From f76cfa3c2496c462b5bc01bd0c9340c2715b73ca Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Wed, 10 Apr 2013 15:28:25 +0200 Subject: [PATCH] x86/mm/cpa: Convert noop to functional fix Commit: a8aed3e0752b ("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 a8aed3e0752b 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 Signed-off-by: Andrea Arcangeli Acked-by: Borislav Petkov Cc: Andy Whitcroft Cc: Mel Gorman Link: http://lkml.kernel.org/r/1365600505-19314-1-git-send-email-aarcange@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/mm/pageattr.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 091934e1d0d9..7896f7190fda 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -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 -- GitLab