Messages in this thread Patch in this message | | | From | Mark Salyzyn <> | Subject | [PATCH] arm64: write_sysreg asm illegal for aarch32 | Date | Wed, 1 Nov 2017 09:58:33 -0700 |
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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 <salyzyn@android.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Christoffer Dall <cdall@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Stefan Traby <stefan@hello-penguin.com> Cc: Dave Martin <Dave.Martin@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@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
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