| Message ID | 20210723124611.3828908-1-suzuki.poulose@arm.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | coresight: TRBE and Self-Hosted trace fixes | expand |
On 23/07/2021 13:46, Suzuki K Poulose wrote: > This series fixes the following issues with the TRBE and Self-Hosted > trace for CoreSight. > > The Self-hosted trace filter control registers are now save-restored > across CPU PM event. And more importantly the Trace Filtering is now > used to control per ETM session (rather than allowing the trace > throughout the life time of the system). i.e, ETM configuration of > the given run is used to enforce trace filtering (TRFCR) along with the > Trace Exclusion controls in TRCVICTLR. > > For the TRBE, we were using the TRUNCATED flag in the AUX buffer on > every IRQ to indicate that we may have lost a few bytes of trace. But > this causes the event to be disabled until the userspace re-enables > it back, even when there is space left in the ring buffer. To make > things worse, we were restarting the AUX handle, which would soon > be disabled, potentially creating 0 sized records (without truncation), > which the perf tool tends to ignore. This might cause the event to be > disabled permanently. Also, sometimes we leave the buffer TRUNCATED, > but delay the closing of the handle to event schedule out, which could > cause significant black out in the trace capture. This was reported > by Tamas Zsoldos. > > This series removes the use of TRUNCATED flag for every IRQ. Instead, > it is only used if we really run out of space in the buffer. And also > we make sure the "handle" is closed immediately on TRUNCATED case, > which triggers the userspace to take action. The core perf layer has > been hardened to handle this case where a "handle" is closed out. > Finally, we make sure that the CPU trace is prohibited, when the TRBE > is left disabled. The ETE/ETM driver will program the Trace Filtering > appropriately since we do this dynamically now with the first half > of the series. > > The series is also available here : https://git.gitlab.arm.com/linux-arm/linux-skp.git coresight/trbe-self-hosted-fixes/v2 Suzuki
This series fixes the following issues with the TRBE and Self-Hosted trace for CoreSight. The Self-hosted trace filter control registers are now save-restored across CPU PM event. And more importantly the Trace Filtering is now used to control per ETM session (rather than allowing the trace throughout the life time of the system). i.e, ETM configuration of the given run is used to enforce trace filtering (TRFCR) along with the Trace Exclusion controls in TRCVICTLR. For the TRBE, we were using the TRUNCATED flag in the AUX buffer on every IRQ to indicate that we may have lost a few bytes of trace. But this causes the event to be disabled until the userspace re-enables it back, even when there is space left in the ring buffer. To make things worse, we were restarting the AUX handle, which would soon be disabled, potentially creating 0 sized records (without truncation), which the perf tool tends to ignore. This might cause the event to be disabled permanently. Also, sometimes we leave the buffer TRUNCATED, but delay the closing of the handle to event schedule out, which could cause significant black out in the trace capture. This was reported by Tamas Zsoldos. This series removes the use of TRUNCATED flag for every IRQ. Instead, it is only used if we really run out of space in the buffer. And also we make sure the "handle" is closed immediately on TRUNCATED case, which triggers the userspace to take action. The core perf layer has been hardened to handle this case where a "handle" is closed out. Finally, we make sure that the CPU trace is prohibited, when the TRBE is left disabled. The ETE/ETM driver will program the Trace Filtering appropriately since we do this dynamically now with the first half of the series. Changes since v1 [0]: - Moved TRFCR related accessors to a new header file - Following a discussion, dropped the TRUNCATED flag from the TRBE IRQ handler on WRAP. Instead mark COLLISION. - Added new patches to harden the ETM perf layer to handle an error in the sink driver. - Fix TRBE spurious IRQ handling - Cleanup TRBE driver to make the "TRUNCATE" cases managed at a central place. [0] https://lkml.kernel.org/r/20210712113830.2803257-1-suzuki.poulose@arm.com Suzuki K Poulose (10): coresight: etm4x: Save restore TRFCR_EL1 coresight: etm4x: Use Trace Filtering controls dynamically coresight: etm-pmu: Ensure the AUX handle is valid coresight: trbe: Ensure the format flag is set on truncation coresight: trbe: Drop duplicate TRUNCATE flags coresight: trbe: Fix handling of spurious interrupts coresight: trbe: Do not truncate buffer on IRQ coresight: trbe: Unify the enabling sequence coresight: trbe: End the AUX handle on truncation coresight: trbe: Prohibit trace before disabling TRBE .../hwtracing/coresight/coresight-etm-perf.c | 27 ++++- .../coresight/coresight-etm4x-core.c | 98 ++++++++++++---- drivers/hwtracing/coresight/coresight-etm4x.h | 7 +- .../coresight/coresight-self-hosted-trace.h | 34 ++++++ drivers/hwtracing/coresight/coresight-trbe.c | 109 ++++++++++-------- 5 files changed, 197 insertions(+), 78 deletions(-) create mode 100644 drivers/hwtracing/coresight/coresight-self-hosted-trace.h