* [PATCH 2/2] perf iostat: Fix Segmentation fault from NULL 'struct perf_counts_values *'
2021-09-27 8:11 [PATCH 1/2] perf iostat: Use system-wide mode if the target cpu_list is unspecified Like Xu
@ 2021-09-27 8:11 ` Like Xu
2021-09-27 12:42 ` Arnaldo Carvalho de Melo
2021-09-27 12:40 ` [PATCH 1/2] perf iostat: Use system-wide mode if the target cpu_list is unspecified Arnaldo Carvalho de Melo
2021-09-28 9:06 ` Alexander Antonov
2 siblings, 1 reply; 5+ messages in thread
From: Like Xu @ 2021-09-27 8:11 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo, Ian Rogers
Cc: Alexander Antonov, Jiri Olsa, Alexander Shishkin, Namhyung Kim,
Mark Rutland, Stephane Eranian, Peter Zijlstra, Ingo Molnar,
linux-perf-users, linux-kernel
From: Like Xu <likexu@tencent.com>
If the perf-iostat user specifies two or more iio_root_ports and
also specifies the cpu(s) by -C which is not *connected to all*
the above iio ports, the iostat_print_metric() will run into trouble:
For example:
$ perf iostat list
S0-uncore_iio_0<0000:16>
S1-uncore_iio_0<0000:97> # <--- CPU 1 is located in the socket S0
$ perf iostat 0000:16,0000:97 -C 1 -- ls
port Inbound Read(MB) Inbound Write(MB) Outbound Read(MB) Outbound
Write(MB) ../perf-iostat: line 12: 104418 Segmentation fault
(core dumped) perf stat --iostat$DELIMITER$*
The core-dump stack says, in the above corner case, the returned
(struct perf_counts_values *) count will be NULL, and the caller
iostat_print_metric() apparently doesn't not handle this case.
433 struct perf_counts_values *count = perf_counts(evsel->counts, die, 0);
434
435 if (count->run && count->ena) {
(gdb) p count
$1 = (struct perf_counts_values *) 0x0
The deeper reason is that there are actually no statistics from the user
specified pair "iostat 0000:X, -C (disconnected) Y ", but let's fix it with
minimum cost by adding a NULL check in the user space.
Signed-off-by: Like Xu <likexu@tencent.com>
---
tools/perf/arch/x86/util/iostat.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/arch/x86/util/iostat.c b/tools/perf/arch/x86/util/iostat.c
index eeafe97b8105..792cd75ade33 100644
--- a/tools/perf/arch/x86/util/iostat.c
+++ b/tools/perf/arch/x86/util/iostat.c
@@ -432,7 +432,7 @@ void iostat_print_metric(struct perf_stat_config *config, struct evsel *evsel,
u8 die = ((struct iio_root_port *)evsel->priv)->die;
struct perf_counts_values *count = perf_counts(evsel->counts, die, 0);
- if (count->run && count->ena) {
+ if (count && count->run && count->ena) {
if (evsel->prev_raw_counts && !out->force_header) {
struct perf_counts_values *prev_count =
perf_counts(evsel->prev_raw_counts, die, 0);
--
2.32.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH 2/2] perf iostat: Fix Segmentation fault from NULL 'struct perf_counts_values *'
2021-09-27 8:11 ` [PATCH 2/2] perf iostat: Fix Segmentation fault from NULL 'struct perf_counts_values *' Like Xu
@ 2021-09-27 12:42 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; 5+ messages in thread
From: Arnaldo Carvalho de Melo @ 2021-09-27 12:42 UTC (permalink / raw)
To: Like Xu
Cc: Ian Rogers, Alexander Antonov, Jiri Olsa, Alexander Shishkin,
Namhyung Kim, Mark Rutland, Stephane Eranian, Peter Zijlstra,
Ingo Molnar, linux-perf-users, linux-kernel
Em Mon, Sep 27, 2021 at 04:11:15PM +0800, Like Xu escreveu:
> From: Like Xu <likexu@tencent.com>
>
> If the perf-iostat user specifies two or more iio_root_ports and
> also specifies the cpu(s) by -C which is not *connected to all*
> the above iio ports, the iostat_print_metric() will run into trouble:
>
> For example:
>
> $ perf iostat list
> S0-uncore_iio_0<0000:16>
> S1-uncore_iio_0<0000:97> # <--- CPU 1 is located in the socket S0
>
> $ perf iostat 0000:16,0000:97 -C 1 -- ls
> port Inbound Read(MB) Inbound Write(MB) Outbound Read(MB) Outbound
> Write(MB) ../perf-iostat: line 12: 104418 Segmentation fault
> (core dumped) perf stat --iostat$DELIMITER$*
>
> The core-dump stack says, in the above corner case, the returned
> (struct perf_counts_values *) count will be NULL, and the caller
> iostat_print_metric() apparently doesn't not handle this case.
>
> 433 struct perf_counts_values *count = perf_counts(evsel->counts, die, 0);
> 434
> 435 if (count->run && count->ena) {
> (gdb) p count
> $1 = (struct perf_counts_values *) 0x0
>
> The deeper reason is that there are actually no statistics from the user
> specified pair "iostat 0000:X, -C (disconnected) Y ", but let's fix it with
> minimum cost by adding a NULL check in the user space.
Added:
Fixes: f9ed693e8bc0e7de ("perf stat: Enable iostat mode for x86 platforms")
Please do that next time,
- Arnaldo
> Signed-off-by: Like Xu <likexu@tencent.com>
> ---
> tools/perf/arch/x86/util/iostat.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/arch/x86/util/iostat.c b/tools/perf/arch/x86/util/iostat.c
> index eeafe97b8105..792cd75ade33 100644
> --- a/tools/perf/arch/x86/util/iostat.c
> +++ b/tools/perf/arch/x86/util/iostat.c
> @@ -432,7 +432,7 @@ void iostat_print_metric(struct perf_stat_config *config, struct evsel *evsel,
> u8 die = ((struct iio_root_port *)evsel->priv)->die;
> struct perf_counts_values *count = perf_counts(evsel->counts, die, 0);
>
> - if (count->run && count->ena) {
> + if (count && count->run && count->ena) {
> if (evsel->prev_raw_counts && !out->force_header) {
> struct perf_counts_values *prev_count =
> perf_counts(evsel->prev_raw_counts, die, 0);
> --
> 2.32.0
--
- Arnaldo
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 1/2] perf iostat: Use system-wide mode if the target cpu_list is unspecified
2021-09-27 8:11 [PATCH 1/2] perf iostat: Use system-wide mode if the target cpu_list is unspecified Like Xu
2021-09-27 8:11 ` [PATCH 2/2] perf iostat: Fix Segmentation fault from NULL 'struct perf_counts_values *' Like Xu
@ 2021-09-27 12:40 ` Arnaldo Carvalho de Melo
2021-09-28 9:06 ` Alexander Antonov
2 siblings, 0 replies; 5+ messages in thread
From: Arnaldo Carvalho de Melo @ 2021-09-27 12:40 UTC (permalink / raw)
To: Like Xu
Cc: Ian Rogers, Alexander Antonov, Jiri Olsa, Alexander Shishkin,
Namhyung Kim, Mark Rutland, Stephane Eranian, Peter Zijlstra,
Ingo Molnar, linux-perf-users, linux-kernel
Em Mon, Sep 27, 2021 at 04:11:14PM +0800, Like Xu escreveu:
> From: Like Xu <likexu@tencent.com>
>
> An iostate use case like "perf iostat 0000:16,0000:97 -- ls" should be
> implemented to work in system-wide mode to ensure that the output from
> print_header() is consistent with the user documentation perf-iostat.txt,
> rather than incorrectly assuming that the kernel does not support it:
>
> Error:
> The sys_perf_event_open() syscall returned with 22 (Invalid argument) \
> for event (uncore_iio_0/event=0x83,umask=0x04,ch_mask=0xF,fc_mask=0x07/).
> /bin/dmesg | grep -i perf may provide additional information.
>
> This error is easily fixed by assigning system-wide mode by default
> for IOSTAT_RUN only when the target cpu_list is unspecified.
Looks ok, added:
Fixes: f07952b179697771 ("perf stat: Basic support for iostat in perf")
For stable@vger.kernel.org sake.
- Arnaldo
> Signed-off-by: Like Xu <likexu@tencent.com>
> ---
> tools/perf/builtin-stat.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index f6e87b7be5fa..f0ecfda34ece 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -2408,6 +2408,8 @@ int cmd_stat(int argc, const char **argv)
> goto out;
> } else if (verbose)
> iostat_list(evsel_list, &stat_config);
> + if (iostat_mode == IOSTAT_RUN && !target__has_cpu(&target))
> + target.system_wide = true;
> }
>
> if (add_default_attributes())
> --
> 2.32.0
--
- Arnaldo
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH 1/2] perf iostat: Use system-wide mode if the target cpu_list is unspecified
2021-09-27 8:11 [PATCH 1/2] perf iostat: Use system-wide mode if the target cpu_list is unspecified Like Xu
2021-09-27 8:11 ` [PATCH 2/2] perf iostat: Fix Segmentation fault from NULL 'struct perf_counts_values *' Like Xu
2021-09-27 12:40 ` [PATCH 1/2] perf iostat: Use system-wide mode if the target cpu_list is unspecified Arnaldo Carvalho de Melo
@ 2021-09-28 9:06 ` Alexander Antonov
2 siblings, 0 replies; 5+ messages in thread
From: Alexander Antonov @ 2021-09-28 9:06 UTC (permalink / raw)
To: Like Xu, Arnaldo Carvalho de Melo, Ian Rogers
Cc: Jiri Olsa, Alexander Shishkin, Namhyung Kim, Mark Rutland,
Stephane Eranian, Peter Zijlstra, Ingo Molnar, linux-perf-users,
linux-kernel
On 9/27/2021 11:11 AM, Like Xu wrote:
> From: Like Xu <likexu@tencent.com>
>
> An iostate use case like "perf iostat 0000:16,0000:97 -- ls" should be
> implemented to work in system-wide mode to ensure that the output from
> print_header() is consistent with the user documentation perf-iostat.txt,
> rather than incorrectly assuming that the kernel does not support it:
>
> Error:
> The sys_perf_event_open() syscall returned with 22 (Invalid argument) \
> for event (uncore_iio_0/event=0x83,umask=0x04,ch_mask=0xF,fc_mask=0x07/).
> /bin/dmesg | grep -i perf may provide additional information.
>
> This error is easily fixed by assigning system-wide mode by default
> for IOSTAT_RUN only when the target cpu_list is unspecified.
Hello,
Thank you for your fixes.
Tested-by: Alexander Antonov <alexander.antonov@linux.intel.com>
> Signed-off-by: Like Xu <likexu@tencent.com>
> ---
> tools/perf/builtin-stat.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index f6e87b7be5fa..f0ecfda34ece 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -2408,6 +2408,8 @@ int cmd_stat(int argc, const char **argv)
> goto out;
> } else if (verbose)
> iostat_list(evsel_list, &stat_config);
> + if (iostat_mode == IOSTAT_RUN && !target__has_cpu(&target))
> + target.system_wide = true;
> }
>
> if (add_default_attributes())
^ permalink raw reply [flat|nested] 5+ messages in thread