From f93a7d0caccd6ab76dacfd620013cfc41f49fb8d Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 20 Nov 2025 18:15:14 -0500 Subject: [PATCH] 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 Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Mark Rutland Cc: Tom Zanussi Link: https://patch.msgid.link/20251120181514.736f2d5f@gandalf.local.home Signed-off-by: Steven Rostedt (Google) --- kernel/trace/Kconfig | 14 ++++++++++++++ kernel/trace/Makefile | 17 +++++++++++++++++ 2 files changed, 31 insertions(+) diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 99283b2dcfd6..e1214b9dc990 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -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 diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index dcb4e02afc5f..fc5dcc888e13 100644 --- a/kernel/trace/Makefile +++ b/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