arm64: armv8_deprecated: ensure extension of addr

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")
Cc: <stable@vger.kernel.org> # 3.19.x-
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>

diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
index 657977e..f0e6d71 100644 (file)
--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -306,7 +306,8 @@ do {                                                                \
        _ASM_EXTABLE(0b, 4b)                                    \
        _ASM_EXTABLE(1b, 4b)                                    \
        : "=&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");                                            \
        uaccess_disable();                                      \