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From:   Ian Rogers <irogers@google.com>
Date:   Tue, 10 Oct 2023 23:50:25 -0700
Message-ID: <CAP-5=fVe9v=KOxJE5TfmivBQCD=7SRFpnqkob7e05U76d_bSPQ@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 Tue, Oct 10, 2023 at 10:56=E2=80=AFPM Namhyung Kim <namhyung@kernel.org>=
 wrote:
>
> On Mon, Oct 9, 2023 at 8:31=E2=80=AFAM Ian Rogers <irogers@google.com> wr=
ote:
> >
> > On Sun, Oct 8, 2023 at 10:29=E2=80=AFPM Namhyung Kim <namhyung@kernel.o=
rg> wrote:
> > >
> > > On Thu, Oct 5, 2023 at 2:24=E2=80=AFPM Ian Rogers <irogers@google.com=
> wrote:
> > > >
> > > > On Thu, Oct 5, 2023 at 12:06=E2=80=AFPM Adrian Hunter <adrian.hunte=
r@intel.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@goog=
le.com> wrote:
> > > > > >>
> > > > > >> The byte aligned buffer is cast to large types and dereference=
d
> > > > > >> causing misaligned pointer warnings from undefined behavior sa=
nitizer.
> > > > > >> 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. Adri=
an, 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 th=
e
> > > 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.
>
> It seems it's done without further changes.  Can I get your Ack's now?

With the unaligned.h patch on its own, I think patch 1 of 5 needs
dropping. For the rest I'm happy to acked-by.

Thanks,
Ian

> Thanks,
> Namhyung