Another security flaw that has appeared in modern processors is GoFetch. This error can be found in all Apple Silicon processors, i.e. models M1, M2 and M3. It also appeared on Intel Raptor Lake processors (including Refresh). This is a bug in DMP (Data Memory-dependent Prefetchers), which is a function to speed up calculations by fetching data even before it is needed. Such speculative acceleration techniques are nothing new, we have been using them in processors for decades. The problem is that with the right targeted attack, this data can be leaked due to a bug, and since it’s possible to bypass even the strongest encryption with 2048-bit keys that were meant to be resistant to quantum computers, it’s not exactly a problem that any practical impact.
One solution can logically be to turn off this function, which will understandably have a negative effect on performance (predictions that can increase performance will not occur). The problem is that while the Intel Raptor Lake and Apple M3 can disable this feature, the Apple M1 and M2 cannot. On these processors, DMP is always on regardless of the control bit settings, so the risk is there and cannot be avoided by disabling this feature simply because it cannot be disabled. But there is one more solution. Only powerful P-Core (Firestorm) cores have DMP in Apple processors, while economical E-Core (Icestorm) cores do not have this function. Cryptographic calculations transferred to Icestorm will therefore be safe, or at least they won’t be threatened by this problem. But even here it is necessary to take into account that there will be a decrease in performance. The question now is how the new generation of Apple M4 processors will deal with this problem.
