Re: [PATCH v2 2/3] Makefile: support flag -fsanitizer-coverage=trace-cmp

From: Alexander Potapenko <glider@google.com>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Popov <alex.popov@linux.com>,
	Quentin Casasnovas <quentin.casasnovas@oracle.com>,
	Dmitriy Vyukov <dvyukov@google.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Kees Cook <keescook@chromium.org>,
	Vegard Nossum <vegard.nossum@oracle.com>,
	syzkaller <syzkaller@googlegroups.com>,
	Linux Memory Management List <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 2/3] Makefile: support flag -fsanitizer-coverage=trace-cmp
Date: Tue, 10 Oct 2017 17:28:01 +0200	[thread overview]
Message-ID: <CAG_fn=WaC2hk6i=CLq2u37MhZ_5FtOgbjyXScmqAnRh46uNNiQ@mail.gmail.com> (raw)
In-Reply-To: <0e1d9dbe-6c09-979d-e0ba-c39368028cbf@virtuozzo.com>

On Mon, Oct 9, 2017 at 8:53 AM, Andrey Ryabinin <aryabinin@virtuozzo.com> wrote:
>
>
> On 10/09/2017 06:05 PM, Alexander Potapenko wrote:
>
>> v2: - updated KCOV_ENABLE_COMPARISONS description
>> ---
>>  Makefile             |  5 +++--
>>  lib/Kconfig.debug    | 10 ++++++++++
>>  scripts/Makefile.lib |  6 ++++++
>>  3 files changed, 19 insertions(+), 2 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index 2835863bdd5a..c2a8e56df748 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -374,7 +374,7 @@ AFLAGS_KERNEL     =
>>  LDFLAGS_vmlinux =
>>  CFLAGS_GCOV  := -fprofile-arcs -ftest-coverage -fno-tree-loop-im $(call cc-disable-warning,maybe-uninitialized,)
>>  CFLAGS_KCOV  := $(call cc-option,-fsanitize-coverage=trace-pc,)
>> -
>> +CFLAGS_KCOV_COMPS := $(call cc-option,-fsanitize-coverage=trace-cmp,)
>>
>>  # Use USERINCLUDE when you must reference the UAPI directories only.
>>  USERINCLUDE    := \
>> @@ -420,7 +420,7 @@ export MAKE AWK GENKSYMS INSTALLKERNEL PERL PYTHON UTS_MACHINE
>>  export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
>>
>>  export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
>> -export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV CFLAGS_KCOV CFLAGS_KASAN CFLAGS_UBSAN
>> +export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV CFLAGS_KCOV CFLAGS_KCOV_COMPS CFLAGS_KASAN CFLAGS_UBSAN
>>  export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
>>  export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
>>  export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
>> @@ -822,6 +822,7 @@ KBUILD_CFLAGS   += $(call cc-option,-Werror=designated-init)
>>  KBUILD_ARFLAGS := $(call ar-option,D)
>>
>>  include scripts/Makefile.kasan
>> +include scripts/Makefile.kcov
>
> scripts/Makefile.kcov doesn't exist.
Good catch! Will fix.

>
>
>
>> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
>> index 5e975fee0f5b..7ddd5932c832 100644
>> --- a/scripts/Makefile.lib
>> +++ b/scripts/Makefile.lib
>> @@ -142,6 +142,12 @@ _c_flags += $(if $(patsubst n%,, \
>>       $(CFLAGS_KCOV))
>>  endif
>>
>> +ifeq ($(CONFIG_KCOV_ENABLE_COMPARISONS),y)
>> +_c_flags += $(if $(patsubst n%,, \
>> +     $(KCOV_INSTRUMENT_$(basetarget).o)$(KCOV_INSTRUMENT)$(CONFIG_KCOV_INSTRUMENT_ALL)), \
>> +     $(CFLAGS_KCOV_COMPS))
>> +endif
>> +
>
> Instead of this you could simply add -fsanitize-coverage=trace-cmp to CFLAGS_KCOV.
Indeed. I've refactored these bits and moved them to Makefile.kcov.
>
>>  # If building the kernel in a separate objtree expand all occurrences
>>  # of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/').
>>
>>


-- 
Alexander Potapenko
Software Engineer

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