[okanat]

ARM chips are mainly much simpler. The fight with Spectre-like side-channels is a fight against thermodynamics we cannot win, only mitigate.

Any performance improvement relies on the patterns of data also exposes the data itself. Intel and AMD wanted to make faster returns by analyzing the patterns in the return instructions by putting a branch prediction logic. When they do that it behaves differently depending on the data hence it is "observable" to outside world.

If any ARM manufacturer implements a similar feature, it will be vulnerable. There is only one question: When will it be practically exploitable?