With this our protnone becomes a present pte with READ/WRITE/EXEC bit cleared.
By default we also set _PAGE_PRIVILEGED on such pte. This is now used to help
us identify a protnone pte that as saved write bit. For such pte, we will clear
the _PAGE_PRIVILEGED bit. The pte still remain non-accessible from both user
and kernel.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/book3s/64/mmu-hash.h | 3 +++
arch/powerpc/include/asm/book3s/64/pgtable.h | 32 +++++++++++++++++++++++++--
2 files changed, 33 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
index 0735d5a8049f..8720a406bbbe 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
@@ -16,6 +16,9 @@
#include <asm/page.h>
#include <asm/bug.h>
+#ifndef __ASSEMBLY__
+#include <linux/mmdebug.h>
+#endif
/*
* This is necessary to get the definition of PGTABLE_RANGE which we
* need for various slices related matters. Note that this isn't the
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index e91ada786d48..efff910a84b1 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -443,8 +443,8 @@ static inline pte_t pte_clear_soft_dirty(pte_t pte)
*/
static inline int pte_protnone(pte_t pte)
{
- return (pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_PRIVILEGED)) ==
- cpu_to_be64(_PAGE_PRESENT | _PAGE_PRIVILEGED);
+ return (pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_RWX)) ==
+ cpu_to_be64(_PAGE_PRESENT);
}
#endif /* CONFIG_NUMA_BALANCING */
@@ -514,6 +514,32 @@ static inline pte_t pte_mkhuge(pte_t pte)
return pte;
}
+#define pte_mk_savedwrite pte_mk_savedwrite
+static inline pte_t pte_mk_savedwrite(pte_t pte)
+{
+ /*
+ * Used by Autonuma subsystem to preserve the write bit
+ * while marking the pte PROT_NONE. Only allow this
+ * on PROT_NONE pte
+ */
+ VM_BUG_ON((pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_RWX | _PAGE_PRIVILEGED)) !=
+ cpu_to_be64(_PAGE_PRESENT | _PAGE_PRIVILEGED));
+ return __pte(pte_val(pte) & ~_PAGE_PRIVILEGED);
+}
+
+#define pte_savedwrite pte_savedwrite
+static inline bool pte_savedwrite(pte_t pte)
+{
+ /*
+ * Saved write ptes are prot none ptes that doesn't have
+ * privileged bit sit. We mark prot none as one which has
+ * present and pviliged bit set and RWX cleared. To mark
+ * protnone which used to have _PAGE_WRITE set we clear
+ * the privileged bit.
+ */
+ return !(pte_raw(pte) & cpu_to_be64(_PAGE_RWX | _PAGE_PRIVILEGED));
+}
+
static inline pte_t pte_mkdevmap(pte_t pte)
{
return __pte(pte_val(pte) | _PAGE_SPECIAL|_PAGE_DEVMAP);
@@ -885,6 +911,7 @@ static inline pte_t *pmdp_ptep(pmd_t *pmd)
#define pmd_mkclean(pmd) pte_pmd(pte_mkclean(pmd_pte(pmd)))
#define pmd_mkyoung(pmd) pte_pmd(pte_mkyoung(pmd_pte(pmd)))
#define pmd_mkwrite(pmd) pte_pmd(pte_mkwrite(pmd_pte(pmd)))
+#define pmd_mk_savedwrite(pmd) pte_pmd(pte_mk_savedwrite(pmd_pte(pmd)))
#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
#define pmd_soft_dirty(pmd) pte_soft_dirty(pmd_pte(pmd))
@@ -901,6 +928,7 @@ static inline int pmd_protnone(pmd_t pmd)
#define __HAVE_ARCH_PMD_WRITE
#define pmd_write(pmd) pte_write(pmd_pte(pmd))
+#define pmd_savedwrite(pmd) pte_savedwrite(pmd_pte(pmd))
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
extern pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot);
--
2.7.4
--
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