From: Janosch Frank <frankja@linux.ibm.com>
To: Thomas Huth <thuth@redhat.com>,
kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Cc: Laurent Vivier <lvivier@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
David Hildenbrand <david@redhat.com>
Subject: Re: [kvm-unit-tests PATCH 3/4] lib/s390x: Fix the epsw inline assembly
Date: Wed, 23 Jun 2021 09:33:58 +0200 [thread overview]
Message-ID: <559e9999-3f52-5843-de28-481d90b41da5@linux.ibm.com> (raw)
In-Reply-To: <20210622135517.234801-4-thuth@redhat.com>
On 6/22/21 3:55 PM, Thomas Huth wrote:
> According to the Principles of Operation, the epsw instruction
> does not touch the second register if it is r0. With GCC we were
> lucky so far that it never tried to use r0 here, but when compiling
> the kvm-unit-tests with Clang, this indeed happens and leads to
> very weird crashes. Thus let's make sure to never use r0 for the
> second operand of the epsw instruction.
>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
> lib/s390x/asm/arch_def.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
> index 3aa5da9..15cf7d4 100644
> --- a/lib/s390x/asm/arch_def.h
> +++ b/lib/s390x/asm/arch_def.h
> @@ -265,7 +265,7 @@ static inline uint64_t extract_psw_mask(void)
>
> asm volatile(
> " epsw %0,%1\n"
> - : "+r" (mask_upper), "+r" (mask_lower) : : );
> + : "=r" (mask_upper), "=a" (mask_lower));
>
> return (uint64_t) mask_upper << 32 | mask_lower;
> }
>
With Claudio's nits fixed:
Acked-by: Janosch Frank <frankja@linux.ibm.com>
next prev parent reply other threads:[~2021-06-23 7:34 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-22 13:55 [kvm-unit-tests PATCH 0/4] Test compiling with Clang in the Travis-CI Thomas Huth
2021-06-22 13:55 ` [kvm-unit-tests PATCH 1/4] configure: Add the possibility to specify additional cflags Thomas Huth
2021-06-22 13:55 ` [kvm-unit-tests PATCH 2/4] powerpc: Probe whether the compiler understands -mabi=no-altivec Thomas Huth
2021-06-22 13:55 ` [kvm-unit-tests PATCH 3/4] lib/s390x: Fix the epsw inline assembly Thomas Huth
2021-06-22 14:12 ` Claudio Imbrenda
2021-06-22 16:40 ` Thomas Huth
2021-06-23 7:33 ` Janosch Frank [this message]
2021-06-22 13:55 ` [kvm-unit-tests PATCH 4/4] Test compilation with Clang on aarch64, ppc64le and s390x in Travis-CI Thomas Huth
2021-06-22 16:25 ` [kvm-unit-tests PATCH 0/4] Test compiling with Clang in the Travis-CI Paolo Bonzini
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