From 1a54420aeb4da1ba5b28283aa5696898220c9a27 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:11 -0700 Subject: x86/mm: Remove extra filtering in pageattr code The pageattr code has a mode where it can set or clear PTE bits in existing PTEs, so the page protections of the *new* PTEs come from one of two places: 1. The set/clear masks: cpa->mask_clr / cpa->mask_set 2. The existing PTE We filter ->mask_set/clr for supported PTE bits at entry to __change_page_attr() so we never need to filter them again. The only other place permissions can come from is an existing PTE and those already presumably have good bits. We do not need to filter them again. Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205511.BC072352@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/pageattr.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index d3442dfdfced..968f51a2e39b 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -598,7 +598,6 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, req_prot = pgprot_clear_protnone_bits(req_prot); if (pgprot_val(req_prot) & _PAGE_PRESENT) pgprot_val(req_prot) |= _PAGE_PSE; - req_prot = canon_pgprot(req_prot); /* * old_pfn points to the large page base pfn. So we need @@ -718,7 +717,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, */ pfn = ref_pfn; for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc) - set_pte(&pbase[i], pfn_pte(pfn, canon_pgprot(ref_prot))); + set_pte(&pbase[i], pfn_pte(pfn, ref_prot)); if (virt_addr_valid(address)) { unsigned long pfn = PFN_DOWN(__pa(address)); @@ -935,7 +934,6 @@ static void populate_pte(struct cpa_data *cpa, pte = pte_offset_kernel(pmd, start); pgprot = pgprot_clear_protnone_bits(pgprot); - pgprot = canon_pgprot(pgprot); while (num_pages-- && start < end) { set_pte(pte, pfn_pte(cpa->pfn, pgprot)); @@ -1234,7 +1232,7 @@ repeat: * after all we're only going to change it's attributes * not the memory it points to */ - new_pte = pfn_pte(pfn, canon_pgprot(new_prot)); + new_pte = pfn_pte(pfn, new_prot); cpa->pfn = pfn; /* * Do we really change anything ? -- cgit v1.2.3