On Fri, Jul 24, 2015 at 11:29:29AM -0700, Linus Torvalds wrote: > On Fri, Jul 24, 2015 at 8:30 AM, Peter Zijlstra <pet...@infradead.org> wrote: > > On Fri, Jul 24, 2015 at 05:26:37PM +0200, Willy Tarreau wrote: > >> > > >> > The point is, if we trigger a #DB on an instruction breakpoint > >> > while !IF, then we simply disable that breakpoint and do the RET. > >> > >> Yes but the breakpoint remains disabled then. Or I'm missing > >> something. > > > > http://marc.info/?l=linux-kernel&m=143773601130974 > > > > We re-enable before going back to userspace. > > Actually, Andy had a good argument that we don't even need this. > > We just don't ever need to disable data breakpoints. Even if we end up doing > > cli(); > copy_from_user_inatomic(); > > that actually works fine. If there are data breakpoints, we will have
I worry that we'll end up running the do_debug() handlers from effective NMI context. The NMI might have preempted locks which these handlers require etc.. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
