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[PATCH 4.9 130/164] arm64: armv8_deprecated: ensure extension of addr

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  [PATCH 4.9 130/164] arm64: armv8_deprecated: ensure extension of addr Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-23 23:30 +0200

#1648766 — [PATCH 4.9 130/164] arm64: armv8_deprecated: ensure extension of addr

4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Mark Rutland <mark.rutland@arm.com>

commit 55de49f9aa17b0b2b144dd2af587177b9aadf429 upstream.

Our compat swp emulation holds the compat user address in an unsigned
int, which it passes to __user_swpX_asm(). When a 32-bit value is passed
in a register, the upper 32 bits of the register are unknown, and we
must extend the value to 64 bits before we can use it as a base address.

This patch casts the address to unsigned long to ensure it has been
suitably extended, avoiding the potential issue, and silencing a related
warning from clang.

Fixes: bd35a4adc413 ("arm64: Port SWP/SWPB emulation support from arm")
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/kernel/armv8_deprecated.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -309,7 +309,8 @@ static void __init register_insn_emulati
 	ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,	\
 		CONFIG_ARM64_PAN)				\
 	: "=&r" (res), "+r" (data), "=&r" (temp), "=&r" (temp2)	\
-	: "r" (addr), "i" (-EAGAIN), "i" (-EFAULT),		\
+	: "r" ((unsigned long)addr), "i" (-EAGAIN),		\
+	  "i" (-EFAULT),					\
 	  "i" (__SWP_LL_SC_LOOPS)				\
 	: "memory")
 

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