Enable synchronous memory tagging

[hansjansen2]

This PR enables synchronous memory tagging (MTE). Synchronous memory tagging was chosen over asynchronous memory tagging because it performs memory checks immediately at runtime, improving security and helping catch memory safety issues in real time. Asynchronous memory tagging reduces overhead but may delay detection of invalid memory accesses.

Solves: #1156

[deniscerri]

there is no point adding this
because the app relies on reproducible builds through github

i could do this manually on my pc when im testing, but shouldn't be in the code at all times

[hansjansen2]

there is no point adding this, because the app relies on reproducible builds through github

That does not matter. Organic Maps and LibreTube also have this feature and they have reproducible builds through GitHub. When memory tagging is put on sync/async it will only enable it for devices that support it. So reproducibility should not be affected.

i could do this manually on my pc when im testing, but shouldn't be in the code at all times

You could use it during development. But enabling memory tagging as I stated earlier provides security benefits for devices with support for it. And memory bugs can be discovered and reported easier. As I showed with the Organic Maps issue.

But I respect the decision if you want to keep it disabled in production, I just think there was a miscommunication. More about it can be found here in case you have not seen it:

https://developer.android.com/ndk/guides/arm-mte

[deniscerri]

one question
because im concerned about performance and i think this hinders performance by adding overhead

[hansjansen2]

To be honest I am not sure how much it impact performance. What I can say is that I used the signal app which does not have asynchronous memory tagging. And I currently use the signal-fork Molly which does have it and there is not much difference in my opinion. Maybe we can ask GrapheneOS for more information about that?