arm64: io: Ensure value passed to __iormb() is held in a 64-bit register

[ Upstream commit 1b57ec8c75279b873639eb44a215479236f93481 ]

As of commit 6460d3201471 ("arm64: io: Ensure calls to delay routines
are ordered against prior readX()"), MMIO reads smaller than 64 bits
fail to compile under clang because we end up mixing 32-bit and 64-bit
register operands for the same data processing instruction:

./include/asm-generic/io.h:695:9: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
        return readb(addr);
               ^
./arch/arm64/include/asm/io.h:147:58: note: expanded from macro 'readb'
                                                                       ^
./include/asm-generic/io.h:695:9: note: use constraint modifier "w"
./arch/arm64/include/asm/io.h:147:50: note: expanded from macro 'readb'
                                                               ^
./arch/arm64/include/asm/io.h:118:24: note: expanded from macro '__iormb'
        asm volatile("eor       %0, %1, %1\n"                           \
                                    ^

Fix the build by casting the macro argument to 'unsigned long' when used
as an input to the inline asm.

Reported-by: Nick Desaulniers <nick.desaulniers@gmail.com>
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index b2bc7db..49bb9a0 100644 (file)
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -119,7 +119,8 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
         */                                                             \
        asm volatile("eor       %0, %1, %1\n"                           \
                     "cbnz      %0, ."                                  \
-                    : "=r" (tmp) : "r" (v) : "memory");                \
+                    : "=r" (tmp) : "r" ((unsigned long)(v))            \
+                    : "memory");                                       \
 })
 
 #define __iowmb()              wmb()