linux-kernel - Re: [PATCH for 5.2 12/12] rseq/selftests: add -no-integrated-as for clang

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Message-ID: <CAKwvOdnbH0+ju5Ny-mB-Z4kC+ALyCJOU4Q8OCLHHjFAQzJqsXA@mail.gmail.com>
Date:   Mon, 29 Apr 2019 10:03:13 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Shuah Khan <shuah@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
        linux-api@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Andy Lutomirski <luto@...capital.net>,
        Dave Watson <davejwatson@...com>, Paul Turner <pjt@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Russell King <linux@....linux.org.uk>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Andi Kleen <andi@...stfloor.org>, Chris Lameter <cl@...ux.com>,
        Ben Maurer <bmaurer@...com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Josh Triplett <josh@...htriplett.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Joel Fernandes <joelaf@...gle.com>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH for 5.2 12/12] rseq/selftests: add -no-integrated-as for clang

On Mon, Apr 29, 2019 at 8:29 AM Mathieu Desnoyers
<mathieu.desnoyers@...icios.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@...icios.com>
> CC: Nick Desaulniers <ndesaulniers@...gle.com>
> CC: Thomas Gleixner <tglx@...utronix.de>
> CC: Joel Fernandes <joelaf@...gle.com>
> CC: Peter Zijlstra <peterz@...radead.org>
> CC: Catalin Marinas <catalin.marinas@....com>
> CC: Dave Watson <davejwatson@...com>
> CC: Will Deacon <will.deacon@....com>
> CC: Shuah Khan <shuah@...nel.org>
> CC: Andi Kleen <andi@...stfloor.org>
> CC: linux-kselftest@...r.kernel.org
> CC: "H . Peter Anvin" <hpa@...or.com>
> CC: Chris Lameter <cl@...ux.com>
> CC: Russell King <linux@....linux.org.uk>
> CC: Michael Kerrisk <mtk.manpages@...il.com>
> CC: "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>
> CC: Paul Turner <pjt@...gle.com>
> CC: Boqun Feng <boqun.feng@...il.com>
> CC: Josh Triplett <josh@...htriplett.org>
> CC: Steven Rostedt <rostedt@...dmis.org>
> CC: Ben Maurer <bmaurer@...com>
> CC: linux-api@...r.kernel.org
> CC: Andy Lutomirski <luto@...capital.net>
> CC: Andrew Morton <akpm@...ux-foundation.org>
> CC: Linus Torvalds <torvalds@...ux-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.

If not, maybe the test for CONFIG_CC_IS_CLANG is cleaner?

Thanks for the patch, and helping test asm goto in Clang!
-- 
Thanks,
~Nick Desaulniers