Indirect Calling of Nested Functions on GCC Without Executable Stack

GCC creates trampolines on the stack to enable calling nested functions, which requires executable stack permissions for security reasons. The article describes a technique to extract the code address and static chain information from these trampolines and call nested functions directly using `__builtin_call_with_static_chain`, allowing the stack to be marked non-executable with `patchelf --clear-execstack` while maintaining compatibility with older GCC versions.