powerpc/mm: Fix crashes with 16G huge pages

To support memory keys, we moved the hash pte slot information to the
second half of the page table. This was ok with PTE entries at level
4 (PTE page) and level 3 (PMD). We already allocate larger page table
pages at those levels to accomodate extra details. For level 4 we
already have the extra space which was used to track 4k hash page
table entry details and at level 3 the extra space was allocated to
track the THP details.

With hugetlbfs PTE, we used this extra space at the PMD level to store
the slot details. But we also support hugetlbfs PTE at PUD level for
16GB pages and PUD level page didn't allocate extra space. This
resulted in memory corruption.

Fix this by allocating extra space at PUD level when HUGETLB is
enabled.

Fixes: bf9a95f9a6 ("powerpc: Free up four 64K PTE bits in 64K backed HPTE pages")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/book3s/32/pgtable.h

@@ -16,6 +16,7 @@
 #define PGD_INDEX_SIZE	(32 - PGDIR_SHIFT)
 
 #define PMD_CACHE_INDEX	PMD_INDEX_SIZE
+#define PUD_CACHE_INDEX	PUD_INDEX_SIZE
 
 #ifndef __ASSEMBLY__
 #define PTE_TABLE_SIZE	(sizeof(pte_t) << PTE_INDEX_SIZE)

arch/powerpc/include/asm/book3s/64/hash-64k.h

@@ -146,7 +146,12 @@ static inline int hash__remap_4k_pfn(struct vm_area_struct *vma, unsigned long a
 #else
 #define H_PMD_TABLE_SIZE	(sizeof(pmd_t) << PMD_INDEX_SIZE)
 #endif
+#ifdef CONFIG_HUGETLB_PAGE
+#define H_PUD_TABLE_SIZE	((sizeof(pud_t) << PUD_INDEX_SIZE) +	\
+				 (sizeof(unsigned long) << PUD_INDEX_SIZE))
+#else
 #define H_PUD_TABLE_SIZE	(sizeof(pud_t) << PUD_INDEX_SIZE)
+#endif
 #define H_PGD_TABLE_SIZE	(sizeof(pgd_t) << PGD_INDEX_SIZE)
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE

arch/powerpc/include/asm/book3s/64/hash.h

@@ -32,6 +32,16 @@
 #else
 #define H_PMD_CACHE_INDEX	H_PMD_INDEX_SIZE
 #endif
+/*
+ * We store the slot details in the second half of page table.
+ * Increase the pud level table so that hugetlb ptes can be stored
+ * at pud level.
+ */
+#if defined(CONFIG_HUGETLB_PAGE) &&  defined(CONFIG_PPC_64K_PAGES)
+#define H_PUD_CACHE_INDEX	(H_PUD_INDEX_SIZE + 1)
+#else
+#define H_PUD_CACHE_INDEX	(H_PUD_INDEX_SIZE)
+#endif
 /*
  * Define the address range of the kernel non-linear virtual area
  */

arch/powerpc/include/asm/book3s/64/pgalloc.h

@@ -93,13 +93,13 @@ static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pud_t *pud)
 
 static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
 {
-	return kmem_cache_alloc(PGT_CACHE(PUD_INDEX_SIZE),
+	return kmem_cache_alloc(PGT_CACHE(PUD_CACHE_INDEX),
 		pgtable_gfp_flags(mm, GFP_KERNEL));
 }
 
 static inline void pud_free(struct mm_struct *mm, pud_t *pud)
 {
-	kmem_cache_free(PGT_CACHE(PUD_INDEX_SIZE), pud);
+	kmem_cache_free(PGT_CACHE(PUD_CACHE_INDEX), pud);
 }
 
 static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
@@ -115,7 +115,7 @@ static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
 	 * ahead and flush the page walk cache
 	 */
 	flush_tlb_pgtable(tlb, address);
-        pgtable_free_tlb(tlb, pud, PUD_INDEX_SIZE);
+	pgtable_free_tlb(tlb, pud, PUD_CACHE_INDEX);
 }
 
 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)

arch/powerpc/include/asm/book3s/64/pgtable.h

@@ -232,11 +232,13 @@ extern unsigned long __pmd_index_size;
 extern unsigned long __pud_index_size;
 extern unsigned long __pgd_index_size;
 extern unsigned long __pmd_cache_index;
+extern unsigned long __pud_cache_index;
 #define PTE_INDEX_SIZE  __pte_index_size
 #define PMD_INDEX_SIZE  __pmd_index_size
 #define PUD_INDEX_SIZE  __pud_index_size
 #define PGD_INDEX_SIZE  __pgd_index_size
 #define PMD_CACHE_INDEX __pmd_cache_index
+#define PUD_CACHE_INDEX __pud_cache_index
 /*
  * Because of use of pte fragments and THP, size of page table
  * are not always derived out of index size above.

arch/powerpc/include/asm/nohash/32/pgtable.h

@@ -24,6 +24,7 @@ extern int icache_44x_need_flush;
 #define PGD_INDEX_SIZE	(32 - PGDIR_SHIFT)
 
 #define PMD_CACHE_INDEX	PMD_INDEX_SIZE
+#define PUD_CACHE_INDEX	PUD_INDEX_SIZE
 
 #ifndef __ASSEMBLY__
 #define PTE_TABLE_SIZE	(sizeof(pte_t) << PTE_INDEX_SIZE)

arch/powerpc/include/asm/nohash/64/pgtable.h

@@ -27,6 +27,7 @@
 #else
 #define PMD_CACHE_INDEX	PMD_INDEX_SIZE
 #endif
+#define PUD_CACHE_INDEX PUD_INDEX_SIZE
 
 /*
  * Define the address range of the kernel non-linear virtual area

arch/powerpc/mm/hash_utils_64.c

@@ -1008,6 +1008,7 @@ void __init hash__early_init_mmu(void)
 	__pmd_index_size = H_PMD_INDEX_SIZE;
 	__pud_index_size = H_PUD_INDEX_SIZE;
 	__pgd_index_size = H_PGD_INDEX_SIZE;
+	__pud_cache_index = H_PUD_CACHE_INDEX;
 	__pmd_cache_index = H_PMD_CACHE_INDEX;
 	__pte_table_size = H_PTE_TABLE_SIZE;
 	__pmd_table_size = H_PMD_TABLE_SIZE;

arch/powerpc/mm/init-common.c

@@ -100,6 +100,6 @@ void pgtable_cache_init(void)
 	 * same size as either the pgd or pmd index except with THP enabled
 	 * on book3s 64
 	 */
-	if (PUD_INDEX_SIZE && !PGT_CACHE(PUD_INDEX_SIZE))
-		pgtable_cache_add(PUD_INDEX_SIZE, pud_ctor);
+	if (PUD_CACHE_INDEX && !PGT_CACHE(PUD_CACHE_INDEX))
+		pgtable_cache_add(PUD_CACHE_INDEX, pud_ctor);
 }

arch/powerpc/mm/pgtable-radix.c

@@ -553,6 +553,7 @@ void __init radix__early_init_mmu(void)
 	__pmd_index_size = RADIX_PMD_INDEX_SIZE;
 	__pud_index_size = RADIX_PUD_INDEX_SIZE;
 	__pgd_index_size = RADIX_PGD_INDEX_SIZE;
+	__pud_cache_index = RADIX_PUD_INDEX_SIZE;
 	__pmd_cache_index = RADIX_PMD_INDEX_SIZE;
 	__pte_table_size = RADIX_PTE_TABLE_SIZE;
 	__pmd_table_size = RADIX_PMD_TABLE_SIZE;

arch/powerpc/mm/pgtable_64.c

@@ -82,6 +82,8 @@ unsigned long __pgd_index_size;
 EXPORT_SYMBOL(__pgd_index_size);
 unsigned long __pmd_cache_index;
 EXPORT_SYMBOL(__pmd_cache_index);
+unsigned long __pud_cache_index;
+EXPORT_SYMBOL(__pud_cache_index);
 unsigned long __pte_table_size;
 EXPORT_SYMBOL(__pte_table_size);
 unsigned long __pmd_table_size;