parisc: Fix double-word compare and exchange in LWS code on 32-bit kernels

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commit 374b3bf8e8 upstream.

As discussed on the debian-hppa list, double-wordcompare and exchange
operations fail on 32-bit kernels.  Looking at the code, I realized that
the ",ma" completer does the wrong thing in the  "ldw,ma  4(%r26), %r29"
instruction.  This increments %r26 and causes the following store to
write to the wrong location.

Note by Helge Deller:
The patch applies cleanly to stable kernel series if this upstream
commit is merged in advance:
f4125cfdb3 ("parisc: Avoid trashing sr2 and sr3 in LWS code").

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Tested-by: Christoph Biedl <debian.axhn@manchmal.in-ulm.de>
Fixes: 8920649120 ("parisc: Implement new LWS CAS supporting 64 bit operations.")
Signed-off-by: Helge Deller <deller@gmx.de>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

...

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John David Anglin 2017-09-30 17:24:23 -04:00 • committed by Ben Hutchings

parent 30fe79f817

commit 83527ee6a7

1 changed files with 3 additions and 3 deletions

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arch/parisc/kernel/syscall.S

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