powerpc/mm: refactor definition of pgtable_cache[]

pgtable_cache[] is the same for the 4 subarches, lets make it common.

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 21 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/pgalloc.h b/arch/powerpc/include/asm/pgalloc.h
index c2c6fd438840..5761bee0f004 100644
--- a/arch/powerpc/include/asm/pgalloc.h
+++ b/arch/powerpc/include/asm/pgalloc.h
@@ -45,6 +45,27 @@ static inline void pte_free(struct mm_struct *mm, pgtable_t ptepage)
 	pte_fragment_free((unsigned long *)ptepage, 0);
 }
 
+/*
+ * Functions that deal with pagetables that could be at any level of
+ * the table need to be passed an "index_size" so they know how to
+ * handle allocation.  For PTE pages, the allocation size will be
+ * (2^index_size * sizeof(pointer)) and allocations are drawn from
+ * the kmem_cache in PGT_CACHE(index_size).
+ *
+ * The maximum index size needs to be big enough to allow any
+ * pagetable sizes we need, but small enough to fit in the low bits of
+ * any page table pointer.  In other words all pagetables, even tiny
+ * ones, must be aligned to allow at least enough low 0 bits to
+ * contain this value.  This value is also used as a mask, so it must
+ * be one less than a power of two.
+ */
+#define MAX_PGTABLE_INDEX_SIZE	0xf
+
+extern struct kmem_cache *pgtable_cache[];
+#define PGT_CACHE(shift) pgtable_cache[shift]
+
+static inline void check_pgt_cache(void) { }
+
 #ifdef CONFIG_PPC_BOOK3S
 #include <asm/book3s/pgalloc.h>
 #else