[POWERPC] Avoid unpaired stwcx. on some processors

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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>

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Becky Bruce 2007-11-10 09:17:49 +11:00 • committed by Paul Mackerras

parent 64c911a3f7

commit b64f87c16f

3 changed files with 24 additions and 10 deletions

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6

arch/powerpc/kernel/entry_32.S

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6

arch/ppc/kernel/entry.S

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22

include/asm-powerpc/cputable.h

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