提交 1760f1eb 编写于 作者: C Christian Borntraeger

x86/xen/p2m: Replace ACCESS_ONCE with READ_ONCE

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: NChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: NJuergen Gross <jgross@suse.com>
Acked-by: NDavid Vrabel <david.vrabel@citrix.com>
上级 da1a288d
......@@ -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 */
......
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