[PATCH 0/2] of: dynamic: restrict overlay by targets

[PATCH 0/2] of: dynamic: restrict overlay by targets

[Alan Tull]

Restrict which nodes are valid targets for a DT overlay.

Add a flag bit to struct device_node allowing nodes to be marked as
valid target for overlays.

A driver that is always intended to handle DT overlays can
enable overlays by calling a function for its DT node.

For individual nodes that need to be opened up for a specific use,
adding the property "overlay-allowed" enables overlays targeting
that node.  I'll need to document the DT property, not sure where
specifically.  New file bindings/overlay.txt?

This patchset differs from the RFC:
* Added a flag bit and got rid of the whitelist
* Renamed the functions that enable a node
* Added a DT property

Alan Tull (2):
  of: overlay: add flag enabling overlays and enable fpga-region
    overlays
  of: dynamic: add overlay-allowed DT property

 drivers/fpga/of-fpga-region.c |  4 ++++
 drivers/of/base.c             |  4 ++--
 drivers/of/dynamic.c          |  3 +++
 drivers/of/fdt.c              |  3 +++
 drivers/of/of_private.h       |  2 ++
 drivers/of/overlay.c          | 26 ++++++++++++++++++++++++++
 include/linux/of.h            | 19 +++++++++++++++++++
 7 files changed, 59 insertions(+), 2 deletions(-)

-- 
2.7.4

[PATCH 1/2] of: overlay: add flag enabling overlays and enable fpga-region overlays

[Alan Tull]

Add a flag to struct device_node marking the node as a valid target
for device tree overlays.  When an overlay is submitted, if any target
in the overlay is not enabled for overlays, the overlay is rejected.
Drivers that support dynamic configuration can enable/disable their
device node with:

  void of_node_overlay_enable(struct device_node *np)
  void of_node_overlay_disable(struct device_node *np)

During each FPGA region's probe, enable its node for overlays.

Signed-off-by: Alan Tull <atull-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
v1: (changes from the rfc)
    Add a flag instead of implementing a list
    rename functions for what they do, not how they're implemented
    squash with patch that enables fpga-region nodes
    add a helpful error message
---
 drivers/fpga/of-fpga-region.c |  4 ++++
 drivers/of/overlay.c          | 26 ++++++++++++++++++++++++++
 include/linux/of.h            | 19 +++++++++++++++++++
 3 files changed, 49 insertions(+)

diff --git a/drivers/fpga/of-fpga-region.c b/drivers/fpga/of-fpga-region.c
index 119ff75..8633eea 100644
--- a/drivers/fpga/of-fpga-region.c
+++ b/drivers/fpga/of-fpga-region.c
@@ -438,6 +438,7 @@ static int of_fpga_region_probe(struct platform_device *pdev)
 		goto eprobe_mgr_put;
 
 	of_platform_populate(np, fpga_region_of_match, NULL, &region->dev);
+	of_node_overlay_enable(np);
 
 	dev_info(dev, "FPGA Region probed\n");
 
@@ -451,7 +452,10 @@ static int of_fpga_region_probe(struct platform_device *pdev)
 static int of_fpga_region_remove(struct platform_device *pdev)
 {
 	struct fpga_region *region = platform_get_drvdata(pdev);
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
 
+	of_node_overlay_disable(np);
 	fpga_region_unregister(region);
 	fpga_mgr_put(region->mgr);
 
diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 53bc9e3..a9758d6 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -21,6 +21,7 @@
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/idr.h>
+#include <linux/spinlock.h>
 
 #include "of_private.h"
 
@@ -646,6 +647,27 @@ static void free_overlay_changeset(struct overlay_changeset *ovcs)
 	kfree(ovcs);
 }
 
+static int of_overlay_check_targets(struct overlay_changeset *ovcs)
+{
+	struct device_node *target;
+	int i;
+
+	for (i = 0; i < ovcs->count; i++) {
+		target = ovcs->fragments[i].target;
+
+		if (!of_node_cmp(target->name, "__symbols__"))
+			continue;
+
+		if (!of_node_check_flag(target, OF_OVERLAY_ENABLED)) {
+			pr_err("Overlays not enabled for target %pOF\n",
+			       target);
+			return -EPERM;
+		}
+	}
+
+	return 0;
+}
+
 /**
  * of_overlay_apply() - Create and apply an overlay changeset
  * @tree:	Expanded overlay device tree
@@ -717,6 +739,10 @@ int of_overlay_apply(struct device_node *tree, int *ovcs_id)
 	if (ret)
 		goto err_free_overlay_changeset;
 
+	ret = of_overlay_check_targets(ovcs);
+	if (ret)
+		goto err_free_overlay_changeset;
+
 	ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
 	if (ret) {
 		pr_err("overlay changeset pre-apply notify error %d\n", ret);
diff --git a/include/linux/of.h b/include/linux/of.h
index d3dea1d..16a2cae 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -147,6 +147,7 @@ extern raw_spinlock_t devtree_lock;
 #define OF_DETACHED	2 /* node has been detached from the device tree */
 #define OF_POPULATED	3 /* device already created for the node */
 #define OF_POPULATED_BUS	4 /* of_platform_populate recursed to children of this node */
+#define OF_OVERLAY_ENABLED	5 /* allow DT overlay targeting this node */
 
 #define OF_BAD_ADDR	((u64)-1)
 
@@ -1364,6 +1365,16 @@ int of_overlay_remove_all(void);
 int of_overlay_notifier_register(struct notifier_block *nb);
 int of_overlay_notifier_unregister(struct notifier_block *nb);
 
+static inline void of_node_overlay_enable(struct device_node *np)
+{
+	of_node_set_flag(np, OF_OVERLAY_ENABLED);
+}
+
+static inline void of_node_overlay_disable(struct device_node *np)
+{
+	of_node_clear_flag(np, OF_OVERLAY_ENABLED);
+}
+
 #else
 
 static inline int of_overlay_apply(struct device_node *tree, int *ovcs_id)
@@ -1391,6 +1402,14 @@ static inline int of_overlay_notifier_unregister(struct notifier_block *nb)
 	return 0;
 }
 
+static inline void of_node_overlay_enable(struct device_node *np)
+{
+}
+
+static inline void of_node_overlay_disable(struct device_node *np)
+{
+}
+
 #endif
 
 #endif /* _LINUX_OF_H */
-- 
2.7.4

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[PATCH 2/2] of: dynamic: add overlay-allowed DT property

[Alan Tull]

Allow DT nodes to be marked as valid targets for DT
overlays by the added "overlay-allowed" property.

Signed-off-by: Alan Tull <atull-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 drivers/of/base.c       | 4 ++--
 drivers/of/dynamic.c    | 3 +++
 drivers/of/fdt.c        | 3 +++
 drivers/of/of_private.h | 2 ++
 4 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 26618ba..ac6b326 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -116,8 +116,8 @@ void __init of_core_init(void)
 		proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");
 }
 
-static struct property *__of_find_property(const struct device_node *np,
-					   const char *name, int *lenp)
+struct property *__of_find_property(const struct device_node *np,
+				    const char *name, int *lenp)
 {
 	struct property *pp;
 
diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index ab988d8..fae9b85 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -207,6 +207,9 @@ static void __of_attach_node(struct device_node *np)
 	np->name = __of_get_property(np, "name", NULL) ? : "<NULL>";
 	np->type = __of_get_property(np, "device_type", NULL) ? : "<NULL>";
 
+	if (__of_find_property(np, "overlay-allowed", NULL))
+		of_node_set_flag(np, OF_OVERLAY_ENABLED);
+
 	phandle = __of_get_property(np, "phandle", &sz);
 	if (!phandle)
 		phandle = __of_get_property(np, "linux,phandle", &sz);
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 4675e5a..9237f30 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -323,6 +323,9 @@ static bool populate_node(const void *blob,
 			np->name = "<NULL>";
 		if (!np->type)
 			np->type = "<NULL>";
+
+		if (of_find_property(np, "overlay-allowed", NULL))
+			of_node_set_flag(np, OF_OVERLAY_ENABLED);
 	}
 
 	*pnp = np;
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 92a9a36..75fcba3 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -115,6 +115,8 @@ struct device_node *__of_find_node_by_path(struct device_node *parent,
 struct device_node *__of_find_node_by_full_path(struct device_node *node,
 						const char *path);
 
+extern struct property *__of_find_property(const struct device_node *np,
+					   const char *name, int *lenp);
 extern const void *__of_get_property(const struct device_node *np,
 				     const char *name, int *lenp);
 extern int __of_add_property(struct device_node *np, struct property *prop);
-- 
2.7.4

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Re: [PATCH 2/2] of: dynamic: add overlay-allowed DT property

[Rob Herring]

On Mon, Dec 4, 2017 at 1:13 PM, Alan Tull <atull-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
> Allow DT nodes to be marked as valid targets for DT
> overlays by the added "overlay-allowed" property.

Why do you need a property for this? I'm not all that keen on putting
this policy into the DT. It can change over time in the kernel. For
example, as we define use cases that work, then we can loosen
restrictions in the kernel.

Rob
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Re: [PATCH 2/2] of: dynamic: add overlay-allowed DT property

[Alan Tull]

On Mon, Dec 4, 2017 at 2:04 PM, Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
> On Mon, Dec 4, 2017 at 1:13 PM, Alan Tull <atull-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
>> Allow DT nodes to be marked as valid targets for DT
>> overlays by the added "overlay-allowed" property.
>
> Why do you need a property for this? I'm not all that keen on putting
> this policy into the DT. It can change over time in the kernel. For
> example, as we define use cases that work, then we can loosen
> restrictions in the kernel.

For FPGA regions, I don't need it.  Yes, if the other patch is
accepted, I'm sure we will hear more from people who will need some
specific loosening.  I was trying to anticipate that, but I don't have
a specific need.

Alan

>
> Rob
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Re: [PATCH 0/2] of: dynamic: restrict overlay by targets

[Moritz Fischer]

[-- Attachment #1: Type: text/plain, Size: 1493 bytes --]

On Mon, Dec 04, 2017 at 01:13:55PM -0600, Alan Tull wrote:
> Restrict which nodes are valid targets for a DT overlay.
> 
> Add a flag bit to struct device_node allowing nodes to be marked as
> valid target for overlays.
> 
> A driver that is always intended to handle DT overlays can
> enable overlays by calling a function for its DT node.
> 
> For individual nodes that need to be opened up for a specific use,
> adding the property "overlay-allowed" enables overlays targeting
> that node.  I'll need to document the DT property, not sure where
> specifically.  New file bindings/overlay.txt?
> 
> This patchset differs from the RFC:
> * Added a flag bit and got rid of the whitelist
> * Renamed the functions that enable a node
> * Added a DT property
> 
> Alan Tull (2):
>   of: overlay: add flag enabling overlays and enable fpga-region
>     overlays
>   of: dynamic: add overlay-allowed DT property

I think [1/2] and [2/2] are backwards order. If applied like this,
it won't work. [1/2] uses stuff that gets added in [2/2]

> 
>  drivers/fpga/of-fpga-region.c |  4 ++++
>  drivers/of/base.c             |  4 ++--
>  drivers/of/dynamic.c          |  3 +++
>  drivers/of/fdt.c              |  3 +++
>  drivers/of/of_private.h       |  2 ++
>  drivers/of/overlay.c          | 26 ++++++++++++++++++++++++++
>  include/linux/of.h            | 19 +++++++++++++++++++
>  7 files changed, 59 insertions(+), 2 deletions(-)
> 
> -- 
> 2.7.4
> 

Moritz

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Re: [PATCH 0/2] of: dynamic: restrict overlay by targets

[Moritz Fischer]

On Mon, Dec 04, 2017 at 11:18:49AM -0800, Moritz Fischer wrote:
> On Mon, Dec 04, 2017 at 01:13:55PM -0600, Alan Tull wrote:
> > Restrict which nodes are valid targets for a DT overlay.
> > 
> > Add a flag bit to struct device_node allowing nodes to be marked as
> > valid target for overlays.
> > 
> > A driver that is always intended to handle DT overlays can
> > enable overlays by calling a function for its DT node.
> > 
> > For individual nodes that need to be opened up for a specific use,
> > adding the property "overlay-allowed" enables overlays targeting
> > that node.  I'll need to document the DT property, not sure where
> > specifically.  New file bindings/overlay.txt?
> > 
> > This patchset differs from the RFC:
> > * Added a flag bit and got rid of the whitelist
> > * Renamed the functions that enable a node
> > * Added a DT property
> > 
> > Alan Tull (2):
> >   of: overlay: add flag enabling overlays and enable fpga-region
> >     overlays
> >   of: dynamic: add overlay-allowed DT property
> 
> I think [1/2] and [2/2] are backwards order. If applied like this,
> it won't work. [1/2] uses stuff that gets added in [2/2]

Ignore that, my mailclient is being funny.

Moritz
> 
> > 
> >  drivers/fpga/of-fpga-region.c |  4 ++++
> >  drivers/of/base.c             |  4 ++--
> >  drivers/of/dynamic.c          |  3 +++
> >  drivers/of/fdt.c              |  3 +++
> >  drivers/of/of_private.h       |  2 ++
> >  drivers/of/overlay.c          | 26 ++++++++++++++++++++++++++
> >  include/linux/of.h            | 19 +++++++++++++++++++
> >  7 files changed, 59 insertions(+), 2 deletions(-)
> > 
> > -- 
> > 2.7.4
> > 
> 
> Moritz

Re: [PATCH 0/2] of: dynamic: restrict overlay by targets

[Frank Rowand]

Hi Alan,

In the RFC thread "of: Add whitelist", I did not understand the use case and
asked you some questions (30 Nov 2017 07:46:36 -0500), that you seem to have
overlooked (or my mail server failed to deliver your answer to me).  Can you
please answer that question so I can better understand this patch set is
needed for.

Thanks,

Frank


On 12/04/17 14:13, Alan Tull wrote:
> Restrict which nodes are valid targets for a DT overlay.
> 
> Add a flag bit to struct device_node allowing nodes to be marked as
> valid target for overlays.
> 
> A driver that is always intended to handle DT overlays can
> enable overlays by calling a function for its DT node.
> 
> For individual nodes that need to be opened up for a specific use,
> adding the property "overlay-allowed" enables overlays targeting
> that node.  I'll need to document the DT property, not sure where
> specifically.  New file bindings/overlay.txt?
> 
> This patchset differs from the RFC:
> * Added a flag bit and got rid of the whitelist
> * Renamed the functions that enable a node
> * Added a DT property
> 
> Alan Tull (2):
>   of: overlay: add flag enabling overlays and enable fpga-region
>     overlays
>   of: dynamic: add overlay-allowed DT property
> 
>  drivers/fpga/of-fpga-region.c |  4 ++++
>  drivers/of/base.c             |  4 ++--
>  drivers/of/dynamic.c          |  3 +++
>  drivers/of/fdt.c              |  3 +++
>  drivers/of/of_private.h       |  2 ++
>  drivers/of/overlay.c          | 26 ++++++++++++++++++++++++++
>  include/linux/of.h            | 19 +++++++++++++++++++
>  7 files changed, 59 insertions(+), 2 deletions(-)
> 

Re: [PATCH 0/2] of: dynamic: restrict overlay by targets

[Alan Tull]

On Mon, Dec 4, 2017 at 7:14 PM, Frank Rowand <frowand.list@gmail.com> wrote:
> Hi Alan,
>
> In the RFC thread "of: Add whitelist", I did not understand the use case and
> asked you some questions (30 Nov 2017 07:46:36 -0500), that you seem to have
> overlooked (or my mail server failed to deliver your answer to me).  Can you
> please answer that question so I can better understand this patch set is
> needed for.

Hi Frank,

Sorry I missed those, I've replied to the original questions now.

Alan

>
> Thanks,
>
> Frank
>
>
> On 12/04/17 14:13, Alan Tull wrote:
>> Restrict which nodes are valid targets for a DT overlay.
>>
>> Add a flag bit to struct device_node allowing nodes to be marked as
>> valid target for overlays.
>>
>> A driver that is always intended to handle DT overlays can
>> enable overlays by calling a function for its DT node.
>>
>> For individual nodes that need to be opened up for a specific use,
>> adding the property "overlay-allowed" enables overlays targeting
>> that node.  I'll need to document the DT property, not sure where
>> specifically.  New file bindings/overlay.txt?
>>
>> This patchset differs from the RFC:
>> * Added a flag bit and got rid of the whitelist
>> * Renamed the functions that enable a node
>> * Added a DT property
>>
>> Alan Tull (2):
>>   of: overlay: add flag enabling overlays and enable fpga-region
>>     overlays
>>   of: dynamic: add overlay-allowed DT property
>>
>>  drivers/fpga/of-fpga-region.c |  4 ++++
>>  drivers/of/base.c             |  4 ++--
>>  drivers/of/dynamic.c          |  3 +++
>>  drivers/of/fdt.c              |  3 +++
>>  drivers/of/of_private.h       |  2 ++
>>  drivers/of/overlay.c          | 26 ++++++++++++++++++++++++++
>>  include/linux/of.h            | 19 +++++++++++++++++++
>>  7 files changed, 59 insertions(+), 2 deletions(-)
>>
>

Re: [PATCH 0/2] of: dynamic: restrict overlay by targets

[Frank Rowand]

On 12/05/17 12:07, Alan Tull wrote:
> On Mon, Dec 4, 2017 at 7:14 PM, Frank Rowand <frowand.list-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> Hi Alan,
>>
>> In the RFC thread "of: Add whitelist", I did not understand the use case and
>> asked you some questions (30 Nov 2017 07:46:36 -0500), that you seem to have
>> overlooked (or my mail server failed to deliver your answer to me).  Can you
>> please answer that question so I can better understand this patch set is
>> needed for.
> 
> Hi Frank,
> 
> Sorry I missed those, I've replied to the original questions now.

Thanks!  I have now replied to several comments in that thread, hoping to keep
the conversation in one thread instead of split across two threads.

-Frank

> 
> Alan
> 
>>
>> Thanks,
>>
>> Frank
>>
>>
>> On 12/04/17 14:13, Alan Tull wrote:
>>> Restrict which nodes are valid targets for a DT overlay.
>>>
>>> Add a flag bit to struct device_node allowing nodes to be marked as
>>> valid target for overlays.
>>>
>>> A driver that is always intended to handle DT overlays can
>>> enable overlays by calling a function for its DT node.
>>>
>>> For individual nodes that need to be opened up for a specific use,
>>> adding the property "overlay-allowed" enables overlays targeting
>>> that node.  I'll need to document the DT property, not sure where
>>> specifically.  New file bindings/overlay.txt?
>>>
>>> This patchset differs from the RFC:
>>> * Added a flag bit and got rid of the whitelist
>>> * Renamed the functions that enable a node
>>> * Added a DT property
>>>
>>> Alan Tull (2):
>>>   of: overlay: add flag enabling overlays and enable fpga-region
>>>     overlays
>>>   of: dynamic: add overlay-allowed DT property
>>>
>>>  drivers/fpga/of-fpga-region.c |  4 ++++
>>>  drivers/of/base.c             |  4 ++--
>>>  drivers/of/dynamic.c          |  3 +++
>>>  drivers/of/fdt.c              |  3 +++
>>>  drivers/of/of_private.h       |  2 ++
>>>  drivers/of/overlay.c          | 26 ++++++++++++++++++++++++++
>>>  include/linux/of.h            | 19 +++++++++++++++++++
>>>  7 files changed, 59 insertions(+), 2 deletions(-)
>>>
>>
> 

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