From: Nathan Chancellor <nathan@kernel.org>
To: Russell King <linux@armlinux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>, Ard Biesheuvel <ardb@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
patches@lists.linux.dev, Nathan Chancellor <nathan@kernel.org>,
"kernelci.org bot" <bot@kernelci.org>,
Nick Desaulniers <ndesaulniers@google.com>
Subject: [PATCH v2] ARM: Drop '-mthumb' from AFLAGS_ISA
Date: Thu, 17 Nov 2022 17:30:58 -0700 [thread overview]
Message-ID: <20221118003057.3223394-1-nathan@kernel.org> (raw)
When building with CONFIG_THUMB2_KERNEL=y + a version of clang from
Debian using CROSS_COMPILE=arm-linux-gnueabihf-, the following warning
occurs frequently:
<built-in>:383:9: warning: '__thumb2__' macro redefined [-Wmacro-redefined]
#define __thumb2__ 2
^
<built-in>:353:9: note: previous definition is here
#define __thumb2__ 1
^
1 warning generated.
Debian carries a downstream patch that changes the default CPU of the
arm-linux-gnueabihf target from 'arm1176jzf-s' (v6) to 'cortex-a7' (v7).
As a result, '-mthumb' defines both '__thumb__' and '__thumb2__'. The
define of '__thumb2__' via the command line was purposefully added to
catch a situation like this.
In a similar vein as commit 26b12e084bce ("ARM: 9264/1: only use
-mtp=cp15 for the compiler"), do not add '-mthumb' to AFLAGS_ISA, as it
is already passed to the assembler via '-Wa,-mthumb' and '__thumb2__' is
already defined for preprocessing.
Fixes: 1d2e9b67b001 ("ARM: 9265/1: pass -march= only to compiler")
Link: https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/raw/622dbcbd40b316ed3905a2d25d9623544a06e6b1/debian/patches/930008-arm.diff
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
v2:
* Add Nick's review and test tags.
* Call out explicitly that CROSS_COMPILE=arm-linux-gnueabihf- is
needed to reproduce this issue in commit message (Nick).
* Fix dead link in commit message (Nick).
* Use the snapshot branch for the patch link, as the diff is more up
to date against upstream LLVM (Nick).
v1: https://lore.kernel.org/20221114225719.1657174-1-nathan@kernel.org/
arch/arm/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 357f0d9b8607..d1ebb746ff40 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -131,8 +131,9 @@ endif
AFLAGS_NOWARN :=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W)
ifeq ($(CONFIG_THUMB2_KERNEL),y)
-CFLAGS_ISA :=-mthumb -Wa,-mimplicit-it=always $(AFLAGS_NOWARN)
+CFLAGS_ISA :=-Wa,-mimplicit-it=always $(AFLAGS_NOWARN)
AFLAGS_ISA :=$(CFLAGS_ISA) -Wa$(comma)-mthumb -D__thumb2__=2
+CFLAGS_ISA +=-mthumb
else
CFLAGS_ISA :=$(call cc-option,-marm,) $(AFLAGS_NOWARN)
AFLAGS_ISA :=$(CFLAGS_ISA)
base-commit: 0c52591d22e99759da3793f19249bbf45ad742bd
--
2.38.1
WARNING: multiple messages have this Message-ID (diff)
From: Nathan Chancellor <nathan@kernel.org>
To: Russell King <linux@armlinux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>, Ard Biesheuvel <ardb@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
patches@lists.linux.dev, Nathan Chancellor <nathan@kernel.org>,
"kernelci.org bot" <bot@kernelci.org>,
Nick Desaulniers <ndesaulniers@google.com>
Subject: [PATCH v2] ARM: Drop '-mthumb' from AFLAGS_ISA
Date: Thu, 17 Nov 2022 17:30:58 -0700 [thread overview]
Message-ID: <20221118003057.3223394-1-nathan@kernel.org> (raw)
When building with CONFIG_THUMB2_KERNEL=y + a version of clang from
Debian using CROSS_COMPILE=arm-linux-gnueabihf-, the following warning
occurs frequently:
<built-in>:383:9: warning: '__thumb2__' macro redefined [-Wmacro-redefined]
#define __thumb2__ 2
^
<built-in>:353:9: note: previous definition is here
#define __thumb2__ 1
^
1 warning generated.
Debian carries a downstream patch that changes the default CPU of the
arm-linux-gnueabihf target from 'arm1176jzf-s' (v6) to 'cortex-a7' (v7).
As a result, '-mthumb' defines both '__thumb__' and '__thumb2__'. The
define of '__thumb2__' via the command line was purposefully added to
catch a situation like this.
In a similar vein as commit 26b12e084bce ("ARM: 9264/1: only use
-mtp=cp15 for the compiler"), do not add '-mthumb' to AFLAGS_ISA, as it
is already passed to the assembler via '-Wa,-mthumb' and '__thumb2__' is
already defined for preprocessing.
Fixes: 1d2e9b67b001 ("ARM: 9265/1: pass -march= only to compiler")
Link: https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/raw/622dbcbd40b316ed3905a2d25d9623544a06e6b1/debian/patches/930008-arm.diff
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
v2:
* Add Nick's review and test tags.
* Call out explicitly that CROSS_COMPILE=arm-linux-gnueabihf- is
needed to reproduce this issue in commit message (Nick).
* Fix dead link in commit message (Nick).
* Use the snapshot branch for the patch link, as the diff is more up
to date against upstream LLVM (Nick).
v1: https://lore.kernel.org/20221114225719.1657174-1-nathan@kernel.org/
arch/arm/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 357f0d9b8607..d1ebb746ff40 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -131,8 +131,9 @@ endif
AFLAGS_NOWARN :=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W)
ifeq ($(CONFIG_THUMB2_KERNEL),y)
-CFLAGS_ISA :=-mthumb -Wa,-mimplicit-it=always $(AFLAGS_NOWARN)
+CFLAGS_ISA :=-Wa,-mimplicit-it=always $(AFLAGS_NOWARN)
AFLAGS_ISA :=$(CFLAGS_ISA) -Wa$(comma)-mthumb -D__thumb2__=2
+CFLAGS_ISA +=-mthumb
else
CFLAGS_ISA :=$(call cc-option,-marm,) $(AFLAGS_NOWARN)
AFLAGS_ISA :=$(CFLAGS_ISA)
base-commit: 0c52591d22e99759da3793f19249bbf45ad742bd
--
2.38.1
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next reply other threads:[~2022-11-18 0:34 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-18 0:30 Nathan Chancellor [this message]
2022-11-18 0:30 ` [PATCH v2] ARM: Drop '-mthumb' from AFLAGS_ISA Nathan Chancellor
2022-11-18 8:23 ` Ard Biesheuvel
2022-11-18 8:23 ` Ard Biesheuvel
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