path: root/lib
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authorVegard Nossum <vegard.nossum@oracle.com>2016-08-02 14:07:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-08-02 19:35:43 -0400
commita4691deabf284a601149a067525759939cc563b2 (patch)
tree40524fe55bd55def7831a68e6a3d775b4a1ea3fd /lib
parentf1cb637e75b59a07450cf81ad68b04f3f46b03d7 (diff)
kcov: allow more fine-grained coverage instrumentation
For more targeted fuzzing, it's better to disable kernel-wide instrumentation and instead enable it on a per-subsystem basis. This follows the pattern of UBSAN and allows you to compile in the kcov driver without instrumenting the whole kernel. To instrument a part of the kernel, you can use either # for a single file in the current directory KCOV_INSTRUMENT_filename.o := y or # for all the files in the current directory (excluding subdirectories) KCOV_INSTRUMENT := y or # (same as above) ccflags-y += $(CFLAGS_KCOV) or # for all the files in the current directory (including subdirectories) subdir-ccflags-y += $(CFLAGS_KCOV) Link: http://lkml.kernel.org/r/1464008380-11405-1-git-send-email-vegard.nossum@oracle.com Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
1 files changed, 11 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index f07842e2d69f..cc02f282d05b 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -719,6 +719,17 @@ config KCOV
For more details, see Documentation/kcov.txt.
+ bool "Instrument all code by default"
+ depends on KCOV
+ default y if KCOV
+ help
+ If you are doing generic system call fuzzing (like e.g. syzkaller),
+ then you will want to instrument the whole kernel and you should
+ say y here. If you are doing more targeted fuzzing (like e.g.
+ filesystem fuzzing with AFL) then you will want to enable coverage
+ for more specific subsets of files, and should say n here.
bool "Debug shared IRQ handlers"
depends on DEBUG_KERNEL