ARM: decompressor: avoid speculative prefetch from non-RAM areas

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We setup identity MMU mappings across the entire 4GB of space, which
are permissionless because the domain is set to manager.

This unfortunately allows ARMv6 and later CPUs to speculatively
prefetch from the entire address space, which can cause undesirable
side effects if those regions contain devices.

As we setup the mappings with read/write permission, we can switch
the domain to client mode, and then use the XN bit for ARMv6 and
above to control speculative prefetch to non-RAM areas.

Reported-by: R Sricharan <r.sricharan@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

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Russell King 2012-05-10 09:48:34 +01:00

parent bd0493eaaf

commit 1fdc08abfa

1 changed files with 18 additions and 11 deletions

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arch/arm/boot/compressed/head.S

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