Re: [PATCH v3] selftests: Fix seccomp to support relocatable build (O=objdir)

Kees Cook
2020-03-13T23:18:10Z

On Fri, Mar 13, 2020 at 03:24:04PM -0600, Shuah Khan wrote:
> Fix seccomp relocatable builds. This is a simple fix to use the right
> lib.mk variable TEST_GEN_PROGS with dependency on kselftest_harness.h
> header, and defining LDFLAGS for pthread lib.
>
> Removes custom clean rule which is no longer necessary with the use of
> TEST_GEN_PROGS.
>
> Uses $(OUTPUT) defined in lib.mk to handle build relocation.
>
> The following use-cases work with this change:
>
> In seccomp directory:
> make all and make clean
>
> From top level from main Makefile:
> make kselftest-install O=objdir ARCH=arm64 HOSTCC=gcc \
> CROSS_COMPILE=aarch64-linux-gnu- TARGETS=seccomp
>
> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
> ---
>
> Changes since v2:
> -- Using TEST_GEN_PROGS is sufficient to generate objects.
> Addresses review comments from Kees Cook.
>
> tools/testing/selftests/seccomp/Makefile | 18 ++++++++----------
> 1 file changed, 8 insertions(+), 10 deletions(-)
>
> diff --git a/tools/testing/selftests/seccomp/Makefile b/tools/testing/selftests/seccomp/Makefile
> index 1760b3e39730..a0388fd2c3f2 100644
> --- a/tools/testing/selftests/seccomp/Makefile
> +++ b/tools/testing/selftests/seccomp/Makefile
> @@ -1,17 +1,15 @@
> # SPDX-License-Identifier: GPL-2.0
> -all:
> -
> -include ../lib.mk
> +CFLAGS += -Wl,-no-as-needed -Wall
> +LDFLAGS += -lpthread
>
> .PHONY: all clean

Isn't this line redundant to ../lib.mk's?

>
> -BINARIES := seccomp_bpf seccomp_benchmark
> -CFLAGS += -Wl,-no-as-needed -Wall
> +include ../lib.mk
> +
> +# OUTPUT set by lib.mk
> +TEST_GEN_PROGS := $(OUTPUT)/seccomp_bpf $(OUTPUT)/seccomp_benchmark
>
> -seccomp_bpf: seccomp_bpf.c ../kselftest_harness.h
> - $(CC) $(CFLAGS) $(LDFLAGS) $< -lpthread -o $@
> +$(TEST_GEN_PROGS): ../kselftest_harness.h
>
> -TEST_PROGS += $(BINARIES)
> -EXTRA_CLEAN := $(BINARIES)
> +all: $(TEST_GEN_PROGS)

And isn't this one too?

I think if those are removed it should all still work? Regardless:

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

>
> -all: $(BINARIES)
> --
> 2.20.1
>

--
Kees Cook