On Wed, 10 Jul 2013, H. Peter Anvin wrote: > > If any CPU instruction execution would collide with the patching, > > it'd be trapped by the int3 breakpoint and redirected to the provided > > "handler" (which would typically mean just skipping over the patched > > region, acting as "nop" has been there, in case we are doing nop -> jump > > and jump -> nop transitions). > > > > I'm wondering if it would be easier/more general to just return to the > instruction. The "more general" bit would allow this to be used for > other things, like alternatives,
As Boris already pointed out, this is not really that interesting, as it's being done through text_poke_early(), which is rather a different story anyway. > and perhaps eventually dynamic call patching. Umm ... could you please elaborate either what exactly do you mean by that, or why it can't be used currently as-is? > Returning to the instruction will, in effect, be a busy-wait for the > faulted CPU until the patch is complete; more or less what stop_machine > would do, but only for a CPU which actually strays into the affected > region. To be honest, I fail to see a clear advantage ... we don't avoid any extra IPI by it, and wrt. "correctness", the end result is the same. Thanks, -- Jiri Kosina SUSE Labs -- 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/
