ARM: 7840/1: LPAE: don't reject mapping /dev/mem above 4GB

With LPAE enabled, physical address space is larger than 4GB. Allow mapping any
part of it via /dev/mem by using PHYS_MASK to determine valid range.

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

Bug 1474982

Reported-by: Vassili Karpov <av1474@comtv.ru>
Signed-off-by: Sergey Dyasly <dserrg@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
(cherry picked from commit 3159f372354e8e1f5dee714663d705dd2c7e0759)

Change-Id: I37133a68642b5856c358486bddacc7c4383ea812
Signed-off-by: Sami Kiminki <skiminki@nvidia.com>
Reviewed-on: http://git-master/r/417795
(cherry picked from commit 032975cbe364d06754c3b5e2788313ea07c38ac7)
Reviewed-on: http://git-master/r/419640
GVS: Gerrit_Virtual_Submit
Reviewed-by: Mitch Luban <mluban@nvidia.com>

diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 8bc7479eb7d85274d5508edac88e51f80bec847b..a5b1934e711ba93e2150653ca113da934ca02951 100644 (file)
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -219,13 +219,11 @@ 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 + (size >> PAGE_SHIFT)) <= (1 + (PHYS_MASK >> PAGE_SHIFT));
 }
 
 #ifdef CONFIG_STRICT_DEVMEM