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From:   Ian Rogers <irogers@google.com>
Date:   Mon, 9 Oct 2023 08:31:33 -0700
Message-ID: <CAP-5=fUo-vuLofC4jgHC9z=BTe80OEiY_PoQWqQtyVdvHcf+KQ@mail.gmail.com>
Subject: Re: [PATCH v1] perf intel-pt: pkt-decoder: Fix alignment issues
To:     Namhyung Kim <namhyung@kernel.org>
Cc:     Adrian Hunter <adrian.hunter@intel.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Jiri Olsa <jolsa@kernel.org>, Miguel Ojeda <ojeda@kernel.org>,
        Liam Howlett <liam.howlett@oracle.com>,
        linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org
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On Sun, Oct 8, 2023 at 10:29=E2=80=AFPM Namhyung Kim <namhyung@kernel.org> =
wrote:
>
> On Thu, Oct 5, 2023 at 2:24=E2=80=AFPM Ian Rogers <irogers@google.com> wr=
ote:
> >
> > On Thu, Oct 5, 2023 at 12:06=E2=80=AFPM Adrian Hunter <adrian.hunter@in=
tel.com> wrote:
> > >
> > > On 5/10/23 18:48, Ian Rogers wrote:
> > > > On Mon, Oct 2, 2023 at 3:19=E2=80=AFPM Ian Rogers <irogers@google.c=
om> wrote:
> > > >>
> > > >> The byte aligned buffer is cast to large types and dereferenced
> > > >> causing misaligned pointer warnings from undefined behavior saniti=
zer.
> > > >> Fix the alignment issues with memcpy which may require the
> > > >> introduction of temporaries.
> > > >>
> > > >> Signed-off-by: Ian Rogers <irogers@google.com>
> > > >> ---
> > > >
> > > > This is a relatively small change that fixes building with
> > > > -fsanitize=3Dalignment -fsanitize-undefined-trap-on-error. Adrian, =
as
> > > > this is Intel-PT could you take a look?
> > >
> > > Thanks! This has been down my list of things to do for ages,
> > > but using get_unaligned_le16() etc seems nicer.  I sent a patch
> > > set for that.
> >
> > Thanks Adrian! Your patch set looks good and I think after Arnaldo's
> > comment is addressed we should go with it.
>
> I think it can be done as a later step as long as the interface is the
> same.  Can I add your Ack's to the Adrian's patchset?

I think addressing Arnaldo's comment:
https://lore.kernel.org/lkml/ZR8QnasisGEsaaDR@kernel.org/
will need some changes to the patch series, and so I was waiting to
see the outcome of that.

Thanks,
Ian

> Thanks,
> Namhyung