How about enabling mitigations in Javascript engines?
Some are there, otherwise they couldn't be disabled in Linux kernel for faster performance. Which means that they could be enabled on demand.
apple tries, and even then people already managed to run code via pdf engines; on android it's at least more clear you have no control.
You probably have apps in your phone runnig rigth now that ship with their own JS engine for advertising purposes. Do you expect them to have all the necessary safeguards?
The position that all of the browser vendors have landed on at this point is that mitigating this class of attacks in the browser is simply not possible.
Can you please elaborate? Did these effort fail completely or is it that if you use your browser a certain way then you can never be protected? (Which implies that using it another way would be safe.)
> Fourth, we found that effective mitigation of some variants of Spectre, particularly variant 4, to be simply infeasible in software, even after a heroic effort by our partners at Apple to combat the problem in their JIT compiler.
Apple released a new one for the newest vulnerability so they didn’t have to reduce the performance of macOS by ~30%.
> Fourth, we found that effective mitigation of some variants of Spectre, particularly variant 4, to be simply infeasible in software, even after a heroic effort by our partners at Apple to combat the problem in their JIT compiler.
Apple released an update with some mitigations, but they are by no means perfect, and their message is that if you want to truly be safe, either don’t run JS, or disable hyperthreading.