I just committed a little change to MoarVM that'll turn off the jit if we notice we're not allowed to turn a page executable.
https://github.com/MoarVM/MoarVM/commit/b07acdfd92a88d1e40ad42c1c853922b20f1a056 now it won't crash if deny_execmem is turned on. it'll just be slower. There's apparently a way around this which involves creating a temporary file (immediately unlinked) and mmapping it into memory twice (once writable, once executable). That's a bit hairy, since we can't assume that /tmp isn't mounted "noexec". However, we could notice we're not allowed to change modes on a page and just switch over to the file-mapped-twice approach and only disable the jit completely if that fails (because "noexec" or because no write permissions to /tmp or something like that). that's very internalsy and i'd like brrt - our jit maker - to look over this a bit before attempting anything more drastic thanks! - Timo
