[PATCH v2] ARM: LPAE: don't reject mapping /dev/mem above 4GB

[dserrg@gmail.com (Sergey Dyasly)]

With LPAE enabled, physical address space is larger than 4GB. Allow mapping any
part of it via /dev/mem by utilizing the same check as in arm64.

PHYS_MASK covers 40 bits with LPAE enabled and 32 bits otherwise.

Signed-off-by: Sergey Dyasly <dserrg@gmail.com>
---

v2:
- Removed #ifdef and changed original function as suggested by Catalin Marinas

 arch/arm/mm/mmap.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 10062ce..09bab92 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -204,13 +204,11 @@ int valid_phys_addr_range(phys_addr_t addr, size_t size)
 }
 
 /*
- * We don't use supersection mappings for mmap() on /dev/mem, which
- * means that we can't map the memory area above the 4G barrier into
- * userspace.
+ * Do not allow /dev/mem mappings beyond the supported physical range.
  */
 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
 {
-	return !(pfn + (size >> PAGE_SHIFT) > 0x00100000);
+	return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK);
 }
 
 #ifdef CONFIG_STRICT_DEVMEM
-- 
1.8.1.2