Commit-ID: dcb32d9913b7ed527b135a7e221f8d14b67bb952 Gitweb: http://git.kernel.org/tip/dcb32d9913b7ed527b135a7e221f8d14b67bb952 Author: Dave Hansen <dave.han...@linux.intel.com> AuthorDate: Thu, 7 Jul 2016 17:19:15 -0700 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Wed, 13 Jul 2016 09:43:25 +0200
x86/mm: Use pte_none() to test for empty PTE The page table manipulation code seems to have grown a couple of sites that are looking for empty PTEs. Just in case one of these entries got a stray bit set, use pte_none() instead of checking for a zero pte_val(). The use pte_same() makes me a bit nervous. If we were doing a pte_same() check against two cleared entries and one of them had a stray bit set, it might fail the pte_same() check. But, I don't think we ever _do_ pte_same() for cleared entries. It is almost entirely used for checking for races in fault-in paths. Signed-off-by: Dave Hansen <dave.han...@linux.intel.com> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Andy Lutomirski <l...@kernel.org> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Dave Hansen <d...@sr71.net> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Josh Poimboeuf <jpoim...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Luis R. Rodriguez <mcg...@suse.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Toshi Kani <toshi.k...@hp.com> Cc: dave.han...@intel.com Cc: linux...@kvack.org Cc: mho...@suse.com Link: http://lkml.kernel.org/r/20160708001915.81370...@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/mm/init_64.c | 12 ++++++------ arch/x86/mm/pageattr.c | 2 +- arch/x86/mm/pgtable_32.c | 2 +- 3 files changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index bce2e5d..bb88fbc 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -354,7 +354,7 @@ phys_pte_init(pte_t *pte_page, unsigned long addr, unsigned long end, * pagetable pages as RO. So assume someone who pre-setup * these mappings are more intelligent. */ - if (pte_val(*pte)) { + if (!pte_none(*pte)) { if (!after_bootmem) pages++; continue; @@ -396,7 +396,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end, continue; } - if (pmd_val(*pmd)) { + if (!pmd_none(*pmd)) { if (!pmd_large(*pmd)) { spin_lock(&init_mm.page_table_lock); pte = (pte_t *)pmd_page_vaddr(*pmd); @@ -470,7 +470,7 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end, continue; } - if (pud_val(*pud)) { + if (!pud_none(*pud)) { if (!pud_large(*pud)) { pmd = pmd_offset(pud, 0); last_map_addr = phys_pmd_init(pmd, addr, end, @@ -673,7 +673,7 @@ static void __meminit free_pte_table(pte_t *pte_start, pmd_t *pmd) for (i = 0; i < PTRS_PER_PTE; i++) { pte = pte_start + i; - if (pte_val(*pte)) + if (!pte_none(*pte)) return; } @@ -691,7 +691,7 @@ static void __meminit free_pmd_table(pmd_t *pmd_start, pud_t *pud) for (i = 0; i < PTRS_PER_PMD; i++) { pmd = pmd_start + i; - if (pmd_val(*pmd)) + if (!pmd_none(*pmd)) return; } @@ -710,7 +710,7 @@ static bool __meminit free_pud_table(pud_t *pud_start, pgd_t *pgd) for (i = 0; i < PTRS_PER_PUD; i++) { pud = pud_start + i; - if (pud_val(*pud)) + if (!pud_none(*pud)) return false; } diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 7a1f7bb..7514215 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -1185,7 +1185,7 @@ repeat: return __cpa_process_fault(cpa, address, primary); old_pte = *kpte; - if (!pte_val(old_pte)) + if (pte_none(old_pte)) return __cpa_process_fault(cpa, address, primary); if (level == PG_LEVEL_4K) { diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c index 75cc097..e67ae0e6 100644 --- a/arch/x86/mm/pgtable_32.c +++ b/arch/x86/mm/pgtable_32.c @@ -47,7 +47,7 @@ void set_pte_vaddr(unsigned long vaddr, pte_t pteval) return; } pte = pte_offset_kernel(pmd, vaddr); - if (pte_val(pteval)) + if (!pte_none(pteval)) set_pte_at(&init_mm, vaddr, pte, pteval); else pte_clear(&init_mm, vaddr, pte);
