----- On Apr 29, 2019, at 1:03 PM, ndesaulniers ndesaulniers@google.com wrote:

On Mon, Apr 29, 2019 at 8:29 AM Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:

...

Ongoing work for asm goto support from clang requires the -no-integrated-as compiler flag.

This compiler flag is present in the toplevel kernel Makefile, but is not replicated for selftests. Add it specifically for the rseq selftest which requires asm goto.

Link: https://reviews.llvm.org/D56571 Signed-off-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com CC: Nick Desaulniers ndesaulniers@google.com CC: Thomas Gleixner tglx@linutronix.de CC: Joel Fernandes joelaf@google.com CC: Peter Zijlstra peterz@infradead.org CC: Catalin Marinas catalin.marinas@arm.com CC: Dave Watson davejwatson@fb.com CC: Will Deacon will.deacon@arm.com CC: Shuah Khan shuah@kernel.org CC: Andi Kleen andi@firstfloor.org CC: linux-kselftest@vger.kernel.org CC: "H . Peter Anvin" hpa@zytor.com CC: Chris Lameter cl@linux.com CC: Russell King linux@arm.linux.org.uk CC: Michael Kerrisk mtk.manpages@gmail.com CC: "Paul E . McKenney" paulmck@linux.vnet.ibm.com CC: Paul Turner pjt@google.com CC: Boqun Feng boqun.feng@gmail.com CC: Josh Triplett josh@joshtriplett.org CC: Steven Rostedt rostedt@goodmis.org CC: Ben Maurer bmaurer@fb.com CC: linux-api@vger.kernel.org CC: Andy Lutomirski luto@amacapital.net CC: Andrew Morton akpm@linux-foundation.org CC: Linus Torvalds torvalds@linux-foundation.org

---

tools/testing/selftests/rseq/Makefile | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/rseq/Makefile b/tools/testing/selftests/rseq/Makefile index c30c52e1d0d2..d6469535630a 100644 --- a/tools/testing/selftests/rseq/Makefile +++ b/tools/testing/selftests/rseq/Makefile @@ -1,5 +1,11 @@ # SPDX-License-Identifier: GPL-2.0+ OR MIT -CFLAGS += -O2 -Wall -g -I./ -I../../../../usr/include/ -L./ -Wl,-rpath=./

+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=./ \

•     $(CLANG_FLAGS)
  

The top level Makefile exports $(CLANG_FLAGS), which should contain `-no-integrated-as`. Is that available here? If so, then you can just add `$(CLANG_FLAGS)`, no compiler check needed.

AFAIU, the makefiles under tools/testing/selftests all end up including tools/testing/selftests/lib.mk, which states:

"# This mimics the top-level Makefile. We do it explicitly here so that this # Makefile can operate with or without the kbuild infrastructure."

So I don't think it's using any of the definitions from the toplevel Makefile.

If not, maybe the test for CONFIG_CC_IS_CLANG is cleaner?

A quick test indicates that the toplevel CONFIG_* definitions are unavailable from the kernel selftests makefiles.

Thanks for the patch, and helping test asm goto in Clang!

You're very welcome! Considering that I intend to have rseq widely adopted in user-space, it's only natural to consider that its user-space side needs to be compiled by clang as well.

Thanks,

Mathieu