From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: mathieu.poirier@linaro.org, linux-arm-kernel@lists.infradead.org
Cc: anshuman.khandual@arm.com, mike.leach@linaro.org,
leo.yan@linaro.org, coresight@lists.linaro.org,
linux-kernel@vger.kernel.org,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Will Deacon <will@kernel.org>
Subject: [PATCH v4 4/5] coresight: trbe: End the AUX handle on truncation
Date: Thu, 23 Sep 2021 15:39:18 +0100 [thread overview]
Message-ID: <20210923143919.2944311-5-suzuki.poulose@arm.com> (raw)
In-Reply-To: <20210923143919.2944311-1-suzuki.poulose@arm.com>
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>
---
drivers/hwtracing/coresight/coresight-trbe.c | 26 ++++++++++++--------
1 file changed, 16 insertions(+), 10 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 0a9106c15639..4174300f1344 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -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;
}
--
2.24.1
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next prev parent reply other threads:[~2021-09-23 14:41 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 14:39 [PATCH v4 0/5] coresight: TRBE and Self-Hosted trace fixes Suzuki K Poulose
2021-09-23 14:39 ` [PATCH v4 1/5] coresight: trbe: irq handler: Do not disable TRBE if no action is needed Suzuki K Poulose
2021-09-23 14:39 ` [PATCH v4 2/5] coresight: trbe: Fix handling of spurious interrupts Suzuki K Poulose
2021-09-23 14:39 ` [PATCH v4 3/5] coresight: trbe: Do not truncate buffer on IRQ Suzuki K Poulose
2021-09-23 14:39 ` Suzuki K Poulose [this message]
2021-09-23 14:39 ` [PATCH v4 5/5] coresight: trbe: Prohibit trace before disabling TRBE Suzuki K Poulose
2021-09-23 16:55 ` [PATCH v4 0/5] coresight: TRBE and Self-Hosted trace fixes Mathieu Poirier
2021-09-23 18:07 ` Suzuki K Poulose
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