On Thu, Dec 13, 2012 at 10:42:28AM -0800, H. Peter Anvin wrote: > On 12/13/2012 10:37 AM, Borislav Petkov wrote: > >> > >> If appropriate, the code could be changed to > >> > >> (void *)(unsigned long)m->ip > > > > Can we explicitly cast it to what it is so that we can be explicit as to > > what we're casting it? IOW: > > > > (void *)(__u64)m->ip; > > > > Does that even work on 32bit? > > > > Also, does the compiler bitch about this useless cast when building with > > W=123? > > > > Uh... no. > > The point is that (void *)(unsigned long) casts it to an integer of > pointer size -- in userspace you would to (void *)(size_t) or (void > *)(uintptr_t) -- so that the compiler knows "I meant to do that."
Ok, I grok it now. So, in most cases, mce.ip comes from pt_regs.ip which is unsigned long so we're fine for both 32- and 64-bit. There's only the case with precise RIP reporting where we get the rip from an MSR but even then, it should be 4 bytes on 32-bit since our addresses there are 4 bytes. So, actually struct mce should've had ->ip defined as an unsigned long from the very beginning. But we can't change that now because this struct is shared with userspace :( So yes Joe, make it (void *)(unsigned long). Thanks guys. -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. -- ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user