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Commit 452938cb authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'trace-v4.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace 

Pull tracing fixes from Steven Rostedt:
 "Masami found an off by one bug in the code that keeps "notrace"
  functions from being traced by kprobes. During my testing, I found
  that there's places that we may want to add kprobes to notrace, thus
  we may end up changing this code before 4.19 is released.

  The history behind this change is that we found that adding kprobes to
  various notrace functions caused the kernel to crashed. We took the
  safe route and decided not to allow kprobes to trace any notrace
  function.

  But because notrace is added to functions that just cause weird side
  effects to the function tracer, but are still safe, preventing kprobes
  for all notrace functios may be too much of a big hammer.

  One such place is __schedule() is marked notrace, to keep function
  tracer from doing strange recursive loops when it gets traced with
  NEED_RESCHED set. With this change, one can not add kprobes to the
  scheduler.

  Masami also added code to use gcov on ftrace"

* tag 'trace-v4.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing/kprobes: Fix to check notrace function with correct range
  tracing: Allow gcov profiling on only ftrace subsystem
parents 815f0ddb 9161a864

kernel/trace/Kconfig

+12 −0
Original line number Diff line number Diff line
@@ -774,6 +774,18 @@ config TRACING_EVENTS_GPIO 
	help

	  Enable tracing events for gpio subsystem



config GCOV_PROFILE_FTRACE

	bool "Enable GCOV profiling on ftrace subsystem"

	depends on GCOV_KERNEL

	help

	  Enable GCOV profiling on ftrace subsystem for checking

	  which functions/lines are tested.



	  If unsure, say N.



	  Note that on a kernel compiled with this config, ftrace will

	  run significantly slower.



endif # FTRACE



endif # TRACING_SUPPORT

kernel/trace/Makefile

+5 −0
Original line number Diff line number Diff line
@@ -23,6 +23,11 @@ ifdef CONFIG_TRACING_BRANCHES 
KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING

endif



# for GCOV coverage profiling

ifdef CONFIG_GCOV_PROFILE_FTRACE

GCOV_PROFILE := y

endif



CFLAGS_trace_benchmark.o := -I$(src)

CFLAGS_trace_events_filter.o := -I$(src)

kernel/trace/trace_kprobe.c

+8 −1
Original line number Diff line number Diff line
@@ -513,7 +513,14 @@ static bool within_notrace_func(struct trace_kprobe *tk) 
	if (!addr || !kallsyms_lookup_size_offset(addr, &size, &offset))

		return false;



	return !ftrace_location_range(addr - offset, addr - offset + size);

	/* Get the entry address of the target function */

	addr -= offset;



	/*

	 * Since ftrace_location_range() does inclusive range check, we need

	 * to subtract 1 byte from the end address.

	 */

	return !ftrace_location_range(addr, addr + size - 1);

}

#else

#define within_notrace_func(tk)	(false)