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You are building a basic CPU with a classic RISC pipeline. Answer the following about a seemingly harmless instruction you may use, for 10 points each.
[10m] Name this instruction, which can be used to implement a pipeline stall in certain architectures, including x86 and MIPS (“mips”). A “sled” or “slide” is named for this instruction, which does nothing when executed.
ANSWER: NOP [or no-op or NOOP or no operation]
[10h] In x86, a NOP is implemented by completing this atomic action equivalent to three MOV instructions on the AX register. This action can be used to implement a semaphore in x86 because it activates a bus lock.
ANSWER: XCHG [or exchanging two registers; accept descriptions of swapping the contents of two registers]
[10e] An attacker may install a NOP slide in memory while exploiting this type of vulnerability where the bounds of allocated memory are exceeded. A common coding website is named for this effect occurring to a stack.
ANSWER: overflow [or overrun; accept buffer overflow or buffer overrun; accept Stack Overflow]
<KJ, Other Science: Computer Science>

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