A8 erratum. This was ages ago, but if I recall you could place a thumb2 instruction straddling two pages, only one of which was loaded in the TLBs. If you got everything right, the A8 would hang without trapping.
Edit: it was errata #657417, long since scrubbed from arm.com
The A8 errata doc is at https://developer.arm.com/documentation/prdc008070/latest/ these days and does have a description of 657417 with enough detail to make writing a reproducer possible. Instructions crossing page boundaries are tricky beasts :-)
Edit: it was errata #657417, long since scrubbed from arm.com