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From: Nathan Chancellor <nathan@kernel.org>
To: Nick Desaulniers <ndesaulniers@google.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Joe Perches <joe@perches.com>, Arnd Bergmann <arnd@kernel.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	llvm@lists.linux.dev, linux-kernel@vger.kernel.org,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Segher Boessenkool <segher@kernel.crashing.org>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 06/10] powerpc: remove GCC version check for UPD_CONSTR
Date: Fri, 10 Sep 2021 16:48:20 -0700	[thread overview]
Message-ID: <b940bd2c-21d2-dfe9-e171-e265085a2b11@kernel.org> (raw)
In-Reply-To: <20210910234047.1019925-7-ndesaulniers@google.com>

On 9/10/2021 4:40 PM, Nick Desaulniers wrote:
> Now that GCC 5.1 is the minimum supported version, we can drop this
> workaround for older versions of GCC. This adversely affected clang,
> too.
> 
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Segher Boessenkool <segher@kernel.crashing.org>
> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
>   arch/powerpc/include/asm/asm-const.h | 10 ----------
>   1 file changed, 10 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/asm-const.h b/arch/powerpc/include/asm/asm-const.h
> index 0ce2368bd20f..dbfa5e1e3198 100644
> --- a/arch/powerpc/include/asm/asm-const.h
> +++ b/arch/powerpc/include/asm/asm-const.h
> @@ -12,16 +12,6 @@
>   #  define ASM_CONST(x)		__ASM_CONST(x)
>   #endif
>   
> -/*
> - * Inline assembly memory constraint
> - *
> - * GCC 4.9 doesn't properly handle pre update memory constraint "m<>"
> - *
> - */
> -#if defined(GCC_VERSION) && GCC_VERSION < 50000
> -#define UPD_CONSTR ""
> -#else
>   #define UPD_CONSTR "<>"
> -#endif

The only reason this exists is because of commit 592bbe9c505d 
("powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9"). It is 
probably just worth sinking "<>" into all of the callsites and removing
UPD_CONSTR.

>   
>   #endif /* _ASM_POWERPC_ASM_CONST_H */
> 

WARNING: multiple messages have this Message-ID (diff)
From: Nathan Chancellor <nathan@kernel.org>
To: Nick Desaulniers <ndesaulniers@google.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
	linuxppc-dev@lists.ozlabs.org, Arnd Bergmann <arnd@kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	llvm@lists.linux.dev, Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
	Joe Perches <joe@perches.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 06/10] powerpc: remove GCC version check for UPD_CONSTR
Date: Fri, 10 Sep 2021 16:48:20 -0700	[thread overview]
Message-ID: <b940bd2c-21d2-dfe9-e171-e265085a2b11@kernel.org> (raw)
In-Reply-To: <20210910234047.1019925-7-ndesaulniers@google.com>

On 9/10/2021 4:40 PM, Nick Desaulniers wrote:
> Now that GCC 5.1 is the minimum supported version, we can drop this
> workaround for older versions of GCC. This adversely affected clang,
> too.
> 
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Segher Boessenkool <segher@kernel.crashing.org>
> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
>   arch/powerpc/include/asm/asm-const.h | 10 ----------
>   1 file changed, 10 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/asm-const.h b/arch/powerpc/include/asm/asm-const.h
> index 0ce2368bd20f..dbfa5e1e3198 100644
> --- a/arch/powerpc/include/asm/asm-const.h
> +++ b/arch/powerpc/include/asm/asm-const.h
> @@ -12,16 +12,6 @@
>   #  define ASM_CONST(x)		__ASM_CONST(x)
>   #endif
>   
> -/*
> - * Inline assembly memory constraint
> - *
> - * GCC 4.9 doesn't properly handle pre update memory constraint "m<>"
> - *
> - */
> -#if defined(GCC_VERSION) && GCC_VERSION < 50000
> -#define UPD_CONSTR ""
> -#else
>   #define UPD_CONSTR "<>"
> -#endif

The only reason this exists is because of commit 592bbe9c505d 
("powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9"). It is 
probably just worth sinking "<>" into all of the callsites and removing
UPD_CONSTR.

>   
>   #endif /* _ASM_POWERPC_ASM_CONST_H */
> 

  reply	other threads:[~2021-09-10 23:48 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-10 23:40 [PATCH 00/10] raise minimum GCC version to 5.1 Nick Desaulniers
2021-09-10 23:40 ` [PATCH 01/10] Documentation: raise minimum supported version of GCC " Nick Desaulniers
2021-09-10 23:55   ` Nathan Chancellor
2021-09-11  0:16     ` Nick Desaulniers
2021-09-13 16:22   ` Kees Cook
2021-09-10 23:40 ` [PATCH 02/10] compiler.h: drop fallback overflow checkers Nick Desaulniers
2021-09-11  0:04   ` Nathan Chancellor
2021-09-14 15:33     ` Nick Desaulniers
2021-09-14 16:04       ` Nathan Chancellor
2021-09-13 16:21   ` Kees Cook
2021-09-10 23:40 ` [PATCH 03/10] mm/ksm: remove old GCC 4.9+ check Nick Desaulniers
2021-09-11  0:07   ` Nathan Chancellor
2021-09-13 16:22   ` Kees Cook
2021-09-10 23:40 ` [PATCH 04/10] Kconfig.debug: drop GCC 5+ version check for DWARF5 Nick Desaulniers
2021-09-11  0:08   ` Nathan Chancellor
2021-09-13 16:23   ` Kees Cook
2021-09-10 23:40 ` [PATCH 05/10] riscv: remove Kconfig check for GCC version for ARCH_RV64I Nick Desaulniers
2021-09-10 23:40   ` Nick Desaulniers
2021-09-11  0:09   ` Nathan Chancellor
2021-09-11  0:09     ` Nathan Chancellor
2021-09-13 16:23   ` Kees Cook
2021-09-13 16:23     ` Kees Cook
2021-10-05  0:40     ` Palmer Dabbelt
2021-10-05  0:40       ` Palmer Dabbelt
2021-10-05  0:50       ` Kees Cook
2021-10-05  0:50         ` Kees Cook
2021-10-05  0:57         ` Palmer Dabbelt
2021-10-05  0:57           ` Palmer Dabbelt
2021-09-10 23:40 ` [PATCH 06/10] powerpc: remove GCC version check for UPD_CONSTR Nick Desaulniers
2021-09-10 23:40   ` Nick Desaulniers
2021-09-10 23:48   ` Nathan Chancellor [this message]
2021-09-10 23:48     ` Nathan Chancellor
2021-09-11 10:43     ` Michael Ellerman
2021-09-11 10:43       ` Michael Ellerman
2021-09-11 15:34   ` Christophe Leroy
2021-09-11 15:34     ` Christophe Leroy
2021-09-10 23:40 ` [PATCH 07/10] arm64: remove GCC version check for ARCH_SUPPORTS_INT128 Nick Desaulniers
2021-09-10 23:40   ` Nick Desaulniers
2021-09-11  0:10   ` Nathan Chancellor
2021-09-11  0:10     ` Nathan Chancellor
2021-09-13 16:25   ` Kees Cook
2021-09-13 16:25     ` Kees Cook
2021-09-16 13:23   ` Catalin Marinas
2021-09-16 13:23     ` Catalin Marinas
2021-09-10 23:40 ` [PATCH 08/10] Makefile: drop GCC < 5 -fno-var-tracking-assignments workaround Nick Desaulniers
2021-09-11  0:11   ` Nathan Chancellor
2021-09-13 16:25   ` Kees Cook
2021-09-10 23:40 ` [PATCH 09/10] compiler-gcc.h: drop checks for older GCC versions Nick Desaulniers
2021-09-11  0:12   ` Nathan Chancellor
2021-09-13 16:26   ` Kees Cook
2021-09-10 23:40 ` [PATCH 10/10] vmlinux.lds.h: remove old check for GCC 4.9 Nick Desaulniers
2021-09-10 23:50   ` Nathan Chancellor
2021-09-14 15:21     ` Nick Desaulniers
2021-09-13 16:28   ` Kees Cook
2021-09-11  2:19 ` [PATCH 00/10] raise minimum GCC version to 5.1 Kees Cook
2021-09-11 10:42   ` Michael Ellerman
2021-09-13  9:49 ` Pavel Machek
2021-09-13 16:20   ` Kees Cook
2021-09-13 11:27 ` Arnd Bergmann

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