linux-kernel - [PATCH v2 03/17] coresight: trbe: Add a helper to calculate the trace generated

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Message-Id: <20210921134121.2423546-4-suzuki.poulose@arm.com>
Date:   Tue, 21 Sep 2021 14:41:07 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, maz@...nel.org,
        catalin.marinas@....com, mark.rutland@....com, james.morse@....com,
        anshuman.khandual@....com, leo.yan@...aro.org,
        mike.leach@...aro.org, mathieu.poirier@...aro.org, will@...nel.org,
        lcherian@...vell.com, coresight@...ts.linaro.org,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH v2 03/17] coresight: trbe: Add a helper to calculate the trace generated

We collect the trace from the TRBE on FILL event from IRQ context
and when via update_buffer(), when the event is stopped. Let us
consolidate how we calculate the trace generated into a helper.

Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Mike Leach <mike.leach@...aro.org>
Cc: Leo Yan <leo.yan@...aro.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 drivers/hwtracing/coresight/coresight-trbe.c | 48 ++++++++++++--------
 1 file changed, 30 insertions(+), 18 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 63f7edd5fd1f..063c4505a203 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -527,6 +527,30 @@ static enum trbe_fault_action trbe_get_fault_act(u64 trbsr)
 	return TRBE_FAULT_ACT_SPURIOUS;
 }
 
+static unsigned long trbe_get_trace_size(struct perf_output_handle *handle,
+					 struct trbe_buf *buf,
+					 bool wrap)
+{
+	u64 write;
+	u64 start_off, end_off;
+
+	/*
+	 * If the TRBE has wrapped around the write pointer has
+	 * wrapped and should be treated as limit.
+	 */
+	if (wrap)
+		write = get_trbe_limit_pointer();
+	else
+		write = get_trbe_write_pointer();
+
+	end_off = write - buf->trbe_base;
+	start_off = PERF_IDX2OFF(handle->head, buf);
+
+	if (WARN_ON_ONCE(end_off < start_off))
+		return 0;
+	return (end_off - start_off);
+}
+
 static void *arm_trbe_alloc_buffer(struct coresight_device *csdev,
 				   struct perf_event *event, void **pages,
 				   int nr_pages, bool snapshot)
@@ -588,9 +612,9 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev,
 	struct trbe_cpudata *cpudata = dev_get_drvdata(&csdev->dev);
 	struct trbe_buf *buf = config;
 	enum trbe_fault_action act;
-	unsigned long size, offset;
-	unsigned long write, base, status;
+	unsigned long size, status;
 	unsigned long flags;
+	bool wrap = false;
 
 	WARN_ON(buf->cpudata != cpudata);
 	WARN_ON(cpudata->cpu != smp_processor_id());
@@ -630,8 +654,6 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev,
 	 * handle gets freed in etm_event_stop().
 	 */
 	trbe_drain_and_disable_local();
-	write = get_trbe_write_pointer();
-	base = get_trbe_base_pointer();
 
 	/* Check if there is a pending interrupt and handle it here */
 	status = read_sysreg_s(SYS_TRBSR_EL1);
@@ -655,20 +677,11 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev,
 			goto done;
 		}
 
-		/*
-		 * Otherwise, the buffer is full and the write pointer
-		 * has reached base. Adjust this back to the Limit pointer
-		 * for correct size. Also, mark the buffer truncated.
-		 */
-		write = get_trbe_limit_pointer();
 		perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION);
+		wrap = true;
 	}
 
-	offset = write - base;
-	if (WARN_ON_ONCE(offset < PERF_IDX2OFF(handle->head, buf)))
-		size = 0;
-	else
-		size = offset - PERF_IDX2OFF(handle->head, buf);
+	size = trbe_get_trace_size(handle, buf, wrap);
 
 done:
 	local_irq_restore(flags);
@@ -749,11 +762,10 @@ 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);
-	unsigned long offset, size;
+	unsigned long size;
 	struct etm_event_data *event_data;
 
-	offset = get_trbe_limit_pointer() - get_trbe_base_pointer();
-	size = offset - PERF_IDX2OFF(handle->head, buf);
+	size = trbe_get_trace_size(handle, buf, true);
 	if (buf->snapshot)
 		handle->head += size;
 
-- 
2.24.1