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Subject[PATCH 3.11 50/70] ARM: 7840/1: LPAE: don't reject mapping /dev/mem above 4GB
Date
3.11.10.10 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sergey Dyasly <dserrg@gmail.com>

commit 3159f372354e8e1f5dee714663d705dd2c7e0759 upstream.

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 <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>
Cc: hujianyang <hujianyang@huawei.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
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 304661d..5e85ed3 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -202,13 +202,11 @@ 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
--
1.9.1


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