linux-kernel - Re: [PATCH] selftests/rseq: Fix out-of-tree compilation

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Message-ID: <763647628.2256.1582215383750.JavaMail.zimbra@efficios.com>
Date:   Thu, 20 Feb 2020 11:16:23 -0500 (EST)
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Shuah Khan <skhan@...uxfoundation.org>
Cc:     linux-kselftest <linux-kselftest@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        paulmck <paulmck@...nel.org>, Boqun Feng <boqun.feng@...il.com>
Subject: Re: [PATCH] selftests/rseq: Fix out-of-tree compilation

----- On Feb 20, 2020, at 6:37 AM, Michael Ellerman mpe@...erman.id.au wrote:

> Currently if you build with O=... the rseq tests don't build:
> 
>  $ make O=$PWD/output -C tools/testing/selftests/ TARGETS=rseq
>  make: Entering directory '/linux/tools/testing/selftests'
>  ...
>  make[1]: Entering directory '/linux/tools/testing/selftests/rseq'
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/ -L./ -Wl,-rpath=./  -shared
>  -fPIC rseq.c -lpthread -o /linux/output/rseq/librseq.so
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/ -L./ -Wl,-rpath=./
>  basic_test.c -lpthread -lrseq -o /linux/output/rseq/basic_test
>  /usr/bin/ld: cannot find -lrseq
>  collect2: error: ld returned 1 exit status
> 
> This is because the library search path points to the source
> directory, not the output.
> 
> We can fix it by changing the library search path to $(OUTPUT).

Good catch!

Acked-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>

Shuah, can you pick this up please ?

Thanks,

Mathieu

> 
> Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
> ---
> 
> This works in all cases.
> 
> With O= set:
> 
>  $ make O=$PWD/output -C tools/testing/selftests/ TARGETS=rseq
>  ...
>  make[1]: Entering directory '/linux/tools/testing/selftests/rseq'
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/ -L/linux/output/rseq
>  -Wl,-rpath=./  basic_test.c -lpthread -lrseq -o /linux/output/rseq/basic_test
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/ -L/linux/output/rseq
>  -Wl,-rpath=./  basic_percpu_ops_test.c -lpthread -lrseq -o
>  /linux/output/rseq/basic_percpu_ops_test
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/ -L/linux/output/rseq
>  -Wl,-rpath=./  param_test.c -lpthread -lrseq -o /linux/output/rseq/param_test
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/ -L/linux/output/rseq
>  -Wl,-rpath=./  -DBENCHMARK param_test.c -lpthread -lrseq -o
>  /linux/output/rseq/param_test_benchmark
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/ -L/linux/output/rseq
>  -Wl,-rpath=./  -DRSEQ_COMPARE_TWICE param_test.c -lpthread -lrseq -o
>  /linux/output/rseq/param_test_compare_twice
>  make[1]: Leaving directory '/linux/tools/testing/selftests/rseq'
>  make: Leaving directory '/linux/tools/testing/selftests'
> 
> And also without, in which case the selftest makefiles set OUTPUT to
> the full path of the source directory:
> 
>  $ make -C tools/testing/selftests/ TARGETS=rseq
>  ...
>  make[1]: Entering directory '/linux/tools/testing/selftests/rseq'
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  -shared -fPIC rseq.c
>  -lpthread -o /linux/tools/testing/selftests/rseq/librseq.so
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  basic_test.c -lpthread
>  -lrseq -o /linux/tools/testing/selftests/rseq/basic_test
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  basic_percpu_ops_test.c
>  -lpthread -lrseq -o /linux/tools/testing/selftests/rseq/basic_percpu_ops_test
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  param_test.c -lpthread
>  -lrseq -o /linux/tools/testing/selftests/rseq/param_test
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  -DBENCHMARK param_test.c
>  -lpthread -lrseq -o /linux/tools/testing/selftests/rseq/param_test_benchmark
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  -DRSEQ_COMPARE_TWICE
>  param_test.c -lpthread -lrseq -o
>  /linux/tools/testing/selftests/rseq/param_test_compare_twice
>  make[1]: Leaving directory '/linux/tools/testing/selftests/rseq'
>  make: Leaving directory '/linux/tools/testing/selftests'
> 
> And finally, it also works if you build directly in the rseq
> directory, eg:
> 
>  $ cd tools/testing/selftests/rseq
>  $ make
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  -shared -fPIC rseq.c
>  -lpthread -o /linux/tools/testing/selftests/rseq/librseq.so
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  basic_test.c -lpthread
>  -lrseq -o /linux/tools/testing/selftests/rseq/basic_test
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  basic_percpu_ops_test.c
>  -lpthread -lrseq -o /linux/tools/testing/selftests/rseq/basic_percpu_ops_test
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  param_test.c -lpthread
>  -lrseq -o /linux/tools/testing/selftests/rseq/param_test
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  -DBENCHMARK param_test.c
>  -lpthread -lrseq -o /linux/tools/testing/selftests/rseq/param_test_benchmark
>  gcc -O2 -Wall -g -I./ -I../../../../usr/include/
>  -L/linux/tools/testing/selftests/rseq -Wl,-rpath=./  -DRSEQ_COMPARE_TWICE
>  param_test.c -lpthread -lrseq -o
>  /linux/tools/testing/selftests/rseq/param_test_compare_twice
> ---
> tools/testing/selftests/rseq/Makefile | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/rseq/Makefile
> b/tools/testing/selftests/rseq/Makefile
> index d6469535630a..708c1b345245 100644
> --- a/tools/testing/selftests/rseq/Makefile
> +++ b/tools/testing/selftests/rseq/Makefile
> @@ -4,7 +4,7 @@ ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
> CLANG_FLAGS += -no-integrated-as
> endif
> 
> -CFLAGS += -O2 -Wall -g -I./ -I../../../../usr/include/ -L./ -Wl,-rpath=./ \
> +CFLAGS += -O2 -Wall -g -I./ -I../../../../usr/include/ -L$(OUTPUT)
> -Wl,-rpath=./ \
> 	  $(CLANG_FLAGS)
> LDLIBS += -lpthread
> 
> 
> base-commit: 11a48a5a18c63fd7621bb050228cebf13566e4d8
> --
> 2.21.1

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com