Porting the Meltdown attack on the gem5 architecture simulator

Ported the original source code for the Meltdown attack on a non-mitigated Linux 4.19 kernel, running on the gem5 architecture simulator. This helped further research on Microarchitectural Side-Channel attacks (\emph{e.g.}, evaluation of side-channel resistance of common cryptography implementations). The project required a fair amount of kernel configuration, syscall tracing and memory inspection.