On Thu, 2016-03-10 at 14:04 +0100, Torsten Duwe wrote: > On Thu, Mar 10, 2016 at 01:51:16PM +0100, Petr Mladek wrote: > > On Thu 2016-03-10 13:25:08, Petr Mladek wrote: > > > On Wed 2016-03-09 18:30:17, Torsten Duwe wrote: > > > > After the mini stack frame is no longer required for TOC storage, it can > > > > be eliminated iff the functionality of klp_return_helper, which required > > > > a stack frame for the extra return address previously, is carried out > > > > by the replacement function now. This requires _every_ live patch replacement > > > > function to execute the following (or similar) sequence of machine instructions > > > > just before every return to the original caller: > > > > > > I have thought about it and it is a nono from my point of view. > > > It is too error prone, especially that there are functions that > > > call return on several locations. > > Yes, that's what I think as well when I look at it. > > BTW: How is this solved in kretprobes? Or is it easier there? > > Without any look at the code I assume it uses solution 3. Once > you have a probing framework in place, you can remember the real > return addresses in a data structure. As I wrote, the function > graph tracer does it this way so it would be abvious. Yeah it has a linked list of struct kretprobe_instance's, each of which stores the real return address. I have some ideas for how to fix livepatch, but this week is a bit busy with merge window prep. cheers -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
