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

3 files changed, 25 insertions, 1 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index c042a455afc6..5e3de28c7677 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -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
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 98d53b39a8ee..f81dadbc7c4a 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -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)
 
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 2bfb2bbeb3d2..c30032367aab 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -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)