On Wed, Oct 18, 2017 at 10:53 AM, Pantelis Antoniou
[off-list ref] wrote:

On Wed, 2017-10-18 at 10:44 -0500, Rob Herring wrote:

quoted

On Wed, Oct 18, 2017 at 10:12 AM, Alan Tull [off-list ref] wrote:

quoted

On Tue, Oct 17, 2017 at 6:51 PM, Frank Rowand [off-list ref] wrote:

quoted

On 10/17/17 14:46, Rob Herring wrote:

quoted

On Tue, Oct 17, 2017 at 4:32 PM, Alan Tull [off-list ref] wrote:

quoted

On Mon, Aug 21, 2017 at 10:16 AM, Rob Herring [off-list ref] wrote:

Hi Rob,

quoted

With dependencies on a statically allocated full path name converted to
use %pOF format specifier, we can store just the basename of node, and
the unflattening of the FDT can be simplified.

This commit will affect the remaining users of full_name. After
analyzing these users, the remaining cases should only change some print
messages. The main users of full_name are providing a name for struct
resource. The resource names shouldn't be important other than providing
/proc/iomem names.

We no longer distinguish between pre and post 0x10 dtb formats as either
a full path or basename will work. However, less than 0x10 formats have
been broken since the conversion to use libfdt (and no one has cared).
The conversion of the unflattening code to be non-recursive also broke
pre 0x10 formats as the populate_node function would return 0 in that
case.

Signed-off-by: Rob Herring <redacted>
---
v2:
- rebase to linux-next

 drivers/of/fdt.c | 69 +++++++++-----------------------------------------------
 1 file changed, 11 insertions(+), 58 deletions(-)

I've just updated to the latest next branch and am finding problems
applying overlays.   Reverting this commit alleviates things.  The
errors I get are:

[   88.498704] OF: overlay: Failed to apply prop @/__symbols__/clk_0
[   88.513447] OF: overlay: apply failed '/__symbols__'
[   88.518423] create_overlay: Failed to create overlay (err=-12)

Frank's series with overlay updates should fix this.

Yes, it does:

  [PATCH v3 11/12] of: overlay: remove a dependency on device node full_name

Thanks for the fast response.  I fetched the dt/next branch to test
this but there are sufficient changes that Pantelis' "OF: DT-Overlay
configfs interface (v7)" is broken now.  I've been adding that
downstream since 4.4.  We're using it as an interface for applying
overlays to program FPGAs.  If we fix it again, is there any chance
that can go upstream now?

With a drive-by posting once every few years, no.

I take offense to that. There's nothing changed in the patch for years.
Reposting the same patch without changes would achieve nothing.

quoted

The issue remains that the kernel is not really setup to deal with any
random property or node to be changed at any point in run-time.

Yeah, I'm not super surprised :)  I have some whitelist ideas below.

quoted

I
think there needs to be some restrictions around what the overlays can
touch. We can't have it be wide open and then lock things down later
and break users. One example of what you could do is you can only add
sub-trees to whitelisted nodes. That's probably acceptable for your
usecase.

I can take a look at making OF_OVERLAY_PRE_APPLY and
OF_OVERLAY_PRE_REMOVE notifiers mandatory if that's interesting.  The
behavior would be: If an overlay is applied, there's got to be some
handler in the kernel that verifies that it is acceptable.   In my
case, the handler for FPGA regions would look at the overlay and see
it only added stuff under a FPGA region.

And we would change the default to be: if there is no handler, reject
the overlay.

quoted

Defining what can and what cannot be changed is not as trivial as a
list of white-listed nodes.

In some cases there is a whole node hierarchy being inserted (like in
a FPGA).

For FPGA, the insertion points are always FPGA regions.

In others, it's merely changing a status property to "okay" and
a few device parameters.

The real issue is that the kernel has no way to verify that a given
device tree, either at boot time or at overlay application time, is
correct.

When the tree is wrong at boot-time you'll hang (if you're lucky).
If the tree is wrong at run-time you'll get some into some unidentified
funky state.

Finally what is, and what is not 'correct' is not for the kernel to
decide arbitrarily, it's a matter of policy, different for each
use-case.

quoted

Rob

Regards

-- Pantelis

Alan Tull

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