powerpc/mm: Make page table size a variable

Radix and hash MMU models support different page table sizes. Make
the #defines a variable so that existing code can work with variable
sizes.

Slice related code is only used by hash, so use hash constants there. We
will replicate some of the boundary conditions with resepct to TASK_SIZE
using radix values too. Right now we do boundary condition check using
hash constants.

Swapper pgdir size is initialized in asm code. We select the max pgd
size to keep it simple. For now we select hash pgdir. When adding radix
we will switch that to radix pgdir which is 64K.

BUILD_BUG_ON check which is removed is already done in hugepage_init()
using MAYBE_BUILD_BUG_ON().

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 60 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 7ec176674b78..f30f40443343 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -144,6 +144,66 @@
 #define PAGE_KERNEL_EXEC	PAGE_KERNEL_X
 #define PAGE_AGP		(PAGE_KERNEL_NC)
 
+#ifndef __ASSEMBLY__
+/*
+ * page table defines
+ */
+extern unsigned long __pte_index_size;
+extern unsigned long __pmd_index_size;
+extern unsigned long __pud_index_size;
+extern unsigned long __pgd_index_size;
+extern unsigned long __pmd_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
+/*
+ * Because of use of pte fragments and THP, size of page table
+ * are not always derived out of index size above.
+ */
+extern unsigned long __pte_table_size;
+extern unsigned long __pmd_table_size;
+extern unsigned long __pud_table_size;
+extern unsigned long __pgd_table_size;
+#define PTE_TABLE_SIZE	__pte_table_size
+#define PMD_TABLE_SIZE	__pmd_table_size
+#define PUD_TABLE_SIZE	__pud_table_size
+#define PGD_TABLE_SIZE	__pgd_table_size
+/*
+ * Pgtable size used by swapper, init in asm code
+ * We will switch this later to radix PGD
+ */
+#define MAX_PGD_TABLE_SIZE (sizeof(pgd_t) << H_PGD_INDEX_SIZE)
+
+#define PTRS_PER_PTE	(1 << PTE_INDEX_SIZE)
+#define PTRS_PER_PMD	(1 << PMD_INDEX_SIZE)
+#define PTRS_PER_PUD	(1 << PUD_INDEX_SIZE)
+#define PTRS_PER_PGD	(1 << PGD_INDEX_SIZE)
+
+/* PMD_SHIFT determines what a second-level page table entry can map */
+#define PMD_SHIFT	(PAGE_SHIFT + PTE_INDEX_SIZE)
+#define PMD_SIZE	(1UL << PMD_SHIFT)
+#define PMD_MASK	(~(PMD_SIZE-1))
+
+/* PUD_SHIFT determines what a third-level page table entry can map */
+#define PUD_SHIFT	(PMD_SHIFT + PMD_INDEX_SIZE)
+#define PUD_SIZE	(1UL << PUD_SHIFT)
+#define PUD_MASK	(~(PUD_SIZE-1))
+
+/* PGDIR_SHIFT determines what a fourth-level page table entry can map */
+#define PGDIR_SHIFT	(PUD_SHIFT + PUD_INDEX_SIZE)
+#define PGDIR_SIZE	(1UL << PGDIR_SHIFT)
+#define PGDIR_MASK	(~(PGDIR_SIZE-1))
+
+/* Bits to mask out from a PMD to get to the PTE page */
+#define PMD_MASKED_BITS		0xc0000000000000ffUL
+/* Bits to mask out from a PUD to get to the PMD page */
+#define PUD_MASKED_BITS		0xc0000000000000ffUL
+/* Bits to mask out from a PGD to get to the PUD page */
+#define PGD_MASKED_BITS		0xc0000000000000ffUL
+#endif /* __ASSEMBLY__ */
+
 #include <asm/book3s/64/hash.h>
 #include <asm/barrier.h>