Commit 89b329a1 authored by Suzuki K Poulose's avatar Suzuki K Poulose Committed by Ma Wupeng
Browse files

coresight: trbe: End the AUX handle on truncation 

mainline inclusion
from mainline-v5.15-rc3
commit 9bef9d08
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5YCYK
CVE: NA

Reference: https://lore.kernel.org/r/20210923143919.2944311-5-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: default avatarAnshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20210923143919.2944311-5-suzuki.poulose@arm.com


Signed-off-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
parent 76cde988

drivers/hwtracing/coresight/coresight-trbe.c

+16 −10
Original line number Diff line number Diff line
@@ -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;

}