Indirect Calling of Nested Functions on GCC Without Executable Stack

I realized that, instead of a configuration file, I could configure the executable instead! So, any changes in configuration meant the editor would patch its own exe file!

This marvelous technique came to an end when attempts to stop malware got folded into the operating system.

The overhead of cache flushing means some old school techniques are no longer viable, like modifying a constant in the next instruction. However it is still interesting to write machine code snippets once and execute them many times, like the nested function trampolines. I had a case where I had RGB masks like R=0x00ff0000 etc and wanted to convert 0x00rrggbb to match the mask (so no-op in the common case but not always) which could have involved setting the shift amounts in a series of shift instructions.