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| author |   Vegard Nossum <vegard.nossum@oracle.com> | 2016-08-02 14:07:30 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2016-08-02 19:35:43 -0400 |
| commit | a4691deabf284a601149a067525759939cc563b2 (patch) | |
| tree | 40524fe55bd55def7831a68e6a3d775b4a1ea3fd | |
| parent | init/Kconfig: add clarification for out-of-tree modules (diff) | |
| download | linux-dev-a4691deabf284a601149a067525759939cc563b2.tar.xz linux-dev-a4691deabf284a601149a067525759939cc563b2.zip | |
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 += $(CFLAGS_KCOV)
Link: http://lkml.kernel.org/r/1464008380-11405-1-git-send-email-vegard.nossum@oracle.com
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | lib/Kconfig.debug | 11 | ||||
| -rw-r--r-- | scripts/Makefile.lib | 2 |
2 files changed, 12 insertions, 1 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index f07842e2d69f..cc02f282d05b 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -719,6 +719,17 @@ config KCOV For more details, see Documentation/kcov.txt. +config KCOV_INSTRUMENT_ALL + bool "Instrument all code by default" + depends on KCOV + default y if KCOV + help + If you are doing generic system call fuzzing (like e.g. syzkaller), + then you will want to instrument the whole kernel and you should + say y here. If you are doing more targeted fuzzing (like e.g. + filesystem fuzzing with AFL) then you will want to enable coverage + for more specific subsets of files, and should say n here. + config DEBUG_SHIRQ bool "Debug shared IRQ handlers" depends on DEBUG_KERNEL diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index e7df0f5db7ec..76494e15417b 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -138,7 +138,7 @@ endif ifeq ($(CONFIG_KCOV),y) _c_flags += $(if $(patsubst n%,, \ - $(KCOV_INSTRUMENT_$(basetarget).o)$(KCOV_INSTRUMENT)y), \ + $(KCOV_INSTRUMENT_$(basetarget).o)$(KCOV_INSTRUMENT)$(CONFIG_KCOV_INSTRUMENT_ALL)), \ $(CFLAGS_KCOV)) endif |