[PATCH] ppc: fix floating point register corruption

[PATCH] ppc: fix floating point register corruption

I recently discovered a bug on PPC which causes the floating point
registers to get corrupted when CONFIG_PREEMPT=y.

The problem occurred while running a multi threaded Java application that
does floating point.  The problem could be reproduced in anywhere from 2 to
6 hours.  With the patch I have included below it ran for over a week
without failure.

Signed-off-by: Paolo Galtieri <pgaltieri@mvista.com>
Cc: Kumar Gala <galak@gate.crashing.org>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Tom Rini <trini@kernel.crashing.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>