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 <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: Li Wei <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Rusty Russell <[email protected]>
Cc: WANG Cong <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Cc: Jeff Dike <[email protected]>
Cc: Al Viro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/include/linux/compiler-gcc3.h b/include/linux/compiler-gcc3.h
index 8005eff..b721129 100644
--- a/include/linux/compiler-gcc3.h
+++ b/include/linux/compiler-gcc3.h
@@ -16,6 +16,12 @@
#define __must_check __attribute__((warn_unused_result))
#endif
+#ifdef CONFIG_GCOV_KERNEL
+# if __GNUC_MINOR__ < 4
+# error "GCOV profiling support for gcc versions below 3.4 not included"
+# endif /* __GNUC_MINOR__ */
+#endif /* CONFIG_GCOV_KERNEL */
+
/*
* A trick to suppress uninitialized variable warning without generating any
* code
