[tip:sched/numa] x86/mm: Introduce pte_accessible()

[tip-bot for Rik van Riel]

Commit-ID:  2a61c579b9c917b81fc71c45274d2e7b73cda23a
Gitweb:     http://git.kernel.org/tip/2a61c579b9c917b81fc71c45274d2e7b73cda23a
Author:     Rik van Riel <riel@xxxxxxxxxx>
AuthorDate: Tue, 9 Oct 2012 15:31:12 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 12 Oct 2012 12:07:14 +0200

x86/mm: Introduce pte_accessible()

We need pte_present to return true for _PAGE_PROTNONE pages, to indicate that
the pte is associated with a page.

However, for TLB flushing purposes, we would like to know whether the pte
points to an actually accessible page.  This allows us to skip remote TLB
flushes for pages that are not actually accessible.

Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-66p11te4uj23gevgh4j987ip@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/pgtable.h |    6 ++++++
 include/asm-generic/pgtable.h  |    4 ++++
 2 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 402704f..4dafd6b 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -409,6 +409,12 @@ static inline int pte_present(pte_t a)
 	return pte_flags(a) & (_PAGE_PRESENT | _PAGE_PROTNONE);
 }
 
+#define __HAVE_ARCH_PTE_ACCESSIBLE
+static inline int pte_accessible(pte_t a)
+{
+	return pte_flags(a) & _PAGE_PRESENT;
+}
+
 static inline int pte_hidden(pte_t pte)
 {
 	return pte_flags(pte) & _PAGE_HIDDEN;
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index ff4947b..0f8e008 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -206,6 +206,10 @@ static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
 #define move_pte(pte, prot, old_addr, new_addr)	(pte)
 #endif
 
+#ifndef __HAVE_ARCH_PTE_ACCESSIBLE
+#define pte_accessible(pte)		pte_present(pte)
+#endif
+
 #ifndef flush_tlb_fix_spurious_fault
 #define flush_tlb_fix_spurious_fault(vma, address) flush_tlb_page(vma, address)
 #endif
--
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