You're absolutely right about the majority of the time in the real world. A ctf level is a contrived case, but that doesn't make this any less interesting for me. This was mostly a challenge of "how fast can I run my existing program?" and I think I nailed it pretty well with lib43 [0] (which is a working extremely minimal libc and crt0 replacement in about 300 lines of code).
My favorite part is my x86_64 linux syscall interface, in which I define a short assembly stub (syscall.c) and simply list syscall names (syscall.list) to wire them up. The calling convention between user-space functions and the kernel was close enough I was able to reduce the inline asm to two instructions (`mov rax, syscall num; syscall;`).
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You're absolutely right about the majority of the time in the real world. A ctf level is a contrived case, but that doesn't make this any less interesting for me. This was mostly a challenge of "how fast can I run my existing program?" and I think I nailed it pretty well with lib43 [0] (which is a working extremely minimal libc and crt0 replacement in about 300 lines of code).
My favorite part is my x86_64 linux syscall interface, in which I define a short assembly stub (syscall.c) and simply list syscall names (syscall.list) to wire them up. The calling convention between user-space functions and the kernel was close enough I was able to reduce the inline asm to two instructions (`mov rax, syscall num; syscall;`).
[0] https://github.com/lunixbochs/lib43