linux-kernel - Re: [PATCH 04/23] perf dwarf-aux: Add die_find_func

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Message-ID: <CAM9d7chdEcA7qFS3k=DGfeXcdZP1xWvdory_-Q0WFPfGi0St_Q@mail.gmail.com>
Date: Tue, 19 Mar 2024 10:42:00 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Ian Rogers <irogers@...gle.com>, 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, 
	Linus Torvalds <torvalds@...ux-foundation.org>, Stephane Eranian <eranian@...gle.com>, 
	Masami Hiramatsu <mhiramat@...nel.org>, linux-toolchains@...r.kernel.org, 
	linux-trace-devel@...r.kernel.org
Subject: Re: [PATCH 04/23] perf dwarf-aux: Add die_find_func_rettype()

On Tue, Mar 19, 2024 at 6:56 AM Arnaldo Carvalho de Melo
<acme@...nel.org> wrote:
>
> On Mon, Mar 18, 2024 at 10:50:56PM -0700, Namhyung Kim wrote:
> > The die_find_func_rettype() is to find a debug entry for the given
> > function name and sets the type information of the return value.  By
> > convention, it'd return the pointer to the type die (should be the
> > same as the given mem_die argument) if found, or NULL otherwise.
> >
> > Cc: Masami Hiramatsu <mhiramat@...nel.org>
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > ---
> >  tools/perf/util/dwarf-aux.c | 43 +++++++++++++++++++++++++++++++++++++
> >  tools/perf/util/dwarf-aux.h |  4 ++++
> >  2 files changed, 47 insertions(+)
> >
> > diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> > index cd9364d296b6..9080119a258c 100644
> > --- a/tools/perf/util/dwarf-aux.c
> > +++ b/tools/perf/util/dwarf-aux.c
> > @@ -696,6 +696,49 @@ Dwarf_Die *die_find_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
> >       return die_mem;
> >  }
> >
> > +static int __die_find_func_rettype_cb(Dwarf_Die *die_mem, void *data)
> > +{
> > +     const char *func_name;
> > +
> > +     if (dwarf_tag(die_mem) != DW_TAG_subprogram)
> > +             return DIE_FIND_CB_SIBLING;
> > +
> > +     func_name = dwarf_diename(die_mem);
> > +     if (func_name && !strcmp(func_name, data))
> > +             return DIE_FIND_CB_END;
> > +
> > +     return DIE_FIND_CB_SIBLING;
> > +}
> > +
> > +/**
> > + * die_find_func_rettype - Search a return type of function
> > + * @cu_die: a CU DIE
> > + * @name: target function name
> > + * @die_mem: a buffer for result DIE
> > + *
> > + * Search a non-inlined function which matches to @name and stores the
> > + * return type of the function to @die_mem and returns it if found.
> > + * Returns NULL if failed.  Note that it doesn't needs to find a
> > + * definition of the function, so it doesn't match with address.
> > + * Most likely, it can find a declaration at the top level.  Thus the
> > + * callback function continues to sibling entries only.
> > + */
> > +Dwarf_Die *die_find_func_rettype(Dwarf_Die *cu_die, const char *name,
> > +                              Dwarf_Die *die_mem)
> > +{
> > +     Dwarf_Die tmp_die;
> > +
> > +     cu_die = die_find_child(cu_die, __die_find_func_rettype_cb,
> > +                             (void *)name, &tmp_die);
> > +     if (!cu_die)
> > +             return NULL;
> > +
> > +     if (die_get_real_type(&tmp_die, die_mem) == NULL)
> > +             return NULL;
>
>
> Here you check die_get_real_type() return, may I go and do the same for
> the previous patch to address my review comment?

Sure thing! :)