[PATCH v11 0/8] Coresight for Kernel panic and watchdog reset

[PATCH v11 0/8] Coresight for Kernel panic and watchdog reset

[Linu Cherian]

This patch series is rebased on coresight-next-v6.12.rc4

* Patches 1 & 2 adds support for allocation of trace buffer pages from reserved RAM
* Patches 3 & 4 adds support for saving metadata at the time of kernel panic 
* Patch 5 adds support for reading trace data captured at the time of panic
* Patches 6 & 7 adds support for disabling coresight blocks at the time of panic
* Patch 8: Gives the full description about this feature as part of documentation 

V10 is posted here,
https://lore.kernel.org/linux-arm-kernel/20240916103437.226816-1-lcherian@marvell.com/

Changelog from v10:
* Converted all csdev_access_* to readl functions in tmc_panic_sync_*
* Added "tmc" prefix for register snapshots in struct tmc_crash_metadata
* Converted dev_info to dev_dbg in panic handlers 
* Converted dsb to dmb in panic handlers 
* Fixed marking metadata as invalid when a user is trying to use the
  reserved buffer. Earlier this was wrongly set at the time of reading
  reserved trace buffer.
* Moved common validation checks to is_tmc_crashdata_valid and minor
  code rearrangements for efficiency
* Got rid of sink specific prepare/unprepare invocations  
* Got rid of full from struct tmc_resrv_buf
* While reading crashdata, size is now calculated from metdata instead 
  of relying on reserved buffer size populated by dtb 
* Minor documenation fixes

Changelog from v9:
* Add common helper function of_tmc_get_reserved_resource_by_name
  for better code reuse
* Reserved buffer validity and crashdata validity has been separated to
  avoid interdependence
* New fields added to crash metadata: version, ffcr, ffsr, mode
* Version checks added for metadata validation
* Special file /dev/crash_tmc_xxx would be available only when
  crash metadata is valid
* Removed READ_CRASHDATA mode meant for special casing crashdata reads.
  Instead, dedicated read function added for crashdata reads from reserved
  buffer which is common for both ETR and ETF sinks as well.
* Documentation added to Documentation/tracing/coresight/panic.rst

Changelog from v8:
* Added missing exit path on error in __tmc_probe.
* Few whitespace fixes, checkpatch fixes.
* With perf sessions honouring stop_on_flush sysfs attribute, 
  removed redundant variable stop_on_flush_en. 

Changelog from v7:
* Fixed breakage on perf test -vvvv  "arm coresight".
  No issues seen with and without "resrv" buffer mode
* Moved the crashdev registration into a separate function.
* Removed redundant variable in tmc_etr_setup_crashdata_buf
* Avoided a redundant memcpy in tmc_panic_sync_etf.
* Tested kernel panic with trace session started uisng perf.   
  Please see the title "Perf based testing" below for details.
  For this, stop_on_flush sysfs attribute is taken into 
  consideration while starting perf sessions as well. 

Changelog from v6:
* Added special device files for reading crashdata, so that
  read_prevboot mode flag is removed. 
* Added new sysfs TMC device attribute, stop_on_flush.
  Stop on flush trigger event is disabled by default. 
  User need to explicitly enable this from sysfs for panic stop
  to work.
* Address parameter for panicstop ETM configuration is   
  chosen as kernel "panic" address by default.
* Added missing tmc_wait_for_tmcready during panic handling
* Few other misc code rearrangements. 

Changelog from v5:
* Fixed issues reported by CONFIG_DEBUG_ATOMIC_SLEEP
* Fixed a memory leak while reading data from /dev/tmc_etrx in
  READ_PREVBOOT mode
* Tested reading trace data from crashdump kernel

Changelog from v4:
* Device tree binding
  - Description is made more explicit on the usage of reserved memory
    region
  - Mismatch in memory region names in dts binding and driver fixed
  - Removed "mem" suffix from the memory region names
* Rename "struct tmc_register_snapshot" ->  "struct tmc_crash_metadata",
  since it contains more than register snapshot.
  Related variables are named accordingly.
* Rename struct tmc_drvdata members
   resrv_buf -> crash_tbuf
   metadata  -> crash_mdata
* Size field in metadata refers to RSZ register and hence indicates the
  size in 32 bit words. ETR metadata follows this convention, the same
  has been extended to ETF metadata as well.
* Added crc32 for more robust metadata and tracedata validation.
* Added/modified dev_dbg messages during metadata validation
* Fixed a typo in patch 5 commit description

Changelog from v3:
* Converted the Coresight ETM driver change to a named configuration.
  RFC tag has been removed with this change.
* Fixed yaml issues reported by "make dt_binding_check"
* Added names for reserved memory regions 0 and 1
* Added prevalidation checks for metadata processing
* Fixed a regression introduced in RFC v3
  - TMC Status register was getting saved wrongly
* Reverted memremap attribute changes from _WB to _WC to match
  with the dma map attributes
* Introduced reserved buffer mode specific .sync op.
  This fixes a possible crash when reserved buffer mode was used in
  normal trace capture, due to unwanted dma maintenance operations.



Linu Cherian (8):
  dt-bindings: arm: coresight-tmc: Add "memory-region" property
  coresight: tmc-etr: Add support to use reserved trace memory
  coresight: core: Add provision for panic callbacks
  coresight: tmc: Enable panic sync handling
  coresight: tmc: Add support for reading crash data
  coresight: tmc: Stop trace capture on FlIn
  coresight: config: Add preloaded configuration
  Documentation: coresight: Panic support

 .../bindings/arm/arm,coresight-tmc.yaml       |  26 ++
 Documentation/trace/coresight/panic.rst       | 356 ++++++++++++++++++
 drivers/hwtracing/coresight/Makefile          |   2 +-
 .../coresight/coresight-cfg-preload.c         |   2 +
 .../coresight/coresight-cfg-preload.h         |   2 +
 .../hwtracing/coresight/coresight-cfg-pstop.c |  83 ++++
 drivers/hwtracing/coresight/coresight-core.c  |  42 +++
 .../hwtracing/coresight/coresight-tmc-core.c  | 326 +++++++++++++++-
 .../hwtracing/coresight/coresight-tmc-etf.c   |  92 ++++-
 .../hwtracing/coresight/coresight-tmc-etr.c   | 181 ++++++++-
 drivers/hwtracing/coresight/coresight-tmc.h   | 104 +++++
 include/linux/coresight.h                     |  12 +
 12 files changed, 1216 insertions(+), 12 deletions(-)
 create mode 100644 Documentation/trace/coresight/panic.rst
 create mode 100644 drivers/hwtracing/coresight/coresight-cfg-pstop.c

-- 
2.34.1

[PATCH v11 1/8] dt-bindings: arm: coresight-tmc: Add "memory-region" property

[Linu Cherian]

memory-region 0: Reserved trace buffer memory

  TMC ETR: When available, use this reserved memory region for
  trace data capture. Same region is used for trace data
  retention after a panic or watchdog reset.

  TMC ETF: When available, use this reserved memory region for
  trace data retention synced from internal SRAM after a panic or
  watchdog reset.

memory-region 1: Reserved meta data memory

  TMC ETR, ETF: When available, use this memory for register
  snapshot retention synced from hardware registers after a panic
  or watchdog reset.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linu Cherian <lcherian@marvell.com>
---
Changelog from v10:
No changes.

 .../bindings/arm/arm,coresight-tmc.yaml       | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml b/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml
index cb8dceaca70e..4787d7c6bac2 100644
--- a/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml
+++ b/Documentation/devicetree/bindings/arm/arm,coresight-tmc.yaml
@@ -101,6 +101,29 @@ properties:
           and ETF configurations.
         $ref: /schemas/graph.yaml#/properties/port
 
+  memory-region:
+    items:
+      - description: Reserved trace buffer memory for ETR and ETF sinks.
+          For ETR, this reserved memory region is used for trace data capture.
+          Same region is used for trace data retention as well after a panic
+          or watchdog reset.
+          This reserved memory region is used as trace buffer or used for trace
+          data retention only if specifically selected by the user in sysfs
+          interface.
+          The default memory usage models for ETR in sysfs/perf modes are
+          otherwise unaltered.
+
+          For ETF, this reserved memory region is used by default for
+          retention of trace data synced from internal SRAM after a panic
+          or watchdog reset.
+      - description: Reserved meta data memory. Used for ETR and ETF sinks
+          for storing metadata.
+
+  memory-region-names:
+    items:
+      - const: tracedata
+      - const: metadata
+
 required:
   - compatible
   - reg
@@ -115,6 +138,9 @@ examples:
     etr@20070000 {
         compatible = "arm,coresight-tmc", "arm,primecell";
         reg = <0x20070000 0x1000>;
+        memory-region = <&etr_trace_mem_reserved>,
+                       <&etr_mdata_mem_reserved>;
+        memory-region-names = "tracedata", "metadata";
 
         clocks = <&oscclk6a>;
         clock-names = "apb_pclk";
-- 
2.34.1

[PATCH v11 2/8] coresight: tmc-etr: Add support to use reserved trace memory

[Linu Cherian]

Add support to use reserved memory for coresight ETR trace buffer.

Introduce a new ETR buffer mode called ETR_MODE_RESRV, which
becomes available when ETR device tree node is supplied with a valid
reserved memory region.

ETR_MODE_RESRV can be selected only by explicit user request.

$ echo resrv >/sys/bus/coresight/devices/tmc_etr<N>/buf_mode_preferred

Signed-off-by: Anil Kumar Reddy <areddy3@marvell.com>
Signed-off-by: Linu Cherian <lcherian@marvell.com>
Reviewed-by: James Clark <james.clark@arm.com>
---
Changelog from v10:
No changes.

 .../hwtracing/coresight/coresight-tmc-core.c  | 50 ++++++++++++
 .../hwtracing/coresight/coresight-tmc-etr.c   | 79 +++++++++++++++++++
 drivers/hwtracing/coresight/coresight-tmc.h   | 25 ++++++
 3 files changed, 154 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
index 3a482fd2cb22..248989833b20 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-core.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
@@ -23,6 +23,7 @@
 #include <linux/spinlock.h>
 #include <linux/pm_runtime.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/coresight.h>
 #include <linux/amba/bus.h>
 #include <linux/platform_device.h>
@@ -398,6 +399,53 @@ static inline bool tmc_etr_has_non_secure_access(struct tmc_drvdata *drvdata)
 
 static const struct amba_id tmc_ids[];
 
+static int of_tmc_get_reserved_resource_by_name(struct device *dev,
+						const char *name,
+						struct resource *res)
+{
+	int index, rc = -ENODEV;
+	struct device_node *node;
+
+	if (!is_of_node(dev->fwnode))
+		return -ENODEV;
+
+	index = of_property_match_string(dev->of_node, "memory-region-names",
+					 name);
+	if (index < 0)
+		return rc;
+
+	node = of_parse_phandle(dev->of_node, "memory-region", index);
+	if (!node)
+		return rc;
+
+	if (!of_address_to_resource(node, 0, res) &&
+	    res->start != 0 && resource_size(res) != 0)
+		rc = 0;
+	of_node_put(node);
+
+	return rc;
+}
+
+static void tmc_get_reserved_region(struct device *parent)
+{
+	struct tmc_drvdata *drvdata = dev_get_drvdata(parent);
+	struct resource res;
+
+	if (of_tmc_get_reserved_resource_by_name(parent, "tracedata", &res))
+		return;
+
+	drvdata->resrv_buf.vaddr = memremap(res.start,
+						resource_size(&res),
+						MEMREMAP_WC);
+	if (IS_ERR_OR_NULL(drvdata->resrv_buf.vaddr)) {
+		dev_err(parent, "Reserved trace buffer mapping failed\n");
+		return;
+	}
+
+	drvdata->resrv_buf.paddr = res.start;
+	drvdata->resrv_buf.size  = resource_size(&res);
+}
+
 /* Detect and initialise the capabilities of a TMC ETR */
 static int tmc_etr_setup_caps(struct device *parent, u32 devid,
 			      struct csdev_access *access)
@@ -508,6 +556,8 @@ static int __tmc_probe(struct device *dev, struct resource *res)
 		drvdata->size = readl_relaxed(drvdata->base + TMC_RSZ) * 4;
 	}
 
+	tmc_get_reserved_region(dev);
+
 	desc.dev = dev;
 
 	switch (drvdata->config_type) {
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index a48bb85d0e7f..8bca5b36334a 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -30,6 +30,7 @@ struct etr_buf_hw {
 	bool	has_iommu;
 	bool	has_etr_sg;
 	bool	has_catu;
+	bool	has_resrv;
 };
 
 /*
@@ -695,6 +696,75 @@ static const struct etr_buf_operations etr_flat_buf_ops = {
 	.get_data = tmc_etr_get_data_flat_buf,
 };
 
+/*
+ * tmc_etr_alloc_resrv_buf: Allocate a contiguous DMA buffer from reserved region.
+ */
+static int tmc_etr_alloc_resrv_buf(struct tmc_drvdata *drvdata,
+				  struct etr_buf *etr_buf, int node,
+				  void **pages)
+{
+	struct etr_flat_buf *resrv_buf;
+	struct device *real_dev = drvdata->csdev->dev.parent;
+
+	/* We cannot reuse existing pages for resrv buf */
+	if (pages)
+		return -EINVAL;
+
+	resrv_buf = kzalloc(sizeof(*resrv_buf), GFP_KERNEL);
+	if (!resrv_buf)
+		return -ENOMEM;
+
+	resrv_buf->daddr = dma_map_resource(real_dev, drvdata->resrv_buf.paddr,
+					   drvdata->resrv_buf.size,
+					   DMA_FROM_DEVICE, 0);
+	if (dma_mapping_error(real_dev, resrv_buf->daddr)) {
+		dev_err(real_dev, "failed to map source buffer address\n");
+		kfree(resrv_buf);
+		return -ENOMEM;
+	}
+
+	resrv_buf->vaddr = drvdata->resrv_buf.vaddr;
+	resrv_buf->size = etr_buf->size = drvdata->resrv_buf.size;
+	resrv_buf->dev = &drvdata->csdev->dev;
+	etr_buf->hwaddr = resrv_buf->daddr;
+	etr_buf->mode = ETR_MODE_RESRV;
+	etr_buf->private = resrv_buf;
+	return 0;
+}
+
+static void tmc_etr_free_resrv_buf(struct etr_buf *etr_buf)
+{
+	struct etr_flat_buf *resrv_buf = etr_buf->private;
+
+	if (resrv_buf && resrv_buf->daddr) {
+		struct device *real_dev = resrv_buf->dev->parent;
+
+		dma_unmap_resource(real_dev, resrv_buf->daddr,
+				resrv_buf->size, DMA_FROM_DEVICE, 0);
+	}
+	kfree(resrv_buf);
+}
+
+static void tmc_etr_sync_resrv_buf(struct etr_buf *etr_buf, u64 rrp, u64 rwp)
+{
+	/*
+	 * Adjust the buffer to point to the beginning of the trace data
+	 * and update the available trace data.
+	 */
+	etr_buf->offset = rrp - etr_buf->hwaddr;
+	if (etr_buf->full)
+		etr_buf->len = etr_buf->size;
+	else
+		etr_buf->len = rwp - rrp;
+}
+
+static const struct etr_buf_operations etr_resrv_buf_ops = {
+	.alloc = tmc_etr_alloc_resrv_buf,
+	.free = tmc_etr_free_resrv_buf,
+	.sync = tmc_etr_sync_resrv_buf,
+	.get_data = tmc_etr_get_data_flat_buf,
+};
+
 /*
  * tmc_etr_alloc_sg_buf: Allocate an SG buf @etr_buf. Setup the parameters
  * appropriately.
@@ -801,6 +871,7 @@ static const struct etr_buf_operations *etr_buf_ops[] = {
 	[ETR_MODE_FLAT] = &etr_flat_buf_ops,
 	[ETR_MODE_ETR_SG] = &etr_sg_buf_ops,
 	[ETR_MODE_CATU] = NULL,
+	[ETR_MODE_RESRV] = &etr_resrv_buf_ops
 };
 
 void tmc_etr_set_catu_ops(const struct etr_buf_operations *catu)
@@ -826,6 +897,7 @@ static inline int tmc_etr_mode_alloc_buf(int mode,
 	case ETR_MODE_FLAT:
 	case ETR_MODE_ETR_SG:
 	case ETR_MODE_CATU:
+	case ETR_MODE_RESRV:
 		if (etr_buf_ops[mode] && etr_buf_ops[mode]->alloc)
 			rc = etr_buf_ops[mode]->alloc(drvdata, etr_buf,
 						      node, pages);
@@ -844,6 +916,7 @@ static void get_etr_buf_hw(struct device *dev, struct etr_buf_hw *buf_hw)
 	buf_hw->has_iommu = iommu_get_domain_for_dev(dev->parent);
 	buf_hw->has_etr_sg = tmc_etr_has_cap(drvdata, TMC_ETR_SG);
 	buf_hw->has_catu = !!tmc_etr_get_catu_device(drvdata);
+	buf_hw->has_resrv = tmc_has_reserved_buffer(drvdata);
 }
 
 static bool etr_can_use_flat_mode(struct etr_buf_hw *buf_hw, ssize_t etr_buf_size)
@@ -1831,6 +1904,7 @@ static const char *const buf_modes_str[] = {
 	[ETR_MODE_FLAT]		= "flat",
 	[ETR_MODE_ETR_SG]	= "tmc-sg",
 	[ETR_MODE_CATU]		= "catu",
+	[ETR_MODE_RESRV]	= "resrv",
 	[ETR_MODE_AUTO]		= "auto",
 };
 
@@ -1849,6 +1923,9 @@ static ssize_t buf_modes_available_show(struct device *dev,
 	if (buf_hw.has_catu)
 		size += sysfs_emit_at(buf, size, "%s ", buf_modes_str[ETR_MODE_CATU]);
 
+	if (buf_hw.has_resrv)
+		size += sysfs_emit_at(buf, size, "%s ", buf_modes_str[ETR_MODE_RESRV]);
+
 	size += sysfs_emit_at(buf, size, "\n");
 	return size;
 }
@@ -1876,6 +1953,8 @@ static ssize_t buf_mode_preferred_store(struct device *dev,
 		drvdata->etr_mode = ETR_MODE_ETR_SG;
 	else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_CATU]) && buf_hw.has_catu)
 		drvdata->etr_mode = ETR_MODE_CATU;
+	else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_RESRV]) && buf_hw.has_resrv)
+		drvdata->etr_mode = ETR_MODE_RESRV;
 	else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_AUTO]))
 		drvdata->etr_mode = ETR_MODE_AUTO;
 	else
diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index 2671926be62a..d2261eddab71 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -135,6 +135,7 @@ enum etr_mode {
 	ETR_MODE_FLAT,		/* Uses contiguous flat buffer */
 	ETR_MODE_ETR_SG,	/* Uses in-built TMC ETR SG mechanism */
 	ETR_MODE_CATU,		/* Use SG mechanism in CATU */
+	ETR_MODE_RESRV,		/* Use reserved region contiguous buffer */
 	ETR_MODE_AUTO,		/* Use the default mechanism */
 };
 
@@ -164,6 +165,17 @@ struct etr_buf {
 	void				*private;
 };
 
+/**
+ * @paddr	: Start address of reserved memory region.
+ * @vaddr	: Corresponding CPU virtual address.
+ * @size	: Size of reserved memory region.
+ */
+struct tmc_resrv_buf {
+	phys_addr_t     paddr;
+	void		*vaddr;
+	size_t		size;
+};
+
 /**
  * struct tmc_drvdata - specifics associated to an TMC component
  * @pclk:	APB clock if present, otherwise NULL
@@ -189,6 +201,10 @@ struct etr_buf {
  * @idr_mutex:	Access serialisation for idr.
  * @sysfs_buf:	SYSFS buffer for ETR.
  * @perf_buf:	PERF buffer for ETR.
+ * @resrv_buf:	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
+ *		(after crash) by default.
  */
 struct tmc_drvdata {
 	struct clk		*pclk;
@@ -214,6 +230,7 @@ struct tmc_drvdata {
 	struct mutex		idr_mutex;
 	struct etr_buf		*sysfs_buf;
 	struct etr_buf		*perf_buf;
+	struct tmc_resrv_buf	resrv_buf;
 };
 
 struct etr_buf_operations {
@@ -331,6 +348,14 @@ tmc_sg_table_buf_size(struct tmc_sg_table *sg_table)
 	return (unsigned long)sg_table->data_pages.nr_pages << PAGE_SHIFT;
 }
 
+static inline bool tmc_has_reserved_buffer(struct tmc_drvdata *drvdata)
+{
+	if (drvdata->resrv_buf.vaddr &&
+	    drvdata->resrv_buf.size)
+		return true;
+	return false;
+}
+
 struct coresight_device *tmc_etr_get_catu_device(struct tmc_drvdata *drvdata);
 
 void tmc_etr_set_catu_ops(const struct etr_buf_operations *catu);
-- 
2.34.1

[PATCH v11 3/8] coresight: core: Add provision for panic callbacks

[Linu Cherian]

Panic callback handlers allows coresight device drivers to sync
relevant trace data and trace metadata to reserved memory
regions so that they can be retrieved later in the subsequent
boot or in the crashdump kernel.

Signed-off-by: Linu Cherian <lcherian@marvell.com>
Reviewed-by: James Clark <james.clark@arm.com>
---
Changelog from v10:
No changes.

 drivers/hwtracing/coresight/coresight-core.c | 42 ++++++++++++++++++++
 include/linux/coresight.h                    | 12 ++++++
 2 files changed, 54 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
index ea38ecf26fcb..8c5fb66911a5 100644
--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -19,6 +19,7 @@
 #include <linux/property.h>
 #include <linux/delay.h>
 #include <linux/pm_runtime.h>
+#include <linux/panic_notifier.h>
 
 #include "coresight-etm-perf.h"
 #include "coresight-priv.h"
@@ -1378,6 +1379,36 @@ const struct bus_type coresight_bustype = {
 	.name	= "coresight",
 };
 
+static int coresight_panic_sync(struct device *dev, void *data)
+{
+	int mode;
+	struct coresight_device *csdev;
+
+	/* Run through panic sync handlers for all enabled devices */
+	csdev = container_of(dev, struct coresight_device, dev);
+	mode = coresight_get_mode(csdev);
+
+	if ((mode == CS_MODE_SYSFS) || (mode == CS_MODE_PERF)) {
+		if (panic_ops(csdev))
+			panic_ops(csdev)->sync(csdev);
+	}
+
+	return 0;
+}
+
+static int coresight_panic_cb(struct notifier_block *self,
+			       unsigned long v, void *p)
+{
+	bus_for_each_dev(&coresight_bustype, NULL, NULL,
+				 coresight_panic_sync);
+
+	return 0;
+}
+
+static struct notifier_block coresight_notifier = {
+	.notifier_call = coresight_panic_cb,
+};
+
 static int __init coresight_init(void)
 {
 	int ret;
@@ -1390,11 +1421,20 @@ static int __init coresight_init(void)
 	if (ret)
 		goto exit_bus_unregister;
 
+	/* Register function to be called for panic */
+	ret = atomic_notifier_chain_register(&panic_notifier_list,
+					     &coresight_notifier);
+	if (ret)
+		goto exit_perf;
+
 	/* initialise the coresight syscfg API */
 	ret = cscfg_init();
 	if (!ret)
 		return 0;
 
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					     &coresight_notifier);
+exit_perf:
 	etm_perf_exit();
 exit_bus_unregister:
 	bus_unregister(&coresight_bustype);
@@ -1404,6 +1444,8 @@ static int __init coresight_init(void)
 static void __exit coresight_exit(void)
 {
 	cscfg_exit();
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					     &coresight_notifier);
 	etm_perf_exit();
 	bus_unregister(&coresight_bustype);
 }
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index c13342594278..2e63f7614551 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -335,6 +335,7 @@ enum cs_mode {
 #define link_ops(csdev)		csdev->ops->link_ops
 #define helper_ops(csdev)	csdev->ops->helper_ops
 #define ect_ops(csdev)		csdev->ops->ect_ops
+#define panic_ops(csdev)	csdev->ops->panic_ops
 
 /**
  * struct coresight_ops_sink - basic operations for a sink
@@ -404,11 +405,22 @@ struct coresight_ops_helper {
 	int (*disable)(struct coresight_device *csdev, void *data);
 };
 
+
+/**
+ * struct coresight_ops_panic - Generic device ops for panic handing
+ *
+ * @sync	: Sync the device register state/trace data
+ */
+struct coresight_ops_panic {
+	int (*sync)(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;
 };
 
 static inline u32 csdev_access_relaxed_read32(struct csdev_access *csa,
-- 
2.34.1

[PATCH v11 4/8] coresight: tmc: Enable panic sync handling

[Linu Cherian]

- Get reserved region from device tree node for metadata
- Define metadata format for TMC
- Add TMC ETR panic sync handler that syncs register snapshot
  to metadata region
- Add TMC ETF panic sync handler that syncs register snapshot
  to metadata region and internal SRAM to reserved trace buffer
  region.

Signed-off-by: Linu Cherian <lcherian@marvell.com>
Reviewed-by: James Clark <james.clark@arm.com>
---
Changelog from v10:
* Converted all csdev_access_* to readl functions in tmc_panic_sync_*
* Added "tmc" prefix for register snapshots in struct tmc_crash_metadata
* Converted dev_info to dev_dbg in panic handlers 
* Converted dsb to dmb in panic handlers 
* Removed a redudant reserved buffer check in panic handler
* Keeping the Reviewed-by as is since the changes are trivial


 .../hwtracing/coresight/coresight-tmc-core.c  | 14 ++++
 .../hwtracing/coresight/coresight-tmc-etf.c   | 80 +++++++++++++++++++
 .../hwtracing/coresight/coresight-tmc-etr.c   | 73 +++++++++++++++++
 drivers/hwtracing/coresight/coresight-tmc.h   | 66 +++++++++++++++
 4 files changed, 233 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
index 248989833b20..1e3938ec12cb 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-core.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
@@ -444,6 +444,20 @@ static void tmc_get_reserved_region(struct device *parent)
 
 	drvdata->resrv_buf.paddr = res.start;
 	drvdata->resrv_buf.size  = resource_size(&res);
+
+	if (of_tmc_get_reserved_resource_by_name(parent, "metadata", &res))
+		return;
+
+	drvdata->crash_mdata.vaddr = memremap(res.start,
+					       resource_size(&res),
+					       MEMREMAP_WC);
+	if (IS_ERR_OR_NULL(drvdata->crash_mdata.vaddr)) {
+		dev_err(parent, "Metadata memory mapping failed\n");
+		return;
+	}
+
+	drvdata->crash_mdata.paddr = res.start;
+	drvdata->crash_mdata.size  = resource_size(&res);
 }
 
 /* Detect and initialise the capabilities of a TMC ETR */
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index d4f641cd9de6..0f9155a10ac2 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -590,6 +590,81 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
 	return to_read;
 }
 
+static int tmc_panic_sync_etf(struct coresight_device *csdev)
+{
+	u32 val;
+	struct tmc_crash_metadata *mdata;
+	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	mdata = (struct tmc_crash_metadata *)drvdata->crash_mdata.vaddr;
+
+	/* Make sure we have valid reserved memory */
+	if (!tmc_has_reserved_buffer(drvdata) ||
+	    !tmc_has_crash_mdata_buffer(drvdata))
+		return 0;
+
+	tmc_crashdata_set_invalid(drvdata);
+
+	CS_UNLOCK(drvdata->base);
+
+	/* Proceed only if ETF is enabled or configured as sink */
+	val = readl(drvdata->base + TMC_CTL);
+	if (!(val & TMC_CTL_CAPT_EN))
+		goto out;
+	val = readl(drvdata->base + TMC_MODE);
+	if (val != TMC_MODE_CIRCULAR_BUFFER)
+		goto out;
+
+	val = readl(drvdata->base + TMC_FFSR);
+	/* Do manual flush and stop only if its not auto-stopped */
+	if (!(val & TMC_FFSR_FT_STOPPED)) {
+		dev_dbg(&csdev->dev,
+			 "%s: Triggering manual flush\n", __func__);
+		tmc_flush_and_stop(drvdata);
+	} else
+		tmc_wait_for_tmcready(drvdata);
+
+	/* Sync registers from hardware to metadata region */
+	mdata->tmc_sts = readl(drvdata->base + TMC_STS);
+	mdata->tmc_mode = readl(drvdata->base + TMC_MODE);
+	mdata->tmc_ffcr = readl(drvdata->base + TMC_FFCR);
+	mdata->tmc_ffsr = readl(drvdata->base + TMC_FFSR);
+
+	/* Sync Internal SRAM to reserved trace buffer region */
+	drvdata->buf = drvdata->resrv_buf.vaddr;
+	tmc_etb_dump_hw(drvdata);
+	/* Store as per RSZ register convention */
+	mdata->tmc_ram_size = drvdata->len >> 2;
+
+	/* Other fields for processing trace buffer reads */
+	mdata->tmc_rrp = 0;
+	mdata->tmc_dba = 0;
+	mdata->tmc_rwp = drvdata->len;
+	mdata->trace_paddr = drvdata->resrv_buf.paddr;
+
+	mdata->version = CS_CRASHDATA_VERSION;
+
+	/*
+	 * Make sure all previous writes are ordered,
+	 * before we mark valid
+	 */
+	dmb(sy);
+	mdata->valid = true;
+	/*
+	 * Below order need to maintained, since crc of metadata
+	 * is dependent on first
+	 */
+	mdata->crc32_tdata = find_crash_tracedata_crc(drvdata, mdata);
+	mdata->crc32_mdata = find_crash_metadata_crc(mdata);
+
+	tmc_disable_hw(drvdata);
+
+	dev_dbg(&csdev->dev, "%s: success\n", __func__);
+out:
+	CS_UNLOCK(drvdata->base);
+	return 0;
+}
+
 static const struct coresight_ops_sink tmc_etf_sink_ops = {
 	.enable		= tmc_enable_etf_sink,
 	.disable	= tmc_disable_etf_sink,
@@ -603,6 +678,10 @@ static const struct coresight_ops_link tmc_etf_link_ops = {
 	.disable	= tmc_disable_etf_link,
 };
 
+static const struct coresight_ops_panic tmc_etf_sync_ops = {
+	.sync		= tmc_panic_sync_etf,
+};
+
 const struct coresight_ops tmc_etb_cs_ops = {
 	.sink_ops	= &tmc_etf_sink_ops,
 };
@@ -610,6 +689,7 @@ const struct coresight_ops tmc_etb_cs_ops = {
 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,
 };
 
 int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 8bca5b36334a..fb944a68a11c 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1814,6 +1814,74 @@ static int tmc_disable_etr_sink(struct coresight_device *csdev)
 	return 0;
 }
 
+static int tmc_panic_sync_etr(struct coresight_device *csdev)
+{
+	u32 val;
+	struct tmc_crash_metadata *mdata;
+	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	mdata = (struct tmc_crash_metadata *)drvdata->crash_mdata.vaddr;
+
+	if (!drvdata->etr_buf)
+		return 0;
+
+	/* Being in RESRV mode implies valid reserved memory as well */
+	if (drvdata->etr_buf->mode != ETR_MODE_RESRV)
+		return 0;
+
+	if (!tmc_has_crash_mdata_buffer(drvdata))
+		return 0;
+
+	CS_UNLOCK(drvdata->base);
+
+	/* Proceed only if ETR is enabled */
+	val = readl(drvdata->base + TMC_CTL);
+	if (!(val & TMC_CTL_CAPT_EN))
+		goto out;
+
+	val = readl(drvdata->base + TMC_FFSR);
+	/* Do manual flush and stop only if its not auto-stopped */
+	if (!(val & TMC_FFSR_FT_STOPPED)) {
+		dev_dbg(&csdev->dev,
+			 "%s: Triggering manual flush\n", __func__);
+		tmc_flush_and_stop(drvdata);
+	} else
+		tmc_wait_for_tmcready(drvdata);
+
+	/* Sync registers from hardware to metadata region */
+	mdata->tmc_ram_size = readl(drvdata->base + TMC_RSZ);
+	mdata->tmc_sts = readl(drvdata->base + TMC_STS);
+	mdata->tmc_mode = readl(drvdata->base + TMC_MODE);
+	mdata->tmc_ffcr = readl(drvdata->base + TMC_FFCR);
+	mdata->tmc_ffsr = readl(drvdata->base + TMC_FFSR);
+	mdata->tmc_rrp = tmc_read_rrp(drvdata);
+	mdata->tmc_rwp = tmc_read_rwp(drvdata);
+	mdata->tmc_dba = tmc_read_dba(drvdata);
+	mdata->trace_paddr = drvdata->resrv_buf.paddr;
+	mdata->version = CS_CRASHDATA_VERSION;
+
+	/*
+	 * Make sure all previous writes are ordered,
+	 * before we mark valid
+	 */
+	dmb(sy);
+	mdata->valid = true;
+	/*
+	 * Below order need to maintained, since crc of metadata
+	 * is dependent on first
+	 */
+	mdata->crc32_tdata = find_crash_tracedata_crc(drvdata, mdata);
+	mdata->crc32_mdata = find_crash_metadata_crc(mdata);
+
+	tmc_disable_hw(drvdata);
+
+	dev_dbg(&csdev->dev, "%s: success\n", __func__);
+out:
+	CS_UNLOCK(drvdata->base);
+
+	return 0;
+}
+
 static const struct coresight_ops_sink tmc_etr_sink_ops = {
 	.enable		= tmc_enable_etr_sink,
 	.disable	= tmc_disable_etr_sink,
@@ -1822,8 +1890,13 @@ static const struct coresight_ops_sink tmc_etr_sink_ops = {
 	.free_buffer	= tmc_free_etr_buffer,
 };
 
+static const struct coresight_ops_panic tmc_etr_sync_ops = {
+	.sync		= tmc_panic_sync_etr,
+};
+
 const struct coresight_ops tmc_etr_cs_ops = {
 	.sink_ops	= &tmc_etr_sink_ops,
+	.panic_ops	= &tmc_etr_sync_ops,
 };
 
 int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index d2261eddab71..d76e83fc840b 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -12,6 +12,7 @@
 #include <linux/miscdevice.h>
 #include <linux/mutex.h>
 #include <linux/refcount.h>
+#include <linux/crc32.h>
 
 #define TMC_RSZ			0x004
 #define TMC_STS			0x00c
@@ -76,6 +77,9 @@
 #define TMC_AXICTL_AXCACHE_OS	(0xf << 2)
 #define TMC_AXICTL_ARCACHE_OS	(0xf << 16)
 
+/* TMC_FFSR - 0x300 */
+#define TMC_FFSR_FT_STOPPED	BIT(1)
+
 /* TMC_FFCR - 0x304 */
 #define TMC_FFCR_FLUSHMAN_BIT	6
 #define TMC_FFCR_EN_FMT		BIT(0)
@@ -94,6 +98,9 @@
 
 #define TMC_AUTH_NSID_MASK	GENMASK(1, 0)
 
+/* Major version 1 Minor version 0 */
+#define CS_CRASHDATA_VERSION	(1 << 16)
+
 enum tmc_config_type {
 	TMC_CONFIG_TYPE_ETB,
 	TMC_CONFIG_TYPE_ETR,
@@ -131,6 +138,25 @@ enum tmc_mem_intf_width {
 #define CORESIGHT_SOC_600_ETR_CAPS	\
 	(TMC_ETR_SAVE_RESTORE | TMC_ETR_AXI_ARCACHE)
 
+/* TMC metadata region for ETR and ETF configurations */
+struct tmc_crash_metadata {
+	uint32_t crc32_mdata;	/* crc of metadata */
+	uint32_t crc32_tdata;	/* crc of tracedata */
+	uint32_t version;	/* 31:16 Major version, 15:0 Minor version */
+	uint32_t valid;         /* Indicate if this ETF/ETR was enabled */
+	uint32_t tmc_ram_size;  /* Ram Size register */
+	uint32_t tmc_sts;       /* Status register */
+	uint32_t tmc_mode;	/* Mode register */
+	uint32_t tmc_ffcr;	/* Formatter and flush control register */
+	uint32_t tmc_ffsr;	/* Formatter and flush status register */
+	uint32_t reserved32;
+	uint64_t tmc_rrp;       /* Ram Read pointer register */
+	uint64_t tmc_rwp;       /* Ram Write pointer register */
+	uint64_t tmc_dba;	/* Data buffer address register */
+	uint64_t trace_paddr;	/* Phys address of trace buffer */
+	uint64_t reserved64[3];
+};
+
 enum etr_mode {
 	ETR_MODE_FLAT,		/* Uses contiguous flat buffer */
 	ETR_MODE_ETR_SG,	/* Uses in-built TMC ETR SG mechanism */
@@ -205,6 +231,8 @@ struct tmc_resrv_buf {
  *		retention (after crash) only when ETR_MODE_RESRV buffer
  *		mode is enabled. Used by ETF for trace data retention
  *		(after crash) by default.
+ * @crash_mdata: Reserved memory for storing tmc crash metadata.
+ *		 Used by ETR/ETF.
  */
 struct tmc_drvdata {
 	struct clk		*pclk;
@@ -231,6 +259,7 @@ struct tmc_drvdata {
 	struct etr_buf		*sysfs_buf;
 	struct etr_buf		*perf_buf;
 	struct tmc_resrv_buf	resrv_buf;
+	struct tmc_resrv_buf	crash_mdata;
 };
 
 struct etr_buf_operations {
@@ -356,6 +385,43 @@ static inline bool tmc_has_reserved_buffer(struct tmc_drvdata *drvdata)
 	return false;
 }
 
+static inline bool tmc_has_crash_mdata_buffer(struct tmc_drvdata *drvdata)
+{
+	if (drvdata->crash_mdata.vaddr &&
+	    drvdata->crash_mdata.size)
+		return true;
+	return false;
+}
+
+static inline void tmc_crashdata_set_invalid(struct tmc_drvdata *drvdata)
+{
+	struct tmc_crash_metadata *mdata;
+
+	mdata = (struct tmc_crash_metadata *)drvdata->crash_mdata.vaddr;
+
+	if (tmc_has_crash_mdata_buffer(drvdata))
+		mdata->valid = false;
+}
+
+static inline uint32_t find_crash_metadata_crc(struct tmc_crash_metadata *md)
+{
+	unsigned long crc_size;
+
+	crc_size = sizeof(struct tmc_crash_metadata) -
+		offsetof(struct tmc_crash_metadata, crc32_tdata);
+	return crc32_le(0, (void *)&md->crc32_tdata, crc_size);
+}
+
+static inline uint32_t find_crash_tracedata_crc(struct tmc_drvdata *drvdata,
+						struct tmc_crash_metadata *md)
+{
+	unsigned long crc_size;
+
+	/* Take CRC of configured buffer size to keep it simple */
+	crc_size = md->tmc_ram_size << 2;
+	return crc32_le(0, (void *)drvdata->resrv_buf.vaddr, crc_size);
+}
+
 struct coresight_device *tmc_etr_get_catu_device(struct tmc_drvdata *drvdata);
 
 void tmc_etr_set_catu_ops(const struct etr_buf_operations *catu);
-- 
2.34.1

[PATCH v11 5/8] coresight: tmc: Add support for reading crash data

[Linu Cherian]

* Add support for reading crashdata using special device files.
  The special device files /dev/crash_tmc_xxx would be available
  for read file operation only when the crash data is valid.

* User can read the crash data as below

  For example, for reading crash data from tmc_etf sink

  #dd if=/dev/crash_tmc_etfXX of=~/cstrace.bin

Signed-off-by: Anil Kumar Reddy <areddy3@marvell.com>
Signed-off-by: Tanmay Jagdale <tanmay@marvell.com>
Signed-off-by: Linu Cherian <lcherian@marvell.com>
---
Changelog from v10:
* Got rid of sink specific prepare/unprepare invocations  
* Fixed marking metadata as invalid when a user is trying to use the
  reserved buffer. Earlier this was wrongly set at the time of reading
  reserved trace buffer.
* Moved common validation checks to is_tmc_crashdata_valid and minor
  code rearrangements for efficiency
* Got rid of "full" member from struct tmc_resrv_buf
* While reading crashdata, size is now calculated from metdata instead 
  of relying on reserved buffer size populated by dtb 


 .../hwtracing/coresight/coresight-tmc-core.c  | 231 +++++++++++++++++-
 .../hwtracing/coresight/coresight-tmc-etr.c   |  19 +-
 drivers/hwtracing/coresight/coresight-tmc.h   |  13 +-
 3 files changed, 260 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
index 1e3938ec12cb..5f3789314c4d 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-core.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
@@ -105,6 +105,151 @@ u32 tmc_get_memwidth_mask(struct tmc_drvdata *drvdata)
 	return mask;
 }
 
+bool is_tmc_crashdata_valid(struct tmc_drvdata *drvdata)
+{
+	struct tmc_crash_metadata *mdata;
+
+	if (!tmc_has_reserved_buffer(drvdata) ||
+	    !tmc_has_crash_mdata_buffer(drvdata))
+		return false;
+
+	mdata = drvdata->crash_mdata.vaddr;
+
+	/* Check version match */
+	if (mdata->version != CS_CRASHDATA_VERSION)
+		return false;
+
+	/* Check for valid metadata */
+	if (!mdata->valid) {
+		dev_dbg(&drvdata->csdev->dev,
+			"Data invalid in tmc crash metadata\n");
+		return false;
+	}
+
+	/*
+	 * 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 (drvdata->resrv_buf.paddr != mdata->trace_paddr) {
+		dev_dbg(&drvdata->csdev->dev,
+			"Trace buffer address of previous boot invalid\n");
+		return false;
+	}
+
+	/* 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");
+		return false;
+	}
+	/* 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");
+		return false;
+	}
+
+	return true;
+}
+
+int tmc_read_prepare_crashdata(struct tmc_drvdata *drvdata)
+{
+	int ret = 0;
+	u32 status, size;
+	u64 rrp, rwp, dba;
+	unsigned long flags;
+	struct tmc_resrv_buf *rbuf;
+	struct tmc_crash_metadata *mdata;
+
+	spin_lock_irqsave(&drvdata->spinlock, flags);
+
+	if (drvdata->reading) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	if (!is_tmc_crashdata_valid(drvdata)) {
+		ret = -ENXIO;
+		goto out;
+	}
+
+	mdata = drvdata->crash_mdata.vaddr;
+	rbuf = &drvdata->resrv_buf;
+
+	rrp = mdata->tmc_rrp;
+	rwp = mdata->tmc_rwp;
+	dba = mdata->tmc_dba;
+	status = mdata->tmc_sts;
+	size = mdata->tmc_ram_size << 2;
+
+	/* Sync the buffer pointers */
+	rbuf->offset = rrp - dba;
+	if (status & TMC_STS_FULL)
+		rbuf->len = size;
+	else
+		rbuf->len = rwp - rrp;
+
+	/* Additional sanity checks for validating metadata */
+	if ((rbuf->offset > size) ||
+	    (rbuf->len > size)) {
+		dev_dbg(&drvdata->csdev->dev,
+			"Offset and length invalid in tmc crash metadata\n");
+		return -EINVAL;
+	}
+
+	if (status & 0x1)
+		coresight_insert_barrier_packet(drvdata->buf);
+
+	drvdata->reading = true;
+out:
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+	return ret;
+}
+
+int tmc_read_unprepare_crashdata(struct tmc_drvdata *drvdata)
+{
+	unsigned long flags;
+	struct tmc_resrv_buf *rbuf;
+
+	spin_lock_irqsave(&drvdata->spinlock, flags);
+
+	rbuf = &drvdata->resrv_buf;
+	/* Reset valid length */
+	rbuf->len = 0;
+
+	drvdata->reading = false;
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+
+	return 0;
+}
+
+static inline ssize_t tmc_get_resvbuf_trace(struct tmc_drvdata *drvdata,
+					  loff_t pos, size_t len, char **bufpp)
+{
+	s64 offset;
+	ssize_t actual = len;
+	struct tmc_resrv_buf *rbuf = &drvdata->resrv_buf;
+
+	if (pos + actual > rbuf->len)
+		actual = rbuf->len - pos;
+	if (actual <= 0)
+		return 0;
+
+	/* Compute the offset from which we read the data */
+	offset = rbuf->offset + pos;
+	if (offset >= rbuf->size)
+		offset -= rbuf->size;
+
+	/* Adjust the length to limit this transaction to end of buffer */
+	actual = (actual < (rbuf->size - offset)) ?
+		actual : rbuf->size - offset;
+
+	*bufpp = (char *)rbuf->vaddr + offset;
+
+	return actual;
+}
+
 static int tmc_read_prepare(struct tmc_drvdata *drvdata)
 {
 	int ret = 0;
@@ -223,6 +368,69 @@ static const struct file_operations tmc_fops = {
 	.release	= tmc_release,
 };
 
+static int tmc_crashdata_open(struct inode *inode, struct file *file)
+{
+	int ret;
+	struct tmc_drvdata *drvdata = container_of(file->private_data,
+						   struct tmc_drvdata,
+						   crashdev);
+
+	ret = tmc_read_prepare_crashdata(drvdata);
+	if (ret)
+		return ret;
+
+	nonseekable_open(inode, file);
+
+	dev_dbg(&drvdata->csdev->dev, "%s: successfully opened\n", __func__);
+	return 0;
+}
+
+static ssize_t tmc_crashdata_read(struct file *file, char __user *data,
+				  size_t len, loff_t *ppos)
+{
+	char *bufp;
+	ssize_t actual;
+	struct tmc_drvdata *drvdata = container_of(file->private_data,
+						   struct tmc_drvdata,
+						   crashdev);
+
+	actual = tmc_get_resvbuf_trace(drvdata, *ppos, len, &bufp);
+	if (actual <= 0)
+		return 0;
+
+	if (copy_to_user(data, bufp, actual)) {
+		dev_dbg(&drvdata->csdev->dev,
+			"%s: copy_to_user failed\n", __func__);
+		return -EFAULT;
+	}
+
+	*ppos += actual;
+	dev_dbg(&drvdata->csdev->dev, "%zu bytes copied\n", actual);
+
+	return actual;
+
+}
+
+static int tmc_crashdata_release(struct inode *inode, struct file *file)
+{
+	int ret = 0;
+	struct tmc_drvdata *drvdata = container_of(file->private_data,
+						   struct tmc_drvdata,
+						   crashdev);
+
+	ret = tmc_read_unprepare_crashdata(drvdata);
+
+	dev_dbg(&drvdata->csdev->dev, "%s: released\n", __func__);
+	return ret;
+}
+
+static const struct file_operations tmc_crashdata_fops = {
+	.owner		= THIS_MODULE,
+	.open		= tmc_crashdata_open,
+	.read		= tmc_crashdata_read,
+	.release	= tmc_crashdata_release,
+};
+
 static enum tmc_mem_intf_width tmc_get_memwidth(u32 devid)
 {
 	enum tmc_mem_intf_width memwidth;
@@ -532,6 +740,20 @@ static u32 tmc_etr_get_max_burst_size(struct device *dev)
 	return burst_size;
 }
 
+static void register_crash_dev_interface(struct tmc_drvdata *drvdata,
+					 const char *name)
+{
+	drvdata->crashdev.name =
+		devm_kasprintf(&drvdata->csdev->dev, GFP_KERNEL, "%s_%s", "crash", name);
+	drvdata->crashdev.minor = MISC_DYNAMIC_MINOR;
+	drvdata->crashdev.fops = &tmc_crashdata_fops;
+	if (misc_register(&drvdata->crashdev)) {
+		dev_dbg(&drvdata->csdev->dev,
+			"Failed to setup user interface for crashdata\n");
+		drvdata->crashdev.fops = NULL;
+	}
+}
+
 static int __tmc_probe(struct device *dev, struct resource *res)
 {
 	int ret = 0;
@@ -632,8 +854,13 @@ static int __tmc_probe(struct device *dev, struct resource *res)
 	drvdata->miscdev.minor = MISC_DYNAMIC_MINOR;
 	drvdata->miscdev.fops = &tmc_fops;
 	ret = misc_register(&drvdata->miscdev);
-	if (ret)
+	if (ret) {
 		coresight_unregister(drvdata->csdev);
+		goto out;
+	}
+
+	if (is_tmc_crashdata_valid(drvdata))
+		register_crash_dev_interface(drvdata, desc.name);
 out:
 	return ret;
 }
@@ -687,6 +914,8 @@ static void __tmc_remove(struct device *dev)
 	 * handler to this device is closed.
 	 */
 	misc_deregister(&drvdata->miscdev);
+	if (drvdata->crashdev.fops)
+		misc_deregister(&drvdata->crashdev);
 	coresight_unregister(drvdata->csdev);
 }
 
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index fb944a68a11c..18752f58dfa6 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -2012,6 +2012,23 @@ static ssize_t buf_mode_preferred_show(struct device *dev,
 	return sysfs_emit(buf, "%s\n", buf_modes_str[drvdata->etr_mode]);
 }
 
+static int buf_mode_set_resrv(struct tmc_drvdata *drvdata)
+{
+	unsigned long flags;
+	int err = 0;
+
+	/* Ensure there are no active crashdata read sessions */
+	spin_lock_irqsave(&drvdata->spinlock, flags);
+	if (!drvdata->reading) {
+		tmc_crashdata_set_invalid(drvdata);
+		drvdata->etr_mode = ETR_MODE_RESRV;
+
+	} else
+		err = -1;
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+	return err;
+}
+
 static ssize_t buf_mode_preferred_store(struct device *dev,
 					  struct device_attribute *attr,
 					  const char *buf, size_t size)
@@ -2027,7 +2044,7 @@ static ssize_t buf_mode_preferred_store(struct device *dev,
 	else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_CATU]) && buf_hw.has_catu)
 		drvdata->etr_mode = ETR_MODE_CATU;
 	else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_RESRV]) && buf_hw.has_resrv)
-		drvdata->etr_mode = ETR_MODE_RESRV;
+		return buf_mode_set_resrv(drvdata) ? -EBUSY : size;
 	else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_AUTO]))
 		drvdata->etr_mode = ETR_MODE_AUTO;
 	else
diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index d76e83fc840b..2ece44e09911 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -195,11 +195,15 @@ struct etr_buf {
  * @paddr	: Start address of reserved memory region.
  * @vaddr	: Corresponding CPU virtual address.
  * @size	: Size of reserved memory region.
+ * @offset	: Offset of the trace data in the buffer for consumption.
+ * @len	: Available trace data @buf (may round up to the beginning).
  */
 struct tmc_resrv_buf {
 	phys_addr_t     paddr;
 	void		*vaddr;
 	size_t		size;
+	unsigned long	offset;
+	s64		len;
 };
 
 /**
@@ -208,6 +212,8 @@ struct tmc_resrv_buf {
  * @base:	memory mapped base address for this component.
  * @csdev:	component vitals needed by the framework.
  * @miscdev:	specifics to handle "/dev/xyz.tmc" entry.
+ * @crashdev:	specifics to handle "/dev/crash_tmc_xyz" entry for reading
+ *		crash tracedata.
  * @spinlock:	only one at a time pls.
  * @pid:	Process ID of the process that owns the session that is using
  *		this component. For example this would be the pid of the Perf
@@ -227,7 +233,7 @@ struct tmc_resrv_buf {
  * @idr_mutex:	Access serialisation for idr.
  * @sysfs_buf:	SYSFS buffer for ETR.
  * @perf_buf:	PERF buffer for ETR.
- * @resrv_buf:	Used by ETR as hardware trace buffer and for trace data
+ * @resrv_buf:  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
  *		(after crash) by default.
@@ -239,6 +245,7 @@ struct tmc_drvdata {
 	void __iomem		*base;
 	struct coresight_device	*csdev;
 	struct miscdevice	miscdev;
+	struct miscdevice	crashdev;
 	spinlock_t		spinlock;
 	pid_t			pid;
 	bool			reading;
@@ -309,6 +316,8 @@ 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_crashdata(struct tmc_drvdata *drvdata);
+int tmc_read_unprepare_crashdata(struct tmc_drvdata *drvdata);
 
 /* ETB/ETF functions */
 int tmc_read_prepare_etb(struct tmc_drvdata *drvdata);
@@ -371,6 +380,8 @@ void tmc_sg_table_sync_data_range(struct tmc_sg_table *table,
 				  u64 offset, u64 size);
 ssize_t tmc_sg_table_get_data(struct tmc_sg_table *sg_table,
 			      u64 offset, size_t len, char **bufpp);
+
+bool is_tmc_crashdata_valid(struct tmc_drvdata *drvdata);
 static inline unsigned long
 tmc_sg_table_buf_size(struct tmc_sg_table *sg_table)
 {
-- 
2.34.1

[PATCH v11 6/8] coresight: tmc: Stop trace capture on FlIn

[Linu Cherian]

Configure TMC ETR and ETF to flush and stop trace capture
on FlIn event based on sysfs attribute,
/sys/bus/coresight/devices/tmc_etXn/stop_on_flush.

Signed-off-by: Linu Cherian <lcherian@marvell.com>
---
Changelog from v10:
No changes.

 .../hwtracing/coresight/coresight-tmc-core.c  | 31 +++++++++++++++++++
 .../hwtracing/coresight/coresight-tmc-etf.c   | 12 ++++---
 .../hwtracing/coresight/coresight-tmc-etr.c   | 12 ++++---
 drivers/hwtracing/coresight/coresight-tmc.h   |  2 ++
 4 files changed, 47 insertions(+), 10 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
index 5f3789314c4d..3d3a2df4303b 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-core.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
@@ -540,9 +540,40 @@ static ssize_t buffer_size_store(struct device *dev,
 
 static DEVICE_ATTR_RW(buffer_size);
 
+static ssize_t stop_on_flush_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->stop_on_flush);
+}
+
+static ssize_t stop_on_flush_store(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t size)
+{
+	int ret;
+	u8 val;
+	struct tmc_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	ret = kstrtou8(buf, 0, &val);
+	if (ret)
+		return ret;
+	if (val)
+		drvdata->stop_on_flush = true;
+	else
+		drvdata->stop_on_flush = false;
+
+	return size;
+}
+
+static DEVICE_ATTR_RW(stop_on_flush);
+
+
 static struct attribute *coresight_tmc_attrs[] = {
 	&dev_attr_trigger_cntr.attr,
 	&dev_attr_buffer_size.attr,
+	&dev_attr_stop_on_flush.attr,
 	NULL,
 };
 
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index 0f9155a10ac2..bdc3a7e9ba06 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -19,6 +19,7 @@ static int tmc_set_etf_buffer(struct coresight_device *csdev,
 static int __tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
 {
 	int rc = 0;
+	u32 ffcr;
 
 	CS_UNLOCK(drvdata->base);
 
@@ -32,10 +33,12 @@ static int __tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
 	}
 
 	writel_relaxed(TMC_MODE_CIRCULAR_BUFFER, drvdata->base + TMC_MODE);
-	writel_relaxed(TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI |
-		       TMC_FFCR_FON_FLIN | TMC_FFCR_FON_TRIG_EVT |
-		       TMC_FFCR_TRIGON_TRIGIN,
-		       drvdata->base + TMC_FFCR);
+
+	ffcr = TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI | TMC_FFCR_FON_FLIN |
+		TMC_FFCR_FON_TRIG_EVT | TMC_FFCR_TRIGON_TRIGIN;
+	if (drvdata->stop_on_flush)
+		ffcr |= TMC_FFCR_STOP_ON_FLUSH;
+	writel_relaxed(ffcr, drvdata->base + TMC_FFCR);
 
 	writel_relaxed(drvdata->trigger_cntr, drvdata->base + TMC_TRG);
 	tmc_enable_hw(drvdata);
@@ -225,7 +228,6 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev)
 		used = true;
 		drvdata->buf = buf;
 	}
-
 	ret = tmc_etb_enable_hw(drvdata);
 	if (!ret) {
 		coresight_set_mode(csdev, CS_MODE_SYSFS);
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 18752f58dfa6..e64b98c8f44c 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1060,7 +1060,7 @@ static void tmc_sync_etr_buf(struct tmc_drvdata *drvdata)
 
 static int __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
 {
-	u32 axictl, sts;
+	u32 axictl, sts, ffcr;
 	struct etr_buf *etr_buf = drvdata->etr_buf;
 	int rc = 0;
 
@@ -1106,10 +1106,12 @@ static int __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
 		writel_relaxed(sts, drvdata->base + TMC_STS);
 	}
 
-	writel_relaxed(TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI |
-		       TMC_FFCR_FON_FLIN | TMC_FFCR_FON_TRIG_EVT |
-		       TMC_FFCR_TRIGON_TRIGIN,
-		       drvdata->base + TMC_FFCR);
+	ffcr = TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI | TMC_FFCR_FON_FLIN |
+		TMC_FFCR_FON_TRIG_EVT | TMC_FFCR_TRIGON_TRIGIN;
+	if (drvdata->stop_on_flush)
+		ffcr |= TMC_FFCR_STOP_ON_FLUSH;
+	writel_relaxed(ffcr, drvdata->base + TMC_FFCR);
+
 	writel_relaxed(drvdata->trigger_cntr, drvdata->base + TMC_TRG);
 	tmc_enable_hw(drvdata);
 
diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index 2ece44e09911..589087682626 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -218,6 +218,7 @@ struct tmc_resrv_buf {
  * @pid:	Process ID of the process that owns the session that is using
  *		this component. For example this would be the pid of the Perf
  *		process.
+ * @stop_on_flush: Stop on flush trigger user configuration.
  * @buf:	Snapshot of the trace data for ETF/ETB.
  * @etr_buf:	details of buffer used in TMC-ETR
  * @len:	size of the available trace for ETF/ETB.
@@ -249,6 +250,7 @@ struct tmc_drvdata {
 	spinlock_t		spinlock;
 	pid_t			pid;
 	bool			reading;
+	bool			stop_on_flush;
 	union {
 		char		*buf;		/* TMC ETB */
 		struct etr_buf	*etr_buf;	/* TMC ETR */
-- 
2.34.1

[PATCH v11 7/8] coresight: config: Add preloaded configuration

[Linu Cherian]

Add a preloaded configuration for generating
external trigger on address match. This can be
used by CTI and ETR blocks to stop trace capture
on kernel panic.

Kernel address for "panic" function is used as the
default trigger address.

This new configuration is available as,
/sys/kernel/config/cs-syscfg/configurations/panicstop

Signed-off-by: Linu Cherian <lcherian@marvell.com>
Reviewed-by: James Clark <james.clark@arm.com>
---
Changelog from v10:
No changes.

 drivers/hwtracing/coresight/Makefile          |  2 +-
 .../coresight/coresight-cfg-preload.c         |  2 +
 .../coresight/coresight-cfg-preload.h         |  2 +
 .../hwtracing/coresight/coresight-cfg-pstop.c | 83 +++++++++++++++++++
 4 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 drivers/hwtracing/coresight/coresight-cfg-pstop.c

diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
index 4ba478211b31..46ce7f39d05f 100644
--- a/drivers/hwtracing/coresight/Makefile
+++ b/drivers/hwtracing/coresight/Makefile
@@ -25,7 +25,7 @@ subdir-ccflags-y += $(condflags)
 obj-$(CONFIG_CORESIGHT) += coresight.o
 coresight-y := coresight-core.o  coresight-etm-perf.o coresight-platform.o \
 		coresight-sysfs.o coresight-syscfg.o coresight-config.o \
-		coresight-cfg-preload.o coresight-cfg-afdo.o \
+		coresight-cfg-preload.o coresight-cfg-afdo.o coresight-cfg-pstop.o \
 		coresight-syscfg-configfs.o coresight-trace-id.o
 obj-$(CONFIG_CORESIGHT_LINK_AND_SINK_TMC) += coresight-tmc.o
 coresight-tmc-y := coresight-tmc-core.o coresight-tmc-etf.o \
diff --git a/drivers/hwtracing/coresight/coresight-cfg-preload.c b/drivers/hwtracing/coresight/coresight-cfg-preload.c
index e237a4edfa09..4980e68483c5 100644
--- a/drivers/hwtracing/coresight/coresight-cfg-preload.c
+++ b/drivers/hwtracing/coresight/coresight-cfg-preload.c
@@ -13,6 +13,7 @@
 static struct cscfg_feature_desc *preload_feats[] = {
 #if IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM4X)
 	&strobe_etm4x,
+	&gen_etrig_etm4x,
 #endif
 	NULL
 };
@@ -20,6 +21,7 @@ static struct cscfg_feature_desc *preload_feats[] = {
 static struct cscfg_config_desc *preload_cfgs[] = {
 #if IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM4X)
 	&afdo_etm4x,
+	&pstop_etm4x,
 #endif
 	NULL
 };
diff --git a/drivers/hwtracing/coresight/coresight-cfg-preload.h b/drivers/hwtracing/coresight/coresight-cfg-preload.h
index 21299e175477..291ba530a6a5 100644
--- a/drivers/hwtracing/coresight/coresight-cfg-preload.h
+++ b/drivers/hwtracing/coresight/coresight-cfg-preload.h
@@ -10,4 +10,6 @@
 #if IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM4X)
 extern struct cscfg_feature_desc strobe_etm4x;
 extern struct cscfg_config_desc afdo_etm4x;
+extern struct cscfg_feature_desc gen_etrig_etm4x;
+extern struct cscfg_config_desc pstop_etm4x;
 #endif
diff --git a/drivers/hwtracing/coresight/coresight-cfg-pstop.c b/drivers/hwtracing/coresight/coresight-cfg-pstop.c
new file mode 100644
index 000000000000..c2bfbd07bfaf
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-cfg-pstop.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright(C) 2023  Marvell.
+ * Based on coresight-cfg-afdo.c
+ */
+
+#include "coresight-config.h"
+
+/* ETMv4 includes and features */
+#if IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM4X)
+#include "coresight-etm4x-cfg.h"
+
+/* preload configurations and features */
+
+/* preload in features for ETMv4 */
+
+/* panic_stop feature */
+static struct cscfg_parameter_desc gen_etrig_params[] = {
+	{
+		.name = "address",
+		.value = (u64)panic,
+	},
+};
+
+static struct cscfg_regval_desc gen_etrig_regs[] = {
+	/* resource selector */
+	{
+		.type = CS_CFG_REG_TYPE_RESOURCE,
+		.offset = TRCRSCTLRn(2),
+		.hw_info = ETM4_CFG_RES_SEL,
+		.val32 = 0x40001,
+	},
+	/* single address comparator */
+	{
+		.type = CS_CFG_REG_TYPE_RESOURCE | CS_CFG_REG_TYPE_VAL_64BIT |
+			CS_CFG_REG_TYPE_VAL_PARAM,
+		.offset =  TRCACVRn(0),
+		.val32 = 0x0,
+	},
+	{
+		.type = CS_CFG_REG_TYPE_RESOURCE,
+		.offset = TRCACATRn(0),
+		.val64 = 0xf00,
+	},
+	/* Driver external output[0] with comparator out */
+	{
+		.type = CS_CFG_REG_TYPE_RESOURCE,
+		.offset = TRCEVENTCTL0R,
+		.val32 = 0x2,
+	},
+	/* end of regs */
+};
+
+struct cscfg_feature_desc gen_etrig_etm4x = {
+	.name = "gen_etrig",
+	.description = "Generate external trigger on address match\n"
+		       "parameter \'address\': address of kernel address\n",
+	.match_flags = CS_CFG_MATCH_CLASS_SRC_ETM4,
+	.nr_params = ARRAY_SIZE(gen_etrig_params),
+	.params_desc = gen_etrig_params,
+	.nr_regs = ARRAY_SIZE(gen_etrig_regs),
+	.regs_desc = gen_etrig_regs,
+};
+
+/* create a panic stop configuration */
+
+/* the total number of parameters in used features */
+#define PSTOP_NR_PARAMS	ARRAY_SIZE(gen_etrig_params)
+
+static const char *pstop_ref_names[] = {
+	"gen_etrig",
+};
+
+struct cscfg_config_desc pstop_etm4x = {
+	.name = "panicstop",
+	.description = "Stop ETM on kernel panic\n",
+	.nr_feat_refs = ARRAY_SIZE(pstop_ref_names),
+	.feat_ref_names = pstop_ref_names,
+	.nr_total_params = PSTOP_NR_PARAMS,
+};
+
+/* end of ETM4x configurations */
+#endif	/* IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM4X) */
-- 
2.34.1

[PATCH v11 8/8] Documentation: coresight: Panic support

[Linu Cherian]

Add documentation on using coresight during panic
and watchdog.

Signed-off-by: Linu Cherian <lcherian@marvell.com>
---
Changelog from v10:
* Converted all commands to literal code blocks
* Minor typo fixes

 Documentation/trace/coresight/panic.rst | 356 ++++++++++++++++++++++++
 1 file changed, 356 insertions(+)
 create mode 100644 Documentation/trace/coresight/panic.rst

diff --git a/Documentation/trace/coresight/panic.rst b/Documentation/trace/coresight/panic.rst
new file mode 100644
index 000000000000..9252e42d235e
--- /dev/null
+++ b/Documentation/trace/coresight/panic.rst
@@ -0,0 +1,356 @@
+===================================================
+Using Coresight for Kernel panic and Watchdog reset
+===================================================
+
+Introduction
+------------
+This documentation is about using Linux coresight trace support to
+debug kernel panic and watchdog reset scenarios.
+
+Coresight trace during Kernel panic
+-----------------------------------
+From the coresight driver point of view, addressing the kernel panic
+situation has four main requirements.
+
+a. Support for allocation of trace buffer pages from reserved memory area.
+   Platform can advertise this using a new device tree property added to
+   relevant coresight nodes.
+
+b. Support for stopping coresight blocks at the time of panic
+
+c. Saving required metadata in the specified format
+
+d. Support for reading trace data captured at the time of panic
+
+Allocation of trace buffer pages from reserved RAM
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+A new optional device tree property "memory-region" is added to the
+Coresight TMC device nodes, that would give the base address and size of trace
+buffer.
+
+Static allocation of trace buffers would ensure that both IOMMU enabled
+and disabled cases are handled. Also, platforms that support persistent
+RAM will allow users to read trace data in the subsequent boot without
+booting the crashdump kernel.
+
+Note:
+For ETR sink devices, this reserved region will be used for both trace
+capture and trace data retrieval.
+For ETF sink devices, internal SRAM would be used for trace capture,
+and they would be synced to reserved region for retrieval.
+
+
+Disabling coresight blocks at the time of panic
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+In order to avoid the situation of losing relevant trace data after a
+kernel panic, it would be desirable to stop the coresight blocks at the
+time of panic.
+
+This can be achieved by configuring the comparator, CTI and sink
+devices as below::
+
+           Trigger on panic
+    Comparator --->External out --->CTI -->External In---->ETR/ETF stop
+
+Saving metadata at the time of kernel panic
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Coresight metadata involves all additional data that are required for a
+successful trace decode in addition to the trace data. This involves
+ETR/ETF/ETB register snapshot etc.
+
+A new optional device property "memory-region" is added to
+the ETR/ETF/ETB device nodes for this.
+
+Reading trace data captured at the time of panic
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Trace data captured at the time of panic, can be read from rebooted kernel
+or from crashdump kernel using a special device file /dev/crash_tmc_xxx.
+This device file is created only when there is a valid crashdata available.
+
+General flow of trace capture and decode incase of kernel panic
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+1. Enable source and sink on all the cores using the sysfs interface.
+   ETR sinks should have trace buffers allocated from reserved memory,
+   by selecting "resrv" buffer mode from sysfs.
+
+2. Run relevant tests.
+
+3. On a kernel panic, all coresight blocks are disabled, necessary
+   metadata is synced by kernel panic handler.
+
+   System would eventually reboot or boot a crashdump kernel.
+
+4. For  platforms that supports crashdump kernel, raw trace data can be
+   dumped using the coresight sysfs interface from the crashdump kernel
+   itself. Persistent RAM is not a requirement in this case.
+
+5. For platforms that supports persistent RAM, trace data can be dumped
+   using the coresight sysfs interface in the subsequent Linux boot.
+   Crashdump kernel is not a requirement in this case. Persistent RAM
+   ensures that trace data is intact across reboot.
+
+Coresight trace during Watchdog reset
+-------------------------------------
+The main difference between addressing the watchdog reset and kernel panic
+case are below,
+
+a. Saving coresight metadata need to be taken care by the
+   SCP(system control processor) firmware in the specified format,
+   instead of kernel.
+
+b. Reserved memory region given by firmware for trace buffer and metadata
+   has to be in persistent RAM.
+   Note: This is a requirement for watchdog reset case but optional
+   in kernel panic case.
+
+Watchdog reset can be supported only on platforms that meet the above
+two requirements.
+
+Sample commands for testing a Kernel panic case with ETR sink
+-------------------------------------------------------------
+
+1. Boot Linux kernel with "crash_kexec_post_notifiers" added to the kernel
+   bootargs. This is mandatory if the user would like to read the tracedata
+   from the crashdump kernel.
+
+2. Enable the preloaded ETM configuration
+
+    #echo 1 > /sys/kernel/config/cs-syscfg/configurations/panicstop/enable
+
+3. Configure CTI using sysfs interface::
+
+    #./cti_setup.sh
+
+    #cat cti_setup.sh
+
+
+    cd /sys/bus/coresight/devices/
+
+    ap_cti_config () {
+      #ETM trig out[0] trigger to Channel 0
+      echo 0 4 > channels/trigin_attach
+    }
+
+    etf_cti_config () {
+      #ETF Flush in trigger from Channel 0
+      echo 0 1 > channels/trigout_attach
+      echo 1 > channels/trig_filter_enable
+    }
+
+    etr_cti_config () {
+      #ETR Flush in from Channel 0
+      echo 0 1 > channels/trigout_attach
+      echo 1 > channels/trig_filter_enable
+    }
+
+    ctidevs=`find . -name "cti*"`
+
+    for i in $ctidevs
+    do
+            cd $i
+
+            connection=`find . -name "ete*"`
+            if [ ! -z "$connection" ]
+            then
+                    echo "AP CTI config for $i"
+                    ap_cti_config
+            fi
+
+            connection=`find . -name "tmc_etf*"`
+            if [ ! -z "$connection" ]
+            then
+                    echo "ETF CTI config for $i"
+                    etf_cti_config
+            fi
+
+            connection=`find . -name "tmc_etr*"`
+            if [ ! -z "$connection" ]
+            then
+                    echo "ETR CTI config for $i"
+                    etr_cti_config
+            fi
+
+            cd ..
+    done
+
+Note: CTI connections are SOC specific and hence the above script is
+added just for reference.
+
+4. Choose reserved buffer mode for ETR buffer
+    #echo "resrv" > /sys/bus/coresight/devices/tmc_etr0/buf_mode_preferred
+
+5. Enable stop on flush trigger configuration
+    #echo 1 > /sys/bus/coresight/devices/tmc_etr0/stop_on_flush
+
+6. Start Coresight tracing on cores 1 and 2 using sysfs interface
+
+7. Run some application on core 1
+    #taskset -c 1 dd if=/dev/urandom of=/dev/null &
+
+8. Invoke kernel panic on core 2
+    #echo 1 > /proc/sys/kernel/panic
+    #taskset -c 2 echo c > /proc/sysrq-trigger
+
+9. From rebooted kernel or crashdump kernel, read crashdata
+
+    #dd if=/dev/crash_tmc_etr0 of=/trace/cstrace.bin
+
+10. Run opencsd decoder tools/scripts to generate the instruction trace.
+
+Sample instruction trace dump
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Core1 dump::
+
+    A                                  etm4_enable_hw: ffff800008ae1dd4
+    CONTEXT EL2                        etm4_enable_hw: ffff800008ae1dd4
+    I                                  etm4_enable_hw: ffff800008ae1dd4:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1dd8:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1ddc:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de0:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de4:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de8:
+    d503233f   paciasp
+    I                                  etm4_enable_hw: ffff800008ae1dec:
+    a9be7bfd   stp     x29, x30, [sp, #-32]!
+    I                                  etm4_enable_hw: ffff800008ae1df0:
+    910003fd   mov     x29, sp
+    I                                  etm4_enable_hw: ffff800008ae1df4:
+    a90153f3   stp     x19, x20, [sp, #16]
+    I                                  etm4_enable_hw: ffff800008ae1df8:
+    2a0003f4   mov     w20, w0
+    I                                  etm4_enable_hw: ffff800008ae1dfc:
+    900085b3   adrp    x19, ffff800009b95000 <reserved_mem+0xc48>
+    I                                  etm4_enable_hw: ffff800008ae1e00:
+    910f4273   add     x19, x19, #0x3d0
+    I                                  etm4_enable_hw: ffff800008ae1e04:
+    f8747a60   ldr     x0, [x19, x20, lsl #3]
+    E                                  etm4_enable_hw: ffff800008ae1e08:
+    b4000140   cbz     x0, ffff800008ae1e30 <etm4_starting_cpu+0x50>
+    I    149.039572921                 etm4_enable_hw: ffff800008ae1e30:
+    a94153f3   ldp     x19, x20, [sp, #16]
+    I    149.039572921                 etm4_enable_hw: ffff800008ae1e34:
+    52800000   mov     w0, #0x0                        // #0
+    I    149.039572921                 etm4_enable_hw: ffff800008ae1e38:
+    a8c27bfd   ldp     x29, x30, [sp], #32
+
+    ..snip
+
+        149.052324811           chacha_block_generic: ffff800008642d80:
+    9100a3e0   add     x0,
+    I    149.052324811           chacha_block_generic: ffff800008642d84:
+    b86178a2   ldr     w2, [x5, x1, lsl #2]
+    I    149.052324811           chacha_block_generic: ffff800008642d88:
+    8b010803   add     x3, x0, x1, lsl #2
+    I    149.052324811           chacha_block_generic: ffff800008642d8c:
+    b85fc063   ldur    w3, [x3, #-4]
+    I    149.052324811           chacha_block_generic: ffff800008642d90:
+    0b030042   add     w2, w2, w3
+    I    149.052324811           chacha_block_generic: ffff800008642d94:
+    b8217882   str     w2, [x4, x1, lsl #2]
+    I    149.052324811           chacha_block_generic: ffff800008642d98:
+    91000421   add     x1, x1, #0x1
+    I    149.052324811           chacha_block_generic: ffff800008642d9c:
+    f100443f   cmp     x1, #0x11
+
+
+Core 2 dump::
+
+    A                                  etm4_enable_hw: ffff800008ae1dd4
+    CONTEXT EL2                        etm4_enable_hw: ffff800008ae1dd4
+    I                                  etm4_enable_hw: ffff800008ae1dd4:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1dd8:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1ddc:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de0:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de4:
+    d503201f   nop
+    I                                  etm4_enable_hw: ffff800008ae1de8:
+    d503233f   paciasp
+    I                                  etm4_enable_hw: ffff800008ae1dec:
+    a9be7bfd   stp     x29, x30, [sp, #-32]!
+    I                                  etm4_enable_hw: ffff800008ae1df0:
+    910003fd   mov     x29, sp
+    I                                  etm4_enable_hw: ffff800008ae1df4:
+    a90153f3   stp     x19, x20, [sp, #16]
+    I                                  etm4_enable_hw: ffff800008ae1df8:
+    2a0003f4   mov     w20, w0
+    I                                  etm4_enable_hw: ffff800008ae1dfc:
+    900085b3   adrp    x19, ffff800009b95000 <reserved_mem+0xc48>
+    I                                  etm4_enable_hw: ffff800008ae1e00:
+    910f4273   add     x19, x19, #0x3d0
+    I                                  etm4_enable_hw: ffff800008ae1e04:
+    f8747a60   ldr     x0, [x19, x20, lsl #3]
+    E                                  etm4_enable_hw: ffff800008ae1e08:
+    b4000140   cbz     x0, ffff800008ae1e30 <etm4_starting_cpu+0x50>
+    I    149.046243445                 etm4_enable_hw: ffff800008ae1e30:
+    a94153f3   ldp     x19, x20, [sp, #16]
+    I    149.046243445                 etm4_enable_hw: ffff800008ae1e34:
+    52800000   mov     w0, #0x0                        // #0
+    I    149.046243445                 etm4_enable_hw: ffff800008ae1e38:
+    a8c27bfd   ldp     x29, x30, [sp], #32
+    I    149.046243445                 etm4_enable_hw: ffff800008ae1e3c:
+    d50323bf   autiasp
+    E    149.046243445                 etm4_enable_hw: ffff800008ae1e40:
+    d65f03c0   ret
+    A                                ete_sysreg_write: ffff800008adfa18
+
+    ..snip
+
+    I     149.05422547                          panic: ffff800008096300:
+    a90363f7   stp     x23, x24, [sp, #48]
+    I     149.05422547                          panic: ffff800008096304:
+    6b00003f   cmp     w1, w0
+    I     149.05422547                          panic: ffff800008096308:
+    3a411804   ccmn    w0, #0x1, #0x4, ne  // ne = any
+    N     149.05422547                          panic: ffff80000809630c:
+    540001e0   b.eq    ffff800008096348 <panic+0xe0>  // b.none
+    I     149.05422547                          panic: ffff800008096310:
+    f90023f9   str     x25, [sp, #64]
+    E     149.05422547                          panic: ffff800008096314:
+    97fe44ef   bl      ffff8000080276d0 <panic_smp_self_stop>
+    A                                           panic: ffff80000809634c
+    I     149.05422547                          panic: ffff80000809634c:
+    910102d5   add     x21, x22, #0x40
+    I     149.05422547                          panic: ffff800008096350:
+    52800020   mov     w0, #0x1                        // #1
+    E     149.05422547                          panic: ffff800008096354:
+    94166b8b   bl      ffff800008631180 <bust_spinlocks>
+    N    149.054225518                 bust_spinlocks: ffff800008631180:
+    340000c0   cbz     w0, ffff800008631198 <bust_spinlocks+0x18>
+    I    149.054225518                 bust_spinlocks: ffff800008631184:
+    f000a321   adrp    x1, ffff800009a98000 <pbufs.0+0xbb8>
+    I    149.054225518                 bust_spinlocks: ffff800008631188:
+    b9405c20   ldr     w0, [x1, #92]
+    I    149.054225518                 bust_spinlocks: ffff80000863118c:
+    11000400   add     w0, w0, #0x1
+    I    149.054225518                 bust_spinlocks: ffff800008631190:
+    b9005c20   str     w0, [x1, #92]
+    E    149.054225518                 bust_spinlocks: ffff800008631194:
+    d65f03c0   ret
+    A                                           panic: ffff800008096358
+
+Perf based testing
+------------------
+
+Starting perf session
+~~~~~~~~~~~~~~~~~~~~~
+ETF:
+perf record -e cs_etm/panicstop,@tmc_etf1/ -C 1
+perf record -e cs_etm/panicstop,@tmc_etf2/ -C 2
+
+ETR:
+perf record -e cs_etm/panicstop,@tmc_etr0/ -C 1,2
+
+Reading trace data after panic
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Same sysfs based method explained above can be used to retrieve and
+decode the trace data after the reboot on kernel panic.
-- 
2.34.1