From: Al Viro <viro@zeniv.linux.org.uk>
Date: Thu, 2 Aug 2012 07:49:43 +0000 (+0400)
Subject: arm: optimized current_pt_regs()
X-Git-Tag: v3.7-rc1~64^2~11
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bfd170d56505bf21cb636b0f1f169eaa815bdfe4;p=pandora-kernel.git

arm: optimized current_pt_regs()

... no need to read current_thread_info()->task only to
feed it to task_thread_page() immediately afterwards.
Moreover, not using current_thread_info() at all ends
up with better assembler - we need a location very close
to the top of kernel stack page and it's actually better
to do or with 0x1fff, followed be subtracting a small
constant than and with ~0x1fff, followed by adding a large
one.  Both & and | would be a couple of insns (mvn lsr/mvn lsl
for |, a pair of bic for &), but the following addition
would cost a pair of add while the subtraction ends up
as a single sub.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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