CS208, Monday 31 Jan 2022

Today

• Puzzles assignment questions
• Exam questions
• Function-calling in x86_64

Puzzles assignment

• What do you wish you had known when you started this assignment?
• rax, eax, ax, al, ah
• How can you tell a register holds a parameter?
• Look at examples of:
  • loop
  • if/else
  • one-parameter / one-return
  • two-parameter / one-return
  • void return
  • etc.
• Other questions?

Function-calling

• What's up with rbp and rsp?
• Seeing "pass-by-value" in action
• What's the difference between parameter types: char, int, long, char *, int *
• Structs as parameters

Coming up in the second half

• Linux Polkit bug, just for fun
• Debugging C and reverse engineering executables using gdb
• Buffer overflow attacks
• Memory allocation algorithms (how does malloc work?)
• Virtual memory (how can each process think it has 2^64 bytes of memory when the computer only has 2^35?) (that's 32GB, so a pretty expensive machine)
• Concurrency (and its scary implications)
• Network programming