parisc: Purge TLB before setting PTE

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commit c78e710c1c upstream.

The attached change interchanges the order of purging the TLB and
setting the corresponding page table entry.  TLB purges are strongly
ordered.  It occurred to me one night that setting the PTE first might
have subtle ordering issues on SMP machines and cause random memory
corruption.

A TLB lock guards the insertion of user TLB entries.  So after the TLB
is purged, a new entry can't be inserted until the lock is released.
This ensures that the new PTE value is used when the lock is released.

Since making this change, no random segmentation faults have been
observed on the Debian hppa buildd servers.

Signed-off-by: John David Anglin  <dave.anglin@bell.net>
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 2016-12-06 21:47:04 -05:00 • committed by Ben Hutchings

parent a4ab1eeb4f

commit 76d794a5ac

1 changed files with 4 additions and 4 deletions

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arch/parisc/include/asm/pgtable.h

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