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[PATCH v6 0/4] of: overlay: kobject & sysfs'ation

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  [PATCH v6 0/4] of: overlay: kobject & sysfs'ation Pantelis Antoniou <pantelis.antoniou@konsulko.com> - 2015-10-20 21:20 +0200
    [PATCH v6 2/4] of: overlay: global sysfs enable attribute Pantelis Antoniou <pantelis.antoniou@konsulko.com> - 2015-10-20 21:20 +0200
      Re: [PATCH v6 2/4] of: overlay: global sysfs enable attribute Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-20 23:10 +0200
        Re: [PATCH v6 2/4] of: overlay: global sysfs enable attribute Rob Herring <robherring2@gmail.com> - 2015-10-21 00:00 +0200
          Re: [PATCH v6 2/4] of: overlay: global sysfs enable attribute Pantelis Antoniou <pantelis.antoniou@konsulko.com> - 2015-10-21 10:50 +0200
    [PATCH v6 4/4] Documentation: ABI: /sys/firmware/devicetree/overlays Pantelis Antoniou <pantelis.antoniou@konsulko.com> - 2015-10-20 21:20 +0200
      Re: [PATCH v6 4/4] Documentation: ABI: /sys/firmware/devicetree/overlays Rob Herring <robherring2@gmail.com> - 2015-10-20 23:00 +0200
        Re: [PATCH v6 4/4] Documentation: ABI: /sys/firmware/devicetree/overlays Pantelis Antoniou <pantelis.antoniou@konsulko.com> - 2015-10-20 23:10 +0200
          Re: [PATCH v6 4/4] Documentation: ABI: /sys/firmware/devicetree/overlays Rob Herring <robherring2@gmail.com> - 2015-10-21 00:10 +0200
    [PATCH v6 1/4] of: overlay: kobjectify overlay objects Pantelis Antoniou <pantelis.antoniou@konsulko.com> - 2015-10-20 21:20 +0200
      Re: [PATCH v6 1/4] of: overlay: kobjectify overlay objects Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-20 23:10 +0200
        Re: [PATCH v6 1/4] of: overlay: kobjectify overlay objects Pantelis Antoniou <pantelis.antoniou@konsulko.com> - 2015-10-21 15:30 +0200
          Re: [PATCH v6 1/4] of: overlay: kobjectify overlay objects Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-21 17:30 +0200
    Re: [PATCH v6 0/4] of: overlay: kobject & sysfs'ation Rob Herring <robherring2@gmail.com> - 2015-10-20 23:10 +0200
      Re: [PATCH v6 0/4] of: overlay: kobject & sysfs'ation Pantelis Antoniou <pantelis.antoniou@konsulko.com> - 2015-10-20 23:20 +0200
        Re: [PATCH v6 0/4] of: overlay: kobject & sysfs'ation Rob Herring <robherring2@gmail.com> - 2015-10-21 00:00 +0200

#1251974 — [PATCH v6 0/4] of: overlay: kobject & sysfs'ation

The first patch puts the overlays as objects in the sysfs in
/sys/firmware/devicetree/overlays.

The next adds a master overlay enable switch (that once is set to
disabled can't be re-enabled), while the one after that
introduces a number of default per overlay attributes.

The patchset is against linus's tree as of today.

The last patch updates the ABI docs for the sysfs entries.

Changes since v5:
* Does a single kobject_put that suffices
* A per-fragment sysfs directory and a single value target.
* Update in the ABI documention.

Changes since v4:
* Rebased against latest mainline.

Changes since v3:
* Used strtobool instead of kstrtoul
* ABI Documentation includes a pointer to the discussion that
requested the sysfs property.

Changes since v2:
* Removed the unittest patch.
* Split the sysfs attribute patch to a global and a per-overlay
  patch.
* Dropped binary attributes using textual kobj_attributes instead.

Changes since v1:
* Maintainer requested changes.
* Documented the sysfs entries
* Per overlay sysfs attributes.


Pantelis Antoniou (4):
  of: overlay: kobjectify overlay objects
  of: overlay: global sysfs enable attribute
  of: overlay: add per overlay sysfs attributes
  Documentation: ABI: /sys/firmware/devicetree/overlays

 .../ABI/testing/sysfs-firmware-devicetree-overlays |  40 +++++
 drivers/of/base.c                                  |   7 +
 drivers/of/of_private.h                            |   9 +
 drivers/of/overlay.c                               | 194 ++++++++++++++++++++-
 4 files changed, 244 insertions(+), 6 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-firmware-devicetree-overlays

-- 
1.7.12

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#1251976 — [PATCH v6 2/4] of: overlay: global sysfs enable attribute

A throw once master enable switch to protect against any
further overlay applications if the administrator desires so.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
---
 drivers/of/overlay.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 12c3e47..067404e 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -21,6 +21,7 @@
 #include <linux/err.h>
 #include <linux/idr.h>
 #include <linux/sysfs.h>
+#include <linux/atomic.h>
 
 #include "of_private.h"
 
@@ -55,8 +56,12 @@ struct of_overlay {
 	struct kobject kobj;
 };
 
+/* master enable switch; once set to 0 can't be re-enabled */
+static atomic_t ov_enable = ATOMIC_INIT(1);
+
 static int of_overlay_apply_one(struct of_overlay *ov,
 		struct device_node *target, const struct device_node *overlay);
+static int overlay_removal_is_ok(struct of_overlay *ov);
 
 static int of_overlay_apply_single_property(struct of_overlay *ov,
 		struct device_node *target, struct property *prop)
@@ -339,6 +344,35 @@ void of_overlay_release(struct kobject *kobj)
 	kfree(ov);
 }
 
+static ssize_t enable_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&ov_enable));
+}
+
+static ssize_t enable_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	int ret;
+	bool new_enable;
+
+	ret = strtobool(buf, &new_enable);
+	if (ret != 0)
+		return ret;
+	/* if we've disabled it, no going back */
+	if (atomic_read(&ov_enable) == 0)
+		return -EPERM;
+	atomic_set(&ov_enable, (int)new_enable);
+	return count;
+}
+
+static struct kobj_attribute enable_attr = __ATTR_RW(enable);
+
+static const struct attribute *overlay_global_attrs[] = {
+	&enable_attr.attr,
+	NULL
+};
+
 static struct kobj_type of_overlay_ktype = {
 	.release = of_overlay_release,
 };
@@ -360,6 +394,10 @@ int of_overlay_create(struct device_node *tree)
 	struct of_overlay *ov;
 	int err, id;
 
+	/* administratively disabled */
+	if (!atomic_read(&ov_enable))
+		return -EPERM;
+
 	/* allocate the overlay structure */
 	ov = kzalloc(sizeof(*ov), GFP_KERNEL);
 	if (ov == NULL)
@@ -594,5 +632,8 @@ int of_overlay_init(void)
 	if (!ov_kset)
 		return -ENOMEM;
 
-	return 0;
+	rc = sysfs_create_files(&ov_kset->kobj, overlay_global_attrs);
+	WARN(rc, "%s: error adding global attributes\n", __func__);
+
+	return rc;
 }
-- 
1.7.12

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#1252044 — Re: [PATCH v6 2/4] of: overlay: global sysfs enable attribute

On Tue, Oct 20, 2015 at 10:13:15PM +0300, Pantelis Antoniou wrote:
> A throw once master enable switch to protect against any
> further overlay applications if the administrator desires so.
> 
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> ---
>  drivers/of/overlay.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 42 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> index 12c3e47..067404e 100644
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
> @@ -21,6 +21,7 @@
>  #include <linux/err.h>
>  #include <linux/idr.h>
>  #include <linux/sysfs.h>
> +#include <linux/atomic.h>
>  
>  #include "of_private.h"
>  
> @@ -55,8 +56,12 @@ struct of_overlay {
>  	struct kobject kobj;
>  };
>  
> +/* master enable switch; once set to 0 can't be re-enabled */
> +static atomic_t ov_enable = ATOMIC_INIT(1);
> +
>  static int of_overlay_apply_one(struct of_overlay *ov,
>  		struct device_node *target, const struct device_node *overlay);
> +static int overlay_removal_is_ok(struct of_overlay *ov);
>  
>  static int of_overlay_apply_single_property(struct of_overlay *ov,
>  		struct device_node *target, struct property *prop)
> @@ -339,6 +344,35 @@ void of_overlay_release(struct kobject *kobj)
>  	kfree(ov);
>  }
>  
> +static ssize_t enable_show(struct kobject *kobj,
> +		struct kobj_attribute *attr, char *buf)
> +{
> +	return snprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&ov_enable));
> +}
> +
> +static ssize_t enable_store(struct kobject *kobj,
> +		struct kobj_attribute *attr, const char *buf, size_t count)
> +{
> +	int ret;
> +	bool new_enable;
> +
> +	ret = strtobool(buf, &new_enable);
> +	if (ret != 0)
> +		return ret;
> +	/* if we've disabled it, no going back */
> +	if (atomic_read(&ov_enable) == 0)
> +		return -EPERM;
> +	atomic_set(&ov_enable, (int)new_enable);
> +	return count;
> +}
> +
> +static struct kobj_attribute enable_attr = __ATTR_RW(enable);
> +
> +static const struct attribute *overlay_global_attrs[] = {
> +	&enable_attr.attr,
> +	NULL
> +};
> +
>  static struct kobj_type of_overlay_ktype = {
>  	.release = of_overlay_release,
>  };
> @@ -360,6 +394,10 @@ int of_overlay_create(struct device_node *tree)
>  	struct of_overlay *ov;
>  	int err, id;
>  
> +	/* administratively disabled */
> +	if (!atomic_read(&ov_enable))
> +		return -EPERM;
> +
>  	/* allocate the overlay structure */
>  	ov = kzalloc(sizeof(*ov), GFP_KERNEL);
>  	if (ov == NULL)
> @@ -594,5 +632,8 @@ int of_overlay_init(void)
>  	if (!ov_kset)
>  		return -ENOMEM;
>  
> -	return 0;
> +	rc = sysfs_create_files(&ov_kset->kobj, overlay_global_attrs);
> +	WARN(rc, "%s: error adding global attributes\n", __func__);
> +
> +	return rc;
>  }

Shouldn't this also be allowed to be overridden as a boot and build time
parameter to prevent any races on systems that don't want this?

thanks,

greg k-h
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#1252139 — Re: [PATCH v6 2/4] of: overlay: global sysfs enable attribute

On Tue, Oct 20, 2015 at 4:06 PM, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
> On Tue, Oct 20, 2015 at 10:13:15PM +0300, Pantelis Antoniou wrote:
>> A throw once master enable switch to protect against any
>> further overlay applications if the administrator desires so.
>>
>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>> ---
>>  drivers/of/overlay.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
>>  1 file changed, 42 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
>> index 12c3e47..067404e 100644
>> --- a/drivers/of/overlay.c
>> +++ b/drivers/of/overlay.c
>> @@ -21,6 +21,7 @@
>>  #include <linux/err.h>
>>  #include <linux/idr.h>
>>  #include <linux/sysfs.h>
>> +#include <linux/atomic.h>
>>
>>  #include "of_private.h"
>>
>> @@ -55,8 +56,12 @@ struct of_overlay {
>>       struct kobject kobj;
>>  };
>>
>> +/* master enable switch; once set to 0 can't be re-enabled */
>> +static atomic_t ov_enable = ATOMIC_INIT(1);
>> +
>>  static int of_overlay_apply_one(struct of_overlay *ov,
>>               struct device_node *target, const struct device_node *overlay);
>> +static int overlay_removal_is_ok(struct of_overlay *ov);
>>
>>  static int of_overlay_apply_single_property(struct of_overlay *ov,
>>               struct device_node *target, struct property *prop)
>> @@ -339,6 +344,35 @@ void of_overlay_release(struct kobject *kobj)
>>       kfree(ov);
>>  }
>>
>> +static ssize_t enable_show(struct kobject *kobj,
>> +             struct kobj_attribute *attr, char *buf)
>> +{
>> +     return snprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&ov_enable));
>> +}
>> +
>> +static ssize_t enable_store(struct kobject *kobj,
>> +             struct kobj_attribute *attr, const char *buf, size_t count)
>> +{
>> +     int ret;
>> +     bool new_enable;
>> +
>> +     ret = strtobool(buf, &new_enable);
>> +     if (ret != 0)
>> +             return ret;
>> +     /* if we've disabled it, no going back */
>> +     if (atomic_read(&ov_enable) == 0)
>> +             return -EPERM;
>> +     atomic_set(&ov_enable, (int)new_enable);
>> +     return count;
>> +}
>> +
>> +static struct kobj_attribute enable_attr = __ATTR_RW(enable);
>> +
>> +static const struct attribute *overlay_global_attrs[] = {
>> +     &enable_attr.attr,
>> +     NULL
>> +};
>> +
>>  static struct kobj_type of_overlay_ktype = {
>>       .release = of_overlay_release,
>>  };
>> @@ -360,6 +394,10 @@ int of_overlay_create(struct device_node *tree)
>>       struct of_overlay *ov;
>>       int err, id;
>>
>> +     /* administratively disabled */
>> +     if (!atomic_read(&ov_enable))
>> +             return -EPERM;
>> +
>>       /* allocate the overlay structure */
>>       ov = kzalloc(sizeof(*ov), GFP_KERNEL);
>>       if (ov == NULL)
>> @@ -594,5 +632,8 @@ int of_overlay_init(void)
>>       if (!ov_kset)
>>               return -ENOMEM;
>>
>> -     return 0;
>> +     rc = sysfs_create_files(&ov_kset->kobj, overlay_global_attrs);
>> +     WARN(rc, "%s: error adding global attributes\n", __func__);
>> +
>> +     return rc;
>>  }
>
> Shouldn't this also be allowed to be overridden as a boot and build time
> parameter to prevent any races on systems that don't want this?

Build time is already there to disable overlays. A command line option
would be good though.

Rob
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#1252567 — Re: [PATCH v6 2/4] of: overlay: global sysfs enable attribute

Hi Rob,

> On Oct 21, 2015, at 00:50 , Rob Herring <robherring2@gmail.com> wrote:
> 
> On Tue, Oct 20, 2015 at 4:06 PM, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
>> On Tue, Oct 20, 2015 at 10:13:15PM +0300, Pantelis Antoniou wrote:
>>> A throw once master enable switch to protect against any
>>> further overlay applications if the administrator desires so.
>>> 
>>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>>> ---
>>> drivers/of/overlay.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
>>> 1 file changed, 42 insertions(+), 1 deletion(-)
>>> 
>>> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
>>> index 12c3e47..067404e 100644
>>> --- a/drivers/of/overlay.c
>>> +++ b/drivers/of/overlay.c
>>> @@ -21,6 +21,7 @@
>>> #include <linux/err.h>
>>> #include <linux/idr.h>
>>> #include <linux/sysfs.h>
>>> +#include <linux/atomic.h>
>>> 
>>> #include "of_private.h"
>>> 
>>> @@ -55,8 +56,12 @@ struct of_overlay {
>>>      struct kobject kobj;
>>> };
>>> 
>>> +/* master enable switch; once set to 0 can't be re-enabled */
>>> +static atomic_t ov_enable = ATOMIC_INIT(1);
>>> +
>>> static int of_overlay_apply_one(struct of_overlay *ov,
>>>              struct device_node *target, const struct device_node *overlay);
>>> +static int overlay_removal_is_ok(struct of_overlay *ov);
>>> 
>>> static int of_overlay_apply_single_property(struct of_overlay *ov,
>>>              struct device_node *target, struct property *prop)
>>> @@ -339,6 +344,35 @@ void of_overlay_release(struct kobject *kobj)
>>>      kfree(ov);
>>> }
>>> 
>>> +static ssize_t enable_show(struct kobject *kobj,
>>> +             struct kobj_attribute *attr, char *buf)
>>> +{
>>> +     return snprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&ov_enable));
>>> +}
>>> +
>>> +static ssize_t enable_store(struct kobject *kobj,
>>> +             struct kobj_attribute *attr, const char *buf, size_t count)
>>> +{
>>> +     int ret;
>>> +     bool new_enable;
>>> +
>>> +     ret = strtobool(buf, &new_enable);
>>> +     if (ret != 0)
>>> +             return ret;
>>> +     /* if we've disabled it, no going back */
>>> +     if (atomic_read(&ov_enable) == 0)
>>> +             return -EPERM;
>>> +     atomic_set(&ov_enable, (int)new_enable);
>>> +     return count;
>>> +}
>>> +
>>> +static struct kobj_attribute enable_attr = __ATTR_RW(enable);
>>> +
>>> +static const struct attribute *overlay_global_attrs[] = {
>>> +     &enable_attr.attr,
>>> +     NULL
>>> +};
>>> +
>>> static struct kobj_type of_overlay_ktype = {
>>>      .release = of_overlay_release,
>>> };
>>> @@ -360,6 +394,10 @@ int of_overlay_create(struct device_node *tree)
>>>      struct of_overlay *ov;
>>>      int err, id;
>>> 
>>> +     /* administratively disabled */
>>> +     if (!atomic_read(&ov_enable))
>>> +             return -EPERM;
>>> +
>>>      /* allocate the overlay structure */
>>>      ov = kzalloc(sizeof(*ov), GFP_KERNEL);
>>>      if (ov == NULL)
>>> @@ -594,5 +632,8 @@ int of_overlay_init(void)
>>>      if (!ov_kset)
>>>              return -ENOMEM;
>>> 
>>> -     return 0;
>>> +     rc = sysfs_create_files(&ov_kset->kobj, overlay_global_attrs);
>>> +     WARN(rc, "%s: error adding global attributes\n", __func__);
>>> +
>>> +     return rc;
>>> }
>> 
>> Shouldn't this also be allowed to be overridden as a boot and build time
>> parameter to prevent any races on systems that don't want this?
> 
> Build time is already there to disable overlays. A command line option
> would be good though.
> 

No problemo. I’ll include it in the next version to go out today.

> Rob

Regards

— Pantelis

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#1251979 — [PATCH v6 4/4] Documentation: ABI: /sys/firmware/devicetree/overlays

Documentation ABI entry for overlays sysfs entries.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
---
 .../ABI/testing/sysfs-firmware-devicetree-overlays | 40 ++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-firmware-devicetree-overlays

diff --git a/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays b/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
new file mode 100644
index 0000000..adc4068
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
@@ -0,0 +1,40 @@
+What:		/sys/firmware/devicetree/overlays/
+Date:		October 2015
+Contact:	Pantelis Antoniou <pantelis.antoniou@konsulko.com>
+Description:
+		This directory contains the applied device tree overlays of
+		the running system, as directories of the overlay id.
+
+		enable: The master enable switch, by default is 1, and when
+		        set to 0 it cannot be re-enabled for security reasons.
+
+		The discussion about this switch takes place in:
+		http://comments.gmane.org/gmane.linux.drivers.devicetree/101871
+
+		Kees Cook:
+		"Coming from the perspective of drawing a bright line between
+		kernel and the root user (which tends to start with disabling
+		kernel module loading), I would say that there at least needs
+		to be a high-level one-way "off" switch for the interface so
+		that systems that have this interface can choose to turn it off
+		during initial boot, etc."
+
+What:		/sys/firmware/devicetree/overlays/<id>
+Date:		October 2015
+Contact:	Pantelis Antoniou <pantelis.antoniou@konsulko.com>
+Description:
+		Each directory represents an applied overlay, containing
+		the following attribute files.
+
+		can_remove: The attribute set to 1 means that the overlay can
+		            be removed, while 0 means that the overlay is being
+			    overlapped therefore removal is prohibited.
+
+What:		/sys/firmware/devicetree/overlays/<id>/<fragment-name>/
+Date:		October 2015
+Contact:	Pantelis Antoniou <pantelis.antoniou@konsulko.com>
+Description:
+		Each of these directories contain information about of the
+		particular overlay fragment.
+
+		target: The full-path of the target of the fragment
-- 
1.7.12

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#1252034 — Re: [PATCH v6 4/4] Documentation: ABI: /sys/firmware/devicetree/overlays

On Tue, Oct 20, 2015 at 2:13 PM, Pantelis Antoniou
<pantelis.antoniou@konsulko.com> wrote:
> Documentation ABI entry for overlays sysfs entries.
>
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> ---
>  .../ABI/testing/sysfs-firmware-devicetree-overlays | 40 ++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
>
> diff --git a/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays b/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
> new file mode 100644
> index 0000000..adc4068
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
> @@ -0,0 +1,40 @@
> +What:          /sys/firmware/devicetree/overlays/
> +Date:          October 2015
> +Contact:       Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> +Description:
> +               This directory contains the applied device tree overlays of
> +               the running system, as directories of the overlay id.
> +
> +               enable: The master enable switch, by default is 1, and when
> +                       set to 0 it cannot be re-enabled for security reasons.
> +
> +               The discussion about this switch takes place in:
> +               http://comments.gmane.org/gmane.linux.drivers.devicetree/101871
> +
> +               Kees Cook:
> +               "Coming from the perspective of drawing a bright line between
> +               kernel and the root user (which tends to start with disabling
> +               kernel module loading), I would say that there at least needs
> +               to be a high-level one-way "off" switch for the interface so
> +               that systems that have this interface can choose to turn it off
> +               during initial boot, etc."
> +
> +What:          /sys/firmware/devicetree/overlays/<id>
> +Date:          October 2015
> +Contact:       Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> +Description:
> +               Each directory represents an applied overlay, containing
> +               the following attribute files.
> +
> +               can_remove: The attribute set to 1 means that the overlay can
> +                           be removed, while 0 means that the overlay is being
> +                           overlapped therefore removal is prohibited.
> +
> +What:          /sys/firmware/devicetree/overlays/<id>/<fragment-name>/
> +Date:          October 2015
> +Contact:       Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> +Description:
> +               Each of these directories contain information about of the
> +               particular overlay fragment.
> +
> +               target: The full-path of the target of the fragment
> --

What happened to attributes within the fragment dir?

Rob
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#1252042 — Re: [PATCH v6 4/4] Documentation: ABI: /sys/firmware/devicetree/overlays

Hi Rob,

> On Oct 20, 2015, at 23:56 , Rob Herring <robherring2@gmail.com> wrote:
> 
> On Tue, Oct 20, 2015 at 2:13 PM, Pantelis Antoniou
> <pantelis.antoniou@konsulko.com> wrote:
>> Documentation ABI entry for overlays sysfs entries.
>> 
>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>> ---
>> .../ABI/testing/sysfs-firmware-devicetree-overlays | 40 ++++++++++++++++++++++
>> 1 file changed, 40 insertions(+)
>> create mode 100644 Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
>> 
>> diff --git a/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays b/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
>> new file mode 100644
>> index 0000000..adc4068
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
>> @@ -0,0 +1,40 @@
>> +What:          /sys/firmware/devicetree/overlays/
>> +Date:          October 2015
>> +Contact:       Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>> +Description:
>> +               This directory contains the applied device tree overlays of
>> +               the running system, as directories of the overlay id.
>> +
>> +               enable: The master enable switch, by default is 1, and when
>> +                       set to 0 it cannot be re-enabled for security reasons.
>> +
>> +               The discussion about this switch takes place in:
>> +               http://comments.gmane.org/gmane.linux.drivers.devicetree/101871
>> +
>> +               Kees Cook:
>> +               "Coming from the perspective of drawing a bright line between
>> +               kernel and the root user (which tends to start with disabling
>> +               kernel module loading), I would say that there at least needs
>> +               to be a high-level one-way "off" switch for the interface so
>> +               that systems that have this interface can choose to turn it off
>> +               during initial boot, etc."
>> +
>> +What:          /sys/firmware/devicetree/overlays/<id>
>> +Date:          October 2015
>> +Contact:       Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>> +Description:
>> +               Each directory represents an applied overlay, containing
>> +               the following attribute files.
>> +
>> +               can_remove: The attribute set to 1 means that the overlay can
>> +                           be removed, while 0 means that the overlay is being
>> +                           overlapped therefore removal is prohibited.
>> +
>> +What:          /sys/firmware/devicetree/overlays/<id>/<fragment-name>/
>> +Date:          October 2015
>> +Contact:       Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>> +Description:
>> +               Each of these directories contain information about of the
>> +               particular overlay fragment.
>> +
>> +               target: The full-path of the target of the fragment
>> --
> 
> What happened to attributes within the fragment dir?
> 

There’s a single attribute named target that contains the target of the fragment.

At the moment this is the only attribute. I eventually intent to put the full contents of the overlay fragment
there as /sysfs/firmware/devicetree/base does, but this would make things quite complicated for now.

Should I add a What: line for that too? 

> Rob

Regards

— Pantelis

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#1252152 — Re: [PATCH v6 4/4] Documentation: ABI: /sys/firmware/devicetree/overlays

On Tue, Oct 20, 2015 at 4:02 PM, Pantelis Antoniou
<pantelis.antoniou@konsulko.com> wrote:
> Hi Rob,
>
>> On Oct 20, 2015, at 23:56 , Rob Herring <robherring2@gmail.com> wrote:
>>
>> On Tue, Oct 20, 2015 at 2:13 PM, Pantelis Antoniou
>> <pantelis.antoniou@konsulko.com> wrote:
>>> Documentation ABI entry for overlays sysfs entries.
>>>
>>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>>> ---
>>> .../ABI/testing/sysfs-firmware-devicetree-overlays | 40 ++++++++++++++++++++++
>>> 1 file changed, 40 insertions(+)
>>> create mode 100644 Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays b/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
>>> new file mode 100644
>>> index 0000000..adc4068
>>> --- /dev/null
>>> +++ b/Documentation/ABI/testing/sysfs-firmware-devicetree-overlays
>>> @@ -0,0 +1,40 @@
>>> +What:          /sys/firmware/devicetree/overlays/
>>> +Date:          October 2015
>>> +Contact:       Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>>> +Description:
>>> +               This directory contains the applied device tree overlays of
>>> +               the running system, as directories of the overlay id.
>>> +
>>> +               enable: The master enable switch, by default is 1, and when
>>> +                       set to 0 it cannot be re-enabled for security reasons.
>>> +
>>> +               The discussion about this switch takes place in:
>>> +               http://comments.gmane.org/gmane.linux.drivers.devicetree/101871
>>> +
>>> +               Kees Cook:
>>> +               "Coming from the perspective of drawing a bright line between
>>> +               kernel and the root user (which tends to start with disabling
>>> +               kernel module loading), I would say that there at least needs
>>> +               to be a high-level one-way "off" switch for the interface so
>>> +               that systems that have this interface can choose to turn it off
>>> +               during initial boot, etc."
>>> +
>>> +What:          /sys/firmware/devicetree/overlays/<id>
>>> +Date:          October 2015
>>> +Contact:       Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>>> +Description:
>>> +               Each directory represents an applied overlay, containing
>>> +               the following attribute files.
>>> +
>>> +               can_remove: The attribute set to 1 means that the overlay can
>>> +                           be removed, while 0 means that the overlay is being
>>> +                           overlapped therefore removal is prohibited.
>>> +
>>> +What:          /sys/firmware/devicetree/overlays/<id>/<fragment-name>/
>>> +Date:          October 2015
>>> +Contact:       Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>>> +Description:
>>> +               Each of these directories contain information about of the
>>> +               particular overlay fragment.
>>> +
>>> +               target: The full-path of the target of the fragment
>>> --
>>
>> What happened to attributes within the fragment dir?
>>
>
> There’s a single attribute named target that contains the target of the fragment.
>
> At the moment this is the only attribute. I eventually intent to put the full contents of the overlay fragment
> there as /sysfs/firmware/devicetree/base does, but this would make things quite complicated for now.
>
> Should I add a What: line for that too?

There should be an entry for every file. These should not be in the
description. So "enable" and "can_remove" need entries too.

Rob
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#1251980 — [PATCH v6 1/4] of: overlay: kobjectify overlay objects

We are going to need the overlays to appear on sysfs with runtime
global properties (like master enable) so turn them into kobjects.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
---
 drivers/of/base.c       |  7 +++++++
 drivers/of/of_private.h |  9 +++++++++
 drivers/of/overlay.c    | 50 +++++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 8b5a187..31c0c8f 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -192,6 +192,7 @@ int __of_attach_node_sysfs(struct device_node *np)
 void __init of_core_init(void)
 {
 	struct device_node *np;
+	int ret;
 
 	/* Create the kset, and register existing nodes */
 	mutex_lock(&of_mutex);
@@ -208,6 +209,12 @@ void __init of_core_init(void)
 	/* Symlink in /proc as required by userspace ABI */
 	if (of_root)
 		proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");
+
+	ret = of_overlay_init();
+	if (ret != 0)
+		pr_warn("of_init: of_overlay_init failed!\n");
+
+	return 0;
 }
 
 static struct property *__of_find_property(const struct device_node *np,
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 8e882e7..120eb44 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -90,4 +90,13 @@ extern void __of_detach_node_sysfs(struct device_node *np);
 #define for_each_transaction_entry_reverse(_oft, _te) \
 	list_for_each_entry_reverse(_te, &(_oft)->te_list, node)
 
+#if defined(CONFIG_OF_OVERLAY)
+extern int of_overlay_init(void);
+#else
+static inline int of_overlay_init(void)
+{
+	return 0;
+}
+#endif
+
 #endif /* _LINUX_OF_PRIVATE_H */
diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 24e025f..12c3e47 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -20,6 +20,7 @@
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/idr.h>
+#include <linux/sysfs.h>
 
 #include "of_private.h"
 
@@ -51,6 +52,7 @@ struct of_overlay {
 	int count;
 	struct of_overlay_info *ovinfo_tab;
 	struct of_changeset cset;
+	struct kobject kobj;
 };
 
 static int of_overlay_apply_one(struct of_overlay *ov,
@@ -325,6 +327,24 @@ static int of_free_overlay_info(struct of_overlay *ov)
 static LIST_HEAD(ov_list);
 static DEFINE_IDR(ov_idr);
 
+static inline struct of_overlay *kobj_to_overlay(struct kobject *kobj)
+{
+	return container_of(kobj, struct of_overlay, kobj);
+}
+
+void of_overlay_release(struct kobject *kobj)
+{
+	struct of_overlay *ov = kobj_to_overlay(kobj);
+
+	kfree(ov);
+}
+
+static struct kobj_type of_overlay_ktype = {
+	.release = of_overlay_release,
+};
+
+static struct kset *ov_kset;
+
 /**
  * of_overlay_create() - Create and apply an overlay
  * @tree:	Device node containing all the overlays
@@ -350,6 +370,9 @@ int of_overlay_create(struct device_node *tree)
 
 	of_changeset_init(&ov->cset);
 
+	/* initialize kobject */
+	kobject_init(&ov->kobj, &of_overlay_ktype);
+
 	mutex_lock(&of_mutex);
 
 	id = idr_alloc(&ov_idr, ov, 0, 0, GFP_KERNEL);
@@ -385,6 +408,14 @@ int of_overlay_create(struct device_node *tree)
 		goto err_revert_overlay;
 	}
 
+	ov->kobj.kset = ov_kset;
+	err = kobject_add(&ov->kobj, NULL, "%d", id);
+	if (err != 0) {
+		pr_err("%s: kobject_add() failed for tree@%s\n",
+				__func__, tree->full_name);
+		goto err_cancel_overlay;
+	}
+
 	/* add to the tail of the overlay list */
 	list_add_tail(&ov->node, &ov_list);
 
@@ -392,6 +423,8 @@ int of_overlay_create(struct device_node *tree)
 
 	return id;
 
+err_cancel_overlay:
+	of_changeset_revert(&ov->cset);
 err_revert_overlay:
 err_abort_trans:
 	of_free_overlay_info(ov);
@@ -512,7 +545,8 @@ int of_overlay_destroy(int id)
 	of_free_overlay_info(ov);
 	idr_remove(&ov_idr, id);
 	of_changeset_destroy(&ov->cset);
-	kfree(ov);
+
+	kobject_put(&ov->kobj);
 
 	err = 0;
 
@@ -542,7 +576,7 @@ int of_overlay_destroy_all(void)
 		of_changeset_revert(&ov->cset);
 		of_free_overlay_info(ov);
 		idr_remove(&ov_idr, ov->id);
-		kfree(ov);
+		kobject_put(&ov->kobj);
 	}
 
 	mutex_unlock(&of_mutex);
@@ -550,3 +584,15 @@ int of_overlay_destroy_all(void)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(of_overlay_destroy_all);
+
+/* called from of_init() */
+int of_overlay_init(void)
+{
+	int rc;
+
+	ov_kset = kset_create_and_add("overlays", NULL, &of_kset->kobj);
+	if (!ov_kset)
+		return -ENOMEM;
+
+	return 0;
+}
-- 
1.7.12

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#1252043 — Re: [PATCH v6 1/4] of: overlay: kobjectify overlay objects

On Tue, Oct 20, 2015 at 10:13:14PM +0300, Pantelis Antoniou wrote:
> We are going to need the overlays to appear on sysfs with runtime
> global properties (like master enable) so turn them into kobjects.

Why kobjects and not 'struct device'?

Why even have them in sysfs at all?  You need more information here as
to why you want to do this.

thanks,

greg k-h
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#1252812 — Re: [PATCH v6 1/4] of: overlay: kobjectify overlay objects

Hi Greg,

> On Oct 21, 2015, at 00:03 , Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> 
> On Tue, Oct 20, 2015 at 10:13:14PM +0300, Pantelis Antoniou wrote:
>> We are going to need the overlays to appear on sysfs with runtime
>> global properties (like master enable) so turn them into kobjects.
> 
> Why kobjects and not 'struct device’?
> 

Cause it’s overkill.

There is no hardware/abstract device connection between an overlay and a device as what’s being used right now in driver core.

kobjs are enough to present them in the filesystem hierarchy.

> Why even have them in sysfs at all?  You need more information here as
> to why you want to do this.
> 

They have to be in sysfs so that people can have information about the overlays applied in the system, i.e. where their targets are and whether removal is possible. That’s what’s possible for now; in the future we might present the full contents of the overlay there, and what changes to the live tree were made.

> thanks,
> 
> greg k-h

Regards

— Pantelis

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#1252950 — Re: [PATCH v6 1/4] of: overlay: kobjectify overlay objects

On Wed, Oct 21, 2015 at 04:28:33PM +0300, Pantelis Antoniou wrote:
> Hi Greg,
> 
> > On Oct 21, 2015, at 00:03 , Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> > 
> > On Tue, Oct 20, 2015 at 10:13:14PM +0300, Pantelis Antoniou wrote:
> >> We are going to need the overlays to appear on sysfs with runtime
> >> global properties (like master enable) so turn them into kobjects.
> > 
> > Why kobjects and not 'struct device’?
> > 
> 
> Cause it’s overkill.
> 
> There is no hardware/abstract device connection between an overlay and a device as what’s being used right now in driver core.
> 
> kobjs are enough to present them in the filesystem hierarchy.
> 
> > Why even have them in sysfs at all?  You need more information here as
> > to why you want to do this.
> > 
> 
> They have to be in sysfs so that people can have information about the overlays applied in the system, i.e. where their targets are and whether removal is possible. That’s what’s possible for now; in the future we might present the full contents of the overlay there, and what changes to the live tree were made.

Ok, then say that in the changelog to explain what you are doing here :)

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#1252039

On Tue, Oct 20, 2015 at 2:13 PM, Pantelis Antoniou
<pantelis.antoniou@konsulko.com> wrote:
> The first patch puts the overlays as objects in the sysfs in
> /sys/firmware/devicetree/overlays.
>
> The next adds a master overlay enable switch (that once is set to
> disabled can't be re-enabled), while the one after that
> introduces a number of default per overlay attributes.
>
> The patchset is against linus's tree as of today.
>
> The last patch updates the ABI docs for the sysfs entries.

I think I told you I would take patches 1 and 2 if you split out the
sysfs documentation for that part of it.

Rob
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#1252046

Hi Rob,

> On Oct 21, 2015, at 00:06 , Rob Herring <robherring2@gmail.com> wrote:
> 
> On Tue, Oct 20, 2015 at 2:13 PM, Pantelis Antoniou
> <pantelis.antoniou@konsulko.com> wrote:
>> The first patch puts the overlays as objects in the sysfs in
>> /sys/firmware/devicetree/overlays.
>> 
>> The next adds a master overlay enable switch (that once is set to
>> disabled can't be re-enabled), while the one after that
>> introduces a number of default per overlay attributes.
>> 
>> The patchset is against linus's tree as of today.
>> 
>> The last patch updates the ABI docs for the sysfs entries.
> 
> I think I told you I would take patches 1 and 2 if you split out the
> sysfs documentation for that part of it.
> 

Sorry, but I haven’t seen them being picked up anywhere, so I resent them to be on the safe side.

> Rob

Regards

— Pantelis

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#1252140

On Tue, Oct 20, 2015 at 4:11 PM, Pantelis Antoniou
<pantelis.antoniou@konsulko.com> wrote:
> Hi Rob,
>
>> On Oct 21, 2015, at 00:06 , Rob Herring <robherring2@gmail.com> wrote:
>>
>> On Tue, Oct 20, 2015 at 2:13 PM, Pantelis Antoniou
>> <pantelis.antoniou@konsulko.com> wrote:
>>> The first patch puts the overlays as objects in the sysfs in
>>> /sys/firmware/devicetree/overlays.
>>>
>>> The next adds a master overlay enable switch (that once is set to
>>> disabled can't be re-enabled), while the one after that
>>> introduces a number of default per overlay attributes.
>>>
>>> The patchset is against linus's tree as of today.
>>>
>>> The last patch updates the ABI docs for the sysfs entries.
>>
>> I think I told you I would take patches 1 and 2 if you split out the
>> sysfs documentation for that part of it.
>>
>
> Sorry, but I haven’t seen them being picked up anywhere, so I resent them to be on the safe side.

You would need to separate the kill switch sysfs documentation in
patch 4 for me to take just the global part. Or just continue to send
them all. :)

Rob
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