tree 9f0ae1913e0e637ec3aa104cc5e81557e5661b3c
parent 379070491e1e744a59e69e5bcf3765012d15ecb4
author Dave Kleikamp <shaggy@linux.vnet.ibm.com> 1215440934 +1000
committer Benjamin Herrenschmidt <benh@kernel.crashing.org> 1215585045 +1000

powerpc/mm: Add Strong Access Ordering support

Allow an application to enable Strong Access Ordering on specific pages of
memory on Power 7 hardware. Currently, power has a weaker memory model than
x86. Implementing a stronger memory model allows an emulator to more
efficiently translate x86 code into power code, resulting in faster code
execution.

On Power 7 hardware, storing 0b1110 in the WIMG bits of the hpte enables
strong access ordering mode for the memory page.  This patchset allows a
user to specify which pages are thus enabled by passing a new protection
bit through mmap() and mprotect().  I have defined PROT_SAO to be 0x10.

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>