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From: Richard Henderson <richard.henderson@linaro.org>
To: Thomas Huth <thuth@redhat.com>,
	qemu-devel@nongnu.org, David Hildenbrand <david@redhat.com>,
	Ilya Leoshkevich <iii@linux.ibm.com>
Cc: qemu-s390x@nongnu.org
Subject: Re: [PATCH v2 for-8.0] target/s390x/tcg: Fix and improve the SACF instruction
Date: Thu, 1 Dec 2022 12:51:55 -0800	[thread overview]
Message-ID: <2ab9d798-4feb-62d3-3713-aa12235a7034@linaro.org> (raw)
In-Reply-To: <20221201184443.136355-1-thuth@redhat.com>

On 12/1/22 10:44, Thomas Huth wrote:
> The SET ADDRESS SPACE CONTROL FAST instruction is not privileged, it can be
> used from problem space, too. Just the switching to the home address space
> is privileged and should still generate a privilege exception. This bug is
> e.g. causing programs like Java that use the "getcpu" vdso kernel function
> to crash (see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=990417#26 ).
> 
> While we're at it, also check if DAT is not enabled. In that case the
> instruction is supposed to generate a special operation exception.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/655
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---

Looks ok, as far as it goes.  We appear to be missing the check for CR0_SECONDARY, which 
is unpredictable for SACF but mandatory for SAC.

I'll give you

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

for fixing the incorrect IF_PRIV check, which by itself should be enough to fix the Java 
issue.


r~


  reply	other threads:[~2022-12-01 20:52 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-01 18:44 [PATCH v2 for-8.0] target/s390x/tcg: Fix and improve the SACF instruction Thomas Huth
2022-12-01 20:51 ` Richard Henderson [this message]
2022-12-02  7:41   ` Thomas Huth
2022-12-02 12:31 ` David Hildenbrand
2022-12-02 23:39 ` Ilya Leoshkevich

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