Re: how to write paxctl MPROTECT-safe JIT code?

[Thomas Klausner <tk%giga.or.at@localhost>]

On Tue, Nov 15, 2016 at 01:42:56PM +0100, Joerg Sonnenberger wrote:
> On Tue, Nov 15, 2016 at 12:34:14PM +0100, Thomas Klausner wrote:
> > I've filed some upstream bug reports about paxctl issues, some existed
> > already.
> > 
> > One developer asks how to fix the issue:
> > 
> > https://bugs.exim.org/show_bug.cgi?id=1749
> > 
> > Can someone please help out here?
> 
> The only safe and performant way I know is to create a temporary file,
> unlink it and mmap it twice via the fd. It's a PITA.

So mkstemp() to get a file, unlink() to remove it, write the JIT code
to the file. What are the two mmap()s for, what flags do they get?
 Thomas