tree 1e0c63707b73c4b2f316a01b2e3c6ebd82c6356a
parent 64c911a3f7c9864a4bbddbb77b722d5553ddcd32
author Becky Bruce <becky.bruce@freescale.com> 1194646669 +1100
committer Paul Mackerras <paulus@samba.org> 1194931363 +1100

[POWERPC] Avoid unpaired stwcx. on some processors

The context switch code in the kernel issues a dummy stwcx. to clear the
reservation, as recommended by the architecture.  However, some processors
can have issues if this stwcx to address A occurs while the reservation
is already held to a different address B.  To avoid this problem, the dummy
stwcx. needs to be paired with a dummy lwarx to the same address.

This adds the dummy lwarx, and creates a cpu feature bit to indicate
which cpus are affected.  Tested on mpc8641_hpcn_defconfig in
arch/powerpc; build tested in arch/ppc.

Signed-off-by: Becky Bruce <becky.bruce@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>