linux-kernel - Re: [PATCH 2/4] perf report: Load PE files from debug cache only

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Date:   Tue, 16 Feb 2021 10:55:09 -0500
From:   Nicholas Fraser <nfraser@...eweavers.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        "Frank Ch. Eigler" <fche@...hat.com>,
        Song Liu <songliubraving@...com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kim Phillips <kim.phillips@....com>,
        Tommi Rantala <tommi.t.rantala@...ia.com>,
        Remi Bernon <rbernon@...eweavers.com>,
        linux-kernel@...r.kernel.org,
        Ulrich Czekalla <uczekalla@...eweavers.com>,
        Huw Davies <huw@...eweavers.com>
Subject: Re: [PATCH 2/4] perf report: Load PE files from debug cache only

Oops, you are correct; it is doing these checks twice. Not sure how I missed that. I'll send another patch to fix it.

Nick


On 2021-02-15 9:36 a.m., Jiri Olsa wrote:
> On Wed, Feb 10, 2021 at 02:17:38PM -0500, Nicholas Fraser wrote:
>> dso__load_bfd_symbols() attempts to load a DSO at its original path,
>> then closes it and loads the file in the debug cache. This is incorrect.
>> It should ignore the original file and work with only the debug cache.
>> The original file may have changed or may not even exist, for example if
>> the debug cache has been transferred to another machine via "perf
>> archive".
>>
>> This fix makes it only load the file in the debug cache.
>>
>> Signed-off-by: Nicholas Fraser <nfraser@...eweavers.com>
>> ---
>>  tools/perf/util/symbol.c | 8 +-------
>>  1 file changed, 1 insertion(+), 7 deletions(-)
>>
>> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
>> index 64a039cbba1b..aa9ae875b995 100644
>> --- a/tools/perf/util/symbol.c
>> +++ b/tools/perf/util/symbol.c
>> @@ -1569,7 +1569,7 @@ int dso__load_bfd_symbols(struct dso *dso, const char *debugfile)
>>  	u_int i;
>>  	u64 start, len;
>>  
>> -	abfd = bfd_openr(dso->long_name, NULL);
>> +	abfd = bfd_openr(debugfile, NULL);
>>  	if (!abfd)
>>  		return -1;
>>  
>> @@ -1586,12 +1586,6 @@ int dso__load_bfd_symbols(struct dso *dso, const char *debugfile)
>>  	if (section)
>>  		dso->text_offset = section->vma - section->filepos;
>>  
>> -	bfd_close(abfd);
>> -
>> -	abfd = bfd_openr(debugfile, NULL);
>> -	if (!abfd)
>> -		return -1;
>> -
> 
> hum, should you also remove the following code?
> 
>         if (!bfd_check_format(abfd, bfd_object)) {
>                 pr_debug2("%s: cannot read %s bfd file.\n", __func__,
>                           debugfile);
>                 goto out_close;
>         }
> 
>         if (bfd_get_flavour(abfd) == bfd_target_elf_flavour)
>                 goto out_close;
> 
> it seems to be called already above
> 
> thanks,
> jirka
> 
>>  	if (!bfd_check_format(abfd, bfd_object)) {
>>  		pr_debug2("%s: cannot read %s bfd file.\n", __func__,
>>  			  debugfile);
>> -- 
>> 2.30.0
>>
>