This is a note to let you know that I've just added the patch titled
x86/xen/p2m: Replace ACCESS_ONCE with READ_ONCE
to the 3.19-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:
x86-xen-p2m-replace-access_once-with-read_once.patch
and it can be found in the queue-3.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1760f1eb7ec485197bd3a8a9c13e4160bb740275 Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Date: Sun, 7 Dec 2014 22:01:59 +0100
Subject: x86/xen/p2m: Replace ACCESS_ONCE with READ_ONCE
From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
commit 1760f1eb7ec485197bd3a8a9c13e4160bb740275 upstream.
ACCESS_ONCE does not work reliably on non-scalar types. For
example gcc 4.6 and 4.7 might remove the volatile tag for such
accesses during the SRA (scalar replacement of aggregates) step
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145)
Change the p2m code to replace ACCESS_ONCE with READ_ONCE.
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Acked-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/xen/p2m.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -554,7 +554,7 @@ static bool alloc_p2m(unsigned long pfn)
mid_mfn = NULL;
}
- p2m_pfn = pte_pfn(ACCESS_ONCE(*ptep));
+ p2m_pfn = pte_pfn(READ_ONCE(*ptep));
if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
/* p2m leaf page is missing */
Patches currently in stable-queue which might be from borntraeger@xxxxxxxxxx are
queue-3.19/x86-spinlocks-paravirt-fix-memory-corruption-on-unlock.patch
queue-3.19/kernel-make-read_once-valid-on-const-arguments.patch
queue-3.19/kvm-s390-base-hrtimer-on-a-monotonic-clock.patch
queue-3.19/kernel-tighten-rules-for-access-once.patch
queue-3.19/kvm-s390-floating-irqs-fix-user-triggerable-endless-loop.patch
queue-3.19/kvm-s390-forward-hrtimer-if-guest-ckc-not-pending-yet.patch
queue-3.19/kernel-fix-sparse-warning-for-access_once.patch
queue-3.19/kvm-s390-avoid-memory-leaks-if-__inject_vm-fails.patch
queue-3.19/x86-xen-p2m-replace-access_once-with-read_once.patch
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