From: Arnd Bergmann <arnd@arndb.de>
To: linux-arch <linux-arch@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Vineet Gupta <vgupta@synopsys.com>,
Russell King <linux@armlinux.org.uk>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: [RFC 06/12] asm-generic: unaligned: remove byteshift helpers
Date: Sat, 8 May 2021 13:38:01 +0200 [thread overview]
Message-ID: <CAK8P3a3GP7Wwyes_08nRQ-ESfx2dQr2Ygdz6jpSC1754M2s82A@mail.gmail.com> (raw)
In-Reply-To: <20210507220813.365382-7-arnd@kernel.org>
On Sat, May 8, 2021 at 12:11 AM Arnd Bergmann <arnd@kernel.org> wrote:
>
> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> I've included this patch in the series because Linus asked about
> removing the byteshift version, but after trying it out, I'd
> prefer to drop this and use the byteshift version for the
> generic code as well.
Update: I've tried to create a small test case that illustrates the problem
with using the swab() based version, however all cases combinations
I tried showed either both producing identical output, or the shift
version being worse, see https://godbolt.org/z/bTdsjnjfT
I'll rewrite the patch description accordingly and leave this in place.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: linux-arch <linux-arch@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Vineet Gupta <vgupta@synopsys.com>,
Russell King <linux@armlinux.org.uk>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: [RFC 06/12] asm-generic: unaligned: remove byteshift helpers
Date: Sat, 8 May 2021 13:38:01 +0200 [thread overview]
Message-ID: <CAK8P3a3GP7Wwyes_08nRQ-ESfx2dQr2Ygdz6jpSC1754M2s82A@mail.gmail.com> (raw)
In-Reply-To: <20210507220813.365382-7-arnd@kernel.org>
On Sat, May 8, 2021 at 12:11 AM Arnd Bergmann <arnd@kernel.org> wrote:
>
> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> I've included this patch in the series because Linus asked about
> removing the byteshift version, but after trying it out, I'd
> prefer to drop this and use the byteshift version for the
> generic code as well.
Update: I've tried to create a small test case that illustrates the problem
with using the swab() based version, however all cases combinations
I tried showed either both producing identical output, or the shift
version being worse, see https://godbolt.org/z/bTdsjnjfT
I'll rewrite the patch description accordingly and leave this in place.
Arnd
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next prev parent reply other threads:[~2021-05-08 11:38 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-07 22:07 [RFC 0/12] Unify asm/unaligned.h around struct helper Arnd Bergmann
2021-05-07 22:07 ` [OpenRISC] " Arnd Bergmann
2021-05-07 22:07 ` Arnd Bergmann
2021-05-07 22:07 ` Arnd Bergmann
2021-05-07 22:07 ` [RFC 01/12] asm-generic: use asm-generic/unaligned.h for most architectures Arnd Bergmann
2021-05-07 22:07 ` Arnd Bergmann
2021-05-07 22:07 ` Arnd Bergmann
2021-05-07 23:02 ` Thomas Gleixner
2021-05-07 23:02 ` Thomas Gleixner
2021-05-07 23:02 ` Thomas Gleixner
2021-05-10 10:16 ` Geert Uytterhoeven
2021-05-10 10:16 ` Geert Uytterhoeven
2021-05-10 10:16 ` Geert Uytterhoeven
2021-05-10 13:12 ` Arnd Bergmann
2021-05-10 13:12 ` Arnd Bergmann
2021-05-10 13:12 ` Arnd Bergmann
2021-05-07 22:07 ` [RFC 02/12] openrisc: always use unaligned-struct header Arnd Bergmann
2021-05-07 22:07 ` [OpenRISC] " Arnd Bergmann
2021-05-07 23:02 ` Stafford Horne
2021-05-07 23:02 ` [OpenRISC] " Stafford Horne
2021-05-08 11:42 ` David Laight
2021-05-08 11:42 ` [OpenRISC] " David Laight
2021-05-07 22:07 ` [RFC 03/12] sh: remove unaligned access for sh4a Arnd Bergmann
2021-05-10 21:11 ` Rob Landley
2021-05-07 22:07 ` [RFC 04/12] m68k: select CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS Arnd Bergmann
2021-05-10 10:18 ` Geert Uytterhoeven
2021-05-07 22:07 ` [RFC 05/12] powerpc: use linux/unaligned/le_struct.h on LE power7 Arnd Bergmann
2021-05-07 22:07 ` Arnd Bergmann
2021-05-07 22:07 ` [RFC 06/12] asm-generic: unaligned: remove byteshift helpers Arnd Bergmann
2021-05-07 22:07 ` Arnd Bergmann
2021-05-08 11:38 ` Arnd Bergmann [this message]
2021-05-08 11:38 ` Arnd Bergmann
2021-05-07 22:07 ` [RFC 07/12] asm-generic: unaligned always use struct helpers Arnd Bergmann
2021-05-07 22:07 ` Arnd Bergmann
2021-05-07 22:07 ` [RFC 08/12] partitions: msdos: fix one-byte get_unaligned() Arnd Bergmann
2021-05-07 22:07 ` [RFC 09/12] apparmor: use get_unaligned() only for multi-byte words Arnd Bergmann
2021-05-10 8:17 ` John Johansen
2021-05-07 22:07 ` [RFC 10/12] mwifiex: re-fix for unaligned accesses Arnd Bergmann
2021-05-07 22:07 ` [RFC 11/12] netpoll: avoid put_unaligned() on single character Arnd Bergmann
2021-05-07 22:07 ` [RFC 12/12] asm-generic: simplify asm/unaligned.h Arnd Bergmann
2021-05-07 23:54 ` Linus Torvalds
2021-05-08 9:28 ` Arnd Bergmann
2021-05-08 15:23 ` Linus Torvalds
2021-05-08 11:03 ` David Laight
2021-05-08 14:18 ` David Laight
2021-05-10 6:39 ` Geert Uytterhoeven
2021-05-07 22:07 ` [RFC 0/12] Unify asm/unaligned.h around struct helper Arnd Bergmann
2021-05-07 22:07 ` [OpenRISC] " Arnd Bergmann
2021-05-07 22:07 ` Arnd Bergmann
2021-05-07 22:07 ` Arnd Bergmann
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