commit b24c29a6417ea30b79efbcb93bbdd81ee6e2fac6
author Suzuki K Poulose <suzuki.poulose@arm.com> Thu Feb 11 10:20:37 2021 -0700
committer Todd Kjos <tkjos@google.com> Mon Mar 01 12:52:12 2021 -0800
tree e050f2aee962596db6ad74463655ffb67bccda57
parent 60fa5196c8862631270dd371cd806b90f591b421

UPSTREAM: coresight: etm-perf: Support PID tracing for kernel at EL2

When the kernel is running at EL2, the PID is stored in CONTEXTIDR_EL2.
So, tracing CONTEXTIDR_EL1 doesn't give us the pid of the process.
Thus we should trace the VMID with VMIDOPT set to trace CONTEXTIDR_EL2
instead of CONTEXTIDR_EL1.  Given that we have an existing config
option "contextid" and this will be useful for tracing virtual machines
(when we get to support virtualization).

So instead, this patch extends option CTXTID with an extra bit
ETM_OPT_CTXTID2 (bit 15), thus on an EL2 kernel, we will have another
bit available for the perf tool: ETM_OPT_CTXTID is for kernel running in
EL1, ETM_OPT_CTXTID2 is used when kernel runs in EL2 with VHE enabled.

The tool must be backward compatible for users, i.e, "contextid" today
traces PID and that should remain the same; for this purpose, the perf
tool is updated to automatically set corresponding bit for the
"contextid" config, therefore, the user doesn't have to bother which EL
the kernel is running.

  i.e, perf record -e cs_etm/contextid/u --

will always do the "pid" tracing, independent of the kernel EL.

The driver parses the format "contextid", which traces CONTEXTIDR_EL1
for ETM_OPT_CTXTID (on EL1 kernel) and traces CONTEXTIDR_EL2 for
ETM_OPT_CTXTID2 (on EL2 kernel).

Besides the enhancement for format "contexid", extra two formats are
introduced: "contextid1" and "contextid2".  This considers to support
tracing both CONTEXTIDR_EL1 and CONTEXTIDR_EL2 when the kernel is
running at EL2.  Finally, the PMU formats are defined as follow:

  "contextid1": Available on both EL1 kernel and EL2 kernel.  When the
                kernel is running at EL1, "contextid1" enables the PID
		tracing; when the kernel is running at EL2, this enables
		tracing the PID of guest applications.

  "contextid2": Only usable when the kernel is running at EL2.  When
                selected, enables PID tracing on EL2 kernel.

  "contextid":  Will be an alias for the option that enables PID
                tracing.  I.e,
                contextid == contextid1, on EL1 kernel.
                contextid == contextid2, on EL2 kernel.

Bug: 174685394
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Al Grant <al.grant@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
[ Added two config formats: contextid1, contextid2 ]
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20210206150833.42120-4-leo.yan@linaro.org
Link: https://lore.kernel.org/r/20210211172038.2483517-3-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 88f11864cf1d1324f620059ec747d74b72d9d736)
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Change-Id: Ied5b90940eb99386e70ad977ed10dd8ef0bd40e6