[mtgx]

They talk a bit about them in these posts:

https://copperhead.co/blog/2015/06/11/android-pax

https://copperhead.co/blog/2015/07/27/hardening-bionic

https://copperhead.co/blog/2015/05/11/aslr-android-zygote

[strcat]

https://copperhead.co/android/docs/technical_overview covers much more and is mostly up-to-date.