[PATCH v1 3/4] coresight: tmc: hook panic callback for ETB/ETF

From: Leo Yan
Date: Sat Jun 03 2017 - 10:43:45 EST


The panic dump functionality has been ready, this patch is to hook
panic callback function for ETB/ETF. Because the driver data structure
has allocated buffer when the session started, so simply save ETB/ETF
trace data into the buffer when panic happens.

Below is simple usage when we connect kdump to extract trace data:

- During kernel panic, tmc driver prints out below log.
Dump ETB buffer 0x2000@0xffff80003bd5a180

- After get kernel dump file 'vmcore', use below command to extract
ETB/ETF trace data.
crash vmlinux vmcore
rd 0xffff80003bd5a180 0x2000 -r cs_etb_trace.bin

- Generate perf formatted file, so can be analyzed by perf tool:
python perf_cs_dump_wrapper.py -i cs_etb_trace.bin -o perf.data
./perf script -v -F cpu,event,ip,sym,symoff --kallsyms ksymbol -i perf.data -k vmlinux

Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
---
drivers/hwtracing/coresight/coresight-tmc-etf.c | 26 +++++++++++++++++++++++++
1 file changed, 26 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index e3b9fb8..4cadbb1 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -476,6 +476,31 @@ static void tmc_update_etf_buffer(struct coresight_device *csdev,
CS_LOCK(drvdata->base);
}

+static int tmc_panic_cb(struct coresight_device *csdev)
+{
+ struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+ unsigned long flags;
+
+ if (WARN_ON_ONCE(drvdata->config_type != TMC_CONFIG_TYPE_ETB &&
+ drvdata->config_type != TMC_CONFIG_TYPE_ETF))
+ return -EINVAL;
+
+ spin_lock_irqsave(&drvdata->spinlock, flags);
+
+ CS_UNLOCK(drvdata->base);
+
+ tmc_flush_and_stop(drvdata);
+ tmc_etb_dump_hw(drvdata);
+
+ CS_LOCK(drvdata->base);
+
+ dev_err(drvdata->dev, "Dump ETB buffer 0x%x@0x%p\n",
+ drvdata->len, drvdata->buf);
+
+ spin_unlock_irqrestore(&drvdata->spinlock, flags);
+ return 0;
+}
+
static const struct coresight_ops_sink tmc_etf_sink_ops = {
.enable = tmc_enable_etf_sink,
.disable = tmc_disable_etf_sink,
@@ -484,6 +509,7 @@ static const struct coresight_ops_sink tmc_etf_sink_ops = {
.set_buffer = tmc_set_etf_buffer,
.reset_buffer = tmc_reset_etf_buffer,
.update_buffer = tmc_update_etf_buffer,
+ .panic_cb = tmc_panic_cb,
};

static const struct coresight_ops_link tmc_etf_link_ops = {
--
2.7.4