Commit f76cfa3c authored Apr 10, 2013 by Andrea Arcangeli Committed by Ingo Molnar Apr 11, 2013

x86/mm/cpa: Convert noop to functional fix



Commit:

  a8aed3e0 ("x86/mm/pageattr: Prevent PSE and GLOABL leftovers to confuse pmd/pte_present and pmd_huge")

introduced a valid fix but one location that didn't trigger the bug that
lead to finding those (small) problems, wasn't updated using the
right variable.

The wrong variable was also initialized for no good reason, that
may have been the source of the confusion. Remove the noop
initialization accordingly.

Commit a8aed3e0 also erroneously removed one canon_pgprot pass meant
to clear pmd bitflags not supported in hardware by older CPUs, that
automatically gets corrected by this patch too by applying it to the right
variable in the new location.

Reported-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Mel Gorman <mgorman@suse.de>
Link: http://lkml.kernel.org/r/1365600505-19314-1-git-send-email-aarcange@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 511ba86e

arch/x86/mm/pageattr.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -467,7 +467,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
		* We are safe now. Check whether the new pgprot is the same:
		*/
		old_pte = *kpte;
		old_prot = new_prot = req_prot = pte_pgprot(old_pte);
		old_prot = req_prot = pte_pgprot(old_pte);

		pgprot_val(req_prot) &= ~pgprot_val(cpa->mask_clr);
		pgprot_val(req_prot) \|= pgprot_val(cpa->mask_set);
		@@ -478,12 +478,12 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
		* a non present pmd. The canon_pgprot will clear _PAGE_GLOBAL
		* for the ancient hardware that doesn't support it.
		*/
		if (pgprot_val(new_prot) & _PAGE_PRESENT)
		pgprot_val(new_prot) \|= _PAGE_PSE \| _PAGE_GLOBAL;
		if (pgprot_val(req_prot) & _PAGE_PRESENT)
		pgprot_val(req_prot) \|= _PAGE_PSE \| _PAGE_GLOBAL;
		else
		pgprot_val(new_prot) &= ~(_PAGE_PSE \| _PAGE_GLOBAL);
		pgprot_val(req_prot) &= ~(_PAGE_PSE \| _PAGE_GLOBAL);

		new_prot = canon_pgprot(new_prot);
		req_prot = canon_pgprot(req_prot);

		/*
		* old_pte points to the large page base address. So we need

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