linux-kernel - Re: [PATCH 12/52] perf annotate-data: Add find_data

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Date:   Mon, 20 Nov 2023 12:43:00 -0800
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Stephane Eranian <eranian@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Linux Trace Devel <linux-trace-devel@...r.kernel.org>,
        linux-toolchains@...r.kernel.org
Subject: Re: [PATCH 12/52] perf annotate-data: Add find_data_type()

Hi Arnaldo,

On Sat, Nov 11, 2023 at 10:55 AM Arnaldo Carvalho de Melo
<arnaldo.melo@...il.com> wrote:
>
> On Thu, Nov 9, 2023, 9:00 PM Namhyung Kim <namhyung@...nel.org> wrote:
>>
>>
>> +static bool find_cu_die(struct debuginfo *di, u64 pc, Dwarf_Die *cu_die)
>> +{
>> +       Dwarf_Off off, next_off;
>> +       size_t header_size;
>> +
>> +       if (dwarf_addrdie(di->dbg, pc, cu_die) != NULL)
>> +               return cu_die;
>
> Isn't the return type a bool?
>
> Shouldn't be 'return true;'?
>
> Ends up like that as cu_die isn't NULL, but looks confusing.

Ok, will change.

>
>> +
>> +       /*
>> +        * There are some kernels don't have full aranges and contain only a few
>> +        * aranges entries.  Fallback to iterate all CU entries in .debug_info
>> +        * in case it's missing.
>> +        */
>> +       off = 0;
>> +       while (dwarf_nextcu(di->dbg, off, &next_off, &header_size,
>> +                           NULL, NULL, NULL) == 0) {
>> +               if (dwarf_offdie(di->dbg, off + header_size, cu_die) &&
>> +                   dwarf_haspc(cu_die, pc))
>> +                       return true;
>> +
>> +               off = next_off;
>> +       }
>> +       return false;
>> +}
>> +
>>
>> +struct annotated_data_type *find_data_type(struct map_symbol *ms, u64 ip,
>> +                                          int reg, int offset)
>> +{
>> +       struct annotated_data_type *result = NULL;
>> +       struct dso *dso = ms->map->dso;
>> +       struct debuginfo *di;
>> +       Dwarf_Die type_die;
>> +       struct strbuf sb;
>> +       u64 pc;
>> +
>> +       di = debuginfo__new(dso->long_name);
>> +       if (di == NULL) {
>> +               pr_debug("cannot get the debug info\n");
>
>
> Shouldn't inform the dso->long_name and function name to ease debugging?

Sounds good, I'll update it in the v3.

Thanks,
Namhyung