Comment 18 for bug 1921948

Peter Maydell <email address hidden> writes:

> On Wed, 7 Apr 2021 at 19:54, Alex Bennée <email address hidden> wrote:
>>
>>
>> Richard Henderson <email address hidden> writes:
>>
>> > 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, the first failure is always either the first byte of the
>> > access, or the first byte of the granule.
>> >
>> > In addition, some of the arithmetic is off for last-first -> count.
>> > This does not become directly visible until a later patch that passes
>> > single bytes into this function, so ptr == ptr_last.
>> >
>> > Buglink: https://bugs.launchpad.net/bugs/1921948
>>
>> Minor note: you can Cc: Bug 1921948 <email address hidden> to
>> automatically copy patches to the appropriate bugs which is useful if
>> you don't have the Cc for the reporter.
>
> I'm not sure cc'ing bugs on patches is very useful, though (and especially
> not for big series). I usually prefer to just add a note to the bug with
> the URL of the series in patchew afterwards.

Ideally the tooling would pick up bug links in Patchew and automatically
update the relevant bugs when new series are posted. I only mentioned it
because the original bug reporters weren't Cc'ed on the patches and lo
now they know about the iteration they have tested it ;-)

--
Alex Bennée