> However, cooperation from the operating system is necessary, as the constant-time execution mode may need to be enabled by setting certain CPU-control bits in protected registers (e.g. IA32_UARCH_MISC_CTL[DOITM]).
The way ARM does this is way better, since it doesn't need help from the operating system: user-space can directly set and clear the DIT bit. Operating system cooperation is necessary only to know whether that bit exists (because the ID registers are not directly readable by user mode).
The way ARM does this is way better, since it doesn't need help from the operating system: user-space can directly set and clear the DIT bit. Operating system cooperation is necessary only to know whether that bit exists (because the ID registers are not directly readable by user mode).