From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: Add PI/robust mutexes support for SMP kernels
Date: Mon, 7 Jun 2010 20:44:57 +0100 [thread overview]
Message-ID: <20100607194457.GC7220@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20100607173630.GA10489@oksana.dev.rtsoft.ru>
On Mon, Jun 07, 2010 at 09:36:30PM +0400, Anton Vorontsov wrote:
> To support PI or robust mutexes, the kernel needs to perform some
> operations atomically on userspace addresses, and yet ARM lacked
> the support for the SMP case.
>
> ARMv6 adds exclusive access variants of ldr and str instructions,
> which means that support for PI/robust mutexes should now be
> relatively straightforward.
It isn't this straight forward. You're now bypassing the MMU protections
in that 'strex' can bypass the read-only protection of the user page.
This can result in the zero BSS page being corrupted, or worse corruption
to page cache pages.
next prev parent reply other threads:[~2010-06-07 19:44 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-07 17:36 [PATCH] ARM: Add PI/robust mutexes support for SMP kernels Anton Vorontsov
2010-06-07 19:44 ` Russell King - ARM Linux [this message]
2010-06-07 20:27 ` Anton Vorontsov
2010-06-07 20:40 ` Nicolas Pitre
2010-06-07 21:35 ` Anton Vorontsov
2010-06-08 10:14 ` Catalin Marinas
2010-06-07 21:05 ` Catalin Marinas
2010-06-07 21:52 ` Russell King - ARM Linux
2010-06-08 10:04 ` Catalin Marinas
2010-06-08 10:26 ` Russell King - ARM Linux
2010-06-08 10:42 ` Catalin Marinas
2010-06-07 20:56 ` Catalin Marinas
2010-06-07 21:31 ` Anton Vorontsov
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