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

PATCH New Sergey Dyasly 2 participants 2 messages Jul 4, 2013 Arm (32-bit)

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Sergey Dyasly

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PATCH v3 1/1 ARM: 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.

Reported-by Vassili Karpov <[email protected]>
Signed-off-by Sergey Dyasly <[email protected]>

---

v3:
- Fixed 32-bit overflow

v2:
- Removed #ifdef and changed original function

 arch/arm/mm/mmap.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
arch/arm/mm/mmap.c +2 -4
index 10062ce..2db5d2d 100644
@@ -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 + (size >> PAGE_SHIFT)) <= (1 + (PHYS_MASK >> PAGE_SHIFT));
 }
 
 #ifdef CONFIG_STRICT_DEVMEM
Signature · 1 line
1.8.1.2