From: Richard Henderson <richard.henderson@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-arm <qemu-arm@nongnu.org>, QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [PATCH 2/2] target/arm: Fix unaligned mte checks
Date: Fri, 2 Apr 2021 11:44:58 -0700 [thread overview]
Message-ID: <09b35fc8-89c3-0440-40ea-6f58561b1dce@linaro.org> (raw)
In-Reply-To: <CAFEAcA-jky04K9d3WFxj+JU31mP_NS+yrEDXzXaffYC7CRTFLQ@mail.gmail.com>
On 4/2/21 11:35 AM, Peter Maydell wrote:
> On Fri, 2 Apr 2021 at 06:42, Richard Henderson
> <richard.henderson@linaro.org> wrote:
>>
>> We were incorrectly assuming that only the first byte of an MTE access
>> is checked against the tags. But per the ARM, unaligned accesses are
>> pre-decomposed into single-byte accesses. So by the time we reach the
>> actual MTE check in the ARM pseudocode, all accesses are aligned.
>>
>> Therefore, drop mte_check1, since we cannot know a priori that an
>> access is aligned. Rename mte_checkN to mte_check, which now handles
>> all accesses. Rename mte_probe1 to mte_probe, and use a common helper.
>>
>> Drop the computation of the faulting nth element, since all accesses
>> can be considered to devolve to bytes, and simply compute the faulting
>> address.
>>
>> Buglink: https://bugs.launchpad.net/bugs/1921948
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>
> This is a pretty chunky patch for this point in the release cycle.
> I don't suppose there's a way to make it more digestible for review?
Hmm. I guess I could split it into more pieces...
I had thought one of the intermediary steps was larger than the result, simply
because one of the interfaces was adjusted instead of simply being removed.
I'll see what I can come up with.
r~
next prev parent reply other threads:[~2021-04-02 18:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-02 5:37 [PATCH 0/2] target/arm: Fix unaligned mte checks Richard Henderson
2021-04-02 5:37 ` [PATCH 1/2] target/arm: Check PAGE_WRITE_ORG for MTE writeability Richard Henderson
2021-04-02 5:37 ` [PATCH 2/2] target/arm: Fix unaligned mte checks Richard Henderson
2021-04-02 15:43 ` Richard Henderson
2021-04-02 18:35 ` Peter Maydell
2021-04-02 18:44 ` Richard Henderson [this message]
2021-04-02 5:45 ` [PATCH 0/2] " no-reply
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