arm64: io: Ensure value passed to __iormb() is held in a 64-bit register
authorWill Deacon <will.deacon@arm.com>
Thu, 29 Nov 2018 16:31:04 +0000 (16:31 +0000)
committerWill Deacon <will.deacon@arm.com>
Thu, 29 Nov 2018 16:36:18 +0000 (16:36 +0000)
commit1b57ec8c75279b873639eb44a215479236f93481
tree3095f250ec6151dcde24902726588ce02a963c07
parent3d65b6bbc01ecece8142e62a8a5f1d48ba41a240
arm64: io: Ensure value passed to __iormb() is held in a 64-bit register

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>
arch/arm64/include/asm/io.h