On Mon, 2014-12-15 at 14:25 +0000, Luis Henriques wrote: > 3.16.7-ckt3 -stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Steven Capper <steve.capper@xxxxxxxxxx> > > commit f2950706871c4b6e8c0f0d7c3f62d35930b8de63 upstream. > > Long descriptors on ARM are 64 bits, and some pte functions such as > pte_dirty return a bitwise-and of a flag with the pte value. If the > flag to be tested resides in the upper 32 bits of the pte, then we run > into the danger of the result being dropped if downcast. > > For example: > gather_stats(page, md, pte_dirty(*pte), 1); > where pte_dirty(*pte) is downcast to an int. > > This patch introduces a new macro pte_isset which performs the bitwise > and, then performs a double logical invert (where needed) to ensure > predictable downcasting. The logical inverse pte_isclear is also > introduced. > > Equivalent pmd functions for Transparent HugePages have also been > added. > > Signed-off-by: Steve Capper <steve.capper@xxxxxxxxxx> > Reviewed-by: Will Deacon <will.deacon@xxxxxxx> > Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> > Cc: Hou Pengyang <houpengyang@xxxxxxxxxx> > Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx> [...] This has only been applied to 3.16 so far, but it appears to be suitable for every branch from 3.4 onwards as ARM LPAE was introduced in 3.3. Ben. -- Ben Hutchings The world is coming to an end. Please log off.
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