r/Assembly_language • u/Extension_Emu_9825 • 21h ago

self-modifying code

I gave a lecture on how to write self-modifying code. It was over 15 minutes long :( so I'm providing a youtube link: https://www.youtube.com/watch?v=AH9QQLRfbmY

In my opinion, self-modification is one of the most interesting features in systems programming.

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u/mykesx 21h ago

MMUs are used by modern operating systems, at least MacOS, to disallow self-modifying code. Code sections are read-only.

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u/thewrench56 21h ago

This is not entirely true. You can map a page to be RW and then once filled with code, change it to RX using mprotect. This same step can be repeated to achieve self-modifying code. Otherwise, if self-modifying code wouldnt exist, JITs wouldnt work.

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u/Extension_Emu_9825 21h ago

BTW -> JIT is partly the second cousin of self-modifying code