On 11/04/2015 10:03 AM, Josh Poimboeuf wrote: > On Wed, Nov 04, 2015 at 10:52:52AM +0100, Miroslav Benes wrote: >> On Tue, 3 Nov 2015, Josh Poimboeuf wrote: >>>> Object entry would be empty for not loaded object. I would not >>>> dare to propose to remove such object entries. It would make things worse. >>> >>> Why would removing an empty object entry make things worse? >> >> I think it all comes down to a question whether the sysfs entries say what >> a patch is capable to patch or what this patch is currently patching in >> the system. I am inclined to the former so the removal would make me >> nervous. But I am not against the second approach. We are still in testing >> mode as far as sysfs is concerned so we can try even harsh changes and see >> how it's gonna go. > > I see your point. This approach only describes what is patched now, but > it doesn't describe what *will* be patched. Ideally we could find a way > to describe both. > > Speaking of harsh changes, here's an idea. > > What if we require the patch author to supply the value of 'n' instead > of supplying the symbol address? We could get rid of 'old_addr' as an > input in klp_func and and replace it with 'old_sympos' which has the > value of 'n'. Or alternatively we could require old_name to be of the > format "func,n". I like the idea of old_sympos better than modifying the string. In addition if no old_sympos is specified then it should default to 0, since this will probably be the more common case. > > That would uniquely identify each patched function, even _before_ the > object is loaded. > > It would also fix another big problem we have today, where there's no > way to disambiguate duplicate symbols in modules, for both function > addresses and for relocs. > > It would simplify the code in other places as well: no special handling > for kASLR, no need for klp_verify_vmlinux_symbol() vs > klp_find_object_symbol(). > > A drawback is that it requires the patch author to do a little more due > diligence when filling out klp_func. But we already require them to be > careful. > > Thoughts? > I'll hold off on my v3 for now. Very interesting discussion : ). --chris -- 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
