Suppose my non-root 32-bit app runs on a 64-bit system, all filesystems of which are mounted as read-only. The app creates an image of a 64-bit ELF in memory. But due to read-only filesystems it can't dump this image to a file to do an `execve` on. Is there still a supported way to launch a process from this image?

Note: the main problem here is to switch from 32-bit mode to 64-bit, not doing any [potentially unreliable hacks](https://stackoverflow.com/a/32384358/673852). If this is solved, then the whole issue becomes trivial — just make a custom loader.