powerpc/mm: Split the various pgtable-* headers based on MMU type

This patch moves the definition of the PTE format for each MMU type
to separate files instead of all in one file. This improves overall
maintainability and will make it easier to add new types.

On 64-bit, additionally, I've separated the headers relative to the
format of the page table tree (3 vs. 4 levels for 64K vs 4K pages)
from the headers specific to the PTE format for hash based processors,
this will make it easier to add support for Book3 "E" 64-bit
implementations.

There are still some type-related ifdef's in the generic headers,
we might remove them in the long run, but this patch shouldn't result
in any code change, -hopefully- just definitions being moved around.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 49 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/pte-hash32.h b/arch/powerpc/include/asm/pte-hash32.h
new file mode 100644
index 000000000000..6afe22b02f2f
--- /dev/null
+++ b/arch/powerpc/include/asm/pte-hash32.h
@@ -0,0 +1,49 @@
+#ifndef _ASM_POWERPC_PTE_HASH32_H
+#define _ASM_POWERPC_PTE_HASH32_H
+#ifdef __KERNEL__
+
+/*
+ * The "classic" 32-bit implementation of the PowerPC MMU uses a hash
+ * table containing PTEs, together with a set of 16 segment registers,
+ * to define the virtual to physical address mapping.
+ *
+ * We use the hash table as an extended TLB, i.e. a cache of currently
+ * active mappings.  We maintain a two-level page table tree, much
+ * like that used by the i386, for the sake of the Linux memory
+ * management code.  Low-level assembler code in hash_low_32.S
+ * (procedure hash_page) is responsible for extracting ptes from the
+ * tree and putting them into the hash table when necessary, and
+ * updating the accessed and modified bits in the page table tree.
+ */
+
+#define _PAGE_PRESENT	0x001	/* software: pte contains a translation */
+#define _PAGE_HASHPTE	0x002	/* hash_page has made an HPTE for this pte */
+#define _PAGE_FILE	0x004	/* when !present: nonlinear file mapping */
+#define _PAGE_USER	0x004	/* usermode access allowed */
+#define _PAGE_GUARDED	0x008	/* G: prohibit speculative access */
+#define _PAGE_COHERENT	0x010	/* M: enforce memory coherence (SMP systems) */
+#define _PAGE_NO_CACHE	0x020	/* I: cache inhibit */
+#define _PAGE_WRITETHRU	0x040	/* W: cache write-through */
+#define _PAGE_DIRTY	0x080	/* C: page changed */
+#define _PAGE_ACCESSED	0x100	/* R: page referenced */
+#define _PAGE_EXEC	0x200	/* software: i-cache coherency required */
+#define _PAGE_RW	0x400	/* software: user write access allowed */
+#define _PAGE_SPECIAL	0x800	/* software: Special page */
+
+#ifdef CONFIG_PTE_64BIT
+/* We never clear the high word of the pte */
+#define _PTE_NONE_MASK	(0xffffffff00000000ULL | _PAGE_HASHPTE)
+#else
+#define _PTE_NONE_MASK	_PAGE_HASHPTE
+#endif
+
+#define _PMD_PRESENT	0
+#define _PMD_PRESENT_MASK (PAGE_MASK)
+#define _PMD_BAD	(~PAGE_MASK)
+
+/* Hash table based platforms need atomic updates of the linux PTE */
+#define PTE_ATOMIC_UPDATES	1
+
+
+#endif /* __KERNEL__ */
+#endif /*  _ASM_POWERPC_PTE_HASH32_H */