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Apple did just that in Safari on macOS.

• msbarnett 7y ago
  Apple attempted to do that (I believe it was the Google security team’s MDS writeup that referred to it as a “Herculean effort” on the WebKit team’s part), but even they fell short. 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.
  • pdimitar 7y ago
    > ...but even they fell short. 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.)
    • msbarnett 7y ago
      per the v8 team, efforts to fully secure the JS JIT engine are simply infeasible against some Spectre class attacks: > 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.
  • Asmod4n 7y ago
    You talking about the Update they released some days ago? Or those who are several months old? Apple released a new one for the newest vulnerability so they didn’t have to reduce the performance of macOS by ~30%.
    • msbarnett 7y ago
      I’m talking about the Chrome v8 team’s white paper on why they are giving up on trying to mitigate Spectre class attacks in software, which mentions, among other issues: > 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.