linux-kernel - [PATCH AUTOSEL 4.20 099/304] arm64: io: Ensure value passed to _

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Date:   Mon, 28 Jan 2019 10:40:16 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Will Deacon <will.deacon@....com>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.20 099/304] arm64: io: Ensure value passed to __iormb() is held in a 64-bit register

From: Will Deacon <will.deacon@....com>

[ 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@...il.com>
Reported-by: Nathan Chancellor <natechancellor@...il.com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/include/asm/io.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index d42d00d8d5b6..ee723835c1f4 100644
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -117,7 +117,8 @@ 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()
-- 
2.19.1