From: Nathan Chancellor <natechancellor@gmail.com>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-kbuild@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Michal Marek <michal.lkml@markovi.net>,
Nick Desaulniers <ndesaulniers@google.com>,
Stephen Boyd <swboyd@chromium.org>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will@kernel.org>,
clang-built-linux@googlegroups.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] kbuild: remove cc-option test of -fno-strict-overflow
Date: Thu, 10 Sep 2020 09:26:17 -0700 [thread overview]
Message-ID: <20200910162617.GA3119896@ubuntu-n2-xlarge-x86> (raw)
In-Reply-To: <20200910135120.3527468-1-masahiroy@kernel.org>
On Thu, Sep 10, 2020 at 10:51:17PM +0900, Masahiro Yamada wrote:
> The minimal compiler versions, GCC 4.9 and Clang 10 support this flag.
>
> Here is the godbolt:
> https://godbolt.org/z/odq8h9
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Appeared in clang 3.0.0 in commit 6e50103acda2b918545f30141edeb991d766f2a4.
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>
> Makefile | 2 +-
> arch/arm64/kernel/vdso32/Makefile | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 4b5a305e30d2..059b36f2ea53 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -922,7 +922,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
> KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized)
>
> # disable invalid "can't wrap" optimizations for signed / pointers
> -KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow)
> +KBUILD_CFLAGS += -fno-strict-overflow
>
> # clang sets -fmerge-all-constants by default as optimization, but this
> # is non-conforming behavior for C and in fact breaks the kernel, so we
> diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
> index d6adb4677c25..dfffd55175a3 100644
> --- a/arch/arm64/kernel/vdso32/Makefile
> +++ b/arch/arm64/kernel/vdso32/Makefile
> @@ -90,7 +90,7 @@ VDSO_CFLAGS += -O2
> # Some useful compiler-dependent flags from top-level Makefile
> VDSO_CFLAGS += $(call cc32-option,-Wdeclaration-after-statement,)
> VDSO_CFLAGS += $(call cc32-option,-Wno-pointer-sign)
> -VDSO_CFLAGS += $(call cc32-option,-fno-strict-overflow)
> +VDSO_CFLAGS += -fno-strict-overflow
> VDSO_CFLAGS += $(call cc32-option,-Werror=strict-prototypes)
> VDSO_CFLAGS += $(call cc32-option,-Werror=date-time)
> VDSO_CFLAGS += $(call cc32-option,-Werror=incompatible-pointer-types)
> --
> 2.25.1
>
WARNING: multiple messages have this Message-ID (diff)
From: Nathan Chancellor <natechancellor@gmail.com>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michal Marek <michal.lkml@markovi.net>,
linux-kbuild@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Nick Desaulniers <ndesaulniers@google.com>,
linux-kernel@vger.kernel.org, Stephen Boyd <swboyd@chromium.org>,
clang-built-linux@googlegroups.com,
Ingo Molnar <mingo@redhat.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/4] kbuild: remove cc-option test of -fno-strict-overflow
Date: Thu, 10 Sep 2020 09:26:17 -0700 [thread overview]
Message-ID: <20200910162617.GA3119896@ubuntu-n2-xlarge-x86> (raw)
In-Reply-To: <20200910135120.3527468-1-masahiroy@kernel.org>
On Thu, Sep 10, 2020 at 10:51:17PM +0900, Masahiro Yamada wrote:
> The minimal compiler versions, GCC 4.9 and Clang 10 support this flag.
>
> Here is the godbolt:
> https://godbolt.org/z/odq8h9
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Appeared in clang 3.0.0 in commit 6e50103acda2b918545f30141edeb991d766f2a4.
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>
> Makefile | 2 +-
> arch/arm64/kernel/vdso32/Makefile | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 4b5a305e30d2..059b36f2ea53 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -922,7 +922,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
> KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized)
>
> # disable invalid "can't wrap" optimizations for signed / pointers
> -KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow)
> +KBUILD_CFLAGS += -fno-strict-overflow
>
> # clang sets -fmerge-all-constants by default as optimization, but this
> # is non-conforming behavior for C and in fact breaks the kernel, so we
> diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
> index d6adb4677c25..dfffd55175a3 100644
> --- a/arch/arm64/kernel/vdso32/Makefile
> +++ b/arch/arm64/kernel/vdso32/Makefile
> @@ -90,7 +90,7 @@ VDSO_CFLAGS += -O2
> # Some useful compiler-dependent flags from top-level Makefile
> VDSO_CFLAGS += $(call cc32-option,-Wdeclaration-after-statement,)
> VDSO_CFLAGS += $(call cc32-option,-Wno-pointer-sign)
> -VDSO_CFLAGS += $(call cc32-option,-fno-strict-overflow)
> +VDSO_CFLAGS += -fno-strict-overflow
> VDSO_CFLAGS += $(call cc32-option,-Werror=strict-prototypes)
> VDSO_CFLAGS += $(call cc32-option,-Werror=date-time)
> VDSO_CFLAGS += $(call cc32-option,-Werror=incompatible-pointer-types)
> --
> 2.25.1
>
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next prev parent reply other threads:[~2020-09-10 16:31 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-10 13:51 [PATCH 1/4] kbuild: remove cc-option test of -fno-strict-overflow Masahiro Yamada
2020-09-10 13:51 ` Masahiro Yamada
2020-09-10 13:51 ` [PATCH 2/4] kbuild: remove cc-option test of -fno-merge-all-constants Masahiro Yamada
2020-09-10 16:33 ` Nathan Chancellor
2020-09-10 16:41 ` Masahiro Yamada
2020-09-10 13:51 ` [PATCH 3/4] kbuild: remove cc-option test of -fno-stack-check Masahiro Yamada
2020-09-10 16:37 ` Nathan Chancellor
2020-09-10 13:51 ` [PATCH 4/4] kbuild: remove cc-option test of -Werror=date-time Masahiro Yamada
2020-09-10 13:51 ` Masahiro Yamada
2020-09-10 16:43 ` Nathan Chancellor
2020-09-10 16:43 ` Nathan Chancellor
2020-09-10 16:26 ` Nathan Chancellor [this message]
2020-09-10 16:26 ` [PATCH 1/4] kbuild: remove cc-option test of -fno-strict-overflow Nathan Chancellor
2020-09-11 15:22 ` Will Deacon
2020-09-11 15:22 ` Will Deacon
2020-09-14 12:51 ` Masahiro Yamada
2020-09-14 12:51 ` Masahiro Yamada
2020-09-14 13:20 ` Will Deacon
2020-09-14 13:20 ` Will Deacon
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