[patch 3/6] powerpc: Define flags for Strong Access Ordering

shaggy
2008-06-18T22:32:57Z

This patch defines:

- PROT_SAO, which is passed into mmap() and mprotect() in the prot field
- VM_SAO in vma->vm_flags, and
- _PAGE_SAO, the combination of WIMG bits in the pte that enables strong
access ordering for the page.

NOTE: There doesn't seem to be a precedent for architecture-dependent vm_flags.
It may be better to define VM_SAO somewhere in include/asm-powerpc/. Since
vm_flags is a long, defining it in the high-order word would help prevent a
collision with any newly added values in architecture-independent code.

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
---

include/asm-powerpc/mman.h | 2 ++
include/asm-powerpc/pgtable-ppc64.h | 3 +++
include/linux/mm.h | 1 +
3 files changed, 6 insertions(+)

Index: linux-2.6.26-rc5/include/asm-powerpc/mman.h
===================================================================
--- linux-2.6.26-rc5.orig/include/asm-powerpc/mman.h
+++ linux-2.6.26-rc5/include/asm-powerpc/mman.h
@@ -10,6 +10,8 @@
* 2 of the License, or (at your option) any later version.
*/

+#define PROT_SAO 0x10 /* Strong Access Ordering */
+
#define MAP_RENAME MAP_ANONYMOUS /* In SunOS terminology */
#define MAP_NORESERVE 0x40 /* don't reserve swap pages */
#define MAP_LOCKED 0x80
Index: linux-2.6.26-rc5/include/asm-powerpc/pgtable-ppc64.h
===================================================================
--- linux-2.6.26-rc5.orig/include/asm-powerpc/pgtable-ppc64.h
+++ linux-2.6.26-rc5/include/asm-powerpc/pgtable-ppc64.h
@@ -94,6 +94,9 @@
#define _PAGE_HASHPTE 0x0400 /* software: pte has an associated HPTE */
#define _PAGE_BUSY 0x0800 /* software: PTE & hash are busy */

+/* Strong Access Ordering */
+#define _PAGE_SAO (_PAGE_WRITETHRU | _PAGE_NO_CACHE | _PAGE_COHERENT)
+
#define _PAGE_BASE (_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_COHERENT)

#define _PAGE_WRENABLE (_PAGE_RW | _PAGE_DIRTY)
Index: linux-2.6.26-rc5/include/linux/mm.h
===================================================================
--- linux-2.6.26-rc5.orig/include/linux/mm.h
+++ linux-2.6.26-rc5/include/linux/mm.h
@@ -108,6 +108,7 @@ extern unsigned int kobjsize(const void

#define VM_CAN_NONLINEAR 0x08000000 /* Has ->fault & does nonlinear pages */
#define VM_MIXEDMAP 0x10000000 /* Can contain "struct page" and pure PFN pages */
+#define VM_SAO 0x20000000 /* Strong Access Ordering (powerpc) */

#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS

--