On Tue, Aug 23, 2011 at 12:43:28PM -0700, Linus Torvalds wrote: > On Tue, Aug 23, 2011 at 12:41 PM, Al Viro <v...@zeniv.linux.org.uk> wrote: > > > > And it's not cheap - doing that on each syscall will be unpleasant... > > Frankly, I'd rather stopped telling the uml userland about vdso in such > > setups. ?And anything that plays with SYSCALL outside of vdso... <shrug> > > we already have a "don't run it native on 32bit", adding "don't run > > it on 32bit uml on amd64 host" is not too serious. ?At least for now... > > I do agree that the solution might well be to just stop using the > non-int80 vdsos for UML. That may just solve everything in practice.
SYSENTER works fine, actually... And we can easily check if we have an affected SYSCALL, simply by forking a child, tracing it into a syscall and doing POKEUSER to ebp on the second stop (i.e. on the way out). If the value ends up in ecx after __kernel_vsyscall(), we have SYSCALL-based variant on amd64 host, if it's lost completely - it's SYSENTER, if it shows up in ebp - int 0x80. ------------------------------------------------------------------------------ EMC VNX: the world's simplest storage, starting under $10K The only unified storage solution that offers unified management Up to 160% more powerful than alternatives and 25% more efficient. Guaranteed. http://p.sf.net/sfu/emc-vnx-dev2dev _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
