From: David Laight <david.laight.linux@gmail.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Thomas Weißschuh" <thomas.weissschuh@linutronix.de>,
"Russell King" <linux@armlinux.org.uk>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Russell King" <rmk+kernel@armlinux.org.uk>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, "Arnd Bergmann" <arnd@arndb.de>,
stable@vger.kernel.org
Subject: Re: [PATCH] ARM: fix memset64() on big-endian
Date: Fri, 2 Jan 2026 23:05:33 +0000 [thread overview]
Message-ID: <20260102230533.4fb1d8ef@pumpkin> (raw)
In-Reply-To: <aVfirJvsYt0-jDRD@casper.infradead.org>
On Fri, 2 Jan 2026 15:22:20 +0000
Matthew Wilcox <willy@infradead.org> wrote:
> On Fri, Jan 02, 2026 at 08:15:46AM +0100, Thomas Weißschuh wrote:
> > On big-endian systems the 32-bit low and high halves need to be swapped,
> > for the underlying assembly implemenation to work correctly.
>
> Heh. In my heart, ARM will always be a litte-endian architecture.
> I'm not really surprised this bug took, er, 8 years to show up; big-endian
> arm is rare enough and memset64() isn't much used on 32-bit systems.
> And it turns out that many of the users pass a constant 0 as the value,
> which was kind of not the point, but it seems to be an easier API to
> use than memset, so whatever ;-)
I'd have thought that part of the point of memset64() was to remove
all the 'alignment' and 'tail handling' that a normal memset() has.
Clearly someone thought otherwise :-)
David
>
> > Fixes: fd1d362600e2 ("ARM: implement memset32 & memset64")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
>
> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
>
prev parent reply other threads:[~2026-01-02 23:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-02 7:15 [PATCH] ARM: fix memset64() on big-endian Thomas Weißschuh
2026-01-02 9:24 ` Arnd Bergmann
2026-01-02 9:34 ` Thomas Weißschuh
2026-01-02 15:22 ` Matthew Wilcox
2026-01-02 23:05 ` David Laight [this message]
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