Handling kernel-mode errors/panics

[sangho2]

We can encounter errors or panics while running kernel-mode code. If they are non-fatal errors, we should fix or suppress them as Linux kernel oops does. Ideally, we need to add more functions to litebox/src/mm/exception_table.rs to replace most of fallible operations, or apply additional clippy rules to the kernel-mode code like #![deny(clippy::arithmetic_side_effects)].

#654