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[PATCH] tee: fix tee_ioctl_object_invoke_arg padding

Arnd Bergmann posted 1 patch 2 weeks, 1 day ago 
include/uapi/linux/tee.h | 1 +
1 file changed, 1 insertion(+)
[PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Arnd Bergmann 2 weeks, 1 day ago 
From: Arnd Bergmann <arnd@arndb.de>

The tee_ioctl_object_invoke_arg structure has padding on some
architectures but not on x86-32 and a few others:

include/linux/tee.h:474:32: error: padding struct to align 'params' [-Werror=padded]

I expect that all current users of this are on architectures that do
have implicit padding here (arm64, arm, x86, riscv), so make the padding
explicit in order to avoid surprises if this later gets used elsewhere.

Fixes: d5b8b0fa1775 ("tee: add TEE_IOCTL_PARAM_ATTR_TYPE_OBJREF")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
The new interface showed up in 6.18, but I only came across this after
that was released. Changing it now is technically an ABI change on
architectures with unusual padding rules, so please consider carefully
whether we want to do it this way or not.

Working around the ABI differences without an ABI change is possible,
but adds a lot of complexity for compat handling.
---
 include/uapi/linux/tee.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
index cab5cadca8ef..5203977ed35d 100644
--- a/include/uapi/linux/tee.h
+++ b/include/uapi/linux/tee.h
@@ -470,6 +470,7 @@ struct tee_ioctl_object_invoke_arg {
 	__u32 op;
 	__u32 ret;
 	__u32 num_params;
+	__u32 :32;
 	/* num_params tells the actual number of element in params */
 	struct tee_ioctl_param params[];
 };
-- 
2.39.5
Re: [PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Jens Wiklander 2 weeks, 1 day ago 
Hi,

On Thu, Dec 4, 2025 at 11:17 AM Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> The tee_ioctl_object_invoke_arg structure has padding on some
> architectures but not on x86-32 and a few others:
>
> include/linux/tee.h:474:32: error: padding struct to align 'params' [-Werror=padded]
>
> I expect that all current users of this are on architectures that do
> have implicit padding here (arm64, arm, x86, riscv), so make the padding
> explicit in order to avoid surprises if this later gets used elsewhere.
>
> Fixes: d5b8b0fa1775 ("tee: add TEE_IOCTL_PARAM_ATTR_TYPE_OBJREF")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> The new interface showed up in 6.18, but I only came across this after
> that was released. Changing it now is technically an ABI change on
> architectures with unusual padding rules, so please consider carefully
> whether we want to do it this way or not.
>
> Working around the ABI differences without an ABI change is possible,
> but adds a lot of complexity for compat handling.

This is currently only used by the recently introduced qcomtee backend
driver. So it's only used on a few arm64 Qualcomm platforms right now.

I think we should take this patch, but let's hear what others think.

Thanks,
Jens

> ---
>  include/uapi/linux/tee.h | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
> index cab5cadca8ef..5203977ed35d 100644
> --- a/include/uapi/linux/tee.h
> +++ b/include/uapi/linux/tee.h
> @@ -470,6 +470,7 @@ struct tee_ioctl_object_invoke_arg {
>         __u32 op;
>         __u32 ret;
>         __u32 num_params;
> +       __u32 :32;
>         /* num_params tells the actual number of element in params */
>         struct tee_ioctl_param params[];
>  };
> --
> 2.39.5
>
Re: [PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Amirreza Zarrabi 1 week, 4 days ago 
Hi,

On 12/5/2025 12:27 AM, Jens Wiklander wrote:
> Hi,
> 
> On Thu, Dec 4, 2025 at 11:17 AM Arnd Bergmann <arnd@kernel.org> wrote:
>>
>> From: Arnd Bergmann <arnd@arndb.de>
>>
>> The tee_ioctl_object_invoke_arg structure has padding on some
>> architectures but not on x86-32 and a few others:
>>
>> include/linux/tee.h:474:32: error: padding struct to align 'params' [-Werror=padded]
>>
>> I expect that all current users of this are on architectures that do
>> have implicit padding here (arm64, arm, x86, riscv), so make the padding
>> explicit in order to avoid surprises if this later gets used elsewhere.
>>
>> Fixes: d5b8b0fa1775 ("tee: add TEE_IOCTL_PARAM_ATTR_TYPE_OBJREF")
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> ---
>> The new interface showed up in 6.18, but I only came across this after
>> that was released. Changing it now is technically an ABI change on
>> architectures with unusual padding rules, so please consider carefully
>> whether we want to do it this way or not.
>>
>> Working around the ABI differences without an ABI change is possible,
>> but adds a lot of complexity for compat handling.
> 
> This is currently only used by the recently introduced qcomtee backend
> driver. So it's only used on a few arm64 Qualcomm platforms right now.
> 
> I think we should take this patch, but let's hear what others think.
> 
> Thanks,
> Jens
> 

I agree. We should take this patch. As noted, there are not many
clients relying on it yet, so updating the userspace should
be straightforward.

Best Regards,
Amir

>> ---
>>  include/uapi/linux/tee.h | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
>> index cab5cadca8ef..5203977ed35d 100644
>> --- a/include/uapi/linux/tee.h
>> +++ b/include/uapi/linux/tee.h
>> @@ -470,6 +470,7 @@ struct tee_ioctl_object_invoke_arg {
>>         __u32 op;
>>         __u32 ret;
>>         __u32 num_params;
>> +       __u32 :32;
>>         /* num_params tells the actual number of element in params */
>>         struct tee_ioctl_param params[];
>>  };
>> --
>> 2.39.5
>>
Re: [PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Sumit Garg 1 week, 4 days ago 
On Mon, Dec 08, 2025 at 04:24:17PM +1100, Amirreza Zarrabi wrote:
> Hi,
> 
> On 12/5/2025 12:27 AM, Jens Wiklander wrote:
> > Hi,
> > 
> > On Thu, Dec 4, 2025 at 11:17 AM Arnd Bergmann <arnd@kernel.org> wrote:
> >>
> >> From: Arnd Bergmann <arnd@arndb.de>
> >>
> >> The tee_ioctl_object_invoke_arg structure has padding on some
> >> architectures but not on x86-32 and a few others:
> >>
> >> include/linux/tee.h:474:32: error: padding struct to align 'params' [-Werror=padded]
> >>
> >> I expect that all current users of this are on architectures that do
> >> have implicit padding here (arm64, arm, x86, riscv), so make the padding
> >> explicit in order to avoid surprises if this later gets used elsewhere.
> >>
> >> Fixes: d5b8b0fa1775 ("tee: add TEE_IOCTL_PARAM_ATTR_TYPE_OBJREF")
> >> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> >> ---
> >> The new interface showed up in 6.18, but I only came across this after
> >> that was released. Changing it now is technically an ABI change on
> >> architectures with unusual padding rules, so please consider carefully
> >> whether we want to do it this way or not.
> >>
> >> Working around the ABI differences without an ABI change is possible,
> >> but adds a lot of complexity for compat handling.
> > 
> > This is currently only used by the recently introduced qcomtee backend
> > driver. So it's only used on a few arm64 Qualcomm platforms right now.
> > 
> > I think we should take this patch, but let's hear what others think.

Yeah since it's not an ABI issue on arm64 platforms where QTEE runs, so:

Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>

> > 
> > Thanks,
> > Jens
> > 
> 
> I agree. We should take this patch. As noted, there are not many
> clients relying on it yet, so updating the userspace should
> be straightforward.

You should rather test without any userspace library update to test it's
not an ABI issue. Just for correctness sake, you can update the library
too.

-Sumit

[...]
Re: [PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Harshal Dev 1 week, 4 days ago 

On 12/8/2025 5:50 PM, Sumit Garg via OP-TEE wrote:
> On Mon, Dec 08, 2025 at 04:24:17PM +1100, Amirreza Zarrabi wrote:
>> Hi,
>>
>> On 12/5/2025 12:27 AM, Jens Wiklander wrote:
>>> Hi,
>>>
>>> On Thu, Dec 4, 2025 at 11:17 AM Arnd Bergmann <arnd@kernel.org> wrote:
>>>>
>>>> From: Arnd Bergmann <arnd@arndb.de>
>>>>
>>>> The tee_ioctl_object_invoke_arg structure has padding on some
>>>> architectures but not on x86-32 and a few others:
>>>>
>>>> include/linux/tee.h:474:32: error: padding struct to align 'params' [-Werror=padded]
>>>>
>>>> I expect that all current users of this are on architectures that do
>>>> have implicit padding here (arm64, arm, x86, riscv), so make the padding
>>>> explicit in order to avoid surprises if this later gets used elsewhere.
>>>>
>>>> Fixes: d5b8b0fa1775 ("tee: add TEE_IOCTL_PARAM_ATTR_TYPE_OBJREF")
>>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>>>> ---
>>>> The new interface showed up in 6.18, but I only came across this after
>>>> that was released. Changing it now is technically an ABI change on
>>>> architectures with unusual padding rules, so please consider carefully
>>>> whether we want to do it this way or not.
>>>>
>>>> Working around the ABI differences without an ABI change is possible,
>>>> but adds a lot of complexity for compat handling.
>>>
>>> This is currently only used by the recently introduced qcomtee backend
>>> driver. So it's only used on a few arm64 Qualcomm platforms right now.
>>>
>>> I think we should take this patch, but let's hear what others think.
> 
> Yeah since it's not an ABI issue on arm64 platforms where QTEE runs, so:
> 
> Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
> 
>>>
>>> Thanks,
>>> Jens
>>>
>>
>> I agree. We should take this patch. As noted, there are not many
>> clients relying on it yet, so updating the userspace should
>> be straightforward.
> 
> You should rather test without any userspace library update to test it's
> not an ABI issue. Just for correctness sake, you can update the library
> too.
> 

I'll take the time to test it at some point this week both with and without updating
the library ABI.

Regards,
Harshal

> -Sumit
> 
> [...]
Re: [PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Amirreza Zarrabi 1 week, 3 days ago 
Hi,

On 12/8/2025 11:54 PM, Harshal Dev wrote:
> 
> 
> On 12/8/2025 5:50 PM, Sumit Garg via OP-TEE wrote:
>> On Mon, Dec 08, 2025 at 04:24:17PM +1100, Amirreza Zarrabi wrote:
>>> Hi,
>>>
>>> On 12/5/2025 12:27 AM, Jens Wiklander wrote:
>>>> Hi,
>>>>
>>>> On Thu, Dec 4, 2025 at 11:17 AM Arnd Bergmann <arnd@kernel.org> wrote:
>>>>>
>>>>> From: Arnd Bergmann <arnd@arndb.de>
>>>>>
>>>>> The tee_ioctl_object_invoke_arg structure has padding on some
>>>>> architectures but not on x86-32 and a few others:
>>>>>
>>>>> include/linux/tee.h:474:32: error: padding struct to align 'params' [-Werror=padded]
>>>>>
>>>>> I expect that all current users of this are on architectures that do
>>>>> have implicit padding here (arm64, arm, x86, riscv), so make the padding
>>>>> explicit in order to avoid surprises if this later gets used elsewhere.
>>>>>
>>>>> Fixes: d5b8b0fa1775 ("tee: add TEE_IOCTL_PARAM_ATTR_TYPE_OBJREF")
>>>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>>>>> ---
>>>>> The new interface showed up in 6.18, but I only came across this after
>>>>> that was released. Changing it now is technically an ABI change on
>>>>> architectures with unusual padding rules, so please consider carefully
>>>>> whether we want to do it this way or not.
>>>>>
>>>>> Working around the ABI differences without an ABI change is possible,
>>>>> but adds a lot of complexity for compat handling.
>>>>
>>>> This is currently only used by the recently introduced qcomtee backend
>>>> driver. So it's only used on a few arm64 Qualcomm platforms right now.
>>>>
>>>> I think we should take this patch, but let's hear what others think.
>>
>> Yeah since it's not an ABI issue on arm64 platforms where QTEE runs, so:
>>
>> Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
>>
>>>>
>>>> Thanks,
>>>> Jens
>>>>
>>>
>>> I agree. We should take this patch. As noted, there are not many
>>> clients relying on it yet, so updating the userspace should
>>> be straightforward.
>>
>> You should rather test without any userspace library update to test it's
>> not an ABI issue. Just for correctness sake, you can update the library
>> too.
>>
> 
> I'll take the time to test it at some point this week both with and without updating
> the library ABI.
> 

Summit, that was the plan from the beginning, that's why I did not add "Reviewed-by:"
in the first place. Thanks Harshal for volunteering.

Best regards,
Amir

> Regards,
> Harshal
> 
>> -Sumit
>>
>> [...]
>
Re: [PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Jens Wiklander 3 days, 8 hours ago 
Hi,

On Tue, Dec 9, 2025 at 4:54 AM Amirreza Zarrabi
<amirreza.zarrabi@oss.qualcomm.com> wrote:
>
> Hi,
>
> On 12/8/2025 11:54 PM, Harshal Dev wrote:
> >
> >
> > On 12/8/2025 5:50 PM, Sumit Garg via OP-TEE wrote:
> >> On Mon, Dec 08, 2025 at 04:24:17PM +1100, Amirreza Zarrabi wrote:
> >>> Hi,
> >>>
> >>> On 12/5/2025 12:27 AM, Jens Wiklander wrote:
> >>>> Hi,
> >>>>
> >>>> On Thu, Dec 4, 2025 at 11:17 AM Arnd Bergmann <arnd@kernel.org> wrote:
> >>>>>
> >>>>> From: Arnd Bergmann <arnd@arndb.de>
> >>>>>
> >>>>> The tee_ioctl_object_invoke_arg structure has padding on some
> >>>>> architectures but not on x86-32 and a few others:
> >>>>>
> >>>>> include/linux/tee.h:474:32: error: padding struct to align 'params' [-Werror=padded]
> >>>>>
> >>>>> I expect that all current users of this are on architectures that do
> >>>>> have implicit padding here (arm64, arm, x86, riscv), so make the padding
> >>>>> explicit in order to avoid surprises if this later gets used elsewhere.
> >>>>>
> >>>>> Fixes: d5b8b0fa1775 ("tee: add TEE_IOCTL_PARAM_ATTR_TYPE_OBJREF")
> >>>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> >>>>> ---
> >>>>> The new interface showed up in 6.18, but I only came across this after
> >>>>> that was released. Changing it now is technically an ABI change on
> >>>>> architectures with unusual padding rules, so please consider carefully
> >>>>> whether we want to do it this way or not.
> >>>>>
> >>>>> Working around the ABI differences without an ABI change is possible,
> >>>>> but adds a lot of complexity for compat handling.
> >>>>
> >>>> This is currently only used by the recently introduced qcomtee backend
> >>>> driver. So it's only used on a few arm64 Qualcomm platforms right now.
> >>>>
> >>>> I think we should take this patch, but let's hear what others think.
> >>
> >> Yeah since it's not an ABI issue on arm64 platforms where QTEE runs, so:
> >>
> >> Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
> >>
> >>>>
> >>>> Thanks,
> >>>> Jens
> >>>>
> >>>
> >>> I agree. We should take this patch. As noted, there are not many
> >>> clients relying on it yet, so updating the userspace should
> >>> be straightforward.
> >>
> >> You should rather test without any userspace library update to test it's
> >> not an ABI issue. Just for correctness sake, you can update the library
> >> too.
> >>
> >
> > I'll take the time to test it at some point this week both with and without updating
> > the library ABI.
> >
>
> Summit, that was the plan from the beginning, that's why I did not add "Reviewed-by:"
> in the first place. Thanks Harshal for volunteering.

Are we good with this patch now?

Cheers,
Jens
Re: [PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Harshal Dev 3 days, 5 hours ago 
Hi Jens,

On 12/16/2025 1:18 PM, Jens Wiklander wrote:
> Hi,
> 
> On Tue, Dec 9, 2025 at 4:54 AM Amirreza Zarrabi
> <amirreza.zarrabi@oss.qualcomm.com> wrote:
>>
>> Hi,
>>
>> On 12/8/2025 11:54 PM, Harshal Dev wrote:
>>>
>>>
>>> On 12/8/2025 5:50 PM, Sumit Garg via OP-TEE wrote:
>>>> On Mon, Dec 08, 2025 at 04:24:17PM +1100, Amirreza Zarrabi wrote:
>>>>> Hi,
>>>>>
>>>>> On 12/5/2025 12:27 AM, Jens Wiklander wrote:
>>>>>> Hi,
>>>>>>
>>>>>> On Thu, Dec 4, 2025 at 11:17 AM Arnd Bergmann <arnd@kernel.org> wrote:
>>>>>>>
>>>>>>> From: Arnd Bergmann <arnd@arndb.de>
>>>>>>>
>>>>>>> The tee_ioctl_object_invoke_arg structure has padding on some
>>>>>>> architectures but not on x86-32 and a few others:
>>>>>>>
>>>>>>> include/linux/tee.h:474:32: error: padding struct to align 'params' [-Werror=padded]
>>>>>>>
>>>>>>> I expect that all current users of this are on architectures that do
>>>>>>> have implicit padding here (arm64, arm, x86, riscv), so make the padding
>>>>>>> explicit in order to avoid surprises if this later gets used elsewhere.
>>>>>>>
>>>>>>> Fixes: d5b8b0fa1775 ("tee: add TEE_IOCTL_PARAM_ATTR_TYPE_OBJREF")
>>>>>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>>>>>>> ---
>>>>>>> The new interface showed up in 6.18, but I only came across this after
>>>>>>> that was released. Changing it now is technically an ABI change on
>>>>>>> architectures with unusual padding rules, so please consider carefully
>>>>>>> whether we want to do it this way or not.
>>>>>>>
>>>>>>> Working around the ABI differences without an ABI change is possible,
>>>>>>> but adds a lot of complexity for compat handling.
>>>>>>
>>>>>> This is currently only used by the recently introduced qcomtee backend
>>>>>> driver. So it's only used on a few arm64 Qualcomm platforms right now.
>>>>>>
>>>>>> I think we should take this patch, but let's hear what others think.
>>>>
>>>> Yeah since it's not an ABI issue on arm64 platforms where QTEE runs, so:
>>>>
>>>> Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> Jens
>>>>>>
>>>>>
>>>>> I agree. We should take this patch. As noted, there are not many
>>>>> clients relying on it yet, so updating the userspace should
>>>>> be straightforward.
>>>>
>>>> You should rather test without any userspace library update to test it's
>>>> not an ABI issue. Just for correctness sake, you can update the library
>>>> too.
>>>>
>>>
>>> I'll take the time to test it at some point this week both with and without updating
>>> the library ABI.
>>>
>>
>> Summit, that was the plan from the beginning, that's why I did not add "Reviewed-by:"
>> in the first place. Thanks Harshal for volunteering.
> 
> Are we good with this patch now?
>

Yes, this is good from our side.

Tested-by: Harshal Dev <harshal.dev@oss.qualcomm.com>

> Cheers,
> Jens
Re: [PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Jens Wiklander 3 days, 2 hours ago 
Hi,

On Tue, Dec 16, 2025 at 11:56 AM Harshal Dev
<harshal.dev@oss.qualcomm.com> wrote:
>
> Hi Jens,
>
> On 12/16/2025 1:18 PM, Jens Wiklander wrote:
> > Hi,
> >
> > On Tue, Dec 9, 2025 at 4:54 AM Amirreza Zarrabi
> > <amirreza.zarrabi@oss.qualcomm.com> wrote:
> >>
> >> Hi,
> >>
> >> On 12/8/2025 11:54 PM, Harshal Dev wrote:
> >>>
> >>>
> >>> On 12/8/2025 5:50 PM, Sumit Garg via OP-TEE wrote:
> >>>> On Mon, Dec 08, 2025 at 04:24:17PM +1100, Amirreza Zarrabi wrote:
> >>>>> Hi,
> >>>>>
> >>>>> On 12/5/2025 12:27 AM, Jens Wiklander wrote:
> >>>>>> Hi,
> >>>>>>
> >>>>>> On Thu, Dec 4, 2025 at 11:17 AM Arnd Bergmann <arnd@kernel.org> wrote:
> >>>>>>>
> >>>>>>> From: Arnd Bergmann <arnd@arndb.de>
> >>>>>>>
> >>>>>>> The tee_ioctl_object_invoke_arg structure has padding on some
> >>>>>>> architectures but not on x86-32 and a few others:
> >>>>>>>
> >>>>>>> include/linux/tee.h:474:32: error: padding struct to align 'params' [-Werror=padded]
> >>>>>>>
> >>>>>>> I expect that all current users of this are on architectures that do
> >>>>>>> have implicit padding here (arm64, arm, x86, riscv), so make the padding
> >>>>>>> explicit in order to avoid surprises if this later gets used elsewhere.
> >>>>>>>
> >>>>>>> Fixes: d5b8b0fa1775 ("tee: add TEE_IOCTL_PARAM_ATTR_TYPE_OBJREF")
> >>>>>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> >>>>>>> ---
> >>>>>>> The new interface showed up in 6.18, but I only came across this after
> >>>>>>> that was released. Changing it now is technically an ABI change on
> >>>>>>> architectures with unusual padding rules, so please consider carefully
> >>>>>>> whether we want to do it this way or not.
> >>>>>>>
> >>>>>>> Working around the ABI differences without an ABI change is possible,
> >>>>>>> but adds a lot of complexity for compat handling.
> >>>>>>
> >>>>>> This is currently only used by the recently introduced qcomtee backend
> >>>>>> driver. So it's only used on a few arm64 Qualcomm platforms right now.
> >>>>>>
> >>>>>> I think we should take this patch, but let's hear what others think.
> >>>>
> >>>> Yeah since it's not an ABI issue on arm64 platforms where QTEE runs, so:
> >>>>
> >>>> Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
> >>>>
> >>>>>>
> >>>>>> Thanks,
> >>>>>> Jens
> >>>>>>
> >>>>>
> >>>>> I agree. We should take this patch. As noted, there are not many
> >>>>> clients relying on it yet, so updating the userspace should
> >>>>> be straightforward.
> >>>>
> >>>> You should rather test without any userspace library update to test it's
> >>>> not an ABI issue. Just for correctness sake, you can update the library
> >>>> too.
> >>>>
> >>>
> >>> I'll take the time to test it at some point this week both with and without updating
> >>> the library ABI.
> >>>
> >>
> >> Summit, that was the plan from the beginning, that's why I did not add "Reviewed-by:"
> >> in the first place. Thanks Harshal for volunteering.
> >
> > Are we good with this patch now?
> >
>
> Yes, this is good from our side.
>
> Tested-by: Harshal Dev <harshal.dev@oss.qualcomm.com>

Good, thank you, Harshal.

Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>

Arnd, what do you prefer, taking this directly or should I send it in
a pull request?

Cheers,
Jens
Re: [PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Harshal Dev 2 weeks ago 
Hi,

On 12/4/2025 6:57 PM, Jens Wiklander wrote:
> Hi,
> 
> On Thu, Dec 4, 2025 at 11:17 AM Arnd Bergmann <arnd@kernel.org> wrote:
>>
>> From: Arnd Bergmann <arnd@arndb.de>
>>
>> The tee_ioctl_object_invoke_arg structure has padding on some
>> architectures but not on x86-32 and a few others:
>>
>> include/linux/tee.h:474:32: error: padding struct to align 'params' [-Werror=padded]
>>
>> I expect that all current users of this are on architectures that do
>> have implicit padding here (arm64, arm, x86, riscv), so make the padding
>> explicit in order to avoid surprises if this later gets used elsewhere.
>>
>> Fixes: d5b8b0fa1775 ("tee: add TEE_IOCTL_PARAM_ATTR_TYPE_OBJREF")
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> ---
>> The new interface showed up in 6.18, but I only came across this after
>> that was released. Changing it now is technically an ABI change on
>> architectures with unusual padding rules, so please consider carefully
>> whether we want to do it this way or not.
>>
>> Working around the ABI differences without an ABI change is possible,
>> but adds a lot of complexity for compat handling.
> 
> This is currently only used by the recently introduced qcomtee backend
> driver. So it's only used on a few arm64 Qualcomm platforms right now.
> 
> I think we should take this patch, but let's hear what others think.
> 
> Thanks,
> Jens
> 
The only user-space client which is currently using this ABI (as per our knowledge)
is the libqcomtee library: https://github.com/quic/quic-teec/blob/main/libqcomtee/src/linux/tee.h#L432

If I understand Arnd's concern correctly, if a compiler used to build the user-space
client skips the padding for tee_ioctl_object_invoke_arg, it could lead to issues.

Let's wait for Amir's view here as well, however I do think the explicit padding would
benefit here.

Regards,
Harshal

>> ---
>>  include/uapi/linux/tee.h | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
>> index cab5cadca8ef..5203977ed35d 100644
>> --- a/include/uapi/linux/tee.h
>> +++ b/include/uapi/linux/tee.h
>> @@ -470,6 +470,7 @@ struct tee_ioctl_object_invoke_arg {
>>         __u32 op;
>>         __u32 ret;
>>         __u32 num_params;
>> +       __u32 :32;
>>         /* num_params tells the actual number of element in params */
>>         struct tee_ioctl_param params[];
>>  };
>> --
>> 2.39.5
>>
Re: [PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Arnd Bergmann 2 weeks ago 
On Fri, Dec 5, 2025, at 14:45, Harshal Dev wrote:
> On 12/4/2025 6:57 PM, Jens Wiklander wrote:
>> On Thu, Dec 4, 2025 at 11:17 AM Arnd Bergmann <arnd@kernel.org> wrote:
>> 
> The only user-space client which is currently using this ABI (as per 
> our knowledge)
> is the libqcomtee library: 
> https://github.com/quic/quic-teec/blob/main/libqcomtee/src/linux/tee.h#L432
>
> If I understand Arnd's concern correctly, if a compiler used to build 
> the user-space
> client skips the padding for tee_ioctl_object_invoke_arg, it could lead 
> to issues.
>
> Let's wait for Amir's view here as well, however I do think the 
> explicit padding would
> benefit here.
>

The problem is much narrower: as the amount of padding is determined
by the architecture specific ABI, kernel and userspace on the same
architecture always agree, and specifically 32-bit Arm userspace
and 64-bit Arm userspace (aarch64) also have the same rules, so there
is no problem on Qualcomm's platforms even with compat 32-bit userspace.

The only actual ABI problem would happen on 32-bit x86 (i386)
userspace running on a 64-bit x86 kernel, since i386-linux compilers
have different alignment rules from most other architectures.

        Arnd
Re: [PATCH] tee: fix tee_ioctl_object_invoke_arg padding
Posted by Harshal Dev 2 weeks ago 

On 12/5/2025 7:26 PM, Arnd Bergmann wrote:
> On Fri, Dec 5, 2025, at 14:45, Harshal Dev wrote:
>> On 12/4/2025 6:57 PM, Jens Wiklander wrote:
>>> On Thu, Dec 4, 2025 at 11:17 AM Arnd Bergmann <arnd@kernel.org> wrote:
>>>
>> The only user-space client which is currently using this ABI (as per 
>> our knowledge)
>> is the libqcomtee library: 
>> https://github.com/quic/quic-teec/blob/main/libqcomtee/src/linux/tee.h#L432
>>
>> If I understand Arnd's concern correctly, if a compiler used to build 
>> the user-space
>> client skips the padding for tee_ioctl_object_invoke_arg, it could lead 
>> to issues.
>>
>> Let's wait for Amir's view here as well, however I do think the 
>> explicit padding would
>> benefit here.
>>
> 
> The problem is much narrower: as the amount of padding is determined
> by the architecture specific ABI, kernel and userspace on the same
> architecture always agree, and specifically 32-bit Arm userspace
> and 64-bit Arm userspace (aarch64) also have the same rules, so there
> is no problem on Qualcomm's platforms even with compat 32-bit userspace.
> 
> The only actual ABI problem would happen on 32-bit x86 (i386)
> userspace running on a 64-bit x86 kernel, since i386-linux compilers
> have different alignment rules from most other architectures.
> 

Well, as Jens pointed out, the TEE_IOC_OBJECT_INVOKE ABI which supports
object-based IPC currently has no back-end drivers that attempt to communicate
with a TEE running on x86 and implementing their end of the object-IPC protocol
in the firmware. So this obviously won't be an immediate issue.

But as you pointed out, the issue would pop up if someone on x86 decides to implement
it at some point in the far away future.

I do not see any harm this patch would do for our existing implementation, we'll
just update our user-space library ABI in-line with this.

Thanks,
Harshal

>         Arnd

Patchew 2.1-devel-b67e4c2

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