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From: Michael Bohan <mbohan@codeaurora.org>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: MT_HIGH_VECTOR mapping set read-only creating illegal access
Date: Tue, 12 Apr 2011 17:42:24 -0700	[thread overview]
Message-ID: <4DA4F170.4020009@codeaurora.org> (raw)

Hi,

In arch/arm/kernel/traps.c:set_tls() and arch/arm/include/asm/tls.h, 
some configurations allow for a assignment of address 0xffff0ff0. This 
address falls within the MT_HIGH_VECTORS mapping setup in 
devicemaps_init(). That mapping is explicitly made read-only. Thus, the 
kernel takes a segfault when writing in set_tls().

It looks like this disparity may have been introduced in this commit:

commit 36bb94ba36f332de767cfaa3af6a5136435a3a9c
Author: Russell King <rmk+kernel@arm.linux.org.uk>
Date:   Tue Nov 16 08:40:36 2010 +0000

     ARM: pgtable: provide RDONLY page table bit rather than WRITE bit

     Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Is there a reason this mapping must be read-only? Perhaps we could apply 
write access for these special cases only?

Thanks,
Mike

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum

WARNING: multiple messages have this Message-ID (diff)
From: mbohan@codeaurora.org (Michael Bohan)
To: linux-arm-kernel@lists.infradead.org
Subject: MT_HIGH_VECTOR mapping set read-only creating illegal access
Date: Tue, 12 Apr 2011 17:42:24 -0700	[thread overview]
Message-ID: <4DA4F170.4020009@codeaurora.org> (raw)

Hi,

In arch/arm/kernel/traps.c:set_tls() and arch/arm/include/asm/tls.h, 
some configurations allow for a assignment of address 0xffff0ff0. This 
address falls within the MT_HIGH_VECTORS mapping setup in 
devicemaps_init(). That mapping is explicitly made read-only. Thus, the 
kernel takes a segfault when writing in set_tls().

It looks like this disparity may have been introduced in this commit:

commit 36bb94ba36f332de767cfaa3af6a5136435a3a9c
Author: Russell King <rmk+kernel@arm.linux.org.uk>
Date:   Tue Nov 16 08:40:36 2010 +0000

     ARM: pgtable: provide RDONLY page table bit rather than WRITE bit

     Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Is there a reason this mapping must be read-only? Perhaps we could apply 
write access for these special cases only?

Thanks,
Mike

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum

             reply	other threads:[~2011-04-13  0:42 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-13  0:42 Michael Bohan [this message]
2011-04-13  0:42 ` MT_HIGH_VECTOR mapping set read-only creating illegal access Michael Bohan
2011-04-13  3:31 ` Nicolas Pitre
2011-04-13  3:31   ` Nicolas Pitre
2011-04-19 22:34   ` Michael Bohan
2011-04-19 22:34     ` Michael Bohan
2011-04-20  0:21     ` Nicolas Pitre
2011-04-20  0:21       ` Nicolas Pitre
2011-04-20  1:44       ` Michael Bohan
2011-04-20  1:44         ` Michael Bohan
2011-04-20  3:01         ` Nicolas Pitre
2011-04-20  3:01           ` Nicolas Pitre
2011-04-20  3:26           ` Colin Cross
2011-04-20  3:26             ` Colin Cross
2011-04-13  7:26 ` Russell King - ARM Linux
2011-04-13  7:26   ` Russell King - ARM Linux

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