linux

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John David Anglin 76d794a5ac parisc: Purge TLB before setting PTE 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>	History 2017-02-23 03:54:43 +00:00
..
asm	parisc: Purge TLB before setting PTE	2017-02-23 03:54:43 +00:00
uapi/asm	parisc: Fix order of EREFUSED define in errno.h	2016-11-20 01:17:14 +00:00

John David Anglin 76d794a5ac parisc: Purge TLB before setting PTE

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>

History

2017-02-23 03:54:43 +00:00

asm parisc: Purge TLB before setting PTE 2017-02-23 03:54:43 +00:00

uapi/asm parisc: Fix order of EREFUSED define in errno.h 2016-11-20 01:17:14 +00:00