Commit f93a7d0c authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt (Google)
Browse files

ftrace: Allow tracing of some of the tracing code 

There is times when tracing the tracing infrastructure can be useful for
debugging the tracing code. Currently all files in the tracing directory
are set to "notrace" the functions.

Add a new config option FUNCTION_SELF_TRACING that will allow some of the
files in the tracing infrastructure to be traced. It requires a config to
enable because it will add noise to the function tracer if events and
other tracing features are enabled. Tracing functions and events together
is quite common, so not tracing the event code should be the default.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Link: https://patch.msgid.link/20251120181514.736f2d5f@gandalf.local.home


Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 400ddf1d

kernel/trace/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -330,6 +330,20 @@ config DYNAMIC_FTRACE_WITH_ARGS 
	depends on DYNAMIC_FTRACE

	depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS



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

kernel/trace/Makefile

+17 −0
Original line number Diff line number Diff line
@@ -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