From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Date: Thu, 5 Jun 2014 08:23:10 +0000 (+0200)
Subject: ARM: make user_addr_max more robust
X-Git-Tag: cleanup-for-v3.18~119^2^2^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=83de911cf897a4317147dd9cb379378c2c4abf4c;p=pandora-kernel.git

ARM: make user_addr_max more robust

With CONFIG_MMU=y get_fs() returns current_thread_info()->addr_limit
which is initialized as USER_DS (which in turn is defined to TASK_SIZE)
for userspace processes. At least theoretically
current_thread_info()->addr_limit is changable by set_fs() to a
different limit, so checking for KERNEL_DS is more robust.

With !CONFIG_MMU get_fs returns KERNEL_DS. To see what the old variant
did you'd have to find out that USER_DS == KERNEL_DS which isn't needed
any more with the variant this patch introduces. So it's a bit easier to
understand, too.

Also if the limit was changed this limit should be returned, not
TASK_SIZE.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
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