From 2521f2c228ad750701ba4702484e31d876dbc386 Mon Sep 17 00:00:00 2001 From: Peter Oberparleiter Date: Wed, 17 Jun 2009 16:28:08 -0700 Subject: gcov: add gcov profiling infrastructure Enable the use of GCC's coverage testing tool gcov [1] with the Linux kernel. gcov may be useful for: * debugging (has this code been reached at all?) * test improvement (how do I change my test to cover these lines?) * minimizing kernel configurations (do I need this option if the associated code is never run?) The profiling patch incorporates the following changes: * change kbuild to include profiling flags * provide functions needed by profiling code * present profiling data as files in debugfs Note that on some architectures, enabling gcc's profiling option "-fprofile-arcs" for the entire kernel may trigger compile/link/ run-time problems, some of which are caused by toolchain bugs and others which require adjustment of architecture code. For this reason profiling the entire kernel is initially restricted to those architectures for which it is known to work without changes. This restriction can be lifted once an architecture has been tested and found compatible with gcc's profiling. Profiling of single files or directories is still available on all platforms (see config help text). [1] http://gcc.gnu.org/onlinedocs/gcc/Gcov.html Signed-off-by: Peter Oberparleiter Cc: Andi Kleen Cc: Huang Ying Cc: Li Wei Cc: Michael Ellerman Cc: Ingo Molnar Cc: Heiko Carstens Cc: Martin Schwidefsky Cc: Rusty Russell Cc: WANG Cong Cc: Sam Ravnborg Cc: Jeff Dike Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- scripts/Makefile.lib | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'scripts') diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 2b706617c89a..7a7778746ea6 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -116,6 +116,17 @@ _a_flags = $(KBUILD_CPPFLAGS) $(KBUILD_AFLAGS) $(KBUILD_SUBDIR_ASFLAGS) \ $(asflags-y) $(AFLAGS_$(basetarget).o) _cpp_flags = $(KBUILD_CPPFLAGS) $(cppflags-y) $(CPPFLAGS_$(@F)) +# +# Enable gcov profiling flags for a file, directory or for all files depending +# on variables GCOV_PROFILE_obj.o, GCOV_PROFILE and CONFIG_GCOV_PROFILE_ALL +# (in this order) +# +ifeq ($(CONFIG_GCOV_KERNEL),y) +_c_flags += $(if $(patsubst n%,, \ + $(GCOV_PROFILE_$(basetarget).o)$(GCOV_PROFILE)$(CONFIG_GCOV_PROFILE_ALL)), \ + $(CFLAGS_GCOV)) +endif + # If building the kernel in a separate objtree expand all occurrences # of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/'). -- cgit v1.2.3