From: "Krzysztof Hałasa" <khalasa@piap.pl>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: Data corruption on i.MX6 IPU in arm_copy_from_user()
Date: Wed, 26 May 2021 14:29:07 +0200 [thread overview]
Message-ID: <m3r1htu19o.fsf@t19.piap.pl> (raw)
In-Reply-To: <20210526100843.GD30436@shell.armlinux.org.uk> (Russell King's message of "Wed, 26 May 2021 11:08:44 +0100")
"Russell King (Oracle)" <linux@armlinux.org.uk> writes:
> Surely someone is not using copy_*_user() to copy data from userspace
> direct to MMIO space... that would be crazy.
No, it's the other way around: reading MMIO mapped to userspace (mmap
on /dev/mem) and copying it to simple kernel buffer (e.g. pipe buffer).
I.e., the MMIO is the userspace here (thus copy_from_user()).
--
Krzysztof Hałasa
Sieć Badawcza Łukasiewicz
Przemysłowy Instytut Automatyki i Pomiarów PIAP
Al. Jerozolimskie 202, 02-486 Warszawa
WARNING: multiple messages have this Message-ID (diff)
From: "Krzysztof Hałasa" <khalasa@piap.pl>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: Data corruption on i.MX6 IPU in arm_copy_from_user()
Date: Wed, 26 May 2021 14:29:07 +0200 [thread overview]
Message-ID: <m3r1htu19o.fsf@t19.piap.pl> (raw)
In-Reply-To: <20210526100843.GD30436@shell.armlinux.org.uk> (Russell King's message of "Wed, 26 May 2021 11:08:44 +0100")
"Russell King (Oracle)" <linux@armlinux.org.uk> writes:
> Surely someone is not using copy_*_user() to copy data from userspace
> direct to MMIO space... that would be crazy.
No, it's the other way around: reading MMIO mapped to userspace (mmap
on /dev/mem) and copying it to simple kernel buffer (e.g. pipe buffer).
I.e., the MMIO is the userspace here (thus copy_from_user()).
--
Krzysztof Hałasa
Sieć Badawcza Łukasiewicz
Przemysłowy Instytut Automatyki i Pomiarów PIAP
Al. Jerozolimskie 202, 02-486 Warszawa
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next prev parent reply other threads:[~2021-05-26 12:29 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-26 8:26 Data corruption on i.MX6 IPU in arm_copy_from_user() Krzysztof Hałasa
2021-05-26 8:26 ` Krzysztof Hałasa
2021-05-26 10:08 ` Russell King (Oracle)
2021-05-26 10:08 ` Russell King (Oracle)
2021-05-26 12:29 ` Krzysztof Hałasa [this message]
2021-05-26 12:29 ` Krzysztof Hałasa
2021-05-26 13:18 ` Russell King (Oracle)
2021-05-26 13:18 ` Russell King (Oracle)
2021-05-27 14:06 ` David Laight
2021-05-27 14:06 ` David Laight
2021-05-28 10:02 ` Krzysztof Hałasa
2021-05-28 10:02 ` Krzysztof Hałasa
2021-05-28 14:35 ` Russell King (Oracle)
2021-05-28 14:35 ` Russell King (Oracle)
2021-05-31 4:30 ` Krzysztof Hałasa
2021-05-31 4:30 ` Krzysztof Hałasa
2021-05-31 6:20 ` Krzysztof Hałasa
2021-05-31 6:20 ` Krzysztof Hałasa
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