[PATCH] unify pfn_to_page: generic functions

There are 3 memory models, FLATMEM, DISCONTIGMEM, SPARSEMEM.
Each arch has its own page_to_pfn(), pfn_to_page() for each models.
But most of them can use the same arithmetic.

This patch adds asm-generic/memory_model.h, which includes generic
page_to_pfn(), pfn_to_page() definitions for each memory model.

When CONFIG_OUT_OF_LINE_PFN_TO_PAGE=y, out-of-line functions are
used instead of macro. This is enabled by some archs and  reduces
text size.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Hirokazu Takata <takata.hirokazu@renesas.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Richard Curnow <rc@rc0.org.uk>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp>
Cc: Chris Zankel <chris@zankel.net>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 77 insertions, 0 deletions

diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
new file mode 100644
index 00000000000..a7bb4978e80
--- /dev/null
+++ b/include/asm-generic/memory_model.h
@@ -0,0 +1,77 @@
+#ifndef __ASM_MEMORY_MODEL_H
+#define __ASM_MEMORY_MODEL_H
+
+#ifdef __KERNEL__
+#ifndef __ASSEMBLY__
+
+#if defined(CONFIG_FLATMEM)
+
+#ifndef ARCH_PFN_OFFSET
+#define ARCH_PFN_OFFSET		(0UL)
+#endif
+
+#elif defined(CONFIG_DISCONTIGMEM)
+
+#ifndef arch_pfn_to_nid
+#define arch_pfn_to_nid(pfn)	pfn_to_nid(pfn)
+#endif
+
+#ifndef arch_local_page_offset
+#define arch_local_page_offset(pfn, nid)	\
+	((pfn) - NODE_DATA(nid)->node_start_pfn)
+#endif
+
+#endif /* CONFIG_DISCONTIGMEM */
+
+#ifdef CONFIG_OUT_OF_LINE_PFN_TO_PAGE
+struct page;
+/* this is useful when inlined pfn_to_page is too big */
+extern struct page *pfn_to_page(unsigned long pfn);
+extern unsigned long page_to_pfn(struct page *page);
+#else
+/*
+ * supports 3 memory models.
+ */
+#if defined(CONFIG_FLATMEM)
+
+#define pfn_to_page(pfn)	(mem_map + ((pfn) - ARCH_PFN_OFFSET))
+#define page_to_pfn(page)	((unsigned long)((page) - mem_map) + \
+				 ARCH_PFN_OFFSET)
+#elif defined(CONFIG_DISCONTIGMEM)
+
+#define pfn_to_page(pfn)			\
+({	unsigned long __pfn = (pfn);		\
+	unsigned long __nid = arch_pfn_to_nid(pfn);  \
+	NODE_DATA(__nid)->node_mem_map + arch_local_page_offset(__pfn, __nid);\
+})
+
+#define page_to_pfn(pg)			\
+({	struct page *__pg = (pg);		\
+	struct zone *__zone = page_zone(__pg);	\
+	(unsigned long)(__pg - __zone->zone_mem_map) +	\
+	 __zone->zone_start_pfn;			\
+})
+
+#elif defined(CONFIG_SPARSEMEM)
+/*
+ * Note: section's mem_map is encorded to reflect its start_pfn.
+ * section[i].section_mem_map == mem_map's address - start_pfn;
+ */
+#define page_to_pfn(pg)					\
+({	struct page *__pg = (pg);				\
+	int __sec = page_to_section(__pg);			\
+	__pg - __section_mem_map_addr(__nr_to_section(__sec));	\
+})
+
+#define pfn_to_page(pfn)				\
+({	unsigned long __pfn = (pfn);			\
+	struct mem_section *__sec = __pfn_to_section(__pfn);	\
+	__section_mem_map_addr(__sec) + __pfn;		\
+})
+#endif /* CONFIG_FLATMEM/DISCONTIGMEM/SPARSEMEM */
+#endif /* CONFIG_OUT_OF_LINE_PFN_TO_PAGE */
+
+#endif /* __ASSEMBLY__ */
+#endif /* __KERNEL__ */
+
+#endif