1 files changed, 38 insertions, 1 deletions

diff --git a/include/asm-powerpc/pgtable-64k.h b/include/asm-powerpc/pgtable-64k.h
index bd54b772fbc6..1cbd6b377eea 100644
--- a/include/asm-powerpc/pgtable-64k.h
+++ b/include/asm-powerpc/pgtable-64k.h
@@ -13,12 +13,49 @@
 #define PTE_TABLE_SIZE  (sizeof(real_pte_t) << PTE_INDEX_SIZE)
 #define PMD_TABLE_SIZE  (sizeof(pmd_t) << PMD_INDEX_SIZE)
 #define PGD_TABLE_SIZE  (sizeof(pgd_t) << PGD_INDEX_SIZE)
-#endif  /* __ASSEMBLY__ */
 
 #define PTRS_PER_PTE    (1 << PTE_INDEX_SIZE)
 #define PTRS_PER_PMD    (1 << PMD_INDEX_SIZE)
 #define PTRS_PER_PGD    (1 << PGD_INDEX_SIZE)
 
+#ifdef CONFIG_PPC_SUBPAGE_PROT
+/*
+ * For the sub-page protection option, we extend the PGD with one of
+ * these.  Basically we have a 3-level tree, with the top level being
+ * the protptrs array.  To optimize speed and memory consumption when
+ * only addresses < 4GB are being protected, pointers to the first
+ * four pages of sub-page protection words are stored in the low_prot
+ * array.
+ * Each page of sub-page protection words protects 1GB (4 bytes
+ * protects 64k).  For the 3-level tree, each page of pointers then
+ * protects 8TB.
+ */
+struct subpage_prot_table {
+        unsigned long maxaddr;  /* only addresses < this are protected */
+        unsigned int **protptrs[2];
+        unsigned int *low_prot[4];
+};
+
+#undef PGD_TABLE_SIZE
+#define PGD_TABLE_SIZE          ((sizeof(pgd_t) << PGD_INDEX_SIZE) + \
+                                 sizeof(struct subpage_prot_table))
+
+#define SBP_L1_BITS             (PAGE_SHIFT - 2)
+#define SBP_L2_BITS             (PAGE_SHIFT - 3)
+#define SBP_L1_COUNT            (1 << SBP_L1_BITS)
+#define SBP_L2_COUNT            (1 << SBP_L2_BITS)
+#define SBP_L2_SHIFT            (PAGE_SHIFT + SBP_L1_BITS)
+#define SBP_L3_SHIFT            (SBP_L2_SHIFT + SBP_L2_BITS)
+
+extern void subpage_prot_free(pgd_t *pgd);
+
+static inline struct subpage_prot_table *pgd_subpage_prot(pgd_t *pgd)
+{
+        return (struct subpage_prot_table *)(pgd + PTRS_PER_PGD);
+}
+#endif /* CONFIG_PPC_SUBPAGE_PROT */
+#endif  /* __ASSEMBLY__ */
+
 /* With 4k base page size, hugepage PTEs go at the PMD level */
 #define MIN_HUGEPTE_SHIFT       PAGE_SHIFT