Re: [PATCH] Fix s390x compile error on F32 utils/stat-display.c

From: Thomas Richter
Date: Tue Aug 25 2020 - 02:17:02 EST

On 8/24/20 10:22 PM, Jiri Olsa wrote:
> On Wed, Aug 12, 2020 at 08:27:08AM -0300, Arnaldo Carvalho de Melo wrote:
>> Em Wed, Jul 22, 2020 at 11:20:53AM +0200, Thomas Richter escreveu:
>>> Fix a compile error on F32 and gcc version 10.1 on s390 in file
>>> utils/stat-display.c. The error does not show up with make DEBUG=y.
>>> In fact the issue shows up when using both compiler options
>>> -O6 and -D_FORTIFY_SOURCE=2 (which are omitted with DEBUG=Y).
>>>
>>> This is the offending call chain:
>>> print_counter_aggr()
>>> printout(config, -1, 0, ...) with 2nd parm id set to -1
>>> aggr_printout(config, x, id --> -1, ...) which leads to this code:
>>> case AGGR_NONE:
>>> if (evsel->percore && !config->percore_show_thread) {
>>> ....
>>> } else {
>>> fprintf(config->output, "CPU%*d%s",
>>> config->csv_output ? 0 : -7,
>>> evsel__cpus(evsel)->map[id],
>>> ^^ id is -1 !!!!
>>> config->csv_sep);
>>> }
>>>
>>> This is a compiler inlining issue which is detected on s390 but not on
>>> other plattforms.
>>
>> What is the sequence of events that gets to this? I.e. is it valid to
>> get a config->aggr_mode == AGGR_NONE, then have evsel not be percore and
>> config->percore_show_thread to be false?
>>
>> I wonder if this won't be papering over some bug :-\
>>
>> Jin?
>>
>> This is where this came from:
>> commit 4fc4d8dfa056dfd48afe73b9ea3b7570ceb80b9c (tag: perf-core-for-mingo-5.2-20190517)
>> Author: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
>> Date: Fri Apr 12 21:59:49 2019 +0800
>>
>> perf stat: Support 'percore' event qualifier
>>
>> With this patch, we can use the 'percore' event qualifier in perf-stat.
>>
>> ---
>>
>> Also please add at least Jiri and Namhyung on the CC list, having the
>> person that added that array usage also helps.
>>
>> [acme@quaco perf]$ scripts/get_maintainer.pl tools/perf | grep reviewer
>> Mark Rutland <mark.rutland@xxxxxxx> (reviewer:PERFORMANCE EVENTS SUBSYSTEM)
>> Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> (reviewer:PERFORMANCE EVENTS SUBSYSTEM)
>> Jiri Olsa <jolsa@xxxxxxxxxx> (reviewer:PERFORMANCE EVENTS SUBSYSTEM)
>> Namhyung Kim <namhyung@xxxxxxxxxx> (reviewer:PERFORMANCE EVENTS SUBSYSTEM)
>> [acme@quaco perf]$
>>
>> Thanks,
>>
>> - Arnaldo
>>
>>> Output before:
>>> # make util/stat-display.o
>>> .....
>>>
>>> util/stat-display.c: In function ‘perf_evlist__print_counters’:
>>> util/stat-display.c:121:4: error: array subscript -1 is below array
>>> bounds of ‘int[]’ [-Werror=array-bounds]
>>> 121 | fprintf(config->output, "CPU%*d%s",
>>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> 122 | config->csv_output ? 0 : -7,
>>> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> 123 | evsel__cpus(evsel)->map[id],
>>> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> 124 | config->csv_sep);
>>> | ~~~~~~~~~~~~~~~~
>>> In file included from util/evsel.h:13,
>>> from util/evlist.h:13,
>>> from util/stat-display.c:9:
>>> /root/linux/tools/lib/perf/include/internal/cpumap.h:10:7:
>>> note: while referencing ‘map’
>>> 10 | int map[];
>>> | ^~~
>>> cc1: all warnings being treated as errors
>>> mv: cannot stat 'util/.stat-display.o.tmp': No such file or directory
>>> make[3]: *** [/root/linux/tools/build/Makefile.build:97: util/stat-display.o]
>>> Error 1
>>> make[2]: *** [Makefile.perf:716: util/stat-display.o] Error 2
>>> make[1]: *** [Makefile.perf:231: sub-make] Error 2
>>> make: *** [Makefile:110: util/stat-display.o] Error 2
>>> [root@t35lp46 perf]#
>
> I tested on s390 with rhel8, but did not get this error,
> f32's gcc must be smarter
>

i Jiri,

that is correct. I have installed Fedora 32 on my LPAR and the gcc version
is:
[root@t35lp46 ~]# gcc --version
gcc (GCC) 10.1.1 20200507 (Red Hat 10.1.1-1)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[root@t35lp46 ~]# cat /etc/redhat-release
Fedora release 32 (Thirty Two)
[root@t35lp46 ~]#

Same commands on a RHEL 8.2 installation reveal
[root@m35lp76 ~]# gcc --version
gcc (GCC) 8.3.1 20191121 (Red Hat 8.3.1-5)
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[root@m35lp76 ~]# cat /etc/redhat-release
Red Hat Enterprise Linux release 8.2 Beta (Ootpa)
[root@m35lp76 ~]#

So there are 2 major revisions difference between a F32 and a RHEL8
gcc compiler installation.

>>>
>>> Output after:
>>> # make util/stat-display.o
>>> .....
>>> CC util/stat-display.o
>>> [root@t35lp46 perf]#
>>>
>>> Signed-off-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>
>>> ---
>>> tools/perf/util/stat-display.c | 9 +++++----
>>> 1 file changed, 5 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
>>> index 57d0706e1330..e49e544188e4 100644
>>> --- a/tools/perf/util/stat-display.c
>>> +++ b/tools/perf/util/stat-display.c
>>> @@ -118,10 +118,11 @@ static void aggr_printout(struct perf_stat_config *config,
>>> config->csv_output ? 0 : -3,
>>> cpu_map__id_to_cpu(id), config->csv_sep);
>>> } else {
>>> - fprintf(config->output, "CPU%*d%s",
>>> - config->csv_output ? 0 : -7,
>>> - evsel__cpus(evsel)->map[id],
>>> - config->csv_sep);
>>> + if (id > -1)
>>> + fprintf(config->output, "CPU%*d%s",
>>> + config->csv_output ? 0 : -7,
>>> + evsel__cpus(evsel)->map[id],
>>> + config->csv_sep);
>
> -1 is only through print_counter_aggr which is called for AGGR_GLOBAL
> case as you described, but I guess we can have this check as precaution
>
> you could put it together with above else
>
> } else if (id > -1)
>
> thanks,
> jirka
>

As suggested I will send a new patch.

--
Thomas Richter, Dept 3252, IBM s390 Linux Development, Boeblingen, Germany
--
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