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coresight: trbe: End the AUX handle on truncation

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When we detect that there isn't enough space left to start a meaningful
session, we disable the TRBE, marking the buffer as TRUNCATED. But we delay
the notification to the perf layer by perf_aux_output_end() until the event
is scheduled out, triggered from the kernel perf layer. This will cause
significant black outs in the trace. Now that the CoreSight PMU layer can
handle a closed "AUX" handle properly, we can close the handle as soon as
we detect the case, allowing the userspace to collect and re-enable the
event.

Also, while in the IRQ handler, move the irq_work_run() after we have
updated the handle, to make sure the "TRUNCATED" flag causes the event to
be disabled as soon as possible.

Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20210923143919.2944311-5-suzuki.poulose@arm.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
This commit is contained in:
Suzuki K Poulose 2021-09-23 15:39:18 +01:00 committed by Mathieu Poirier
parent 0a5f355633
commit 9bef9d0850
1 changed files with 16 additions and 10 deletions
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26
drivers/hwtracing/coresight/coresight-trbe.c
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@ -152,6 +152,7 @@ static void trbe_stop_and_truncate_event(struct perf_output_handle *handle)
*/
trbe_drain_and_disable_local();
perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
perf_aux_output_end(handle, 0);
*this_cpu_ptr(buf->cpudata->drvdata->handle) = NULL;
}
@ -715,7 +716,7 @@ static void trbe_handle_spurious(struct perf_output_handle *handle)
isb();
}
static void trbe_handle_overflow(struct perf_output_handle *handle)
static int trbe_handle_overflow(struct perf_output_handle *handle)
{
struct perf_event *event = handle->event;
struct trbe_buf *buf = etm_perf_sink_config(handle);
@ -739,9 +740,10 @@ static void trbe_handle_overflow(struct perf_output_handle *handle)
*/
trbe_drain_and_disable_local();
*this_cpu_ptr(buf->cpudata->drvdata->handle) = NULL;
return;
return -EINVAL;
}
__arm_trbe_enable(buf, handle);
return __arm_trbe_enable(buf, handle);
}
static bool is_perf_trbe(struct perf_output_handle *handle)
@ -772,6 +774,7 @@ static irqreturn_t arm_trbe_irq_handler(int irq, void *dev)
struct perf_output_handle *handle = *handle_ptr;
enum trbe_fault_action act;
u64 status;
bool truncated = false;
/* Reads to TRBSR_EL1 is fine when TRBE is active */
status = read_sysreg_s(SYS_TRBSR_EL1);
@ -796,24 +799,27 @@ static irqreturn_t arm_trbe_irq_handler(int irq, void *dev)
if (!is_perf_trbe(handle))
return IRQ_NONE;
/*
* Ensure perf callbacks have completed, which may disable
* the trace buffer in response to a TRUNCATION flag.
*/
irq_work_run();
act = trbe_get_fault_act(status);
switch (act) {
case TRBE_FAULT_ACT_WRAP:
trbe_handle_overflow(handle);
truncated = !!trbe_handle_overflow(handle);
break;
case TRBE_FAULT_ACT_SPURIOUS:
trbe_handle_spurious(handle);
break;
case TRBE_FAULT_ACT_FATAL:
trbe_stop_and_truncate_event(handle);
truncated = true;
break;
}
/*
* If the buffer was truncated, ensure perf callbacks
* have completed, which will disable the event.
*/
if (truncated)
irq_work_run();
return IRQ_HANDLED;
}