[PATCH v4 0/2] remoteproc sysfs fixes/improvements

[PATCH v4 0/2] remoteproc sysfs fixes/improvements

[Puranjay Mohan]

This is a refresh of the patches from an old series [1].
Patch 1 of that series is not required now as [2] serves its purpose.
Patch 2 has been improved and is being posted here.
Patch 3 is unchanged, it has been rebased and posted.

The features being introduced here will be needed by the recently posted PRU 
remoteproc driver [3] in addition to the existing Wkup M3 remoteproc driver.
Both of these drivers follow a client-driven boot methodology, with the latter
strictly booted by another driver in kernel. The PRU remoteproc driver will be
supporting both in-kernel clients as well as control from userspace orthogonally.
The logic though is applicable and useful to any remoteproc driver not using
'auto-boot' and using an external driver/application to boot the remoteproc.

[1] https://patchwork.kernel.org/project/linux-remoteproc/cover/20201121030156.22857-1-s-anna@ti.com/[2] https://patchwork.kernel.org/project/linux-remoteproc/patch/20201126210642.897302-4-mathieu.poirier@linaro.org/
[3] https://patchwork.kernel.org/project/linux-remoteproc/cover/20201119140850.12268-1-grzegorz.jaszczyk@linaro.org/

Puranjay Mohan (1):
  remoteproc: Introduce deny_sysfs_ops flag

Suman Anna (1):
  remoteproc: wkup_m3: Set deny_sysfs_ops flag

 drivers/remoteproc/remoteproc_sysfs.c | 18 +++++++++++++++++-
 drivers/remoteproc/wkup_m3_rproc.c    |  1 +
 include/linux/remoteproc.h            |  2 ++
 3 files changed, 20 insertions(+), 1 deletion(-)

-- 
2.17.1


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[PATCH v4 1/2] remoteproc: Introduce deny_sysfs_ops flag

[Puranjay Mohan]

The remoteproc framework provides sysfs interfaces for changing
the firmware name and for starting/stopping a remote processor
through the sysfs files 'state' and 'firmware'. The 'recovery'
sysfs file can also be used similarly to control the error recovery
state machine of a remoteproc. These interfaces are currently
allowed irrespective of how the remoteprocs were booted (like
remoteproc self auto-boot, remoteproc client-driven boot etc).
These interfaces can adversely affect a remoteproc and its clients
especially when a remoteproc is being controlled by a remoteproc
client driver(s). Also, not all remoteproc drivers may want to
support the sysfs interfaces by default.

Add support to deny the sysfs state/firmware/recovery change by
introducing a state flag 'deny_sysfs_ops' that the individual
remoteproc drivers can set based on their usage needs. The default
behavior is to allow the sysfs operations as before.

Implement attribute_group->is_visible() to hide the sysfs
state/firmware/recovery entries when deny_sysfs_ops flag is set.

Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
---
Changes in v3->v4:
Use mode = 0444 in rproc_is_visible() to make the sysfs entries
read-only when the deny_sysfs_ops flag is set.
---
 drivers/remoteproc/remoteproc_sysfs.c | 18 +++++++++++++++++-
 include/linux/remoteproc.h            |  2 ++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
index ea8b89f97d7b..da2d0eecfa44 100644
--- a/drivers/remoteproc/remoteproc_sysfs.c
+++ b/drivers/remoteproc/remoteproc_sysfs.c
@@ -230,6 +230,21 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(name);
 
+static umode_t rproc_is_visible(struct kobject *kobj, struct attribute *attr,
+				int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct rproc *rproc = to_rproc(dev);
+	umode_t mode = attr->mode;
+
+	if (rproc->deny_sysfs_ops && (attr == &dev_attr_recovery.attr ||
+				      attr == &dev_attr_firmware.attr ||
+				      attr == &dev_attr_state.attr))
+		mode = 0444;
+
+	return mode;
+}
+
 static struct attribute *rproc_attrs[] = {
 	&dev_attr_coredump.attr,
 	&dev_attr_recovery.attr,
@@ -240,7 +255,8 @@ static struct attribute *rproc_attrs[] = {
 };
 
 static const struct attribute_group rproc_devgroup = {
-	.attrs = rproc_attrs
+	.attrs = rproc_attrs,
+	.is_visible = rproc_is_visible,
 };
 
 static const struct attribute_group *rproc_devgroups[] = {
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index e0600e1e5c17..3849c66ce38f 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -523,6 +523,7 @@ struct rproc_dump_segment {
  * @table_sz: size of @cached_table
  * @has_iommu: flag to indicate if remote processor is behind an MMU
  * @auto_boot: flag to indicate if remote processor should be auto-started
+ * @deny_sysfs_ops: flag to not permit sysfs operations on state, firmware and recovery
  * @dump_segments: list of segments in the firmware
  * @nb_vdev: number of vdev currently handled by rproc
  * @elf_class: firmware ELF class
@@ -562,6 +563,7 @@ struct rproc {
 	size_t table_sz;
 	bool has_iommu;
 	bool auto_boot;
+	bool deny_sysfs_ops;
 	struct list_head dump_segments;
 	int nb_vdev;
 	u8 elf_class;
-- 
2.17.1


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[PATCH v4 2/2] remoteproc: wkup_m3: Set deny_sysfs_ops flag

[Puranjay Mohan]

From: Suman Anna <s-anna@ti.com>

The Wakeup M3 remote processor is controlled by the wkup_m3_ipc
client driver, so set the newly introduced 'deny_sysfs_ops' flag
to not allow any overriding of the remoteproc firmware or state
from userspace.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
---
 drivers/remoteproc/wkup_m3_rproc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/remoteproc/wkup_m3_rproc.c b/drivers/remoteproc/wkup_m3_rproc.c
index 484f7605823e..bbb84bb28af8 100644
--- a/drivers/remoteproc/wkup_m3_rproc.c
+++ b/drivers/remoteproc/wkup_m3_rproc.c
@@ -163,6 +163,7 @@ static int wkup_m3_rproc_probe(struct platform_device *pdev)
 	}
 
 	rproc->auto_boot = false;
+	rproc->deny_sysfs_ops = true;
 
 	wkupm3 = rproc->priv;
 	wkupm3->rproc = rproc;
-- 
2.17.1


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Re: [PATCH v4 1/2] remoteproc: Introduce deny_sysfs_ops flag

[Mathieu Poirier]

Hi Puranjay,

On Wed, Feb 09, 2022 at 02:33:41PM +0530, Puranjay Mohan wrote:
> The remoteproc framework provides sysfs interfaces for changing
> the firmware name and for starting/stopping a remote processor
> through the sysfs files 'state' and 'firmware'. The 'recovery'
> sysfs file can also be used similarly to control the error recovery
> state machine of a remoteproc. These interfaces are currently
> allowed irrespective of how the remoteprocs were booted (like
> remoteproc self auto-boot, remoteproc client-driven boot etc).
> These interfaces can adversely affect a remoteproc and its clients
> especially when a remoteproc is being controlled by a remoteproc
> client driver(s). Also, not all remoteproc drivers may want to
> support the sysfs interfaces by default.
> 
> Add support to deny the sysfs state/firmware/recovery change by
> introducing a state flag 'deny_sysfs_ops' that the individual
> remoteproc drivers can set based on their usage needs. The default
> behavior is to allow the sysfs operations as before.
> 
> Implement attribute_group->is_visible() to hide the sysfs
> state/firmware/recovery entries when deny_sysfs_ops flag is set.
> 
> Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
> ---
> Changes in v3->v4:
> Use mode = 0444 in rproc_is_visible() to make the sysfs entries
> read-only when the deny_sysfs_ops flag is set.
> ---
>  drivers/remoteproc/remoteproc_sysfs.c | 18 +++++++++++++++++-
>  include/linux/remoteproc.h            |  2 ++
>  2 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
> index ea8b89f97d7b..da2d0eecfa44 100644
> --- a/drivers/remoteproc/remoteproc_sysfs.c
> +++ b/drivers/remoteproc/remoteproc_sysfs.c
> @@ -230,6 +230,21 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr,
>  }
>  static DEVICE_ATTR_RO(name);
>  
> +static umode_t rproc_is_visible(struct kobject *kobj, struct attribute *attr,
> +				int n)
> +{
> +	struct device *dev = kobj_to_dev(kobj);
> +	struct rproc *rproc = to_rproc(dev);
> +	umode_t mode = attr->mode;
> +
> +	if (rproc->deny_sysfs_ops && (attr == &dev_attr_recovery.attr ||
> +				      attr == &dev_attr_firmware.attr ||
> +				      attr == &dev_attr_state.attr))

I was wondering if we should also add coredump to this group to make it an all
or nothing option (name is already read only).

> +		mode = 0444;

Much better.

> +
> +	return mode;
> +}
> +
>  static struct attribute *rproc_attrs[] = {
>  	&dev_attr_coredump.attr,
>  	&dev_attr_recovery.attr,
> @@ -240,7 +255,8 @@ static struct attribute *rproc_attrs[] = {
>  };
>  
>  static const struct attribute_group rproc_devgroup = {
> -	.attrs = rproc_attrs
> +	.attrs = rproc_attrs,
> +	.is_visible = rproc_is_visible,
>  };
>  
>  static const struct attribute_group *rproc_devgroups[] = {
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index e0600e1e5c17..3849c66ce38f 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -523,6 +523,7 @@ struct rproc_dump_segment {
>   * @table_sz: size of @cached_table
>   * @has_iommu: flag to indicate if remote processor is behind an MMU
>   * @auto_boot: flag to indicate if remote processor should be auto-started
> + * @deny_sysfs_ops: flag to not permit sysfs operations on state, firmware and recovery
>   * @dump_segments: list of segments in the firmware
>   * @nb_vdev: number of vdev currently handled by rproc
>   * @elf_class: firmware ELF class
> @@ -562,6 +563,7 @@ struct rproc {
>  	size_t table_sz;
>  	bool has_iommu;
>  	bool auto_boot;
> +	bool deny_sysfs_ops;

Wouldn't "sysfs_read_only" make more sense?


With or without the above and for this set:

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>

>  	struct list_head dump_segments;
>  	int nb_vdev;
>  	u8 elf_class;
> -- 
> 2.17.1
> 

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Re: [EXTERNAL] Re: [PATCH v4 1/2] remoteproc: Introduce deny_sysfs_ops flag

[Puranjay Mohan]

Hi Mathieu,

On 11/02/22 00:18, Mathieu Poirier wrote:
> Hi Puranjay,
> 
> On Wed, Feb 09, 2022 at 02:33:41PM +0530, Puranjay Mohan wrote:
>> The remoteproc framework provides sysfs interfaces for changing
>> the firmware name and for starting/stopping a remote processor
>> through the sysfs files 'state' and 'firmware'. The 'recovery'
>> sysfs file can also be used similarly to control the error recovery
>> state machine of a remoteproc. These interfaces are currently
>> allowed irrespective of how the remoteprocs were booted (like
>> remoteproc self auto-boot, remoteproc client-driven boot etc).
>> These interfaces can adversely affect a remoteproc and its clients
>> especially when a remoteproc is being controlled by a remoteproc
>> client driver(s). Also, not all remoteproc drivers may want to
>> support the sysfs interfaces by default.
>>
>> Add support to deny the sysfs state/firmware/recovery change by
>> introducing a state flag 'deny_sysfs_ops' that the individual
>> remoteproc drivers can set based on their usage needs. The default
>> behavior is to allow the sysfs operations as before.
>>
>> Implement attribute_group->is_visible() to hide the sysfs
>> state/firmware/recovery entries when deny_sysfs_ops flag is set.
>>
>> Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
>> ---
>> Changes in v3->v4:
>> Use mode = 0444 in rproc_is_visible() to make the sysfs entries
>> read-only when the deny_sysfs_ops flag is set.
>> ---
>>  drivers/remoteproc/remoteproc_sysfs.c | 18 +++++++++++++++++-
>>  include/linux/remoteproc.h            |  2 ++
>>  2 files changed, 19 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
>> index ea8b89f97d7b..da2d0eecfa44 100644
>> --- a/drivers/remoteproc/remoteproc_sysfs.c
>> +++ b/drivers/remoteproc/remoteproc_sysfs.c
>> @@ -230,6 +230,21 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr,
>>  }
>>  static DEVICE_ATTR_RO(name);
>>  
>> +static umode_t rproc_is_visible(struct kobject *kobj, struct attribute *attr,
>> +				int n)
>> +{
>> +	struct device *dev = kobj_to_dev(kobj);
>> +	struct rproc *rproc = to_rproc(dev);
>> +	umode_t mode = attr->mode;
>> +
>> +	if (rproc->deny_sysfs_ops && (attr == &dev_attr_recovery.attr ||
>> +				      attr == &dev_attr_firmware.attr ||
>> +				      attr == &dev_attr_state.attr))
> 
> I was wondering if we should also add coredump to this group to make it an all
> or nothing option (name is already read only).

I have sent a v5 where I have added coredump to this.

> 
>> +		mode = 0444;
> 
> Much better.
> 
>> +
>> +	return mode;
>> +}
>> +
>>  static struct attribute *rproc_attrs[] = {
>>  	&dev_attr_coredump.attr,
>>  	&dev_attr_recovery.attr,
>> @@ -240,7 +255,8 @@ static struct attribute *rproc_attrs[] = {
>>  };
>>  
>>  static const struct attribute_group rproc_devgroup = {
>> -	.attrs = rproc_attrs
>> +	.attrs = rproc_attrs,
>> +	.is_visible = rproc_is_visible,
>>  };
>>  
>>  static const struct attribute_group *rproc_devgroups[] = {
>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
>> index e0600e1e5c17..3849c66ce38f 100644
>> --- a/include/linux/remoteproc.h
>> +++ b/include/linux/remoteproc.h
>> @@ -523,6 +523,7 @@ struct rproc_dump_segment {
>>   * @table_sz: size of @cached_table
>>   * @has_iommu: flag to indicate if remote processor is behind an MMU
>>   * @auto_boot: flag to indicate if remote processor should be auto-started
>> + * @deny_sysfs_ops: flag to not permit sysfs operations on state, firmware and recovery
>>   * @dump_segments: list of segments in the firmware
>>   * @nb_vdev: number of vdev currently handled by rproc
>>   * @elf_class: firmware ELF class
>> @@ -562,6 +563,7 @@ struct rproc {
>>  	size_t table_sz;
>>  	bool has_iommu;
>>  	bool auto_boot;
>> +	bool deny_sysfs_ops;
> 
> Wouldn't "sysfs_read_only" make more sense?

I agree, I have renamed it to sysfs_read_only in v5 patch

> 
> 
> With or without the above and for this set:
> 
> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>

Thanks.
Puranjay Mohan

> 
>>  	struct list_head dump_segments;
>>  	int nb_vdev;
>>  	u8 elf_class;
>> -- 
>> 2.17.1
>>

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