[zep fromtree] [1.1] Fix alignment problems with IAR and Zephyr

[zejiang0jason]

In IAR __packed can be used for type definition, as described: https://mypages.iar.com/s/article/Accessing-Unaligned-Data

Zephyr defined __packed as __attribute__((__packed__)), which makes __packed can't be used for typedef. THe error is:

Recover the __packed temporarily, make it can be used for typedef.

The error can reproduced by project samples/drivers/crypto/

[zejiang0jason]

Not sure whether this is a good fix, the root cause is, Zephyr's __packed conflicts with IAR's keyword.

https://github.com/zephyrproject-rtos/zephyr/blob/b9b37edd2cc561cad6f782465a2a5bf5da44df4b/include/zephyr/toolchain/iar/iccarm.h#L153-L155

[tomi-font]

Please submit this fix upstream: https://github.com/Mbed-TLS/TF-PSA-Crypto
And then cherry-pick it here.

[zejiang0jason]

Hi @tomi-font , I also consider push to upstream.

My main consideration is, this __packed definition is done in Zephyr code,
https://github.com/zephyrproject-rtos/zephyr/blob/b9b37edd2cc561cad6f782465a2a5bf5da44df4b/include/zephyr/toolchain/iar/iccarm.h#L153-L155

#ifndef __packed
#define __packed        __attribute__((__packed__))
#endif

Should it be handled in Zephyr? thanks.

[tomi-font]

I think this change is generic enough that it could be accepted upstream. We want to avoid local patches in this repo whenever you can.
@valeriosetti can assist you with moving the PR forward upstream

[valeriosetti]

Wait, I think the concern raised by @zejiang0jason is correct. Upstream TF-PSA-Crypto follows what's being suggested by IAR compiler for when it comes to access unaligned data, so I think this is fine.

I suspect that as @zejiang0jason stated the problem in Zephyr is in https://github.com/zephyrproject-rtos/zephyr/blob/b9b37edd2cc561cad6f782465a2a5bf5da44df4b/include/zephyr/toolchain/iar/iccarm.h#L153-L155, which is in the main Zephyr repo. There __packed is being defined as __attribute__((__packed__)) which is OK for GCC but not for IAR. Somehow when that header is parsed __packed is not defined so it gets redefined in the wrong way.
The commit that introduced this support claims it to be "experimental". Perhaps @RobinKastberg (who worked on that commit) can help us on this?

[RobinKastberg]

Yes, we had a lot of issues with IAR-aware modules using __packed in the expected IAR-way, but rest of zephyr expecing a __packed from GNU.

I will defer this to @LoveKarlsson who has been trying to fix this upstream here: Mbed-TLS#410

[LoveKarlsson]

My fixes for this has now been merged and backported to 1.1 and mbedtls3.6

[valeriosetti]

@zejiang0jason can you please replace the commit in this PR with the cherry-pick -x of Mbed-TLS#779?

[zejiang0jason]

@zejiang0jason can you please replace the commit in this PR with the cherry-pick -x of Mbed-TLS#779?

updated, thanks.

[valeriosetti]

Now you only need to change the commit title to have the [zep fromtree] at the beginning and then we can merge it

[zejiang0jason]

Thanks, added.

Now you only need to change the commit title to have the [zep fromtree] at the [beginning]

[tomi-font]

remove the [1.1] and we're good

[valeriosetti]

remove the [1.1] and we're good

I thought about this as well, but [1.1] is part of the upstream commit to the 1.1 branch. No strong preference on this, I just wanted to let you know

[tomi-font]

ah 😄 we're good then

[tomi-font]

I would just put a space between the two brackets.

[zejiang0jason]

I would just put a space between the two brackets.

done