Geode LX AES/RNG driver triggers warning

Geode LX AES/RNG driver triggers warning

[David Gstir]

Hi!

I recently tested kernel v4.9 on my AMD Geode platform and noticed that its AES hardware driver triggers this warning on initialization:

[    1.265708] ------------[ cut here ]------------
[    1.267932] WARNING: CPU: 0 PID: 1 at drivers/base/dd.c:344 driver_probe_device+0x5d/0x1ad
[    1.272427] CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.0 #2
[    1.277416]  cf82be70 c1153046 cf82be8c c102a98b 00000158 c11ad3ab cf8b9868 c14342b4
[    1.297179]  c14342b4 cf82bea0 c102aa0e 00000009 00000000 00000000 cf82beb8 c11ad3ab
[    1.316912]  00000000 cf8b9868 c14342b4 cf8b989c cf82becc c11ad553 00000000 c14342b4
[    1.336645] Call Trace:
[    1.340044]  [<c1153046>] dump_stack+0x16/0x18
[    1.345423]  [<c102a98b>] __warn+0xa0/0xb7
[    1.349743]  [<c11ad3ab>] ? driver_probe_device+0x5d/0x1ad
[    1.354224]  [<c102aa0e>] warn_slowpath_null+0x11/0x16
[    1.357663]  [<c11ad3ab>] driver_probe_device+0x5d/0x1ad
[    1.361621]  [<c11ad553>] __driver_attach+0x58/0x74
[    1.364282]  [<c11ac1d7>] bus_for_each_dev+0x4b/0x68
[    1.367202]  [<c11ad6c2>] driver_attach+0x14/0x16
[    1.373345]  [<c11ad4fb>] ? driver_probe_device+0x1ad/0x1ad
[    1.378087]  [<c11ac7b4>] bus_add_driver+0xaf/0x181
[    1.380750]  [<c1467007>] ? firmware_map_add_early+0xaa/0xaa
[    1.385746]  [<c11ad9f7>] driver_register+0x6f/0xa4
[    1.388405]  [<c1467007>] ? firmware_map_add_early+0xaa/0xaa
[    1.393414]  [<c117ae35>] __pci_register_driver+0x27/0x2a
[    1.397628]  [<c146701b>] geode_aes_driver_init+0x14/0x16
[    1.401846]  [<c144ab1e>] do_one_initcall+0x7c/0xec
[    1.404516]  [<c103a5a0>] ? parse_args+0x1c3/0x283
[    1.410913]  [<c144ac48>] ? kernel_init_freeable+0xba/0x157
[    1.411646]  [<c144ac68>] kernel_init_freeable+0xda/0x157
[    1.415872]  [<c12f998d>] ? rest_init+0x59/0x59
[    1.421489]  [<c12f9995>] kernel_init+0x8/0xcb
[    1.426856]  [<c12fbb77>] ret_from_fork+0x1b/0x28
[    1.428999] ---[ end trace 24dfe638898c8e1f ]---

I narrowed it down to commit 6e9b5e76882c ("hwrng: geode - Migrate to managed API") which seems to introduce this. It looks to me like some issue between devres, the Geode hwrng and AES drivers which both use the same PCI device.

I'm no expert here, but I curious if this will cause any issues when using the hardware crypto drivers and also what's the best way to get rid of this?

Thanks,
David

Re: Geode LX AES/RNG driver triggers warning

[One Thousand Gnomes]

On Sat, 31 Dec 2016 00:58:54 +0100
David Gstir <david@sigma-star.at> wrote:

> Hi!
> 
> I recently tested kernel v4.9 on my AMD Geode platform and noticed that its AES hardware driver triggers this warning on initialization:

...

> I narrowed it down to commit 6e9b5e76882c ("hwrng: geode - Migrate to managed API") which seems to introduce this. It looks to me like some issue between devres, the Geode hwrng and AES drivers which both use the same PCI device.

It does

> I'm no expert here, but I curious if this will cause any issues when using the hardware crypto drivers and also what's the best way to get rid of this?

Probably to create an mfd device that turns the PCI device into two MFD
devices and bind AES and hwrng one to each MFD device. Take a look in
drivers/mfd. That would also fix the uglies in mod_init for the rng
driver.

Alan

Re: Geode LX AES/RNG driver triggers warning

[PrasannaKumar Muralidharan]

>> I narrowed it down to commit 6e9b5e76882c ("hwrng: geode - Migrate to managed API") which seems to introduce this. It looks to me like some issue between devres, the Geode hwrng and AES drivers which both use the same PCI device.
>
> It does
>
>> I'm no expert here, but I curious if this will cause any issues when using the hardware crypto drivers and also what's the best way to get rid of this?
>
> Probably to create an mfd device that turns the PCI device into two MFD
> devices and bind AES and hwrng one to each MFD device. Take a look in
> drivers/mfd. That would also fix the uglies in mod_init for the rng
> driver.

I am the author of that commit. Code before commit 6e9b5e76882c had
ioremap, wondering why there was no warning message before. Just want
to know if that commit uncovered existing issue or introduced a new
issue? As far as I understand the commit did not change the
functionality. Please feel free to correct if I have missed something.

Regards,
PrasannaKumar

Re: Geode LX AES/RNG driver triggers warning

[David Gstir]

PrasannaKumar,

> On 06.01.2017, at 10:40, PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com> wrote:
> 
>>> I narrowed it down to commit 6e9b5e76882c ("hwrng: geode - Migrate to managed API") which seems to introduce this. It looks to me like some issue between devres, the Geode hwrng and AES drivers which both use the same PCI device.
>> 
>> It does
>> 
>>> I'm no expert here, but I curious if this will cause any issues when using the hardware crypto drivers and also what's the best way to get rid of this?
>> 
>> Probably to create an mfd device that turns the PCI device into two MFD
>> devices and bind AES and hwrng one to each MFD device. Take a look in
>> drivers/mfd. That would also fix the uglies in mod_init for the rng
>> driver.
> 
> I am the author of that commit. Code before commit 6e9b5e76882c had
> ioremap, wondering why there was no warning message before. Just want
> to know if that commit uncovered existing issue or introduced a new
> issue? As far as I understand the commit did not change the
> functionality. Please feel free to correct if I have missed something.

This warning is because commit 6e9b5e76882c introduces devres (devm_ioremap vs ioremap). As soon as I have some spare time, I'll look into resolving this via MFD like Alan suggested.

Thanks,
-David