RE: [EXT] Re: [PATCH v6 5/7] coresight: tmc: Add support for reading tracedata from previous boot

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Suzuki,

> -----Original Message-----
> From: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> Sent: Tuesday, January 9, 2024 4:22 PM
> To: Linu Cherian <lcherian@xxxxxxxxxxx>; mike.leach@xxxxxxxxxx;
> james.clark@xxxxxxx; leo.yan@xxxxxxxxxx
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; coresight@xxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx;
> krzysztof.kozlowski+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; Sunil Kovvuri Goutham
> <sgoutham@xxxxxxxxxxx>; George Cherian <gcherian@xxxxxxxxxxx>; Anil
> Kumar Reddy H <areddy3@xxxxxxxxxxx>; Tanmay Jagdale
> <tanmay@xxxxxxxxxxx>
> Subject: [EXT] Re: [PATCH v6 5/7] coresight: tmc: Add support for reading
> tracedata from previous boot
> 
> External Email
> 
> ----------------------------------------------------------------------
> Hi
> 
> On 05/01/2024 05:58, Linu Cherian wrote:
> > * Introduce a new mode CS_MODE_READ_PREVBOOT for reading
> tracedata
> >    captured in previous boot.
> >
> > * Add special handlers for preparing ETR/ETF for this special mode
> >
> > * User can read the trace data as below
> >
> >    For example, for reading trace data from tmc_etf sink
> >
> >    1. cd /sys/bus/coresight/devices/tmc_etfXX/
> >
> >    2. Change mode to READ_PREVBOOT
> >
> >       #echo 1 > read_prevboot
> 
> I do not like this "new mode" just for reading the crash trace.
> We are in the crash kernel when we have trace metadata available. Could we
> not simply expose this via /dev/tmc_xxx. We can certainly figure this out if
> we are in a crashkernel or not and the trace metadata is valid.
> Also, we should wipe out the trace data/metadata on a normal boot or after
> the crashkernel captures the data.

Somehow couldn’t get the intention behind wiping the tracedata/metadata after retrieval OR its just enough to add a provision to the user for wiping it. Can you please clarify.

 We don't expect the user to do tracing in
> the crashkernel, even if the user does it, it is upto the user to overwrite the
> trace. We could even expose a different file for the crash trace/metadata
> (say /dev/tmc_xxx_crash).
> 
> But please do not bloat the existing sysfs interface.
>
Since we intend to support the watchdog case as well, we cannot  restrict reading the tracedata  only from the crashdump kernel. In that regard, using a separate file /dev/tmc_xxx_crash looks better and cleaner option to me. 



> Suzuki
> 
> >
> >    3. Dump trace buffer data to a file,
> >
> >       #dd if=/dev/tmc_etfXX of=~/cstrace.bin
> >
> >    4. Reset back to normal mode
> >
> >       #echo 0 > read_prevboot
> >
> > Signed-off-by: Anil Kumar Reddy <areddy3@xxxxxxxxxxx>
> > Signed-off-by: Tanmay Jagdale <tanmay@xxxxxxxxxxx>
> > Signed-off-by: Linu Cherian <lcherian@xxxxxxxxxxx>
> > ---
> > Changelog from v5:
> > * Fixed issues reported by CONFIG_DEBUG_ATOMIC_SLEEP in
> tmc_etr_setup_prevboot_buf
> >    and tmc_etb_setup_prevboot_buf
> >    - Kmalloc invoked with spinlock taken is now done with GFP_ATOMIC
> >    - Removed the requirement for memremap with spinlock taken. This is by
> >      making a assumption that the trace buffer address used for capturing
> >      trace data during kernel crash/hang would be same as that used
> >      for trace data retrieval in the subsequent boot. Added additional
> >      verification to ensure this.
> >
> > * Fixed a memory leak in tmc_read_unprepare_etr in READ_PREVBOOT
> mode
> >
> >
> >   .../coresight/coresight-etm4x-core.c          |   1 +
> >   .../hwtracing/coresight/coresight-tmc-core.c  |  96 ++++++++++-
> >   .../hwtracing/coresight/coresight-tmc-etf.c   |  73 +++++++++
> >   .../hwtracing/coresight/coresight-tmc-etr.c   | 154 +++++++++++++++++-
> >   drivers/hwtracing/coresight/coresight-tmc.h   |   6 +
> >   include/linux/coresight.h                     |  13 ++
> >   6 files changed, 341 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > index 34aee59dd147..c26b5f72a494 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > @@ -1010,6 +1010,7 @@ static void etm4_disable(struct coresight_device
> > *csdev,
> >
> >   	switch (mode) {
> >   	case CS_MODE_DISABLED:
> > +	case CS_MODE_READ_PREVBOOT:
> >   		break;
> >   	case CS_MODE_SYSFS:
> >   		etm4_disable_sysfs(csdev);
> > diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c
> > b/drivers/hwtracing/coresight/coresight-tmc-core.c
> > index 4d7530d6ac91..e6525c3dcf66 100644
> > --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
> > @@ -103,6 +103,60 @@ u32 tmc_get_memwidth_mask(struct
> tmc_drvdata *drvdata)
> >   	return mask;
> >   }
> >
> > +int tmc_read_prepare_prevboot(struct tmc_drvdata *drvdata) {
> > +	int ret = 0;
> > +	struct tmc_crash_metadata *mdata;
> > +	struct coresight_device *csdev = drvdata->csdev;
> > +
> > +	if (!drvdata->crash_mdata.vaddr) {
> > +		ret = -ENOMEM;
> > +		goto out;
> > +	}
> > +
> > +	mdata = drvdata->crash_mdata.vaddr;
> > +	/* Check data integrity of metadata */
> > +	if (mdata->crc32_mdata != find_crash_metadata_crc(mdata)) {
> > +		dev_dbg(&drvdata->csdev->dev,
> > +			"CRC mismatch in tmc crash metadata\n");
> > +		ret = -EINVAL;
> > +		goto out;
> > +	}
> > +	/* Check data integrity of tracedata */
> > +	if (mdata->crc32_tdata != find_crash_tracedata_crc(drvdata, mdata))
> {
> > +		dev_dbg(&drvdata->csdev->dev,
> > +			"CRC mismatch in tmc crash tracedata\n");
> > +		ret = -EINVAL;
> > +		goto out;
> > +	}
> > +	/* Check for valid metadata */
> > +	if (!mdata->valid) {
> > +		dev_dbg(&drvdata->csdev->dev,
> > +			"Data invalid in tmc crash metadata\n");
> > +		ret = -EINVAL;
> > +		goto out;
> > +	}
> > +
> > +	/* Sink specific prevboot mode preparation */
> > +	ret = prevboot_ops(csdev)->prepare(csdev);
> > +	if (ret)
> > +		goto out;
> > +
> > +	if (mdata->sts & 0x1)
> > +		coresight_insert_barrier_packet(drvdata->buf);
> > +
> > +out:
> > +	return ret;
> > +}
> > +
> > +int tmc_read_unprepare_prevboot(struct tmc_drvdata *drvdata) {
> > +	struct coresight_device *csdev = drvdata->csdev;
> > +
> > +	/* Sink specific prevboot mode preparation */
> > +	return prevboot_ops(csdev)->unprepare(csdev);
> > +}
> > +
> >   static int tmc_read_prepare(struct tmc_drvdata *drvdata)
> >   {
> >   	int ret = 0;
> > @@ -153,6 +207,10 @@ static int tmc_open(struct inode *inode, struct file
> *file)
> >   	struct tmc_drvdata *drvdata = container_of(file->private_data,
> >   						   struct tmc_drvdata,
> miscdev);
> >
> > +	/* Advertise if we are opening with a special mode */
> > +	if (drvdata->mode == CS_MODE_READ_PREVBOOT)
> > +		dev_dbg(&drvdata->csdev->dev, "TMC read mode for
> previous boot\n");
> > +
> >   	ret = tmc_read_prepare(drvdata);
> >   	if (ret)
> >   		return ret;
> > @@ -331,9 +389,44 @@ static ssize_t buffer_size_store(struct device
> > *dev,
> >
> >   static DEVICE_ATTR_RW(buffer_size);
> >
> > +static ssize_t read_prevboot_show(struct device *dev,
> > +				struct device_attribute *attr, char *buf) {
> > +	struct tmc_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > +
> > +	return sprintf(buf, "%#x\n", (drvdata->mode ==
> > +CS_MODE_READ_PREVBOOT)); }
> > +
> > +static ssize_t read_prevboot_store(struct device *dev,
> > +				 struct device_attribute *attr,
> > +				 const char *buf, size_t size)
> > +{
> > +	int ret;
> > +	unsigned long val, flags;
> > +	struct tmc_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > +
> > +	ret = kstrtoul(buf, 0, &val);
> > +	if (ret)
> > +		return ret;
> > +
> > +	spin_lock_irqsave(&drvdata->spinlock, flags);
> > +
> > +	if (val && (drvdata->mode == CS_MODE_DISABLED))
> > +		drvdata->mode = CS_MODE_READ_PREVBOOT;
> > +	else if (!val && (drvdata->mode == CS_MODE_READ_PREVBOOT))
> > +		drvdata->mode = CS_MODE_DISABLED;
> > +
> > +	spin_unlock_irqrestore(&drvdata->spinlock, flags);
> > +
> > +	return size;
> > +}
> > +
> > +static DEVICE_ATTR_RW(read_prevboot);
> > +
> >   static struct attribute *coresight_tmc_attrs[] = {
> >   	&dev_attr_trigger_cntr.attr,
> >   	&dev_attr_buffer_size.attr,
> > +	&dev_attr_read_prevboot.attr,
> >   	NULL,
> >   };
> >
> > @@ -635,7 +728,8 @@ static void tmc_shutdown(struct amba_device
> *adev)
> >
> >   	spin_lock_irqsave(&drvdata->spinlock, flags);
> >
> > -	if (drvdata->mode == CS_MODE_DISABLED)
> > +	if (drvdata->mode == CS_MODE_DISABLED ||
> > +	    drvdata->mode == CS_MODE_READ_PREVBOOT)
> >   		goto out;
> >
> >   	if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) diff --git
> > a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> > b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> > index b53cef7628ff..72c2315f4e23 100644
> > --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> > +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> > @@ -648,6 +648,56 @@ static int tmc_panic_sync_etf(struct
> coresight_device *csdev)
> >   	return 0;
> >   }
> >
> > +static int tmc_etb_setup_prevboot_buf(struct tmc_drvdata *drvdata) {
> > +	unsigned long size;
> > +	struct tmc_crash_metadata *mdata;
> > +	struct device *dev = &drvdata->csdev->dev;
> > +
> > +	mdata = drvdata->crash_mdata.vaddr;
> > +	size = mdata->size << 2;
> > +
> > +	/*
> > +	 * Buffer address given by metadata for retrieval of trace data
> > +	 * from previous boot is expected to be same as the reserved
> > +	 * trace buffer memory region provided through DTS
> > +	 */
> > +	if (is_tmc_reserved_region_valid(dev->parent)
> > +	    && (drvdata->crash_tbuf.paddr == mdata->trc_paddr))
> > +		drvdata->buf = drvdata->crash_tbuf.vaddr;
> > +	else {
> > +		dev_dbg(dev, "Trace buffer address of previous boot
> invalid\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	drvdata->len = size;
> > +	return 0;
> > +}
> > +
> > +static void tmc_etb_free_prevboot_buf(struct tmc_drvdata *drvdata) {
> > +	void *buf = drvdata->buf;
> > +
> > +	if (!buf)
> > +		return;
> > +	drvdata->buf = NULL;
> > +}
> > +
> > +static int tmc_etb_prepare_prevboot(struct coresight_device *csdev) {
> > +	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev-
> >dev.parent);
> > +
> > +	return  tmc_etb_setup_prevboot_buf(drvdata);
> > +}
> > +
> > +static int tmc_etb_unprepare_prevboot(struct coresight_device *csdev)
> > +{
> > +	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev-
> >dev.parent);
> > +
> > +	tmc_etb_free_prevboot_buf(drvdata);
> > +	return 0;
> > +}
> > +
> >   static const struct coresight_ops_sink tmc_etf_sink_ops = {
> >   	.enable		= tmc_enable_etf_sink,
> >   	.disable	= tmc_disable_etf_sink,
> > @@ -665,6 +715,11 @@ static const struct coresight_ops_panic
> tmc_etf_sync_ops = {
> >   	.sync		= tmc_panic_sync_etf,
> >   };
> >
> > +static const struct coresight_ops_prevboot tmc_etf_prevboot_ops = {
> > +	.prepare	= tmc_etb_prepare_prevboot,
> > +	.unprepare	= tmc_etb_unprepare_prevboot,
> > +};
> > +
> >   const struct coresight_ops tmc_etb_cs_ops = {
> >   	.sink_ops	= &tmc_etf_sink_ops,
> >   };
> > @@ -673,6 +728,7 @@ const struct coresight_ops tmc_etf_cs_ops = {
> >   	.sink_ops	= &tmc_etf_sink_ops,
> >   	.link_ops	= &tmc_etf_link_ops,
> >   	.panic_ops	= &tmc_etf_sync_ops,
> > +	.prevboot_ops	= &tmc_etf_prevboot_ops,
> >   };
> >
> >   int tmc_read_prepare_etb(struct tmc_drvdata *drvdata) @@ -693,6
> > +749,14 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
> >   		goto out;
> >   	}
> >
> > +	if (drvdata->mode == CS_MODE_READ_PREVBOOT) {
> > +		ret = tmc_read_prepare_prevboot(drvdata);
> > +		if (ret)
> > +			goto out;
> > +		else
> > +			goto mode_valid;
> > +	}
> > +
> >   	/* Don't interfere if operated from Perf */
> >   	if (drvdata->mode == CS_MODE_PERF) {
> >   		ret = -EINVAL;
> > @@ -716,6 +780,7 @@ int tmc_read_prepare_etb(struct tmc_drvdata
> *drvdata)
> >   		__tmc_etb_disable_hw(drvdata);
> >   	}
> >
> > +mode_valid:
> >   	drvdata->reading = true;
> >   out:
> >   	spin_unlock_irqrestore(&drvdata->spinlock, flags); @@ -735,8
> > +800,16 @@ int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)
> >   			 drvdata->config_type != TMC_CONFIG_TYPE_ETF))
> >   		return -EINVAL;
> >
> > +
> >   	spin_lock_irqsave(&drvdata->spinlock, flags);
> >
> > +	if (drvdata->mode == CS_MODE_READ_PREVBOOT) {
> > +		tmc_read_unprepare_prevboot(drvdata);
> > +		drvdata->reading = false;
> > +		spin_unlock_irqrestore(&drvdata->spinlock, flags);
> > +		return 0;
> > +	}
> > +
> >   	/* Re-enable the TMC if need be */
> >   	if (drvdata->mode == CS_MODE_SYSFS) {
> >   		/* There is no point in reading a TMC in HW FIFO mode */ diff
> > --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> > b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> > index 23eb35f50571..ab7521bbb2f5 100644
> > --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> > +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> > @@ -1166,7 +1166,12 @@ ssize_t tmc_etr_get_sysfs_trace(struct
> tmc_drvdata *drvdata,
> >   {
> >   	s64 offset;
> >   	ssize_t actual = len;
> > -	struct etr_buf *etr_buf = drvdata->sysfs_buf;
> > +	struct etr_buf *etr_buf;
> > +
> > +	if (drvdata->mode == CS_MODE_READ_PREVBOOT)
> > +		etr_buf = drvdata->prevboot_buf;
> > +	else
> > +		etr_buf = drvdata->sysfs_buf;
> >
> >   	if (pos + actual > etr_buf->len)
> >   		actual = etr_buf->len - pos;
> > @@ -1873,6 +1878,130 @@ static int tmc_panic_sync_etr(struct
> coresight_device *csdev)
> >   	return 0;
> >   }
> >
> > +static int tmc_etr_setup_prevboot_buf(struct tmc_drvdata *drvdata) {
> > +	int rc = 0;
> > +	u64 trace_addr;
> > +	struct etr_buf *etr_buf;
> > +	struct etr_flat_buf *resrv_buf;
> > +	struct tmc_crash_metadata *mdata;
> > +	struct device *dev = &drvdata->csdev->dev;
> > +
> > +	mdata = drvdata->crash_mdata.vaddr;
> > +
> > +	etr_buf = kzalloc(sizeof(*etr_buf), GFP_ATOMIC);
> > +	if (!etr_buf) {
> > +		rc = -ENOMEM;
> > +		goto out;
> > +	}
> > +	etr_buf->size = drvdata->crash_tbuf.size;
> > +
> > +	resrv_buf = kzalloc(sizeof(*resrv_buf), GFP_ATOMIC);
> > +	if (!resrv_buf) {
> > +		rc = -ENOMEM;
> > +		goto rmem_err;
> > +	}
> > +
> > +	/*
> > +	 * Buffer address given by metadata for retrieval of trace data
> > +	 * from previous boot is expected to be same as the reserved
> > +	 * trace buffer memory region provided through DTS
> > +	 */
> > +	if (is_tmc_reserved_region_valid(dev->parent)
> > +	    && (drvdata->crash_tbuf.paddr == mdata->trc_paddr))
> > +		resrv_buf->vaddr = drvdata->crash_tbuf.vaddr;
> > +	else {
> > +		dev_dbg(dev, "Trace buffer address of previous boot
> invalid\n");
> > +		rc = -EINVAL;
> > +		goto map_err;
> > +	}
> > +
> > +	resrv_buf->size = etr_buf->size;
> > +	resrv_buf->dev = &drvdata->csdev->dev;
> > +	etr_buf->hwaddr = trace_addr;
> > +	etr_buf->mode = ETR_MODE_RESRV;
> > +	etr_buf->private = resrv_buf;
> > +	etr_buf->ops = etr_buf_ops[ETR_MODE_RESRV];
> > +
> > +	drvdata->prevboot_buf = etr_buf;
> > +
> > +	return 0;
> > +
> > +map_err:
> > +	kfree(resrv_buf);
> > +
> > +rmem_err:
> > +	kfree(etr_buf);
> > +
> > +out:
> > +	return rc;
> > +}
> > +
> > +static int tmc_etr_sync_prevboot_buf(struct tmc_drvdata *drvdata) {
> > +	u32 status;
> > +	u64 rrp, rwp, dba;
> > +	struct tmc_crash_metadata *mdata;
> > +	struct etr_buf *etr_buf = drvdata->prevboot_buf;
> > +
> > +	mdata = drvdata->crash_mdata.vaddr;
> > +
> > +	rrp = mdata->rrp;
> > +	rwp = mdata->rwp;
> > +	dba = mdata->dba;
> > +	status = mdata->sts;
> > +
> > +	etr_buf->full = !!(status & TMC_STS_FULL);
> > +
> > +	/* Sync the buffer pointers */
> > +	etr_buf->offset = rrp - dba;
> > +	if (etr_buf->full)
> > +		etr_buf->len = etr_buf->size;
> > +	else
> > +		etr_buf->len = rwp - rrp;
> > +
> > +	/* Additional sanity checks for validating metadata */
> > +	if ((etr_buf->offset > etr_buf->size) ||
> > +	    (etr_buf->len > etr_buf->size)) {
> > +		dev_dbg(&drvdata->csdev->dev,
> > +			"Offset and length invalid in tmc crash metadata\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static void tmc_etr_free_prevboot_buf(struct tmc_drvdata *drvdata) {
> > +	struct etr_buf *etr_buf = drvdata->prevboot_buf;
> > +
> > +	if (!etr_buf)
> > +		return;
> > +	drvdata->prevboot_buf = NULL;
> > +}
> > +
> > +static int tmc_etr_prepare_prevboot(struct coresight_device *csdev) {
> > +	int ret = 0;
> > +	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev-
> >dev.parent);
> > +
> > +	ret = tmc_etr_setup_prevboot_buf(drvdata);
> > +	if (ret)
> > +		goto out;
> > +	ret = tmc_etr_sync_prevboot_buf(drvdata);
> > +
> > +out:
> > +	return ret;
> > +}
> > +
> > +static int tmc_etr_unprepare_prevboot(struct coresight_device *csdev)
> > +{
> > +	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev-
> >dev.parent);
> > +
> > +	tmc_etr_free_prevboot_buf(drvdata);
> > +	return 0;
> > +}
> > +
> >   static const struct coresight_ops_sink tmc_etr_sink_ops = {
> >   	.enable		= tmc_enable_etr_sink,
> >   	.disable	= tmc_disable_etr_sink,
> > @@ -1885,9 +2014,15 @@ static const struct coresight_ops_panic
> tmc_etr_sync_ops = {
> >   	.sync		= tmc_panic_sync_etr,
> >   };
> >
> > +static const struct coresight_ops_prevboot tmc_etr_prevboot_ops = {
> > +	.prepare	= tmc_etr_prepare_prevboot,
> > +	.unprepare	= tmc_etr_unprepare_prevboot,
> > +};
> > +
> >   const struct coresight_ops tmc_etr_cs_ops = {
> >   	.sink_ops	= &tmc_etr_sink_ops,
> >   	.panic_ops	= &tmc_etr_sync_ops,
> > +	.prevboot_ops	= &tmc_etr_prevboot_ops,
> >   };
> >
> >   int tmc_read_prepare_etr(struct tmc_drvdata *drvdata) @@ -1899,12
> > +2034,21 @@ int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
> >   	if (WARN_ON_ONCE(drvdata->config_type !=
> TMC_CONFIG_TYPE_ETR))
> >   		return -EINVAL;
> >
> > +
> >   	spin_lock_irqsave(&drvdata->spinlock, flags);
> >   	if (drvdata->reading) {
> >   		ret = -EBUSY;
> >   		goto out;
> >   	}
> >
> > +	if (drvdata->mode == CS_MODE_READ_PREVBOOT) {
> > +		ret = tmc_read_prepare_prevboot(drvdata);
> > +		if (ret)
> > +			goto out;
> > +		else
> > +			goto mode_valid;
> > +	}
> > +
> >   	/*
> >   	 * We can safely allow reads even if the ETR is operating in PERF
> mode,
> >   	 * since the sysfs session is captured in mode specific data.
> > @@ -1919,6 +2063,7 @@ int tmc_read_prepare_etr(struct tmc_drvdata
> *drvdata)
> >   	if (drvdata->mode == CS_MODE_SYSFS)
> >   		__tmc_etr_disable_hw(drvdata);
> >
> > +mode_valid:
> >   	drvdata->reading = true;
> >   out:
> >   	spin_unlock_irqrestore(&drvdata->spinlock, flags); @@ -1937,6
> > +2082,12 @@ int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
> >
> >   	spin_lock_irqsave(&drvdata->spinlock, flags);
> >
> > +	if (drvdata->mode == CS_MODE_READ_PREVBOOT) {
> > +		sysfs_buf = drvdata->prevboot_buf;
> > +		tmc_read_unprepare_prevboot(drvdata);
> > +		goto out;
> > +	}
> > +
> >   	/* RE-enable the TMC if need be */
> >   	if (drvdata->mode == CS_MODE_SYSFS) {
> >   		/*
> > @@ -1954,6 +2105,7 @@ int tmc_read_unprepare_etr(struct tmc_drvdata
> *drvdata)
> >   		drvdata->sysfs_buf = NULL;
> >   	}
> >
> > +out:
> >   	drvdata->reading = false;
> >   	spin_unlock_irqrestore(&drvdata->spinlock, flags);
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-tmc.h
> > b/drivers/hwtracing/coresight/coresight-tmc.h
> > index 6f13caae6495..6e1e910d5ea4 100644
> > --- a/drivers/hwtracing/coresight/coresight-tmc.h
> > +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> > @@ -216,6 +216,9 @@ struct tmc_resrv_buf {
> >    * @idr_mutex:	Access serialisation for idr.
> >    * @sysfs_buf:	SYSFS buffer for ETR.
> >    * @perf_buf:	PERF buffer for ETR.
> > + * @prevboot_buf: Previous boot buffer for ETR. This is a special purpose
> > + *		buffer that is used only for mapping the trace buffer from
> > + *		previous boot and not for capturing trace.
> >    * @crash_tbuf: Used by ETR as hardware trace buffer and for trace data
> >    *		retention (after crash) only when ETR_MODE_RESRV buffer
> >    *		mode is enabled. Used by ETF for trace data retention
> > @@ -247,6 +250,7 @@ struct tmc_drvdata {
> >   	struct mutex		idr_mutex;
> >   	struct etr_buf		*sysfs_buf;
> >   	struct etr_buf		*perf_buf;
> > +	struct etr_buf		*prevboot_buf;
> >   	struct tmc_resrv_buf	crash_tbuf;
> >   	struct tmc_resrv_buf	crash_mdata;
> >   };
> > @@ -298,6 +302,8 @@ void tmc_flush_and_stop(struct tmc_drvdata
> *drvdata);
> >   void tmc_enable_hw(struct tmc_drvdata *drvdata);
> >   void tmc_disable_hw(struct tmc_drvdata *drvdata);
> >   u32 tmc_get_memwidth_mask(struct tmc_drvdata *drvdata);
> > +int tmc_read_prepare_prevboot(struct tmc_drvdata *drvdata); int
> > +tmc_read_unprepare_prevboot(struct tmc_drvdata *drvdata);
> >
> >   /* ETB/ETF functions */
> >   int tmc_read_prepare_etb(struct tmc_drvdata *drvdata); diff --git
> > a/include/linux/coresight.h b/include/linux/coresight.h index
> > 4fd518738958..9f84decf1d7a 100644
> > --- a/include/linux/coresight.h
> > +++ b/include/linux/coresight.h
> > @@ -294,6 +294,7 @@ enum cs_mode {
> >   	CS_MODE_DISABLED,
> >   	CS_MODE_SYSFS,
> >   	CS_MODE_PERF,
> > +	CS_MODE_READ_PREVBOOT, /* Trace data from previous boot */
> >   };
> >
> >   #define source_ops(csdev)	csdev->ops->source_ops
> > @@ -302,6 +303,7 @@ enum cs_mode {
> >   #define helper_ops(csdev)	csdev->ops->helper_ops
> >   #define ect_ops(csdev)		csdev->ops->ect_ops
> >   #define panic_ops(csdev)	csdev->ops->panic_ops
> > +#define prevboot_ops(csdev)	csdev->ops->prevboot_ops
> >
> >   /**
> >    * struct coresight_ops_sink - basic operations for a sink @@
> > -381,12 +383,23 @@ struct coresight_ops_panic {
> >   	int (*sync)(struct coresight_device *csdev);
> >   };
> >
> > +/**
> > + * struct coresight_ops_prevboot - Generic device ops for prevboot
> > +mode
> > + *
> > + * @prepare	: Preparation for prevboot mode
> > + */
> > +struct coresight_ops_prevboot {
> > +	int (*prepare)(struct coresight_device *csdev);
> > +	int (*unprepare)(struct coresight_device *csdev); };
> > +
> >   struct coresight_ops {
> >   	const struct coresight_ops_sink *sink_ops;
> >   	const struct coresight_ops_link *link_ops;
> >   	const struct coresight_ops_source *source_ops;
> >   	const struct coresight_ops_helper *helper_ops;
> >   	const struct coresight_ops_panic *panic_ops;
> > +	const struct coresight_ops_prevboot *prevboot_ops;
> >   };
> >
> >   #if IS_ENABLED(CONFIG_CORESIGHT)





[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]


  Powered by Linux