From: Anton Blanchard <anton@samba.org>
Date: Thu, 5 Apr 2012 03:44:48 +0000 (+0000)
Subject: powerpc: Better scheduling of CR save code in system call path
X-Git-Tag: v3.5-rc1~132^2~54
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fd6c40f3b00a1e76d6a920cb6591907c53450afc;p=pandora-kernel.git

powerpc: Better scheduling of CR save code in system call path

At the moment system call entry looks like:

crclr	so
...
mfcr	r9
...
std	r9,_CCR(r1)

commit bd19c8994a82 ([POWERPC] system call micro optimisation) put
some space between the crclr and mfcr in order to avoid a stall.

There is still a stall seen between the mfcr and std. We can avoid
the crclr by doing it in a GPR with rlwinm which gives us more room
to better schedule the sequence.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

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