ARM: Fix pfn_valid() for sparse memory

On OMAP platforms, some people want to declare to segment up the memory
between the kernel and a separate application such that there is a hole
in the middle of the memory as far as Linux is concerned.  However,
they want to be able to mmap() the hole.

This currently causes problems, because update_mmu_cache() thinks that
there are valid struct pages for the "hole".  Fix this by making
pfn_valid() slightly more expensive, by checking whether the PFN is
contained within the meminfo array.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Khasim Syed Mohammed <khasim@ti.com>

arch/arm/include/asm/memory.h

@@ -212,7 +212,6 @@ static inline __deprecated void *bus_to_virt(unsigned long x)
  *
  *  page_to_pfn(page)	convert a struct page * to a PFN number
  *  pfn_to_page(pfn)	convert a _valid_ PFN number to struct page *
- *  pfn_valid(pfn)	indicates whether a PFN number is valid
  *
  *  virt_to_page(k)	convert a _valid_ virtual address to struct page *
  *  virt_addr_valid(k)	indicates whether a virtual address is valid
@@ -221,10 +220,6 @@ static inline __deprecated void *bus_to_virt(unsigned long x)
 
 #define ARCH_PFN_OFFSET		PHYS_PFN_OFFSET
 
-#ifndef CONFIG_SPARSEMEM
-#define pfn_valid(pfn)		((pfn) >= PHYS_PFN_OFFSET && (pfn) < (PHYS_PFN_OFFSET + max_mapnr))
-#endif
-
 #define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
 #define virt_addr_valid(kaddr)	((unsigned long)(kaddr) >= PAGE_OFFSET && (unsigned long)(kaddr) < (unsigned long)high_memory)
 
@@ -241,18 +236,6 @@ static inline __deprecated void *bus_to_virt(unsigned long x)
 #define arch_pfn_to_nid(pfn)	PFN_TO_NID(pfn)
 #define arch_local_page_offset(pfn, nid) LOCAL_MAP_NR((pfn) << PAGE_SHIFT)
 
-#define pfn_valid(pfn)						\
-	({							\
-		unsigned int nid = PFN_TO_NID(pfn);		\
-		int valid = nid < MAX_NUMNODES;			\
-		if (valid) {					\
-			pg_data_t *node = NODE_DATA(nid);	\
-			valid = (pfn - node->node_start_pfn) <	\
-				node->node_spanned_pages;	\
-		}						\
-		valid;						\
-	})
-
 #define virt_to_page(kaddr)					\
 	(ADDR_TO_MAPBASE(kaddr) + LOCAL_MAP_NR(kaddr))
 

arch/arm/include/asm/page.h

@@ -194,6 +194,10 @@ typedef unsigned long pgprot_t;
 
 typedef struct page *pgtable_t;
 
+#ifndef CONFIG_SPARSEMEM
+extern int pfn_valid(unsigned long);
+#endif
+
 #include <asm/memory.h>
 
 #endif /* !__ASSEMBLY__ */

arch/arm/mm/init.c

@@ -15,6 +15,7 @@
 #include <linux/mman.h>
 #include <linux/nodemask.h>
 #include <linux/initrd.h>
+#include <linux/sort.h>
 #include <linux/highmem.h>
 
 #include <asm/mach-types.h>
@@ -349,12 +350,43 @@ static void __init bootmem_free_node(int node, struct meminfo *mi)
 	free_area_init_node(node, zone_size, min, zhole_size);
 }
 
+#ifndef CONFIG_SPARSEMEM
+int pfn_valid(unsigned long pfn)
+{
+	struct meminfo *mi = &meminfo;
+	unsigned int left = 0, right = mi->nr_banks;
+
+	do {
+		unsigned int mid = (right + left) / 2;
+		struct membank *bank = &mi->bank[mid];
+
+		if (pfn < bank_pfn_start(bank))
+			right = mid;
+		else if (pfn >= bank_pfn_end(bank))
+			left = mid + 1;
+		else
+			return 1;
+	} while (left < right);
+	return 0;
+}
+EXPORT_SYMBOL(pfn_valid);
+#endif
+
+static int __init meminfo_cmp(const void *_a, const void *_b)
+{
+	const struct membank *a = _a, *b = _b;
+	long cmp = bank_pfn_start(a) - bank_pfn_start(b);
+	return cmp < 0 ? -1 : cmp > 0 ? 1 : 0;
+}
+
 void __init bootmem_init(void)
 {
 	struct meminfo *mi = &meminfo;
 	unsigned long min, max_low, max_high;
 	int node, initrd_node;
 
+	sort(&mi->bank, mi->nr_banks, sizeof(mi->bank[0]), meminfo_cmp, NULL);
+
 	/*
 	 * Locate which node contains the ramdisk image, if any.
 	 */