Merge tag 'trace-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:

 - Extend tracing option mask to 64 bits

   The trace options were defined by a 32 bit variable. This limits the
   tracing instances to have a total of 32 different options. As that
   limit has been hit, and more options are being added, increase the
   option mask to a 64 bit number, doubling the number of options
   available.

   As this is required for the kprobe topic branches as well as the
   tracing topic branch, a separate branch was created and merged into
   both.

 - Make trace_user_fault_read() available for the rest of tracing

   The function trace_user_fault_read() is used by trace_marker file
   read to allow reading user space to be done fast and without locking
   or allocations. Make this available so that the system call trace
   events can use it too.

 - Have system call trace events read user space values

   Now that the system call trace events callbacks are called in a
   faultable context, take advantage of this and read the user space
   buffers for various system calls. For example, show the path name of
   the openat system call instead of just showing the pointer to that
   path name in user space. Also show the contents of the buffer of the
   write system call. Several system call trace events are updated to
   make tracing into a light weight strace tool for all applications in
   the system.

 - Update perf system call tracing to do the same

 - And a config and syscall_user_buf_size file to control the size of
   the buffer

   Limit the amount of data that can be read from user space. The
   default size is 63 bytes but that can be expanded to 165 bytes.

 - Allow the persistent ring buffer to print system calls normally

   The persistent ring buffer prints trace events by their type and
   ignores the print_fmt. This is because the print_fmt may change from
   kernel to kernel. As the system call output is fixed by the system
   call ABI itself, there's no reason to limit that. This makes reading
   the system call events in the persistent ring buffer much nicer and
   easier to understand.

 - Add options to show text offset to function profiler

   The function profiler that counts the number of times a function is
   hit currently lists all functions by its name and offset. But this
   becomes ambiguous when there are several functions with the same
   name.

   Add a tracing option that changes the output to be that of
   '_text+offset' instead. Now a user space tool can use this
   information to map the '_text+offset' to the unique function it is
   counting.

 - Report bad dynamic event command

   If a bad command is passed to the dynamic_events file, report it
   properly in the error log.

 - Clean up tracer options

   Clean up the tracer option code a bit, by removing some useless code
   and also using switch statements instead of a series of if
   statements.

 - Have tracing options be instance specific

   Tracers can have their own options (function tracer, irqsoff tracer,
   function graph tracer, etc). But now that the same tracer can be
   enabled in multiple trace instances, their options are still global.
   The API is per instance, thus changing one affects other instances.
   This isn't even consistent, as the option take affect differently
   depending on when an tracer started in an instance. Make the options
   for instances only affect the instance it is changed under.

 - Optimize pid_list lock contention

   Whenever the pid_list is read, it uses a spin lock. This happens at
   every sched switch. Taking the lock at sched switch can be removed by
   instead using a seqlock counter.

 - Clean up the trace trigger structures

   The trigger code uses two different structures to implement a single
   tigger. This was due to trying to reuse code for the two different
   types of triggers (always on trigger, and count limited trigger). But
   by adding a single field to one structure, the other structure could
   be absorbed into the first structure making he code easier to
   understand.

 - Create a bulk garbage collector for trace triggers

   If user space has triggers for several hundreds of events and then
   removes them, it can take several seconds to complete. This is
   because each removal calls tracepoint_synchronize_unregister() that
   can take hundreds of milliseconds to complete.

   Instead, create a helper thread that will do the clean up. When a
   trigger is removed, it will create the kthread if it isn't already
   created, and then add the trigger to a llist. The kthread will take
   the items off the llist, call tracepoint_synchronize_unregister(),
   and then remove the items it took off. It will then check if there's
   more items to free before sleeping.

   This makes user space removing all these triggers to finish in less
   than a second.

 - Allow function tracing of some of the tracing infrastructure code

   Because the tracing code can cause recursion issues if it is traced
   by the function tracer the entire tracing directory disables function
   tracing. But not all of tracing causes issues if it is traced.
   Namely, the event tracing code. Add a config that enables some of the
   tracing code to be traced to help in debugging it. Note, when this is
   enabled, it does add noise to general function tracing, especially if
   events are enabled as well (which is a common case).

 - Add boot-time backup instance for persistent buffer

   The persistent ring buffer is used mostly for kernel crash analysis
   in the field. One issue is that if there's a crash, the data in the
   persistent ring buffer must be read before tracing can begin using
   it. This slows down the boot process. Once tracing starts in the
   persistent ring buffer, the old data must be freed and the addresses
   no longer match and old events can't be in the buffer with new
   events.

   Create a way to create a backup buffer that copies the persistent
   ring buffer at boot up. Then after a crash, the always on tracer can
   begin immediately as well as the normal boot process while the crash
   analysis tooling uses the backup buffer. After the backup buffer is
   finished being read, it can be removed.

 - Enable function graph args and return address options at the same
   time

   Currently the when reading of arguments in the function graph tracer
   is enabled, the option to record the parent function in the entry
   event can not be enabled. Update the code so that it can.

 - Add new struct_offset() helper macro

   Add a new macro that takes a pointer to a structure and a name of one
   of its members and it will return the offset of that member. This
   allows the ring buffer code to simplify the following:

   From:  size = struct_size(entry, buf, cnt - sizeof(entry->id));
     To:  size = struct_offset(entry, id) + cnt;

   There should be other simplifications that this macro can help out
   with as well

* tag 'trace-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (42 commits)
  overflow: Introduce struct_offset() to get offset of member
  function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously
  tracing: Add boot-time backup of persistent ring buffer
  ftrace: Allow tracing of some of the tracing code
  tracing: Use strim() in trigger_process_regex() instead of skip_spaces()
  tracing: Add bulk garbage collection of freeing event_trigger_data
  tracing: Remove unneeded event_mutex lock in event_trigger_regex_release()
  tracing: Merge struct event_trigger_ops into struct event_command
  tracing: Remove get_trigger_ops() and add count_func() from trigger ops
  tracing: Show the tracer options in boot-time created instance
  ftrace: Avoid redundant initialization in register_ftrace_direct
  tracing: Remove unused variable in tracing_trace_options_show()
  fgraph: Make fgraph_no_sleep_time signed
  tracing: Convert function graph set_flags() to use a switch() statement
  tracing: Have function graph tracer option sleep-time be per instance
  tracing: Move graph-time out of function graph options
  tracing: Have function graph tracer option funcgraph-irqs be per instance
  trace/pid_list: optimize pid_list->lock contention
  tracing: Have function graph tracer define options per instance
  tracing: Have function tracer define options per instance
  ...

Author: torvalds

Documentation/trace/ftrace.rst

@@ -366,6 +366,14 @@ of ftrace. Here is a list of some of the key files:
 	for each function. The displayed address is the patch-site address
 	and can differ from /proc/kallsyms address.
 
+  syscall_user_buf_size:
+
+	Some system call trace events will record the data from a user
+	space address that one of the parameters point to. The amount of
+	data per event is limited. This file holds the max number of bytes
+	that will be recorded into the ring buffer to hold this data.
+	The max value is currently 165.
+
   dyn_ftrace_total_info:
 
 	This file is for debugging purposes. The number of functions that

include/linux/ftrace.h

@@ -1167,17 +1167,14 @@ static inline void ftrace_init(void) { }
  */
 struct ftrace_graph_ent {
 	unsigned long func; /* Current function */
-	int depth;
+	unsigned long depth;
 } __packed;
 
 /*
  * Structure that defines an entry function trace with retaddr.
- * It's already packed but the attribute "packed" is needed
- * to remove extra padding at the end.
  */
 struct fgraph_retaddr_ent {
-	unsigned long func; /* Current function */
-	int depth;
+	struct ftrace_graph_ent ent;
 	unsigned long retaddr;  /* Return address */
 } __packed;
 

include/linux/overflow.h

@@ -458,6 +458,18 @@ static inline size_t __must_check size_sub(size_t minuend, size_t subtrahend)
 #define struct_size_t(type, member, count)					\
 	struct_size((type *)NULL, member, count)
 
+/**
+ * struct_offset() - Calculate the offset of a member within a struct
+ * @p: Pointer to the struct
+ * @member: Name of the member to get the offset of
+ *
+ * Calculates the offset of a particular @member of the structure pointed
+ * to by @p.
+ *
+ * Return: number of bytes to the location of @member.
+ */
+#define struct_offset(p, member) (offsetof(typeof(*(p)), member))
+
 /**
  * __DEFINE_FLEX() - helper macro for DEFINE_FLEX() family.
  * Enables caller macro to pass arbitrary trailing expressions

include/linux/seq_buf.h

@@ -149,6 +149,23 @@ static inline void seq_buf_commit(struct seq_buf *s, int num)
 	}
 }
 
+/**
+ * seq_buf_pop - pop off the last written character
+ * @s: the seq_buf handle
+ *
+ * Removes the last written character to the seq_buf @s.
+ *
+ * Returns the last character or -1 if it is empty.
+ */
+static inline int seq_buf_pop(struct seq_buf *s)
+{
+	if (!s->len)
+		return -1;
+
+	s->len--;
+	return (unsigned int)s->buffer[s->len];
+}
+
 extern __printf(2, 3)
 int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
 extern __printf(2, 0)

include/linux/trace_seq.h

@@ -80,6 +80,19 @@ static inline bool trace_seq_has_overflowed(struct trace_seq *s)
 	return s->full || seq_buf_has_overflowed(&s->seq);
 }
 
+/**
+ * trace_seq_pop - pop off the last written character
+ * @s: trace sequence descriptor
+ *
+ * Removes the last written character to the trace_seq @s.
+ *
+ * Returns the last character or -1 if it is empty.
+ */
+static inline int trace_seq_pop(struct trace_seq *s)
+{
+	return seq_buf_pop(&s->seq);
+}
+
 /*
  * Currently only defined when tracing is enabled.
  */

include/trace/syscall.h

@@ -16,6 +16,9 @@
  * @name: name of the syscall
  * @syscall_nr: number of the syscall
  * @nb_args: number of parameters it takes
+ * @user_arg_is_str: set if the arg for @user_arg_size is a string
+ * @user_arg_size: holds @arg that has size of the user space to read
+ * @user_mask: mask of @args that will read user space
  * @types: list of types as strings
  * @args: list of args as strings (args[i] matches types[i])
  * @enter_fields: list of fields for syscall_enter trace event
@@ -25,7 +28,10 @@
 struct syscall_metadata {
 	const char	*name;
 	int		syscall_nr;
-	int		nb_args;
+	u8		nb_args:7;
+	u8		user_arg_is_str:1;
+	s8		user_arg_size;
+	short		user_mask;
 	const char	**types;
 	const char	**args;
 	struct list_head enter_fields;

kernel/trace/Kconfig

@@ -342,6 +342,20 @@ config DYNAMIC_FTRACE_WITH_JMP
 	depends on DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 	depends on HAVE_DYNAMIC_FTRACE_WITH_JMP
 
+config FUNCTION_SELF_TRACING
+	bool "Function trace tracing code"
+	depends on FUNCTION_TRACER
+	help
+	  Normally all the tracing code is set to notrace, where the function
+	  tracer will ignore all the tracing functions. Sometimes it is useful
+	  for debugging to trace some of the tracing infratructure itself.
+	  Enable this to allow some of the tracing infrastructure to be traced
+	  by the function tracer. Note, this will likely add noise to function
+	  tracing if events and other tracing features are enabled along with
+	  function tracing.
+
+	  If unsure, say N.
+
 config FPROBE
 	bool "Kernel Function Probe (fprobe)"
 	depends on HAVE_FUNCTION_GRAPH_FREGS && HAVE_FTRACE_GRAPH_FUNC
@@ -587,6 +601,20 @@ config FTRACE_SYSCALLS
 	help
 	  Basic tracer to catch the syscall entry and exit events.
 
+config TRACE_SYSCALL_BUF_SIZE_DEFAULT
+	int "System call user read max size"
+	range 0 165
+	default 63
+	depends on FTRACE_SYSCALLS
+	help
+	 Some system call trace events will record the data from a user
+	 space address that one of the parameters point to. The amount of
+	 data per event is limited. That limit is set by this config and
+	 this config also affects how much user space data perf can read.
+
+	 For a tracing instance, this size may be changed by writing into
+	 its syscall_user_buf_size file.
+
 config TRACER_SNAPSHOT
 	bool "Create a snapshot trace buffer"
 	select TRACER_MAX_TRACE

kernel/trace/Makefile

@@ -16,6 +16,23 @@ obj-y += trace_selftest_dynamic.o
 endif
 endif
 
+# Allow some files to be function traced
+ifdef CONFIG_FUNCTION_SELF_TRACING
+CFLAGS_trace_output.o = $(CC_FLAGS_FTRACE)
+CFLAGS_trace_seq.o = $(CC_FLAGS_FTRACE)
+CFLAGS_trace_stat.o = $(CC_FLAGS_FTRACE)
+CFLAGS_tracing_map.o = $(CC_FLAGS_FTRACE)
+CFLAGS_synth_event_gen_test.o = $(CC_FLAGS_FTRACE)
+CFLAGS_trace_events.o = $(CC_FLAGS_FTRACE)
+CFLAGS_trace_syscalls.o = $(CC_FLAGS_FTRACE)
+CFLAGS_trace_events_filter.o = $(CC_FLAGS_FTRACE)
+CFLAGS_trace_events_trigger.o = $(CC_FLAGS_FTRACE)
+CFLAGS_trace_events_synth.o = $(CC_FLAGS_FTRACE)
+CFLAGS_trace_events_hist.o = $(CC_FLAGS_FTRACE)
+CFLAGS_trace_events_user.o = $(CC_FLAGS_FTRACE)
+CFLAGS_trace_dynevent.o = $(CC_FLAGS_FTRACE)
+endif
+
 ifdef CONFIG_FTRACE_STARTUP_TEST
 CFLAGS_trace_kprobe_selftest.o = $(CC_FLAGS_FTRACE)
 obj-$(CONFIG_KPROBE_EVENTS) += trace_kprobe_selftest.o

kernel/trace/blktrace.c

@@ -1738,7 +1738,7 @@ static enum print_line_t print_one_line(struct trace_iterator *iter,
 
 	t	   = te_blk_io_trace(iter->ent);
 	what	   = (t->action & ((1 << BLK_TC_SHIFT) - 1)) & ~__BLK_TA_CGROUP;
-	long_act   = !!(tr->trace_flags & TRACE_ITER_VERBOSE);
+	long_act   = !!(tr->trace_flags & TRACE_ITER(VERBOSE));
 	log_action = classic ? &blk_log_action_classic : &blk_log_action;
 	has_cg	   = t->action & __BLK_TA_CGROUP;
 
@@ -1803,9 +1803,9 @@ blk_tracer_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 	/* don't output context-info for blk_classic output */
 	if (bit == TRACE_BLK_OPT_CLASSIC) {
 		if (set)
-			tr->trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
+			tr->trace_flags &= ~TRACE_ITER(CONTEXT_INFO);
 		else
-			tr->trace_flags |= TRACE_ITER_CONTEXT_INFO;
+			tr->trace_flags |= TRACE_ITER(CONTEXT_INFO);
 	}
 	return 0;
 }

kernel/trace/fgraph.c

@@ -498,9 +498,6 @@ void *fgraph_retrieve_parent_data(int idx, int *size_bytes, int depth)
 	return get_data_type_data(current, offset);
 }
 
-/* Both enabled by default (can be cleared by function_graph tracer flags */
-bool fgraph_sleep_time = true;
-
 #ifdef CONFIG_DYNAMIC_FTRACE
 /*
  * archs can override this function if they must do something
@@ -1023,11 +1020,6 @@ void fgraph_init_ops(struct ftrace_ops *dst_ops,
 #endif
 }
 
-void ftrace_graph_sleep_time_control(bool enable)
-{
-	fgraph_sleep_time = enable;
-}
-
 /*
  * Simply points to ftrace_stub, but with the proper protocol.
  * Defined by the linker script in linux/vmlinux.lds.h
@@ -1098,7 +1090,7 @@ ftrace_graph_probe_sched_switch(void *ignore, bool preempt,
 	 * Does the user want to count the time a function was asleep.
 	 * If so, do not update the time stamps.
 	 */
-	if (fgraph_sleep_time)
+	if (!fgraph_no_sleep_time)
 		return;
 
 	timestamp = trace_clock_local();