Re: [PATCH 2/2] target/arm: Fix unaligned mte checks

[Richard Henderson]

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~