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SubjectRe: [PATCH] Fix s390x compile error on F32 utils/stat-display.c
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@linux.intel.com>
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@arm.com> (reviewer:PERFORMANCE EVENTS SUBSYSTEM)
Alexander Shishkin <alexander.shishkin@linux.intel.com> (reviewer:PERFORMANCE EVENTS SUBSYSTEM)
Jiri Olsa <jolsa@redhat.com> (reviewer:PERFORMANCE EVENTS SUBSYSTEM)
Namhyung Kim <namhyung@kernel.org> (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]#
>
> Output after:
> # make util/stat-display.o
> .....
> CC util/stat-display.o
> [root@t35lp46 perf]#
>
> Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
> ---
> 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);
> }
> break;
> case AGGR_THREAD:
> --
> 2.26.2
>

--

- Arnaldo

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