Example from the doc. Probes not being allowed to call other system routines to avoid reentrancy. Dtrace avoids this architecturally, as your link says. I disliked this, so I chose the alternative, which so happens to be mentioned in the same document. My system detects reentrancy and avoided calling probes when it's determined the caller was itself a probe.

I simply chose different constraints. It 'not being secure' is a facade. It's not meant to be, I could make it so though, if I wanted to. I bothered with the entire rust + wasm implementation specifically to show that this argument of not being secure' because I didn't use the D language was untrue. Browsers themselves execute untrusted code via wasm. If the concern is the halting problem, then just use wasm with bounded loops.