - Basic regex callbacks
  *
@@ -1335,6 +1349,8 @@ static int filter_pred_fn_call(struct filter_pred *pred, void *event)
 		return filter_pred_pchar(pred, event);
 	case FILTER_PRED_FN_CPU:
 		return filter_pred_cpu(pred, event);
+	case FILTER_PRED_FN_FUNCTION:
+		return filter_pred_function(pred, event);
 	case FILTER_PRED_TEST_VISITED:
 		return test_pred_visited_fn(pred, event);
 	default:
@@ -1350,8 +1366,13 @@ static int parse_pred(const char *str, void *data,
 	struct trace_event_call *call = data;
 	struct ftrace_event_field *field;
 	struct filter_pred *pred = NULL;
+	unsigned long offset;
+	unsigned long size;
+	unsigned long ip;
 	char num_buf[24];	/* Big enough to hold an address */
 	char *field_name;
+	char *name;
+	bool function = false;
 	bool ustring = false;
 	char q;
 	u64 val;
@@ -1393,6 +1414,12 @@ static int parse_pred(const char *str, void *data,
 		i += len;
 	}
 
+	/* See if the field is a kernel function name */
+	if ((len = str_has_prefix(str + i, ".function"))) {
+		function = true;
+		i += len;
+	}
+
 	while (isspace(str[i]))
 		i++;
 
@@ -1423,7 +1450,71 @@ static int parse_pred(const char *str, void *data,
 	pred->offset = field->offset;
 	pred->op = op;
 
-	if (ftrace_event_is_function(call)) {
+	if (function) {
+		/* The field must be the same size as long */
+		if (field->size != sizeof(long)) {
+			parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i);
+			goto err_free;
+		}
+
+		/* Function only works with '==' or '!=' and an unquoted string */
+		switch (op) {
+		case OP_NE:
+		case OP_EQ:
+			break;
+		default:
+			parse_error(pe, FILT_ERR_INVALID_OP, pos + i);
+			goto err_free;
+		}
+
+		if (isdigit(str[i])) {
+			/* We allow 0xDEADBEEF */
+			while (isalnum(str[i]))
+				i++;
+
+			len = i - s;
+			/* 0xfeedfacedeadbeef is 18 chars max */
+			if (len >= sizeof(num_buf)) {
+				parse_error(pe, FILT_ERR_OPERAND_TOO_LONG, pos + i);
+				goto err_free;
+			}
+
+			strncpy(num_buf, str + s, len);
+			num_buf[len] = 0;
+
+			ret = kstrtoul(num_buf, 0, &ip);
+			if (ret) {
+				parse_error(pe, FILT_ERR_INVALID_VALUE, pos + i);
+				goto err_free;
+			}
+		} else {
+			s = i;
+			for (; str[i] && !isspace(str[i]); i++)
+				;
+
+			len = i - s;
+			name = kmemdup_nul(str + s, len, GFP_KERNEL);
+			if (!name)
+				goto err_mem;
+			ip = kallsyms_lookup_name(name);
+			kfree(name);
+			if (!ip) {
+				parse_error(pe, FILT_ERR_NO_FUNCTION, pos + i);
+				goto err_free;
+			}
+		}
+
+		/* Now find the function start and end address */
+		if (!kallsyms_lookup_size_offset(ip, &size, &offset)) {
+			parse_error(pe, FILT_ERR_NO_FUNCTION, pos + i);
+			goto err_free;
+		}
+
+		pred->fn_num = FILTER_PRED_FN_FUNCTION;
+		pred->val = ip - offset;
+		pred->val2 = pred->val + size;
+
+	} else if (ftrace_event_is_function(call)) {
 		/*
 		 * Perf does things different with function events.
 		 * It only allows an "ip" field, and expects a string.

kernel/trace/trace_events_hist.c

@@ -135,6 +135,7 @@ enum hist_field_fn {
 	HIST_FIELD_FN_DIV_NOT_POWER2,
 	HIST_FIELD_FN_DIV_MULT_SHIFT,
 	HIST_FIELD_FN_EXECNAME,
+	HIST_FIELD_FN_STACK,
 };
 
 /*
@@ -480,10 +481,6 @@ DEFINE_HIST_FIELD_FN(u8);
 #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)
 
@@ -1360,7 +1357,12 @@ static const char *hist_field_name(struct hist_field *field,
 			field_name = field->name;
 	} else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
 		field_name = "common_timestamp";
-	else if (field->flags & HIST_FIELD_FL_HITCOUNT)
+	else if (field->flags & HIST_FIELD_FL_STACKTRACE) {
+		if (field->field)
+			field_name = field->field->name;
+		else
+			field_name = "stacktrace";
+	} else if (field->flags & HIST_FIELD_FL_HITCOUNT)
 		field_name = "hitcount";
 
 	if (field_name == NULL)
@@ -1718,6 +1720,8 @@ static const char *get_hist_field_flags(struct hist_field *hist_field)
 		flags_str = "percent";
 	else if (hist_field->flags & HIST_FIELD_FL_GRAPH)
 		flags_str = "graph";
+	else if (hist_field->flags & HIST_FIELD_FL_STACKTRACE)
+		flags_str = "stacktrace";
 
 	return flags_str;
 }
@@ -1979,7 +1983,14 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 	}
 
 	if (flags & HIST_FIELD_FL_STACKTRACE) {
-		hist_field->fn_num = HIST_FIELD_FN_NOP;
+		if (field)
+			hist_field->fn_num = HIST_FIELD_FN_STACK;
+		else
+			hist_field->fn_num = HIST_FIELD_FN_NOP;
+		hist_field->size = HIST_STACKTRACE_SIZE;
+		hist_field->type = kstrdup_const("unsigned long[]", GFP_KERNEL);
+		if (!hist_field->type)
+			goto free;
 		goto out;
 	}
 
@@ -2312,6 +2323,8 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,
 			*flags |= HIST_FIELD_FL_EXECNAME;
 		else if (strcmp(modifier, "syscall") == 0)
 			*flags |= HIST_FIELD_FL_SYSCALL;
+		else if (strcmp(modifier, "stacktrace") == 0)
+			*flags |= HIST_FIELD_FL_STACKTRACE;
 		else if (strcmp(modifier, "log2") == 0)
 			*flags |= HIST_FIELD_FL_LOG2;
 		else if (strcmp(modifier, "usecs") == 0)
@@ -2351,6 +2364,8 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,
 		hist_data->enable_timestamps = true;
 		if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS)
 			hist_data->attrs->ts_in_usecs = true;
+	} else if (strcmp(field_name, "stacktrace") == 0) {
+		*flags |= HIST_FIELD_FL_STACKTRACE;
 	} else if (strcmp(field_name, "common_cpu") == 0)
 		*flags |= HIST_FIELD_FL_CPU;
 	else if (strcmp(field_name, "hitcount") == 0)
@@ -3111,6 +3126,9 @@ static inline void __update_field_vars(struct tracing_map_elt *elt,
 	unsigned int i, j, var_idx;
 	u64 var_val;
 
+	/* Make sure stacktrace can fit in the string variable length */
+	BUILD_BUG_ON((HIST_STACKTRACE_DEPTH + 1) * sizeof(long) >= STR_VAR_LEN_MAX);
+
 	for (i = 0, j = field_var_str_start; i < n_field_vars; i++) {
 		struct field_var *field_var = field_vars[i];
 		struct hist_field *var = field_var->var;
@@ -3119,13 +3137,26 @@ static inline void __update_field_vars(struct tracing_map_elt *elt,
 		var_val = hist_fn_call(val, elt, buffer, rbe, rec);
 		var_idx = var->var.idx;
 
-		if (val->flags & HIST_FIELD_FL_STRING) {
+		if (val->flags & (HIST_FIELD_FL_STRING |
+				  HIST_FIELD_FL_STACKTRACE)) {
 			char *str = elt_data->field_var_str[j++];
 			char *val_str = (char *)(uintptr_t)var_val;
 			unsigned int size;
 
-			size = min(val->size, STR_VAR_LEN_MAX);
-			strscpy(str, val_str, size);
+			if (val->flags & HIST_FIELD_FL_STRING) {
+				size = min(val->size, STR_VAR_LEN_MAX);
+				strscpy(str, val_str, size);
+			} else {
+				char *stack_start = str + sizeof(unsigned long);
+				int e;
+
+				e = stack_trace_save((void *)stack_start,
+						     HIST_STACKTRACE_DEPTH,
+						     HIST_STACKTRACE_SKIP);
+				if (e < HIST_STACKTRACE_DEPTH - 1)
+					((unsigned long *)stack_start)[e] = 0;
+				*((unsigned long *)str) = e;
+			}
 			var_val = (u64)(uintptr_t)str;
 		}
 		tracing_map_set_var(elt, var_idx, var_val);
@@ -3824,7 +3855,8 @@ static void save_field_var(struct hist_trigger_data *hist_data,
 {
 	hist_data->field_vars[hist_data->n_field_vars++] = field_var;
 
-	if (field_var->val->flags & HIST_FIELD_FL_STRING)
+	/* Stack traces are saved in the string storage too */
+	if (field_var->val->flags & (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE))
 		hist_data->n_field_var_str++;
 }
 
@@ -3849,6 +3881,9 @@ static int check_synth_field(struct synth_event *event,
 	    && field->is_dynamic)
 		return 0;
 
+	if (strstr(hist_field->type, "long[") && field->is_stack)
+		return 0;
+
 	if (strcmp(field->type, hist_field->type) != 0) {
 		if (field->size != hist_field->size ||
 		    (!field->is_string && field->is_signed != hist_field->is_signed))
@@ -4103,7 +4138,8 @@ static int action_create(struct hist_trigger_data *hist_data,
 			}
 
 			hist_data->save_vars[hist_data->n_save_vars++] = field_var;
-			if (field_var->val->flags & HIST_FIELD_FL_STRING)
+			if (field_var->val->flags &
+			    (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE))
 				hist_data->n_save_var_str++;
 			kfree(param);
 		}
@@ -4242,6 +4278,19 @@ static u64 hist_field_execname(struct hist_field *hist_field,
 	return (u64)(unsigned long)(elt_data->comm);
 }
 
+static u64 hist_field_stack(struct hist_field *hist_field,
+			    struct tracing_map_elt *elt,
+			    struct trace_buffer *buffer,
+			    struct ring_buffer_event *rbe,
+			    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_fn_call(struct hist_field *hist_field,
 			struct tracing_map_elt *elt,
 			struct trace_buffer *buffer,
@@ -4305,6 +4354,8 @@ static u64 hist_fn_call(struct hist_field *hist_field,
 		return div_by_mult_and_shift(hist_field, elt, buffer, rbe, event);
 	case HIST_FIELD_FN_EXECNAME:
 		return hist_field_execname(hist_field, elt, buffer, rbe, event);
+	case HIST_FIELD_FN_STACK:
+		return hist_field_stack(hist_field, elt, buffer, rbe, event);
 	default:
 		return 0;
 	}
@@ -4351,7 +4402,8 @@ static int create_var_field(struct hist_trigger_data *hist_data,
 	if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_EXECNAME)
 		update_var_execname(hist_data->fields[val_idx]);
 
-	if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_STRING)
+	if (!ret && hist_data->fields[val_idx]->flags &
+	    (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE))
 		hist_data->fields[val_idx]->var_str_idx = hist_data->n_var_str++;
 
 	return ret;
@@ -5092,7 +5144,8 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
 		if (hist_field->flags & HIST_FIELD_FL_VAR) {
 			var_idx = hist_field->var.idx;
 
-			if (hist_field->flags & HIST_FIELD_FL_STRING) {
+			if (hist_field->flags &
+			    (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE)) {
 				unsigned int str_start, var_str_idx, idx;
 				char *str, *val_str;
 				unsigned int size;
@@ -5105,9 +5158,20 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
 				str = elt_data->field_var_str[idx];
 				val_str = (char *)(uintptr_t)hist_val;
 
-				size = min(hist_field->size, STR_VAR_LEN_MAX);
-				strscpy(str, val_str, size);
-
+				if (hist_field->flags & HIST_FIELD_FL_STRING) {
+					size = min(hist_field->size, STR_VAR_LEN_MAX);
+					strscpy(str, val_str, size);
+				} else {
+					char *stack_start = str + sizeof(unsigned long);
+					int e;
+
+					e = stack_trace_save((void *)stack_start,
+							     HIST_STACKTRACE_DEPTH,
+							     HIST_STACKTRACE_SKIP);
+					if (e < HIST_STACKTRACE_DEPTH - 1)
+						((unsigned long *)stack_start)[e] = 0;
+					*((unsigned long *)str) = e;
+				}
 				hist_val = (u64)(uintptr_t)str;
 			}
 			tracing_map_set_var(elt, var_idx, hist_val);
@@ -5193,8 +5257,17 @@ static void event_hist_trigger(struct event_trigger_data *data,
 
 		if (key_field->flags & HIST_FIELD_FL_STACKTRACE) {
 			memset(entries, 0, HIST_STACKTRACE_SIZE);
-			stack_trace_save(entries, HIST_STACKTRACE_DEPTH,
-					 HIST_STACKTRACE_SKIP);
+			if (key_field->field) {
+				unsigned long *stack, n_entries;
+
+				field_contents = hist_fn_call(key_field, elt, buffer, rbe, rec);
+				stack = (unsigned long *)(long)field_contents;
+				n_entries = *stack;
+				memcpy(entries, ++stack, n_entries * sizeof(unsigned long));
+			} else {
+				stack_trace_save(entries, HIST_STACKTRACE_DEPTH,
+						 HIST_STACKTRACE_SKIP);
+			}
 			key = entries;
 		} else {
 			field_contents = hist_fn_call(key_field, elt, buffer, rbe, rec);
@@ -5297,7 +5370,10 @@ static void hist_trigger_print_key(struct seq_file *m,
 			seq_printf(m, "%s: %-30s[%3llu]", field_name,
 				   syscall_name, uval);
 		} else if (key_field->flags & HIST_FIELD_FL_STACKTRACE) {
-			seq_puts(m, "stacktrace:\n");
+			if (key_field->field)
+				seq_printf(m, "%s.stacktrace", key_field->field->name);
+			else
+				seq_puts(m, "stacktrace:\n");
 			hist_trigger_stacktrace_print(m,
 						      key + key_field->offset,
 						      HIST_STACKTRACE_DEPTH);
@@ -5842,7 +5918,8 @@ static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
 
 	if (hist_field->flags) {
 		if (!(hist_field->flags & HIST_FIELD_FL_VAR_REF) &&
-		    !(hist_field->flags & HIST_FIELD_FL_EXPR)) {
+		    !(hist_field->flags & HIST_FIELD_FL_EXPR) &&
+		    !(hist_field->flags & HIST_FIELD_FL_STACKTRACE)) {
 			const char *flags = get_hist_field_flags(hist_field);
 
 			if (flags)
@@ -5875,9 +5952,12 @@ static int event_hist_trigger_print(struct seq_file *m,
 		if (i > hist_data->n_vals)
 			seq_puts(m, ",");
 
-		if (field->flags & HIST_FIELD_FL_STACKTRACE)
-			seq_puts(m, "stacktrace");
-		else
+		if (field->flags & HIST_FIELD_FL_STACKTRACE) {
+			if (field->field)
+				seq_printf(m, "%s.stacktrace", field->field->name);
+			else
+				seq_puts(m, "stacktrace");
+		} else
 			hist_field_print(m, field);
 	}
 

kernel/trace/trace_events_synth.c

@@ -173,6 +173,14 @@ static int synth_field_is_string(char *type)
 	return false;
 }
 
+static int synth_field_is_stack(char *type)
+{
+	if (strstr(type, "long[") != NULL)
+		return true;
+
+	return false;
+}
+
 static int synth_field_string_size(char *type)
 {
 	char buf[4], *end, *start;
@@ -248,6 +256,8 @@ static int synth_field_size(char *type)
 		size = sizeof(gfp_t);
 	else if (synth_field_is_string(type))
 		size = synth_field_string_size(type);
+	else if (synth_field_is_stack(type))
+		size = 0;
 
 	return size;
 }
@@ -292,6 +302,8 @@ static const char *synth_field_fmt(char *type)
 		fmt = "%x";
 	else if (synth_field_is_string(type))
 		fmt = "%.*s";
+	else if (synth_field_is_stack(type))
+		fmt = "%s";
 
 	return fmt;
 }
@@ -371,6 +383,23 @@ static enum print_line_t print_synth_event(struct trace_iterator *iter,
 						 i == se->n_fields - 1 ? "" : " ");
 				n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
 			}
+		} else if (se->fields[i]->is_stack) {
+			u32 offset, data_offset, len;
+			unsigned long *p, *end;
+
+			offset = (u32)entry->fields[n_u64];
+			data_offset = offset & 0xffff;
+			len = offset >> 16;
+
+			p = (void *)entry + data_offset;
+			end = (void *)p + len - (sizeof(long) - 1);
+
+			trace_seq_printf(s, "%s=STACK:\n", se->fields[i]->name);
+
+			for (; *p && p < end; p++)
+				trace_seq_printf(s, "=> %pS\n", (void *)*p);
+			n_u64++;
+
 		} else {
 			struct trace_print_flags __flags[] = {
 			    __def_gfpflag_names, {-1, NULL} };
@@ -416,8 +445,7 @@ static unsigned int trace_string(struct synth_trace_event *entry,
 	if (is_dynamic) {
 		u32 data_offset;
 
-		data_offset = offsetof(typeof(*entry), fields);
-		data_offset += event->n_u64 * sizeof(u64);
+		data_offset = struct_size(entry, fields, event->n_u64);
 		data_offset += data_size;
 
 		len = kern_fetch_store_strlen((unsigned long)str_val);
@@ -447,6 +475,43 @@ static unsigned int trace_string(struct synth_trace_event *entry,
 	return len;
 }
 
+static unsigned int trace_stack(struct synth_trace_event *entry,
+				 struct synth_event *event,
+				 long *stack,
+				 unsigned int data_size,
+				 unsigned int *n_u64)
+{
+	unsigned int len;
+	u32 data_offset;
+	void *data_loc;
+
+	data_offset = struct_size(entry, fields, event->n_u64);
+	data_offset += data_size;
+
+	for (len = 0; len < HIST_STACKTRACE_DEPTH; len++) {
+		if (!stack[len])
+			break;
+	}
+
+	/* Include the zero'd element if it fits */
+	if (len < HIST_STACKTRACE_DEPTH)
+		len++;
+
+	len *= sizeof(long);
+
+	/* Find the dynamic section to copy the stack into. */
+	data_loc = (void *)entry + data_offset;
+	memcpy(data_loc, stack, len);
+
+	/* Fill in the field that holds the offset/len combo */
+	data_offset |= len << 16;
+	*(u32 *)&entry->fields[*n_u64] = data_offset;
+
+	(*n_u64)++;
+
+	return len;
+}
+
 static notrace void trace_event_raw_event_synth(void *__data,
 						u64 *var_ref_vals,
 						unsigned int *var_ref_idx)
@@ -473,7 +538,12 @@ static notrace void trace_event_raw_event_synth(void *__data,
 		val_idx = var_ref_idx[field_pos];
 		str_val = (char *)(long)var_ref_vals[val_idx];
 
-		len = kern_fetch_store_strlen((unsigned long)str_val);
+		if (event->dynamic_fields[i]->is_stack) {
+			len = *((unsigned long *)str_val);
+			len *= sizeof(unsigned long);
+		} else {
+			len = kern_fetch_store_strlen((unsigned long)str_val);
+		}
 
 		fields_size += len;
 	}
@@ -499,6 +569,12 @@ static notrace void trace_event_raw_event_synth(void *__data,
 					   event->fields[i]->is_dynamic,
 					   data_size, &n_u64);
 			data_size += len; /* only dynamic string increments */
+		} else if (event->fields[i]->is_stack) {
+			long *stack = (long *)(long)var_ref_vals[val_idx];
+
+			len = trace_stack(entry, event, stack,
+					   data_size, &n_u64);
+			data_size += len;
 		} else {
 			struct synth_field *field = event->fields[i];
 			u64 val = var_ref_vals[val_idx];
@@ -561,6 +637,9 @@ static int __set_synth_event_print_fmt(struct synth_event *event,
 		    event->fields[i]->is_dynamic)
 			pos += snprintf(buf + pos, LEN_OR_ZERO,
 				", __get_str(%s)", event->fields[i]->name);
+		else if (event->fields[i]->is_stack)
+			pos += snprintf(buf + pos, LEN_OR_ZERO,
+				", __get_stacktrace(%s)", event->fields[i]->name);
 		else
 			pos += snprintf(buf + pos, LEN_OR_ZERO,
 					", REC->%s", event->fields[i]->name);
@@ -697,7 +776,8 @@ static struct synth_field *parse_synth_field(int argc, char **argv,
 		ret = -EINVAL;
 		goto free;
 	} else if (size == 0) {
-		if (synth_field_is_string(field->type)) {
+		if (synth_field_is_string(field->type) ||
+		    synth_field_is_stack(field->type)) {
 			char *type;
 
 			len = sizeof("__data_loc ") + strlen(field->type) + 1;
@@ -728,6 +808,8 @@ static struct synth_field *parse_synth_field(int argc, char **argv,
 
 	if (synth_field_is_string(field->type))
 		field->is_string = true;
+	else if (synth_field_is_stack(field->type))
+		field->is_stack = true;
 
 	field->is_signed = synth_field_signed(field->type);
  out:

kernel/trace/trace_osnoise.c

@@ -1539,7 +1539,7 @@ static void osnoise_sleep(void)
 	wake_time = ktime_add_us(ktime_get(), interval);
 	__set_current_state(TASK_INTERRUPTIBLE);
 
-	while (schedule_hrtimeout_range(&wake_time, 0, HRTIMER_MODE_ABS)) {
+	while (schedule_hrtimeout(&wake_time, HRTIMER_MODE_ABS)) {
 		if (kthread_should_stop())
 			break;
 	}

kernel/trace/trace_seq.c

@@ -403,3 +403,26 @@ int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str,
 	return 1;
 }
 EXPORT_SYMBOL(trace_seq_hex_dump);
+
+/*
+ * trace_seq_acquire - acquire seq buffer with size len
+ * @s: trace sequence descriptor
+ * @len: size of buffer to be acquired
+ *
+ * acquire buffer with size of @len from trace_seq for output usage,
+ * user can fill string into that buffer.
+ *
+ * Returns start address of acquired buffer.
+ *
+ * it allow multiple usage in one trace output function call.
+ */
+char *trace_seq_acquire(struct trace_seq *s, unsigned int len)
+{
+	char *ret = trace_seq_buffer_ptr(s);
+
+	if (!WARN_ON_ONCE(seq_buf_buffer_left(&s->seq) < len))
+		seq_buf_commit(&s->seq, len);
+
+	return ret;
+}
+EXPORT_SYMBOL(trace_seq_acquire);

kernel/trace/trace_synth.h

@@ -18,6 +18,7 @@ struct synth_field {
 	bool is_signed;
 	bool is_string;
 	bool is_dynamic;
+	bool is_stack;
 };
 
 struct synth_event {

kernel/tracepoint.c

@@ -571,8 +571,8 @@ static void for_each_tracepoint_range(
 bool trace_module_has_bad_taint(struct module *mod)
 {
 	return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP) |
-			       (1 << TAINT_UNSIGNED_MODULE) |
-			       (1 << TAINT_TEST));
+				(1 << TAINT_UNSIGNED_MODULE) | (1 << TAINT_TEST) |
+				(1 << TAINT_LIVEPATCH));
 }
 
 static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list);

samples/Kconfig

@@ -46,6 +46,13 @@ config SAMPLE_FTRACE_DIRECT_MULTI
 	  that hooks to wake_up_process and schedule, and prints
 	  the function addresses.
 
+config SAMPLE_FTRACE_OPS
+	tristate "Build custom ftrace ops example"
+	depends on FUNCTION_TRACER
+	help
+	  This builds an ftrace ops example that hooks two functions and
+	  measures the time taken to invoke one function a number of times.
+
 config SAMPLE_TRACE_ARRAY
         tristate "Build sample module for kernel access to Ftrace instancess"
 	depends on EVENT_TRACING && m

samples/Makefile

@@ -24,6 +24,7 @@ obj-$(CONFIG_SAMPLE_TRACE_CUSTOM_EVENTS) += trace_events/
 obj-$(CONFIG_SAMPLE_TRACE_PRINTK)	+= trace_printk/
 obj-$(CONFIG_SAMPLE_FTRACE_DIRECT)	+= ftrace/
 obj-$(CONFIG_SAMPLE_FTRACE_DIRECT_MULTI) += ftrace/
+obj-$(CONFIG_SAMPLE_FTRACE_OPS)		+= ftrace/
 obj-$(CONFIG_SAMPLE_TRACE_ARRAY)	+= ftrace/
 subdir-$(CONFIG_SAMPLE_UHID)		+= uhid
 obj-$(CONFIG_VIDEO_PCI_SKELETON)	+= v4l/

samples/ftrace/Makefile

@@ -5,6 +5,7 @@ obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct-too.o
 obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct-modify.o
 obj-$(CONFIG_SAMPLE_FTRACE_DIRECT_MULTI) += ftrace-direct-multi.o
 obj-$(CONFIG_SAMPLE_FTRACE_DIRECT_MULTI) += ftrace-direct-multi-modify.o
+obj-$(CONFIG_SAMPLE_FTRACE_OPS) += ftrace-ops.o
 
 CFLAGS_sample-trace-array.o := -I$(src)
 obj-$(CONFIG_SAMPLE_TRACE_ARRAY) += sample-trace-array.o

samples/ftrace/ftrace-direct-modify.c

@@ -3,7 +3,6 @@
 #include <linux/kthread.h>
 #include <linux/ftrace.h>
 #include <asm/asm-offsets.h>
-#include <asm/nospec-branch.h>
 
 extern void my_direct_func1(void);
 extern void my_direct_func2(void);
@@ -26,6 +25,7 @@ static unsigned long my_ip = (unsigned long)schedule;
 #ifdef CONFIG_X86_64
 
 #include <asm/ibt.h>
+#include <asm/nospec-branch.h>
 
 asm (
 "	.pushsection    .text, \"ax\", @progbits\n"

samples/ftrace/ftrace-direct-multi-modify.c

@@ -3,7 +3,6 @@
 #include <linux/kthread.h>
 #include <linux/ftrace.h>
 #include <asm/asm-offsets.h>
-#include <asm/nospec-branch.h>
 
 extern void my_direct_func1(unsigned long ip);
 extern void my_direct_func2(unsigned long ip);
@@ -24,6 +23,7 @@ extern void my_tramp2(void *);
 #ifdef CONFIG_X86_64
 
 #include <asm/ibt.h>
+#include <asm/nospec-branch.h>
 
 asm (
 "	.pushsection    .text, \"ax\", @progbits\n"

samples/ftrace/ftrace-direct-multi.c

@@ -5,7 +5,6 @@
 #include <linux/ftrace.h>
 #include <linux/sched/stat.h>
 #include <asm/asm-offsets.h>
-#include <asm/nospec-branch.h>
 
 extern void my_direct_func(unsigned long ip);
 
@@ -19,6 +18,7 @@ extern void my_tramp(void *);
 #ifdef CONFIG_X86_64
 
 #include <asm/ibt.h>
+#include <asm/nospec-branch.h>
 
 asm (
 "	.pushsection    .text, \"ax\", @progbits\n"

samples/ftrace/ftrace-direct-too.c

@@ -4,7 +4,6 @@
 #include <linux/mm.h> /* for handle_mm_fault() */
 #include <linux/ftrace.h>
 #include <asm/asm-offsets.h>
-#include <asm/nospec-branch.h>
 
 extern void my_direct_func(struct vm_area_struct *vma,
 			   unsigned long address, unsigned int flags);
@@ -21,6 +20,7 @@ extern void my_tramp(void *);
 #ifdef CONFIG_X86_64
 
 #include <asm/ibt.h>
+#include <asm/nospec-branch.h>
 
 asm (
 "	.pushsection    .text, \"ax\", @progbits\n"

samples/ftrace/ftrace-direct.c

@@ -4,7 +4,6 @@
 #include <linux/sched.h> /* for wake_up_process() */
 #include <linux/ftrace.h>
 #include <asm/asm-offsets.h>
-#include <asm/nospec-branch.h>
 
 extern void my_direct_func(struct task_struct *p);
 
@@ -18,6 +17,7 @@ extern void my_tramp(void *);
 #ifdef CONFIG_X86_64
 
 #include <asm/ibt.h>
+#include <asm/nospec-branch.h>
 
 asm (
 "	.pushsection    .text, \"ax\", @progbits\n"

samples/ftrace/ftrace-ops.c

+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt)       KBUILD_MODNAME ": " fmt
+
+#include <linux/ftrace.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+
+#include <asm/barrier.h>
+
+/*
+ * Arbitrary large value chosen to be sufficiently large to minimize noise but
+ * sufficiently small to complete quickly.
+ */
+static unsigned int nr_function_calls = 100000;
+module_param(nr_function_calls, uint, 0);
+MODULE_PARM_DESC(nr_function_calls, "How many times to call the relevant tracee");
+
+/*
+ * The number of ops associated with a call site affects whether a tracer can
+ * be called directly or whether it's necessary to go via the list func, which
+ * can be significantly more expensive.
+ */
+static unsigned int nr_ops_relevant = 1;
+module_param(nr_ops_relevant, uint, 0);
+MODULE_PARM_DESC(nr_ops_relevant, "How many ftrace_ops to associate with the relevant tracee");
+
+/*
+ * On architectures where all call sites share the same trampoline, having
+ * tracers enabled for distinct functions can force the use of the list func
+ * and incur overhead for all call sites.
+ */
+static unsigned int nr_ops_irrelevant;
+module_param(nr_ops_irrelevant, uint, 0);
+MODULE_PARM_DESC(nr_ops_irrelevant, "How many ftrace_ops to associate with the irrelevant tracee");
+
+/*
+ * On architectures with DYNAMIC_FTRACE_WITH_REGS, saving the full pt_regs can
+ * be more expensive than only saving the minimal necessary regs.
+ */
+static bool save_regs;
+module_param(save_regs, bool, 0);
+MODULE_PARM_DESC(save_regs, "Register ops with FTRACE_OPS_FL_SAVE_REGS (save all registers in the trampoline)");
+
+static bool assist_recursion;
+module_param(assist_recursion, bool, 0);
+MODULE_PARM_DESC(assist_reursion, "Register ops with FTRACE_OPS_FL_RECURSION");
+
+static bool assist_rcu;
+module_param(assist_rcu, bool, 0);
+MODULE_PARM_DESC(assist_reursion, "Register ops with FTRACE_OPS_FL_RCU");
+
+/*
+ * By default, a trivial tracer is used which immediately returns to mimimize
+ * overhead. Sometimes a consistency check using a more expensive tracer is
+ * desireable.
+ */
+static bool check_count;
+module_param(check_count, bool, 0);
+MODULE_PARM_DESC(check_count, "Check that tracers are called the expected number of times\n");
+
+/*
+ * Usually it's not interesting to leave the ops registered after the test
+ * runs, but sometimes it can be useful to leave them registered so that they
+ * can be inspected through the tracefs 'enabled_functions' file.
+ */
+static bool persist;
+module_param(persist, bool, 0);
+MODULE_PARM_DESC(persist, "Successfully load module and leave ftrace ops registered after test completes\n");
+
+/*
+ * Marked as noinline to ensure that an out-of-line traceable copy is
+ * generated by the compiler.
+ *
+ * The barrier() ensures the compiler won't elide calls by determining there
+ * are no side-effects.
+ */
+static noinline void tracee_relevant(void)
+{
+	barrier();
+}
+
+/*
+ * Marked as noinline to ensure that an out-of-line traceable copy is
+ * generated by the compiler.
+ *
+ * The barrier() ensures the compiler won't elide calls by determining there
+ * are no side-effects.
+ */
+static noinline void tracee_irrelevant(void)
+{
+	barrier();
+}
+
+struct sample_ops {
+	struct ftrace_ops ops;
+	unsigned int count;
+};
+
+static void ops_func_nop(unsigned long ip, unsigned long parent_ip,
+			 struct ftrace_ops *op,
+			 struct ftrace_regs *fregs)
+{
+	/* do nothing */
+}
+
+static void ops_func_count(unsigned long ip, unsigned long parent_ip,
+			   struct ftrace_ops *op,
+			   struct ftrace_regs *fregs)
+{
+	struct sample_ops *self;
+
+	self = container_of(op, struct sample_ops, ops);
+	self->count++;
+}
+
+static struct sample_ops *ops_relevant;
+static struct sample_ops *ops_irrelevant;
+
+static struct sample_ops *ops_alloc_init(void *tracee, ftrace_func_t func,
+					 unsigned long flags, int nr)
+{
+	struct sample_ops *ops;
+
+	ops = kcalloc(nr, sizeof(*ops), GFP_KERNEL);
+	if (WARN_ON_ONCE(!ops))
+		return NULL;
+
+	for (unsigned int i = 0; i < nr; i++) {
+		ops[i].ops.func = func;
+		ops[i].ops.flags = flags;
+		WARN_ON_ONCE(ftrace_set_filter_ip(&ops[i].ops, (unsigned long)tracee, 0, 0));
+		WARN_ON_ONCE(register_ftrace_function(&ops[i].ops));
+	}
+
+	return ops;
+}
+
+static void ops_destroy(struct sample_ops *ops, int nr)
+{
+	if (!ops)
+		return;
+
+	for (unsigned int i = 0; i < nr; i++) {
+		WARN_ON_ONCE(unregister_ftrace_function(&ops[i].ops));
+		ftrace_free_filter(&ops[i].ops);
+	}
+
+	kfree(ops);
+}
+
+static void ops_check(struct sample_ops *ops, int nr,
+		      unsigned int expected_count)
+{
+	if (!ops || !check_count)
+		return;
+
+	for (unsigned int i = 0; i < nr; i++) {
+		if (ops->count == expected_count)
+			continue;
+		pr_warn("Counter called %u times (expected %u)\n",
+			ops->count, expected_count);
+	}
+}
+
+static ftrace_func_t tracer_relevant = ops_func_nop;
+static ftrace_func_t tracer_irrelevant = ops_func_nop;
+
+static int __init ftrace_ops_sample_init(void)
+{
+	unsigned long flags = 0;
+	ktime_t start, end;
+	u64 period;
+
+	if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && save_regs) {
+		pr_info("this kernel does not support saving registers\n");
+		save_regs = false;
+	} else if (save_regs) {
+		flags |= FTRACE_OPS_FL_SAVE_REGS;
+	}
+
+	if (assist_recursion)
+		flags |= FTRACE_OPS_FL_RECURSION;
+
+	if (assist_rcu)
+		flags |= FTRACE_OPS_FL_RCU;
+
+	if (check_count) {
+		tracer_relevant = ops_func_count;
+		tracer_irrelevant = ops_func_count;
+	}
+
+	pr_info("registering:\n"
+		"  relevant ops: %u\n"
+		"    tracee: %ps\n"
+		"    tracer: %ps\n"
+		"  irrelevant ops: %u\n"
+		"    tracee: %ps\n"
+		"    tracer: %ps\n"
+		"  saving registers: %s\n"
+		"  assist recursion: %s\n"
+		"  assist RCU: %s\n",
+		nr_ops_relevant, tracee_relevant, tracer_relevant,
+		nr_ops_irrelevant, tracee_irrelevant, tracer_irrelevant,
+		save_regs ? "YES" : "NO",
+		assist_recursion ? "YES" : "NO",
+		assist_rcu ? "YES" : "NO");
+
+	ops_relevant = ops_alloc_init(tracee_relevant, tracer_relevant,
+				      flags, nr_ops_relevant);
+	ops_irrelevant = ops_alloc_init(tracee_irrelevant, tracer_irrelevant,
+					flags, nr_ops_irrelevant);
+
+	start = ktime_get();
+	for (unsigned int i = 0; i < nr_function_calls; i++)
+		tracee_relevant();
+	end = ktime_get();
+
+	ops_check(ops_relevant, nr_ops_relevant, nr_function_calls);
+	ops_check(ops_irrelevant, nr_ops_irrelevant, 0);
+
+	period = ktime_to_ns(ktime_sub(end, start));
+
+	pr_info("Attempted %u calls to %ps in %lluns (%lluns / call)\n",
+		nr_function_calls, tracee_relevant,
+		period, div_u64(period, nr_function_calls));
+
+	if (persist)
+		return 0;
+
+	ops_destroy(ops_relevant, nr_ops_relevant);
+	ops_destroy(ops_irrelevant, nr_ops_irrelevant);
+
+	/*
+	 * The benchmark completed sucessfully, but there's no reason to keep
+	 * the module around. Return an error do the user doesn't have to
+	 * manually unload the module.
+	 */
+	return -EINVAL;
+}
+module_init(ftrace_ops_sample_init);
+
+static void __exit ftrace_ops_sample_exit(void)
+{
+	ops_destroy(ops_relevant, nr_ops_relevant);
+	ops_destroy(ops_irrelevant, nr_ops_irrelevant);
+}
+module_exit(ftrace_ops_sample_exit);
+
+MODULE_AUTHOR("Mark Rutland");
+MODULE_DESCRIPTION("Example of using custom ftrace_ops");
+MODULE_LICENSE("GPL");

samples/user_events/example.c

@@ -23,8 +23,8 @@
 #endif
 
 /* Assumes debugfs is mounted */
-const char *data_file = "/sys/kernel/debug/tracing/user_events_data";
-const char *status_file = "/sys/kernel/debug/tracing/user_events_status";
+const char *data_file = "/sys/kernel/tracing/user_events_data";
+const char *status_file = "/sys/kernel/tracing/user_events_status";
 
 static int event_status(long **status)
 {

scripts/tracing/draw_functrace.py

@@ -12,9 +12,9 @@ calls. Only the functions's names and the call time are provided.
 
 Usage:
 	Be sure that you have CONFIG_FUNCTION_TRACER
-	# mount -t debugfs nodev /sys/kernel/debug
-	# echo function > /sys/kernel/debug/tracing/current_tracer
-	$ cat /sys/kernel/debug/tracing/trace_pipe > ~/raw_trace_func
+	# mount -t tracefs nodev /sys/kernel/tracing
+	# echo function > /sys/kernel/tracing/current_tracer
+	$ cat /sys/kernel/tracing/trace_pipe > ~/raw_trace_func
 	Wait some times but not too much, the script is a bit slow.
 	Break the pipe (Ctrl + Z)
 	$ scripts/tracing/draw_functrace.py < ~/raw_trace_func > draw_functrace

tools/lib/api/fs/tracing_path.c

@@ -14,8 +14,8 @@
 #include "tracing_path.h"
 
 static char tracing_mnt[PATH_MAX]  = "/sys/kernel/debug";
-static char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
-static char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
+static char tracing_path[PATH_MAX]        = "/sys/kernel/tracing";
+static char tracing_events_path[PATH_MAX] = "/sys/kernel/tracing/events";
 
 static void __tracing_path_set(const char *tracing, const char *mountpoint)
 {

tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc

+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event filter function - test event filtering on functions
+# requires: set_event events/kmem/kmem_cache_free/filter
+# flags: instance
+
+fail() { #msg
+    echo $1
+    exit_fail
+}
+
+echo "Test event filter function name"
+echo 0 > tracing_on
+echo 0 > events/enable
+echo > trace
+echo 'call_site.function == exit_mmap' > events/kmem/kmem_cache_free/filter
+echo 1 > events/kmem/kmem_cache_free/enable
+echo 1 > tracing_on
+ls > /dev/null
+echo 0 > events/kmem/kmem_cache_free/enable
+
+hitcnt=`grep kmem_cache_free trace| grep exit_mmap | wc -l`
+misscnt=`grep kmem_cache_free trace| grep -v exit_mmap | wc -l`
+
+if [ $hitcnt -eq 0 ]; then
+	exit_fail
+fi
+
+if [ $misscnt -gt 0 ]; then
+	exit_fail
+fi
+
+address=`grep ' exit_mmap$' /proc/kallsyms | cut -d' ' -f1`
+
+echo "Test event filter function address"
+echo 0 > tracing_on
+echo 0 > events/enable
+echo > trace
+echo "call_site.function == 0x$address" > events/kmem/kmem_cache_free/filter
+echo 1 > events/kmem/kmem_cache_free/enable
+echo 1 > tracing_on
+sleep 1
+echo 0 > events/kmem/kmem_cache_free/enable
+
+hitcnt=`grep kmem_cache_free trace| grep exit_mmap | wc -l`
+misscnt=`grep kmem_cache_free trace| grep -v exit_mmap | wc -l`
+
+if [ $hitcnt -eq 0 ]; then
+	exit_fail
+fi
+
+if [ $misscnt -gt 0 ]; then
+	exit_fail
+fi
+
+reset_events_filter
+
+exit 0

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-synthetic-event-stack.tc

+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test inter-event histogram trigger trace action with dynamic string param
+# requires: set_event synthetic_events events/sched/sched_process_exec/hist "long[]' >> synthetic_events":README
+
+fail() { #msg
+    echo $1
+    exit_fail
+}
+
+echo "Test create synthetic event with stack"
+
+
+echo 's:wake_lat pid_t pid; u64 delta; unsigned long[] stack;' > dynamic_events
+echo 'hist:keys=next_pid:ts=common_timestamp.usecs,st=stacktrace  if prev_state == 1||prev_state == 2' >> events/sched/sched_switch/trigger
+echo 'hist:keys=prev_pid:delta=common_timestamp.usecs-$ts,s=$st:onmax($delta).trace(wake_lat,prev_pid,$delta,$s)' >> events/sched/sched_switch/trigger
+echo 1 > events/synthetic/wake_lat/enable
+sleep 1
+
+if ! grep -q "=>.*sched" trace; then
+    fail "Failed to create synthetic event with stack"
+fi
+
+exit 0

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-synthetic-event-syntax.tc

@@ -70,6 +70,12 @@ grep "myevent[[:space:]]unsigned long var" synthetic_events
 echo "myevent char var[10]" > synthetic_events
 grep "myevent[[:space:]]char\[10\] var" synthetic_events
 
+if grep -q 'long\[\]' README; then
+  # test stacktrace type
+  echo "myevent unsigned long[] var" > synthetic_events
+  grep "myevent[[:space:]]unsigned long\[\] var" synthetic_events
+fi
+
 do_reset
 
 exit 0

tools/tracing/latency/latency-collector.c

@@ -1584,7 +1584,7 @@ static void *do_printloop(void *arg)
 		/*
 		 * Toss a coin to decide if we want to sleep before printing
 		 * out the backtrace. The reason for this is that opening
-		 * /sys/kernel/debug/tracing/trace will cause a blackout of
+		 * /sys/kernel/tracing/trace will cause a blackout of
 		 * hundreds of ms, where no latencies will be noted by the
 		 * latency tracer. Thus by randomly sleeping we try to avoid
 		 * missing traces systematically due to this. With this option