Re: [PATCH 2/4] selftests: Fix seccomp to support relocatable build (O=objdir)

From: Shuah Khan <skhan@linuxfoundation.org>
To: Michael Ellerman <mpe@ellerman.id.au>, Kees Cook <keescook@chromium.org>
Cc: shuah@kernel.org, luto@amacapital.net, wad@chromium.org,
	daniel@iogearbox.net, kafai@fb.com, yhs@fb.com, andriin@fb.com,
	gregkh@linuxfoundation.org, tglx@linutronix.de,
	khilman@baylibre.com, linux-kselftest@vger.kernel.org,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	bpf@vger.kernel.org, Shuah Khan <skhan@linuxfoundation.org>
Subject: Re: [PATCH 2/4] selftests: Fix seccomp to support relocatable build (O=objdir)
Date: Wed, 4 Mar 2020 17:29:16 -0700	[thread overview]
Message-ID: <da1b2591-bb19-9dc7-ed5f-cc2481c24f87@linuxfoundation.org> (raw)
In-Reply-To: <87eeu7r6qf.fsf@mpe.ellerman.id.au>

On 3/4/20 5:22 PM, Michael Ellerman wrote:
> Shuah Khan <skhan@linuxfoundation.org> writes:
>> On 3/4/20 3:42 PM, Kees Cook wrote:
>>> On Wed, Mar 04, 2020 at 03:13:33PM -0700, Shuah Khan wrote:
>>>> Fix seccomp relocatable builds. This is a simple fix to use the
>>>> right lib.mk variable TEST_GEN_PROGS for objects to leverage
>>>> lib.mk common framework for relocatable builds.
>>>>
>>>> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
>>>> ---
>>>>    tools/testing/selftests/seccomp/Makefile | 16 +++-------------
>>>>    1 file changed, 3 insertions(+), 13 deletions(-)
>>>>
>>>> diff --git a/tools/testing/selftests/seccomp/Makefile b/tools/testing/selftests/seccomp/Makefile
>>>> index 1760b3e39730..a8a9717fc1be 100644
>>>> --- a/tools/testing/selftests/seccomp/Makefile
>>>> +++ b/tools/testing/selftests/seccomp/Makefile
>>>> @@ -1,17 +1,7 @@
>>>>    # SPDX-License-Identifier: GPL-2.0
>>>> -all:
>>>> -
>>>> -include ../lib.mk
>>>> -
>>>> -.PHONY: all clean
>>>> -
>>>> -BINARIES := seccomp_bpf seccomp_benchmark
>>>>    CFLAGS += -Wl,-no-as-needed -Wall
>>>> +LDFLAGS += -lpthread
>>>>    
>>>> -seccomp_bpf: seccomp_bpf.c ../kselftest_harness.h
>>>
>>> How is the ../kselftest_harness.h dependency detected in the resulting
>>> build rules?
>>>
>>> Otherwise, looks good.
>>
>> Didn't see any problems. I will look into adding the dependency.
> 
> Before:
> 
>    $ make --no-print-directory -C tools/testing/selftests/ TARGETS=seccomp
>    make --no-builtin-rules INSTALL_HDR_PATH=$BUILD/usr \
>            ARCH=powerpc -C ../../.. headers_install
>      INSTALL /home/michael/build/adhoc/kselftest/usr/include
>    gcc -Wl,-no-as-needed -Wall  seccomp_bpf.c -lpthread -o seccomp_bpf
>    gcc -Wl,-no-as-needed -Wall    seccomp_benchmark.c   -o seccomp_benchmark
>    
>    $ touch tools/testing/selftests/kselftest_harness.h
>    
>    $ make --no-print-directory -C tools/testing/selftests/ TARGETS=seccomp
>    make --no-builtin-rules INSTALL_HDR_PATH=$BUILD/usr \
>            ARCH=powerpc -C ../../.. headers_install
>      INSTALL /home/michael/build/adhoc/kselftest/usr/include
>    gcc -Wl,-no-as-needed -Wall  seccomp_bpf.c -lpthread -o seccomp_bpf
>    $
> 
> Note that touching the header causes it to rebuild seccomp_bpf.
> 
> With this patch applied:
> 
>    $ make --no-print-directory -C tools/testing/selftests/ TARGETS=seccomp
>    make -s --no-builtin-rules INSTALL_HDR_PATH=$BUILD/usr \
>            ARCH=powerpc -C ../../.. headers_install
>    gcc -Wl,-no-as-needed -Wall  -lpthread  seccomp_bpf.c  -o /home/michael/build/adhoc/kselftest/seccomp/seccomp_bpf
>    gcc -Wl,-no-as-needed -Wall  -lpthread  seccomp_benchmark.c  -o /home/michael/build/adhoc/kselftest/seccomp/seccomp_benchmark
>    
>    $ touch tools/testing/selftests/kselftest_harness.h
>    
>    $ make --no-print-directory -C tools/testing/selftests/ TARGETS=seccomp
>    make -s --no-builtin-rules INSTALL_HDR_PATH=$BUILD/usr \
>            ARCH=powerpc -C ../../.. headers_install
>    make[1]: Nothing to be done for 'all'.
>    $
> 
> 

Thanks. I realized I overlooked header dependency case.

> So yeah it still needs:
> 
> seccomp_bpf: ../kselftest_harness.h
> 
> 
Yes v2 coming up. It also has to handle OUTPUT relocation.

thanks,
-- Shuah