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>

3 files changed, 36 insertions, 17 deletions

diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index 85763db87449..b3b54c6216a4 100644
--- a/arch/arm/include/asm/memory.h
+++ b/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))
 
diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h
index 9c746af1bf6e..3a32af4cce30 100644
--- a/arch/arm/include/asm/page.h
+++ b/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__ */
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 3a7279c1ce5e..ea36186f32c3 100644
--- a/arch/arm/mm/init.c
+++ b/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.
          */