[PATCH] ppc: make phys_mem_access_prot() work with pfns instead of addresses

Change the phys_mem_access_prot() function to take a pfn instead of an
address.  This allows mmap64() to work on /dev/mem for addresses above 4G
on 32-bit architectures.  We start with a pfn in mmap_mem(), so there's no
need to convert to an address; in fact, it's actively bad, since the
conversion can overflow when the address is above 4G.

Similarly fix the ppc32 page_is_ram() function to avoid a conversion to an
address by directly comparing to max_pfn.  Working with max_pfn instead of
high_memory fixes page_is_ram() to give the right answer for highmem pages.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 695db6a588ce..3ca331728d21 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -88,13 +88,13 @@ int page_is_ram(unsigned long pfn)
 }
 EXPORT_SYMBOL(page_is_ram);
 
-pgprot_t phys_mem_access_prot(struct file *file, unsigned long addr,
+pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
                               unsigned long size, pgprot_t vma_prot)
 {
         if (ppc_md.phys_mem_access_prot)
-                return ppc_md.phys_mem_access_prot(file, addr, size, vma_prot);
+                return ppc_md.phys_mem_access_prot(file, pfn, size, vma_prot);
 
-        if (!page_is_ram(addr >> PAGE_SHIFT))
+        if (!page_is_ram(pfn))
                 vma_prot = __pgprot(pgprot_val(vma_prot)
                                     | _PAGE_GUARDED | _PAGE_NO_CACHE);
         return vma_prot;