[PATCH 0/2] remoteproc sysfs fixes/improvements

[PATCH 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(-)

-- 
2.24.3

[PATCH 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>
---
 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..4a41abdd1f7b 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 = 0;
+
+	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;
-- 
2.24.3

[PATCH 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;
-- 
2.24.3

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

[Mathieu Poirier]

Hi Puranjay,

On Mon, Jan 31, 2022 at 07:41:51PM +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.
> 

The address in the "To:" field of this email doesn't match the one in the SoB,
Something that makes checkpatch angry.

> Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
> ---
>  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..4a41abdd1f7b 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 toyed with this solution for a little while.  I think the use case is valid
but hiding the above options will also result in a system that is difficult to
use (and debug) because they convey important information.

I suggest introducing a new kernel configuration options to make the attributes
of the rproc_devgroup return -EINVAL when it is set.  So in remoteproc_sysfs.c
do something like:

#if CONFIG_REMOTEPROC_SYSFS_RO
static bool option_is_read_only()
{
        return true;
}
#else
static bool option_is_read_only()
{
        return false;
}
#endif

[...]

static ssize_t recovery_store(struct device *dev,
			      struct device_attribute *attr,
			      const char *buf, size_t count)
{
	struct rproc *rproc = to_rproc(dev);

        if (option_is_read_only())
                return -EINVAL;

	if (sysfs_streq(buf, "enabled")) {
		/* change the flag and begin the recovery process if needed */
		rproc->recovery_disabled = false;
		rproc_trigger_recovery(rproc);
	} else if (sysfs_streq(buf, "disabled")) {
		rproc->recovery_disabled = true;
	} else if (sysfs_streq(buf, "recover")) {
		/* begin the recovery process without changing the flag */
		rproc_trigger_recovery(rproc);
	} else {
		return -EINVAL;
	}

	return count;
}

Thanks,
Mathieu

> +		mode = 0;
> +
> +	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;
> -- 
> 2.24.3
> 

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

[Puranjay Mohan]

Hi Mathieu,

On Fri, Feb 4, 2022 at 12:07 AM Mathieu Poirier
<mathieu.poirier@linaro.org> wrote:
>
> Hi Puranjay,
>
> On Mon, Jan 31, 2022 at 07:41:51PM +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.
> >
>
> The address in the "To:" field of this email doesn't match the one in the SoB,
> Something that makes checkpatch angry.

I will try to figure this out.

>
> > Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
> > ---
> >  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..4a41abdd1f7b 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 toyed with this solution for a little while.  I think the use case is valid
> but hiding the above options will also result in a system that is difficult to
> use (and debug) because they convey important information.

I feel most use cases will require it to be read-only and not hidden,
so, we can set mode = 0444 in place of mode = 0 below.
It will make these files read-only without the extra code.
Actually, the idea to implement is_visble() was given by Bjorn in a
reply to the patch in the previous series[1].

>
> I suggest introducing a new kernel configuration options to make the attributes

 We want to do it dynamically and on a per driver basis, hence,
implementing is_visble() would be apt, which can be controlled by the
specific driver using the deny_sysfs_ops flag.

> of the rproc_devgroup return -EINVAL when it is set.  So in remoteproc_sysfs.c
> do something like:
>
> #if CONFIG_REMOTEPROC_SYSFS_RO
> static bool option_is_read_only()
> {
>         return true;
> }
> #else
> static bool option_is_read_only()
> {
>         return false;
> }
> #endif
>
> [...]
>
> static ssize_t recovery_store(struct device *dev,
>                               struct device_attribute *attr,
>                               const char *buf, size_t count)
> {
>         struct rproc *rproc = to_rproc(dev);
>
>         if (option_is_read_only())
>                 return -EINVAL;
>
>         if (sysfs_streq(buf, "enabled")) {
>                 /* change the flag and begin the recovery process if needed */
>                 rproc->recovery_disabled = false;
>                 rproc_trigger_recovery(rproc);
>         } else if (sysfs_streq(buf, "disabled")) {
>                 rproc->recovery_disabled = true;
>         } else if (sysfs_streq(buf, "recover")) {
>                 /* begin the recovery process without changing the flag */
>                 rproc_trigger_recovery(rproc);
>         } else {
>                 return -EINVAL;
>         }
>
>         return count;
> }
>
> Thanks,
> Mathieu
>
> > +             mode = 0;

^^ here we can put mode = 0444; for read-only.

> > +
> > +     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;
> > --
> > 2.24.3
> >

[1] https://patchwork.kernel.org/project/linux-remoteproc/patch/20201121030156.22857-3-s-anna@ti.com/

Thanks,
Puranjay Mohan

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

[Bjorn Andersson]

On Thu 03 Feb 10:37 PST 2022, Mathieu Poirier wrote:

> Hi Puranjay,
> 
> On Mon, Jan 31, 2022 at 07:41:51PM +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.
> > 
> 
> The address in the "To:" field of this email doesn't match the one in the SoB,
> Something that makes checkpatch angry.
> 
> > Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
> > ---
> >  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..4a41abdd1f7b 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 toyed with this solution for a little while.  I think the use case is valid
> but hiding the above options will also result in a system that is difficult to
> use (and debug) because they convey important information.
> 
> I suggest introducing a new kernel configuration options to make the attributes
> of the rproc_devgroup return -EINVAL when it is set.  So in remoteproc_sysfs.c
> do something like:
> 
> #if CONFIG_REMOTEPROC_SYSFS_RO

We should assume that people runs the common multi_v7_defconfig for arm,
or defconfig for arm64, and still want this support.

Based on Puranjay's proposed patch I think it's also reasonable to
assume that we might have platforms with a mixture of "read-only" and
"normal" remoteprocs (e.g. some power-management uC + some DSP).

> static bool option_is_read_only()
> {
>         return true;
> }
> #else
> static bool option_is_read_only()
> {
>         return false;
> }
> #endif
> 
> [...]
> 
> static ssize_t recovery_store(struct device *dev,
> 			      struct device_attribute *attr,
> 			      const char *buf, size_t count)
> {
> 	struct rproc *rproc = to_rproc(dev);
> 
>         if (option_is_read_only())

struct attribute_group has a .is_visible callback which I think is
better to base this on.

Regards,
Bjorn

>                 return -EINVAL;
> 
> 	if (sysfs_streq(buf, "enabled")) {
> 		/* change the flag and begin the recovery process if needed */
> 		rproc->recovery_disabled = false;
> 		rproc_trigger_recovery(rproc);
> 	} else if (sysfs_streq(buf, "disabled")) {
> 		rproc->recovery_disabled = true;
> 	} else if (sysfs_streq(buf, "recover")) {
> 		/* begin the recovery process without changing the flag */
> 		rproc_trigger_recovery(rproc);
> 	} else {
> 		return -EINVAL;
> 	}
> 
> 	return count;
> }
> 
> Thanks,
> Mathieu
> 
> > +		mode = 0;
> > +
> > +	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;
> > -- 
> > 2.24.3
> > 

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

[Puranjay Mohan]

Hi Bjorn,

On Fri, Feb 4, 2022 at 2:12 AM Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:
>
> On Thu 03 Feb 10:37 PST 2022, Mathieu Poirier wrote:
>
> > Hi Puranjay,
> >
> > On Mon, Jan 31, 2022 at 07:41:51PM +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.
> > >
> >
> > The address in the "To:" field of this email doesn't match the one in the SoB,
> > Something that makes checkpatch angry.
> >
> > > Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
> > > ---
> > >  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..4a41abdd1f7b 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 toyed with this solution for a little while.  I think the use case is valid
> > but hiding the above options will also result in a system that is difficult to
> > use (and debug) because they convey important information.
> >
> > I suggest introducing a new kernel configuration options to make the attributes
> > of the rproc_devgroup return -EINVAL when it is set.  So in remoteproc_sysfs.c
> > do something like:
> >
> > #if CONFIG_REMOTEPROC_SYSFS_RO
>
> We should assume that people runs the common multi_v7_defconfig for arm,
> or defconfig for arm64, and still want this support.
>
> Based on Puranjay's proposed patch I think it's also reasonable to
> assume that we might have platforms with a mixture of "read-only" and
> "normal" remoteprocs (e.g. some power-management uC + some DSP).
>

I will send another version with mode = 0444 in the .is_visible(), to
make it read-only when deny_sysfs_ops is true.
Also, this patch should technically be v3 as previous series ended with v2.
So, I will mark my next patch as v4.
Please let me know if any other changes are required to this patch.

> > static bool option_is_read_only()
> > {
> >         return true;
> > }
> > #else
> > static bool option_is_read_only()
> > {
> >         return false;
> > }
> > #endif
> >
> > [...]
> >
> > static ssize_t recovery_store(struct device *dev,
> >                             struct device_attribute *attr,
> >                             const char *buf, size_t count)
> > {
> >       struct rproc *rproc = to_rproc(dev);
> >
> >         if (option_is_read_only())
>
> struct attribute_group has a .is_visible callback which I think is
> better to base this on.
>
> Regards,
> Bjorn
>
> >                 return -EINVAL;
> >
> >       if (sysfs_streq(buf, "enabled")) {
> >               /* change the flag and begin the recovery process if needed */
> >               rproc->recovery_disabled = false;
> >               rproc_trigger_recovery(rproc);
> >       } else if (sysfs_streq(buf, "disabled")) {
> >               rproc->recovery_disabled = true;
> >       } else if (sysfs_streq(buf, "recover")) {
> >               /* begin the recovery process without changing the flag */
> >               rproc_trigger_recovery(rproc);
> >       } else {
> >               return -EINVAL;
> >       }
> >
> >       return count;
> > }
> >
> > Thanks,
> > Mathieu
> >
> > > +           mode = 0;
> > > +
> > > +   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;
> > > --
> > > 2.24.3
> > >



Thanks,
Puranjay Mohan

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

[Mathieu Poirier]

On Fri, Feb 04, 2022 at 01:40:23AM +0530, Puranjay Mohan wrote:
> Hi Mathieu,
> 
> On Fri, Feb 4, 2022 at 12:07 AM Mathieu Poirier
> <mathieu.poirier@linaro.org> wrote:
> >
> > Hi Puranjay,
> >
> > On Mon, Jan 31, 2022 at 07:41:51PM +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.
> > >
> >
> > The address in the "To:" field of this email doesn't match the one in the SoB,
> > Something that makes checkpatch angry.
> 
> I will try to figure this out.
> 
> >
> > > Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
> > > ---
> > >  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..4a41abdd1f7b 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 toyed with this solution for a little while.  I think the use case is valid
> > but hiding the above options will also result in a system that is difficult to
> > use (and debug) because they convey important information.
> 
> I feel most use cases will require it to be read-only and not hidden,
> so, we can set mode = 0444 in place of mode = 0 below.

Perfect.

> It will make these files read-only without the extra code.

I haven't looked the specifics but even better if that is the case.

> Actually, the idea to implement is_visble() was given by Bjorn in a
> reply to the patch in the previous series[1].
> 

I missed Bjorn's reply, which can happen given the high traffic on this mailing
list.  And having different views on how to address problems is a good thing.
It gives us an opportunity to discuss different avenues and pick out the best
one. 

> >
> > I suggest introducing a new kernel configuration options to make the attributes
> 
>  We want to do it dynamically and on a per driver basis, hence,
> implementing is_visble() would be apt, which can be controlled by the
> specific driver using the deny_sysfs_ops flag.

I agree that if you need that kind of granularity then a kernel configuration
option is not the right approach.

> 
> > of the rproc_devgroup return -EINVAL when it is set.  So in remoteproc_sysfs.c
> > do something like:
> >
> > #if CONFIG_REMOTEPROC_SYSFS_RO
> > static bool option_is_read_only()
> > {
> >         return true;
> > }
> > #else
> > static bool option_is_read_only()
> > {
> >         return false;
> > }
> > #endif
> >
> > [...]
> >
> > static ssize_t recovery_store(struct device *dev,
> >                               struct device_attribute *attr,
> >                               const char *buf, size_t count)
> > {
> >         struct rproc *rproc = to_rproc(dev);
> >
> >         if (option_is_read_only())
> >                 return -EINVAL;
> >
> >         if (sysfs_streq(buf, "enabled")) {
> >                 /* change the flag and begin the recovery process if needed */
> >                 rproc->recovery_disabled = false;
> >                 rproc_trigger_recovery(rproc);
> >         } else if (sysfs_streq(buf, "disabled")) {
> >                 rproc->recovery_disabled = true;
> >         } else if (sysfs_streq(buf, "recover")) {
> >                 /* begin the recovery process without changing the flag */
> >                 rproc_trigger_recovery(rproc);
> >         } else {
> >                 return -EINVAL;
> >         }
> >
> >         return count;
> > }
> >
> > Thanks,
> > Mathieu
> >
> > > +             mode = 0;
> 
> ^^ here we can put mode = 0444; for read-only.
> 
> > > +
> > > +     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;
> > > --
> > > 2.24.3
> > >
> 
> [1] https://patchwork.kernel.org/project/linux-remoteproc/patch/20201121030156.22857-3-s-anna@ti.com/
> 
> Thanks,
> Puranjay Mohan