Multi-Byte NOOP Equivalent Sled

Traditionally, NOOP instructions are single-byte opcodes (e.g., 0x90 in x86 assembly language). However, in some cases, mainly when dealing with architectures or environments where a single-byte NOOP opcode is unavailable or unsuitable, multi-byte NOOP sleds can be used. These multi-byte NOOP sleds utilize multi-byte opcodes to achieve the same sled effect.

When creating a multi-byte NOOP sled, it's crucial to thoroughly understand the characteristics of the target architecture and instruction set. The second byte of the operation of the multi-byte operand must support a stand-alone opcode within itself. This means that the opcode should be valid and not interfere with the execution flow when interpreted independently.

For example, in x86 assembly language, the opcode 0x66 0x90 represents a two-byte NOOP instruction. The 0x66 prefix switches to 16-bit mode, and 0x90 is the traditional single-byte NOOP instruction. In this case, 0x90 is the stand-alone opcode within the multi-byte instruction. Similarly, other architectures may have their own multi-byte NOOP instructions with specific characteristics.

When crafting a multi-byte NOOP sled, it's of utmost importance to carefully select an opcode sequence that:

It consists of valid instructions that won't crash or disrupt the execution flow. It has predictable behavior and does not have unintended side effects. It is compatible with the target architecture and instruction set.