[PATCH v3 0/8] coresight: etm-perf: Fix pid tracing with VHE

Leo Yan
2021-02-06T15:10:08Z

This patch series is to support PID tracing with Virtualization Host
Extensions (VHE).

To be backward compatibility, and can both support PID tracing for the
kernel is running at either EL1 or EL2, the two new PMU formats
"contextid1" and "contextid2" are introduced, which works as switches
to trace PID for EL1 kernel and EL2 kernel respectively.

The existed PMU format "contextid" needs to be backward compatible for
users, it's changed as an alias for "contextid1" on EL1 kernel and for
"contextid2" on EL2 kernel. Therefore, even without setting "contextid"
config, the perf tool can dynamically pick up the config for PID
tracing, the user doesn't have to set the "contexid" config manually.

This patch series can be cleanly applied on perf/core branch:

commit cd07e536b020 ("Merge remote-tracking branch 'torvalds/master' into perf/core")

... and applied on the mainline kernel:

commit 1e0d27fce010 ("Merge branch 'akpm' (patches from Andrew)")

The patch series has been tested on Arm Juno-r2 board. Verified the
kernel with EL1 and didn't find issue; after some hacking in kernel
driver and tool to emulate the code paths for kernel on EL2, can see
the code path is hit without failure.

Changes from v2:
* Split into two patches for clarification comment on perf options, one
patch is for kernel change and the another one is for tools' change
(Suzuki);
* Simplified cs_etm__get_pid_fmt() to return ETM_OPT_CTXTID2 OR
ETM_OPT_CTXTID, but not both (Suzuki);
* Cached "pid_fmt" in cs_etm_decoder__set_tid() (Suzuki);
* Refined documentation for more clear description for PMU format usages
(Mike);
* Added Suzuki's and Mike's Reviewed tags.

Changes from v1:
* Refactored PMU formats, added formats "contextid1"/"contextid2", and
reworked format "contextid" (Suzuki/Mathieu);
* Refined the comments for perf configs (Leo/Mike);
* Added patch 07/07 for description PID tracing in docs;
* Found the issue for bitmap for option, extracted patch 03/07 for the
fixing.

Changes from RFC:
* Added comments to clarify cases requested (Leo);
* Explain the change to generic flags for cs_etm_set_option() in the
commit description;
* Stored PID format in metadata and passed it to decoder (Leo);
* Enhanced cs-etm for backward compatibility (Denis Nikitin).

Leo Yan (4):
coresight: etm-perf: Clarify comment on perf options
tools headers UAPI: Update tools' copy of linux/coresight-pmu.h
perf cs-etm: Add helper cs_etm__get_pid_fmt()
Documentation: coresight: Add PID tracing description

Suzuki K Poulose (4):
coresight: etm-perf: Support PID tracing for kernel at EL2
perf cs-etm: Fix bitmap for option
perf cs-etm: Support PID tracing in config
perf cs-etm: Detect pid in VMID for kernel running at EL2

Documentation/trace/coresight/coresight.rst | 32 ++++++++
.../hwtracing/coresight/coresight-etm-perf.c | 32 +++++++-
.../coresight/coresight-etm4x-core.c | 13 ++++
include/linux/coresight-pmu.h | 20 +++--
tools/include/linux/coresight-pmu.h | 20 +++--
tools/perf/arch/arm/util/cs-etm.c | 73 +++++++++++++++----
.../perf/util/cs-etm-decoder/cs-etm-decoder.c | 38 +++++++++-
tools/perf/util/cs-etm.c | 42 +++++++++++
tools/perf/util/cs-etm.h | 1 +
9 files changed, 239 insertions(+), 32 deletions(-)

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2.25.1