On Fri, May 30, 2014 at 1:05 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote: > On 05/30/2014 01:00 PM, Andy Lutomirski wrote: >> >> Do the flags go in the ELF loader or in the executable we're running? >> Or both (and, if both, do we and them or or them)? >> >> I think the interpreter makes a little more sense in general: for the >> most part, use of vsyscalls is a property of the runtime environment, >> not of the program being run. But maybe this is naive. >> > > They go into each object which becomes part of the running program, i.e. > executable, dynamic libraries, and dynamic linker. Well, sure, but the kernel is not about to start reading ELF headers in dynamic libraries. So we need to make a decision based on the interpreter and the executable. The conservative approach is to require both to have the flag set *and* to offer a prctl to twiddle the flags. Then userspace loaders can do whatever they want, and distros get to rebuild the world :) --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
