From: salyzyn@android.com (Mark Salyzyn) Date: Wed, 1 Nov 2017 09:58:33 -0700 Subject: [PATCH] arm64: write_sysreg asm illegal for aarch32 Message-ID: <20171101170014.20931-1-salyzyn@android.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Cross compiling to aarch32 (for vdso32) using clang correctly identifies that (the unused) write_sysreg inline asm directive is illegal in that architectural context: arch/arm64/include/asm/arch_timer.h: error: invalid input constraint 'rZ' in asm write_sysreg(cntkctl, cntkctl_el1); ^ arch/arm64/include/asm/sysreg.h: note: expanded from macro 'write_sysreg' : : "rZ" (__val)); ^ GCC normally checks for correctness everywhere. But uniquely for unused asm, will optimize out and suppress the error report. Signed-off-by: Mark Salyzyn Cc: Catalin Marinas Cc: Will Deacon Cc: Christoffer Dall Cc: Mark Rutland Cc: Marc Zyngier Cc: Suzuki K Poulose Cc: Stefan Traby Cc: Dave Martin Cc: linux-arm-kernel at lists.infradead.org Cc: linux-kernel at vger.kernel.org --- arch/arm64/include/asm/sysreg.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index f707fed5886f..a7b61c9327db 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -492,11 +492,15 @@ asm( * The "Z" constraint normally means a zero immediate, but when combined with * the "%x0" template means XZR. */ +#if defined(__aarch64__) #define write_sysreg(v, r) do { \ u64 __val = (u64)(v); \ asm volatile("msr " __stringify(r) ", %x0" \ : : "rZ" (__val)); \ } while (0) +#else +#define write_sysreg(v, r) BUG() +#endif /* * For registers without architectural names, or simply unsupported by -- 2.15.0.403.gc27cc4dac6-goog