This is a note to let you know that I've just added the patch titled
powerpc/mm: Use read barrier when creating real_pte
to the 3.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-mm-use-read-barrier-when-creating-real_pte.patch
and it can be found in the queue-3.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 85c1fafd7262e68ad821ee1808686b1392b1167d Mon Sep 17 00:00:00 2001
From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Date: Wed, 13 Aug 2014 12:32:03 +0530
Subject: powerpc/mm: Use read barrier when creating real_pte
From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
commit 85c1fafd7262e68ad821ee1808686b1392b1167d upstream.
On ppc64 we support 4K hash pte with 64K page size. That requires
us to track the hash pte slot information on a per 4k basis. We do that
by storing the slot details in the second half of pte page. The pte bit
_PAGE_COMBO is used to indicate whether the second half need to be
looked while building real_pte. We need to use read memory barrier while
doing that so that load of hidx is not reordered w.r.t _PAGE_COMBO
check. On the store side we already do a lwsync in __hash_page_4K
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/pte-hash64-64k.h | 30 +++++++++++++++++++++++++-----
1 file changed, 25 insertions(+), 5 deletions(-)
--- a/arch/powerpc/include/asm/pte-hash64-64k.h
+++ b/arch/powerpc/include/asm/pte-hash64-64k.h
@@ -46,11 +46,31 @@
* in order to deal with 64K made of 4K HW pages. Thus we override the
* generic accessors and iterators here
*/
-#define __real_pte(e,p) ((real_pte_t) { \
- (e), (pte_val(e) & _PAGE_COMBO) ? \
- (pte_val(*((p) + PTRS_PER_PTE))) : 0 })
-#define __rpte_to_hidx(r,index) ((pte_val((r).pte) & _PAGE_COMBO) ? \
- (((r).hidx >> ((index)<<2)) & 0xf) : ((pte_val((r).pte) >> 12) & 0xf))
+#define __real_pte __real_pte
+static inline real_pte_t __real_pte(pte_t pte, pte_t *ptep)
+{
+ real_pte_t rpte;
+
+ rpte.pte = pte;
+ rpte.hidx = 0;
+ if (pte_val(pte) & _PAGE_COMBO) {
+ /*
+ * Make sure we order the hidx load against the _PAGE_COMBO
+ * check. The store side ordering is done in __hash_page_4K
+ */
+ smp_rmb();
+ rpte.hidx = pte_val(*((ptep) + PTRS_PER_PTE));
+ }
+ return rpte;
+}
+
+static inline unsigned long __rpte_to_hidx(real_pte_t rpte, unsigned long index)
+{
+ if ((pte_val(rpte.pte) & _PAGE_COMBO))
+ return (rpte.hidx >> (index<<2)) & 0xf;
+ return (pte_val(rpte.pte) >> 12) & 0xf;
+}
+
#define __rpte_to_pte(r) ((r).pte)
#define __rpte_sub_valid(rpte, index) \
(pte_val(rpte.pte) & (_PAGE_HPTE_SUB0 >> (index)))
Patches currently in stable-queue which might be from aneesh.kumar@xxxxxxxxxxxxxxxxxx are
queue-3.16/powerpc-thp-use-access_once-when-loading-pmdp.patch
queue-3.16/powerpc-thp-add-write-barrier-after-updating-the-valid-bit.patch
queue-3.16/powerpc-mm-use-read-barrier-when-creating-real_pte.patch
queue-3.16/powerpc-thp-handle-combo-pages-in-invalidate.patch
queue-3.16/powerpc-thp-invalidate-old-64k-based-hash-page-mapping-before-insert-of-4k-pte.patch
queue-3.16/powerpc-thp-invalidate-with-vpn-in-loop.patch
queue-3.16/powerpc-thp-don-t-recompute-vsid-and-ssize-in-loop-on-invalidate.patch
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