From: Leo Yan <leo.yan@linaro.org>
To: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Mike Leach <mike.leach@linaro.org>,
Jonathan Corbet <corbet@lwn.net>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
John Garry <john.garry@huawei.com>, Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Mark Rutland <mark.rutland@arm.com>, Jiri Olsa <jolsa@redhat.com>,
Namhyung Kim <namhyung@kernel.org>,
Daniel Kiss <Daniel.Kiss@arm.com>,
Denis Nikitin <denik@chromium.org>,
coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
Al Grant <al.grant@arm.com>
Subject: Re: [PATCH v2 6/7] perf cs-etm: Detect pid in VMID for kernel running at EL2
Date: Thu, 4 Feb 2021 12:00:28 +0800 [thread overview]
Message-ID: <20210204040021.GF11059@leoy-ThinkPad-X240s> (raw)
In-Reply-To: <f5158216-c3d1-10bb-02eb-00ff9a78f617@arm.com>
On Tue, Feb 02, 2021 at 11:29:47PM +0000, Suzuki Kuruppassery Poulose wrote:
> On 2/2/21 4:38 PM, Leo Yan wrote:
> > From: Suzuki K Poulose <suzuki.poulose@arm.com>
> >
> > The PID of the task could be traced as VMID when the kernel is running
> > at EL2. Teach the decoder to look for VMID when the CONTEXTIDR (Arm32)
> > or CONTEXTIDR_EL1 (Arm64) is invalid but we have a valid VMID.
> >
> > Cc: Mike Leach <mike.leach@linaro.org>
> > Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> > Cc: Al Grant <al.grant@arm.com>
> > Co-developed-by: Leo Yan <leo.yan@linaro.org>
> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > ---
> > .../perf/util/cs-etm-decoder/cs-etm-decoder.c | 32 ++++++++++++++++---
> > 1 file changed, 28 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> > index 3f4bc4050477..fb2a163ff74e 100644
> > --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> > +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> > @@ -6,6 +6,7 @@
> > * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
> > */
> > +#include <linux/coresight-pmu.h>
> > #include <linux/err.h>
> > #include <linux/list.h>
> > #include <linux/zalloc.h>
> > @@ -491,13 +492,36 @@ cs_etm_decoder__set_tid(struct cs_etm_queue *etmq,
> > const ocsd_generic_trace_elem *elem,
> > const uint8_t trace_chan_id)
> > {
> > - pid_t tid;
> > + pid_t tid = -1;
> > + u64 pid_fmt;
> > + int ret;
> > - /* Ignore PE_CONTEXT packets that don't have a valid contextID */
> > - if (!elem->context.ctxt_id_valid)
> > + ret = cs_etm__get_pid_fmt(trace_chan_id, &pid_fmt);
> > + if (ret)
>
> Is this something we can cache in this function ? e.g,
> static u64 pid_fmt;
>
> if (!pid_pfmt)
> ret = cs_etm__get_pid_fmt(trace_chan_id, &pid_fmt);
>
> As all the ETMs will be running at the same exception level.
Sorry that I let you repeated your comments again.
To be honest, I considered this after read your comment in the previous
series, but I thought it's possible that multiple CPUs have different
PID format, especially for big.LITTLE arch. After read your suggestion
again, I think my concern is not valid, even for big.LITTLE, all CPUs
should run on the same kernel exception level.
So will follow up your suggestion to cache "pid_fmt".
>
> > + return OCSD_RESP_FATAL_SYS_ERR;
> > +
> > + /*
> > + * Process the PE_CONTEXT packets if we have a valid contextID or VMID.
> > + * If the kernel is running at EL2, the PID is traced in CONTEXTIDR_EL2
> > + * as VMID, Bit ETM_OPT_CTXTID2 is set in this case.
> > + */
> > + switch (pid_fmt) {
> > + case BIT(ETM_OPT_CTXTID):
> > + if (elem->context.ctxt_id_valid)
> > + tid = elem->context.context_id;
> > + break;
> > + case BIT(ETM_OPT_CTXTID2) | BIT(ETM_OPT_CTXTID):
>
> I would rather fix the cs_etm__get_pid_fmt() to return either of these
> as commented. i.e, ETM_OPT_CTXTID or ETM_OPT_CTXTID2. Thus we don't
> need the this case.
I explained why I set both bits for ETM_OPT_CTXTID and ETM_OPT_CTXTID2
in the patch 05/07. Could you take a look for it?
> With the above two addressed:
>
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Thanks,
Leo
next prev parent reply other threads:[~2021-02-04 4:02 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 16:38 [PATCH v2 0/7] coresight: etm-perf: Fix pid tracing with VHE Leo Yan
2021-02-02 16:38 ` [PATCH v2 1/7] coresight: etm-perf: Clarify comment on perf options Leo Yan
2021-02-02 23:00 ` Suzuki K Poulose
2021-02-04 3:36 ` Leo Yan
2021-02-02 16:38 ` [PATCH v2 2/7] coresight: etm-perf: Support PID tracing for kernel at EL2 Leo Yan
2021-02-02 23:06 ` Suzuki K Poulose
2021-02-05 13:47 ` Mike Leach
2021-02-02 16:38 ` [PATCH v2 3/7] perf cs-etm: Fix bitmap for option Leo Yan
2021-02-05 11:47 ` Mike Leach
2021-02-02 16:38 ` [PATCH v2 4/7] perf cs-etm: Support PID tracing in config Leo Yan
2021-02-05 13:48 ` Mike Leach
2021-02-02 16:38 ` [PATCH v2 5/7] perf cs-etm: Add helper cs_etm__get_pid_fmt() Leo Yan
2021-02-02 23:19 ` Suzuki K Poulose
2021-02-04 3:47 ` Leo Yan
2021-02-04 10:54 ` Suzuki K Poulose
2021-02-04 11:23 ` Leo Yan
2021-02-02 16:38 ` [PATCH v2 6/7] perf cs-etm: Detect pid in VMID for kernel running at EL2 Leo Yan
2021-02-02 23:29 ` Suzuki K Poulose
2021-02-04 4:00 ` Leo Yan [this message]
2021-02-04 10:57 ` Suzuki K Poulose
2021-02-02 16:38 ` [PATCH v2 7/7] Documentation: coresight: Add PID tracing description Leo Yan
2021-02-02 23:24 ` Suzuki K Poulose
2021-02-04 4:02 ` Leo Yan
2021-02-03 17:39 ` Mike Leach
2021-02-04 4:09 ` Leo Yan
2021-02-04 11:08 ` Suzuki K Poulose
2021-02-04 12:14 ` Mike Leach
2021-02-05 5:42 ` Leo Yan
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