On Wed, Jul 12, 2017 at 10:10:00AM -0400, Joe Lawrence wrote: > When the livepatch core executes klp_(un)patch_object, call out to a > livepatch-module specified array of callback hooks. These hooks provide > a notification mechanism for livepatch modules when klp_objects are > (un)patching. This may be most interesting when another kernel module > is a klp_object target and the livepatch module needs to execute code > after the target is loaded, but before its module_init code is run. And it's also useful for vmlinux. Patch module load/unload is separate from enable/disable, so the module init/exit functions can't be used for patch-specific changes (e.g., global data changes). > The patch-hook executes right before patching objects and the > unpatch-hook executes right after unpatching objects. > > Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx> Thanks for posting it. We found this to be a useful feature in the past, not quite as useful as shadow data, but still good to have for certain cases. Instead of "load hooks" I think it would be more accurate to call them "enable/disable hooks". (Maybe "callbacks" would be better than "hooks"? Not sure...) Even better, we might want to be specific: "pre enable hooks" and "post disable hooks". (Or "pre patch hooks" and "post unpatch hooks"?) Because we might eventually decide we need the corresponding "post enable hooks" and "pre disable hooks" as well. For the enable case, I think it would be a nice feature if we checked the return code and aborted the patching operation on error. I think that should be easy enough. For the unload case, it's too late to do anything, so I'd say a void return code would be better. Otherwise it implies that we actually do something about it. Maybe in that case we can leave it up to the user to decide whether to print an error or WARN() or whatever. -- Josh -- 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
