switch from region to memmap?

[sunfishcode]

#9 proposes ading a dependency on memmap, so we should consider using memmap rather than region for executable memory too.

[pepyakin]

Yeah, I thought about that, by the memmap API conflates this: map_exec takes File parameter. In our case we want anonymous mapping.

[sunfishcode]

That's ok. We don't want the memory to be executable until after we write to it. We allocate normal anonymous pages and set the protection when they're ready.

[pepyakin]

Hm, and for that we would need region since memmap doesn't have such APIs, don't we?

[sunfishcode]

Could make_read_only and make_exec do it? It's a little unfortunate that there doesn't seem to be a way to do both at the same time though.

[pepyakin]

oh, sorry, didn't know about those!

[sunfishcode]

Actually, it looks like make_exec should be sufficient to also make the memory read-only.

[sunfishcode]

A complicating factor with memmap is that it doesn't naturally support allocations consisting of some writeable pages and non-non-writeable pages. And other than this specialized need, we don't need a lot of other features, so I decided to just implement mmap support directly for now.