Revert "powerpc/mm: Fix bug in pagetable cache cleanup with CONFIG_PPC_SUBPAGE_PROT"

This reverts commit c045256d.

It breaks build when CONFIG_PPC_SUBPAGE_PROT is not set. I will
commit a fixed version separately
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/mmu-hash64.h

@@ -373,38 +373,6 @@ extern void slb_set_size(u16 size);
 
 #ifndef __ASSEMBLY__
 
-#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];
-};
-
-#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(struct mm_struct *mm);
-extern void subpage_prot_init_new_context(struct mm_struct *mm);
-#else
-static inline void subpage_prot_free(pgd_t *pgd) {}
-static inline void subpage_prot_init_new_context(struct mm_struct *mm) { }
-#endif /* CONFIG_PPC_SUBPAGE_PROT */
-
 typedef unsigned long mm_context_id_t;
 
 typedef struct {
@@ -418,9 +386,6 @@ typedef struct {
 	u16 sllp;		/* SLB page size encoding */
 #endif
 	unsigned long vdso_base;
-#ifdef CONFIG_PPC_SUBPAGE_PROT
-	struct subpage_prot_table spt;
-#endif /* CONFIG_PPC_SUBPAGE_PROT */
 } mm_context_t;
 
 

arch/powerpc/include/asm/pgalloc-64.h

@@ -28,6 +28,10 @@
  */
 #define MAX_PGTABLE_INDEX_SIZE	0xf
 
+#ifndef CONFIG_PPC_SUBPAGE_PROT
+static inline void subpage_prot_free(pgd_t *pgd) {}
+#endif
+
 extern struct kmem_cache *pgtable_cache[];
 #define PGT_CACHE(shift) (pgtable_cache[(shift)-1])
 
@@ -38,6 +42,7 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
 
 static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 {
+	subpage_prot_free(pgd);
 	kmem_cache_free(PGT_CACHE(PGD_INDEX_SIZE), pgd);
 }
 

arch/powerpc/include/asm/pte-hash64-64k.h

@@ -76,4 +76,41 @@
 	remap_pfn_range((vma), (addr), (pfn), PAGE_SIZE,		\
 			__pgprot(pgprot_val((prot)) | _PAGE_4K_PFN))
 
+
+#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__ */

arch/powerpc/mm/hash_utils_64.c

@@ -835,9 +835,9 @@ void demote_segment_4k(struct mm_struct *mm, unsigned long addr)
  * Result is 0: full permissions, _PAGE_RW: read-only,
  * _PAGE_USER or _PAGE_USER|_PAGE_RW: no access.
  */
-static int subpage_protection(struct mm_struct *mm, unsigned long ea)
+static int subpage_protection(pgd_t *pgdir, unsigned long ea)
 {
-	struct subpage_prot_table *spt = &mm->context.spt;
+	struct subpage_prot_table *spt = pgd_subpage_prot(pgdir);
 	u32 spp = 0;
 	u32 **sbpm, *sbpp;
 
@@ -865,7 +865,7 @@ static int subpage_protection(struct mm_struct *mm, unsigned long ea)
 }
 
 #else /* CONFIG_PPC_SUBPAGE_PROT */
-static inline int subpage_protection(struct mm_struct *mm, unsigned long ea)
+static inline int subpage_protection(pgd_t *pgdir, unsigned long ea)
 {
 	return 0;
 }

arch/powerpc/mm/mmu_context_hash64.c

@@ -76,7 +76,6 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 	 */
 	if (slice_mm_new_context(mm))
 		slice_set_user_psize(mm, mmu_virtual_psize);
-	subpage_prot_init_new_context(mm);
 	mm->context.id = index;
 
 	return 0;
@@ -93,6 +92,5 @@ EXPORT_SYMBOL_GPL(__destroy_context);
 void destroy_context(struct mm_struct *mm)
 {
 	__destroy_context(mm->context.id);
-	subpage_prot_free(mm);
 	mm->context.id = NO_CONTEXT;
 }

arch/powerpc/mm/subpage-prot.c

@@ -24,9 +24,9 @@
  * Also makes sure that the subpage_prot_table structure is
  * reinitialized for the next user.
  */
-void subpage_prot_free(struct mm_struct *mm)
+void subpage_prot_free(pgd_t *pgd)
 {
-	struct subpage_prot_table *spt = &mm->context.spt;
+	struct subpage_prot_table *spt = pgd_subpage_prot(pgd);
 	unsigned long i, j, addr;
 	u32 **p;
 
@@ -51,13 +51,6 @@ void subpage_prot_free(struct mm_struct *mm)
 	spt->maxaddr = 0;
 }
 
-void subpage_prot_init_new_context(struct mm_struct *mm)
-{
-	struct subpage_prot_table *spt = &mm->context.spt;
-
-	memset(spt, 0, sizeof(*spt));
-}
-
 static void hpte_flush_range(struct mm_struct *mm, unsigned long addr,
 			     int npages)
 {
@@ -94,7 +87,7 @@ static void hpte_flush_range(struct mm_struct *mm, unsigned long addr,
 static void subpage_prot_clear(unsigned long addr, unsigned long len)
 {
 	struct mm_struct *mm = current->mm;
-	struct subpage_prot_table *spt = &mm->context.spt;
+	struct subpage_prot_table *spt = pgd_subpage_prot(mm->pgd);
 	u32 **spm, *spp;
 	int i, nw;
 	unsigned long next, limit;
@@ -143,7 +136,7 @@ static void subpage_prot_clear(unsigned long addr, unsigned long len)
 long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map)
 {
 	struct mm_struct *mm = current->mm;
-	struct subpage_prot_table *spt = &mm->context.spt;
+	struct subpage_prot_table *spt = pgd_subpage_prot(mm->pgd);
 	u32 **spm, *spp;
 	int i, nw;
 	unsigned long next, limit;