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powerpc/mm: Add Strong Access Ordering support

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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>
This commit is contained in:
Dave Kleikamp
2008-07-08 00:28:54 +10:00
committed by Benjamin Herrenschmidt
parent 379070491e
commit ef3d3246a0
2 changed files with 33 additions and 0 deletions
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3
arch/powerpc/kernel/syscalls.c
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@@ -143,6 +143,9 @@ static inline unsigned long do_mmap2(unsigned long addr, size_t len,
struct file * file = NULL;
unsigned long ret = -EINVAL;
if (!arch_validate_prot(prot))
goto out;
if (shift) {
if (off & ((1 << shift) - 1))
goto out;