Re: [PATCH v9 7/9] coresight: add support for CPU debug module

[Leo Yan]

On Thu, May 11, 2017 at 11:12:32AM -0600, Mathieu Poirier wrote:

[...]

> > +static int debug_probe(struct amba_device *adev, const struct amba_id *id)
> > +{
> > +   void __iomem *base;
> > +   struct device *dev = &adev->dev;
> > +   struct debug_drvdata *drvdata;
> > +   struct resource *res = &adev->res;
> > +   struct device_node *np = adev->dev.of_node;
> > +   int ret;
> > +
> > +   drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> > +   if (!drvdata)
> > +   return -ENOMEM;
> > +
> > +   drvdata->cpu = np ? of_coresight_get_cpu(np) : 0;
> > +   if (per_cpu(debug_drvdata, drvdata->cpu)) {
> > +   dev_err(dev, "CPU%d drvdata has been initialized, "
> 
> s/"has been"/"has already been"
> 
> That way it really look like an error message.

Will fix.

> Also debug_probe() uses dev_xyz() but everywhere else in the driver it is
> pr_xyz() - any specific reason for that?  I suggest moving to dev_xyz().

Some logs are shared for all device instances, so I think should use
pr_xyz(); will spin a new version to change other places to use
dev_xyz() if the logs are for specific device instance.

> Otherwise things look good.

[...]

Thanks,
Leo Yan
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Re: [PATCH v9 7/9] coresight: add support for CPU debug module

[Suzuki K Poulose]

On 09/05/17 03:50, Leo Yan wrote:

Coresight includes debug module and usually the module connects with CPU
debug logic. ARMv8 architecture reference manual (ARM DDI 0487A.k) has
description for related info in "Part H: External Debug".

Chapter H7 "The Sample-based Profiling Extension" introduces several
sampling registers, e.g. we can check program counter value with
combined CPU exception level, secure state, etc. So this is helpful for
analysis CPU lockup scenarios, e.g. if one CPU has run into infinite
loop with IRQ disabled. In this case the CPU cannot switch context and
handle any interrupt (including IPIs), as the result it cannot handle
SMP call for stack dump.

This patch is to enable coresight debug module, so firstly this driver
is to bind apb clock for debug module and this is to ensure the debug
module can be accessed from program or external debugger. And the driver
uses sample-based registers for debug purpose, e.g. when system triggers
panic, the driver will dump program counter and combined context
registers (EDCIDSR, EDVIDSR); by parsing context registers so can
quickly get to know CPU secure state, exception level, etc.

Some of the debug module registers are located in CPU power domain, so
this requires the CPU power domain stays on when access related debug
registers, but the power management for CPU power domain is quite
dependent on SoC integration for power management. For the platforms
which with sane power controller implementations, this driver follows
the method to set EDPRCR to try to pull the CPU out of low power state
and then set 'no power down request' bit so the CPU has no chance to
lose power.

If the SoC has not followed up this design well for power management
controller, the user should use the command line parameter or sysfs
to constrain all or partial idle states to ensure the CPU power
domain is enabled and access coresight CPU debug component safely.

Signed-off-by: Leo Yan 


With comments from Mathieu addressed,

Reviewed-by: Suzuki K Poulose 

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Re: [PATCH v9 7/9] coresight: add support for CPU debug module

[Mathieu Poirier]

On Tue, May 09, 2017 at 10:50:00AM +0800, Leo Yan wrote:
> Coresight includes debug module and usually the module connects with CPU
> debug logic. ARMv8 architecture reference manual (ARM DDI 0487A.k) has
> description for related info in "Part H: External Debug".
> 
> Chapter H7 "The Sample-based Profiling Extension" introduces several
> sampling registers, e.g. we can check program counter value with
> combined CPU exception level, secure state, etc. So this is helpful for
> analysis CPU lockup scenarios, e.g. if one CPU has run into infinite
> loop with IRQ disabled. In this case the CPU cannot switch context and
> handle any interrupt (including IPIs), as the result it cannot handle
> SMP call for stack dump.
> 
> This patch is to enable coresight debug module, so firstly this driver
> is to bind apb clock for debug module and this is to ensure the debug
> module can be accessed from program or external debugger. And the driver
> uses sample-based registers for debug purpose, e.g. when system triggers
> panic, the driver will dump program counter and combined context
> registers (EDCIDSR, EDVIDSR); by parsing context registers so can
> quickly get to know CPU secure state, exception level, etc.
> 
> Some of the debug module registers are located in CPU power domain, so
> this requires the CPU power domain stays on when access related debug
> registers, but the power management for CPU power domain is quite
> dependent on SoC integration for power management. For the platforms
> which with sane power controller implementations, this driver follows
> the method to set EDPRCR to try to pull the CPU out of low power state
> and then set 'no power down request' bit so the CPU has no chance to
> lose power.
> 
> If the SoC has not followed up this design well for power management
> controller, the user should use the command line parameter or sysfs
> to constrain all or partial idle states to ensure the CPU power
> domain is enabled and access coresight CPU debug component safely.
> 
> Signed-off-by: Leo Yan 
> ---
>  drivers/hwtracing/coresight/Kconfig   |  14 +
>  drivers/hwtracing/coresight/Makefile  |   1 +
>  drivers/hwtracing/coresight/coresight-cpu-debug.c | 693 
> ++
>  3 files changed, 708 insertions(+)
>  create mode 100644 drivers/hwtracing/coresight/coresight-cpu-debug.c
> 
> diff --git a/drivers/hwtracing/coresight/Kconfig 
> b/drivers/hwtracing/coresight/Kconfig
> index 130cb21..8d55d6d 100644
> --- a/drivers/hwtracing/coresight/Kconfig
> +++ b/drivers/hwtracing/coresight/Kconfig
> @@ -89,4 +89,18 @@ config CORESIGHT_STM
> logging useful software events or data coming from various entities
> in the system, possibly running different OSs
>  
> +config CORESIGHT_CPU_DEBUG
> + tristate "CoreSight CPU Debug driver"
> + depends on ARM || ARM64
> + depends on DEBUG_FS
> + help
> +   This driver provides support for coresight debugging module. This
> +   is primarily used to dump sample-based profiling registers when
> +   system triggers panic, the driver will parse context registers so
> +   can quickly get to know program counter (PC), secure state,
> +   exception level, etc. Before use debugging functionality, platform
> +   needs to ensure the clock domain and power domain are enabled
> +   properly, please refer Documentation/trace/coresight-cpu-debug.txt
> +   for detailed description and the example for usage.
> +
>  endif
> diff --git a/drivers/hwtracing/coresight/Makefile 
> b/drivers/hwtracing/coresight/Makefile
> index af480d9..433d590 100644
> --- a/drivers/hwtracing/coresight/Makefile
> +++ b/drivers/hwtracing/coresight/Makefile
> @@ -16,3 +16,4 @@ obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o \
>   coresight-etm4x-sysfs.o
>  obj-$(CONFIG_CORESIGHT_QCOM_REPLICATOR) += coresight-replicator-qcom.o
>  obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
> +obj-$(CONFIG_CORESIGHT_CPU_DEBUG) += coresight-cpu-debug.o
> diff --git a/drivers/hwtracing/coresight/coresight-cpu-debug.c 
> b/drivers/hwtracing/coresight/coresight-cpu-debug.c
> new file mode 100644
> index 000..ab12ec1
> --- /dev/null
> +++ b/drivers/hwtracing/coresight/coresight-cpu-debug.c
> @@ -0,0 +1,693 @@
> +/*
> + * Copyright (c) 2017 Linaro Limited. All rights reserved.
> + *
> + * Author: Leo Yan 
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published 
> by
> + * the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but 
> WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along 
> with
> + * this program.  If

[PATCH v9 7/9] coresight: add support for CPU debug module

[Leo Yan]

Coresight includes debug module and usually the module connects with CPU
debug logic. ARMv8 architecture reference manual (ARM DDI 0487A.k) has
description for related info in "Part H: External Debug".

Chapter H7 "The Sample-based Profiling Extension" introduces several
sampling registers, e.g. we can check program counter value with
combined CPU exception level, secure state, etc. So this is helpful for
analysis CPU lockup scenarios, e.g. if one CPU has run into infinite
loop with IRQ disabled. In this case the CPU cannot switch context and
handle any interrupt (including IPIs), as the result it cannot handle
SMP call for stack dump.

This patch is to enable coresight debug module, so firstly this driver
is to bind apb clock for debug module and this is to ensure the debug
module can be accessed from program or external debugger. And the driver
uses sample-based registers for debug purpose, e.g. when system triggers
panic, the driver will dump program counter and combined context
registers (EDCIDSR, EDVIDSR); by parsing context registers so can
quickly get to know CPU secure state, exception level, etc.

Some of the debug module registers are located in CPU power domain, so
this requires the CPU power domain stays on when access related debug
registers, but the power management for CPU power domain is quite
dependent on SoC integration for power management. For the platforms
which with sane power controller implementations, this driver follows
the method to set EDPRCR to try to pull the CPU out of low power state
and then set 'no power down request' bit so the CPU has no chance to
lose power.

If the SoC has not followed up this design well for power management
controller, the user should use the command line parameter or sysfs
to constrain all or partial idle states to ensure the CPU power
domain is enabled and access coresight CPU debug component safely.

Signed-off-by: Leo Yan 
---
 drivers/hwtracing/coresight/Kconfig   |  14 +
 drivers/hwtracing/coresight/Makefile  |   1 +
 drivers/hwtracing/coresight/coresight-cpu-debug.c | 693 ++
 3 files changed, 708 insertions(+)
 create mode 100644 drivers/hwtracing/coresight/coresight-cpu-debug.c

diff --git a/drivers/hwtracing/coresight/Kconfig 
b/drivers/hwtracing/coresight/Kconfig
index 130cb21..8d55d6d 100644
--- a/drivers/hwtracing/coresight/Kconfig
+++ b/drivers/hwtracing/coresight/Kconfig
@@ -89,4 +89,18 @@ config CORESIGHT_STM
  logging useful software events or data coming from various entities
  in the system, possibly running different OSs
 
+config CORESIGHT_CPU_DEBUG
+   tristate "CoreSight CPU Debug driver"
+   depends on ARM || ARM64
+   depends on DEBUG_FS
+   help
+ This driver provides support for coresight debugging module. This
+ is primarily used to dump sample-based profiling registers when
+ system triggers panic, the driver will parse context registers so
+ can quickly get to know program counter (PC), secure state,
+ exception level, etc. Before use debugging functionality, platform
+ needs to ensure the clock domain and power domain are enabled
+ properly, please refer Documentation/trace/coresight-cpu-debug.txt
+ for detailed description and the example for usage.
+
 endif
diff --git a/drivers/hwtracing/coresight/Makefile 
b/drivers/hwtracing/coresight/Makefile
index af480d9..433d590 100644
--- a/drivers/hwtracing/coresight/Makefile
+++ b/drivers/hwtracing/coresight/Makefile
@@ -16,3 +16,4 @@ obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o \
coresight-etm4x-sysfs.o
 obj-$(CONFIG_CORESIGHT_QCOM_REPLICATOR) += coresight-replicator-qcom.o
 obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
+obj-$(CONFIG_CORESIGHT_CPU_DEBUG) += coresight-cpu-debug.o
diff --git a/drivers/hwtracing/coresight/coresight-cpu-debug.c 
b/drivers/hwtracing/coresight/coresight-cpu-debug.c
new file mode 100644
index 000..ab12ec1
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-cpu-debug.c
@@ -0,0 +1,693 @@
+/*
+ * Copyright (c) 2017 Linaro Limited. All rights reserved.
+ *
+ * Author: Leo Yan 
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see .
+ *
+ */
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include