From mboxrd@z Thu Jan 1 00:00:00 1970 From: stewart@serissa.com (Lawrence Stewart) Date: Mon, 27 Nov 2017 13:21:25 -0500 Subject: [TUHS] Harvard and Von Neumann Architectures and Unix In-Reply-To: References: <20171127161141.2C9E318C08F@mercury.lcs.mit.edu> <20171127165046.GD3430@mcvoy.com> Message-ID: > On 2017, Nov 27, at 12:08 PM, Clem Cole wrote: > > SPICE2 does the same sort of thing (in semi-portable Fortran-IV) > > On Mon, Nov 27, 2017 at 11:50 AM, Larry McVoy > wrote: > On Mon, Nov 27, 2017 at 11:11:41AM -0500, Noel Chiappa wrote: > > > From: Doug McIlroy > > > > > But if that had been in D space, it couldn't have been executed. > > > > Along those lines, I was wondering about modern OS's, which I gather for > > security reasons prevent execution of data, and prevent writing to code. > > > > Programs which emit these little 'custom code fragments' (I prefer that term, > > since they aren't really 'self-modifying code' - which I define as 'a program > > which _changes_ _existing_ instructions) must have some way of having a chunk > > of memory into which they can write, but which can also be executed. > > Isn't that how dtrace works? > In POSIX systems, the mprotect(2) syscall can set execute permissions. -------------- next part -------------- An HTML attachment was scrubbed... URL: