| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <Yj458u2fMgyCO70i@kernel.org>
Date: Fri, 25 Mar 2022 18:53:54 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Stephane Eranian <eranian@...gle.com>
Cc: linux-kernel@...r.kernel.org, peterz@...radead.org,
kim.phillips@....com, acme@...hat.com, jolsa@...hat.com,
songliubraving@...com, rafael@...nel.org, ravi.bangoria@....com,
sandipan.das@....com
Subject: Re: [PATCH v7 11/13] perf tools: Improve IBS error handling
Em Fri, Mar 25, 2022 at 06:46:08PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Tue, Mar 22, 2022 at 03:15:15PM -0700, Stephane Eranian escreveu:
> > From: Kim Phillips <kim.phillips@....com>
> >
> > improve the error message returned on failed perf_event_open() on AMD when
> > using IBS.
> >
> > Output of executing 'perf record -e ibs_op// true' BEFORE this patch:
> >
> > The sys_perf_event_open() syscall returned with 22 (Invalid argument)for event (ibs_op//u).
> > /bin/dmesg | grep -i perf may provide additional information.
> >
> > Output after:
> >
> > AMD IBS cannot exclude kernel events. Try running at a higher privilege level.
>
> So the error message don't match up the BEFORE part, that didn't have a
> "u" at the end, and with this patch in:
I see, the patch description doesn't mention that the BEFORE command is
run as a NON root user, when the 'u' suffix is auto-added by perf, I'm
ammending the comment log message with this.
Now it reads:
----------------------------------------------------------------------
perf evsel: Improve AMD IBS (Instruction-Based Sampling) error handling messages
Improve the error message returned on failed perf_event_open() on AMD
systems when using IBS (Instruction-Based Sampling).
Output of executing 'perf record -e ibs_op// true' as a non root user
BEFORE this patch (perf will add the 'u' modifier at the end to exclude
kernel/hypervisor sampling):
The sys_perf_event_open() syscall returned with 22 (Invalid argument)for event (ibs_op//u).
/bin/dmesg | grep -i perf may provide additional information.
Output after:
AMD IBS can't exclude kernel events. Try running at a higher privilege level.
Output of executing 'sudo perf record -e ibs_op// true' BEFORE this patch:
Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (ibs_op//).
/bin/dmesg | grep -i perf may provide additional information.
Output after:
Error:
Invalid event (ibs_op//) in per-thread mode, enable system wide with '-a'.
Folowing the suggestion:
$ sudo perf record -a -e ibs_op// true
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 1.664 MB perf.data (194 samples) ]
$
Signed-off-by: Kim Phillips <kim.phillips@....com>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
----------------------------------------------------------------------
This is all with:
[root@...e ~]# uname -a
Linux five 5.16.16-200.fc35.x86_64 #1 SMP PREEMPT Sat Mar 19 13:52:41 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
- Arnaldo
> $ git log --oneline -1
> ca585f91ce13df4c (HEAD -> perf/core) perf evsel: Improve AMD IBS (Instruction-Based Sampling) error handling messages
> # perf -v
> perf version 5.17.gca585f91ce13
> #
>
> On a:
>
> # grep -m1 "model name" /proc/cpuinfo
> model name : AMD Ryzen 9 5950X 16-Core Processor
> #
>
> If I try:
>
> # perf record -e ibs_op//u true
> Error:
> Invalid event (ibs_op//u) in per-thread mode, enable system wide with '-a'.
> #
>
> So now if I try:
>
> # perf record -a -e ibs_op//u true
> Error:
> AMD IBS can't exclude kernel events. Try running at a higher privilege level.
> #
>
> So the problem is with the patch description, I'm fixing it.
>
> > Output of executing 'sudo perf record -e ibs_op// true' BEFORE this patch:
> >
> > Error:
> > The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (ibs_op//).
> > /bin/dmesg | grep -i perf may provide additional information.
> >
> > Output after:
> >
> > Error:
> > AMD IBS may only be available in system-wide/per-cpu mode. Try using -a, or -C and workload affinity
>
> But this one is never reached:
>
> [root@...e ~]# perf record -e ibs_op// true
> Error:
> Invalid event (ibs_op//) in per-thread mode, enable system wide with '-a'
>
> > + if (!evsel->core.system_wide)
> > + return scnprintf(msg, size,
> > + "AMD IBS may only be available in system-wide/per-cpu mode. Try using -a, or -C and workload affinity");
>
>
> I'm applying this to make progress, the message now provides more clues.
>
> - Arnaldo
>
>
> > Signed-off-by: Kim Phillips <kim.phillips@....com>
> > Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> > Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> > Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> > Cc: Ian Rogers <irogers@...gle.com>
> > Cc: Ingo Molnar <mingo@...hat.com>
> > Cc: Jiri Olsa <jolsa@...hat.com>
> > Cc: Joao Martins <joao.m.martins@...cle.com>
> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> > Cc: Mark Rutland <mark.rutland@....com>
> > Cc: Michael Petlan <mpetlan@...hat.com>
> > Cc: Namhyung Kim <namhyung@...nel.org>
> > Cc: Peter Zijlstra <peterz@...radead.org>
> > Cc: Robert Richter <robert.richter@....com>
> > Cc: Stephane Eranian <eranian@...gle.com>
> > ---
> > tools/perf/util/evsel.c | 25 +++++++++++++++++++++++++
> > 1 file changed, 25 insertions(+)
> >
> > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> > index 14b0e7ffa2c7..e8ff7a4bd490 100644
> > --- a/tools/perf/util/evsel.c
> > +++ b/tools/perf/util/evsel.c
> > @@ -2847,9 +2847,23 @@ static bool find_process(const char *name)
> > return ret ? false : true;
> > }
> >
> > +static bool is_amd(const char *arch, const char *cpuid)
> > +{
> > + return arch && !strcmp("x86", arch) && cpuid && strstarts(cpuid, "AuthenticAMD");
> > +}
> > +
> > +static bool is_amd_ibs(struct evsel *evsel)
> > +{
> > + return evsel->core.attr.precise_ip
> > + || (evsel->pmu_name && !strncmp(evsel->pmu_name, "ibs", 3));
> > +}
> > +
> > int evsel__open_strerror(struct evsel *evsel, struct target *target,
> > int err, char *msg, size_t size)
> > {
> > + struct perf_env *env = evsel__env(evsel);
> > + const char *arch = perf_env__arch(env);
> > + const char *cpuid = perf_env__cpuid(env);
> > char sbuf[STRERR_BUFSIZE];
> > int printed = 0, enforced = 0;
> >
> > @@ -2949,6 +2963,17 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
> > return scnprintf(msg, size,
> > "Invalid event (%s) in per-thread mode, enable system wide with '-a'.",
> > evsel__name(evsel));
> > + if (is_amd(arch, cpuid)) {
> > + if (is_amd_ibs(evsel)) {
> > + if (evsel->core.attr.exclude_kernel)
> > + return scnprintf(msg, size,
> > + "AMD IBS can't exclude kernel events. Try running at a higher privilege level.");
> > + if (!evsel->core.system_wide)
> > + return scnprintf(msg, size,
> > + "AMD IBS may only be available in system-wide/per-cpu mode. Try using -a, or -C and workload affinity");
> > + }
> > + }
> > +
> > break;
> > case ENODATA:
> > return scnprintf(msg, size, "Cannot collect data source with the load latency event alone. "
> > --
> > 2.35.1.894.gb6a874cedc-goog
>
> --
>
> - Arnaldo
--
- Arnaldo
Powered by blists - more mailing lists