linux-kernel - Re: [PATCH] perf annotate: Add more x86 mov instruction cases

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Message-ID: <CAM9d7cj1rEjGy0QM2tkJhBn=hac-9Jya+ZJ4SNhBmB29u5KVMg@mail.gmail.com>
Date:   Fri, 8 Sep 2023 16:56:04 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH] perf annotate: Add more x86 mov instruction cases

Hi Ian,

On Thu, Sep 7, 2023 at 11:24 PM Ian Rogers <irogers@...gle.com> wrote:
>
> On Thu, Sep 7, 2023 at 10:22 PM Namhyung Kim <namhyung@...nel.org> wrote:
> >
> > Instructions with sign- and zero- extention like movsbl and movzwq were
> > not handled properly.  As it can check different size suffix (-b, -w, -l
> > or -q) we can omit that and add the common parts even though some
> > combinations are not possible.
> >
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > ---
> >  tools/perf/arch/x86/annotate/instructions.c | 9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/perf/arch/x86/annotate/instructions.c b/tools/perf/arch/x86/annotate/instructions.c
> > index 5f4ac4fc7fcf..5cdf457f5cbe 100644
> > --- a/tools/perf/arch/x86/annotate/instructions.c
> > +++ b/tools/perf/arch/x86/annotate/instructions.c
> > @@ -74,12 +74,15 @@ static struct ins x86__instructions[] = {
> >         { .name = "movdqa",     .ops = &mov_ops,  },
> >         { .name = "movdqu",     .ops = &mov_ops,  },
> >         { .name = "movsd",      .ops = &mov_ops,  },
> > -       { .name = "movslq",     .ops = &mov_ops,  },
> >         { .name = "movss",      .ops = &mov_ops,  },
> > +       { .name = "movsb",      .ops = &mov_ops,  },
> > +       { .name = "movsw",      .ops = &mov_ops,  },
> > +       { .name = "movsl",      .ops = &mov_ops,  },
>
> In Intel's manual some of these names are "Move Data From String to
> String" operations, movsb and movsw in particular. These instructions
> can be used to make simple memcpy loops. Could it be the past omission
> was deliberate due to the different way the addressing works in the
> instructions?

I don't know but in terms of instruction parsing, they are the same
"MOVE" with two operands.  I'm not aware of anything in perf with
the operands of these instructions.  So I guess it'd be fine to add
these instructions even if they have different underlying behaviors.

Thanks,
Namhyung