From: Richard Henderson <richard.henderson@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Linux-sh list <linux-sh@vger.kernel.org>
Subject: Re: [PATCH for-6.2 12/43] target/sh4: Implement do_unaligned_access for user-only
Date: Thu, 29 Jul 2021 14:01:15 -1000 [thread overview]
Message-ID: <3318f1ba-0963-155d-4fe7-3de9bf7ee0f6@linaro.org> (raw)
In-Reply-To: <CAFEAcA9yrj7OZPkeZ2jUqAV4+ULVYm4++y6kXeK2_MC8gR3-bg@mail.gmail.com>
On 7/29/21 3:52 AM, Peter Maydell wrote:
> sh4 kernel default for unaligned accesses seems to be "warn and fixup",
> not SIGBUS, unless the user changes that by writing to /proc/cpu/alignment
> or the process changes it via prctl().
We will still need this for load-locked/store-conditional (MOVLI/MOVCO).
It appears that the sh4 kernel fails to decode these properly, and will do something ugly,
like interpreting MOVLI as a multiple-store instead of a load.
There are also other instructions that the kernel does not attempt to handle, such as MAC.
I suppose we could begin with turning off TARGET_ALIGNED_ONLY for sh4-linux-user, then
re-enabling MO_ALIGN for the atomics (at least).
r~
parent reply other threads:[~2021-07-30 0:01 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <CAFEAcA9yrj7OZPkeZ2jUqAV4+ULVYm4++y6kXeK2_MC8gR3-bg@mail.gmail.com>]
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