On Thu, Apr 16, 2020 at 05:31:31PM +0200, Jessica Yu wrote: > > But I still not a fan of the fact that COMING has two different > > "states". For example, after your patch, when apply_relocate_add() is > > called from klp_module_coming(), it can use memcpy(), but when called > > from klp module init() it has to use text poke. But both are COMING so > > there's no way to look at the module state to know which can be used. > > This is a good observation, thanks for bringing it up. I agree that we > should strive to be consistent with what the module states mean. In my > head, I think it is easiest to assume/establish the following meanings > for each module state: > > MODULE_STATE_UNFORMED - no protections. relocations, alternatives, > ftrace module initialization, etc. any other text modifications are > in the process of being applied. Direct writes are permissible. > > MODULE_STATE_COMING - module fully formed, text modifications are > done, protections applied, module is ready to execute init or is > executing init. > > I wonder if we could enforce the meaning of these two states more > consistently without needing to add another module state. > > Regarding Peter's patches, with the set_all_modules_text_*() api gone, > and ftrace reliance on MODULE_STATE_COMING gone (I think?), is there > anything preventing ftrace_module_init+enable from being called > earlier (i.e., before complete_formation()) while the module is > unformed? Then you don't have to move module_enable_ro/nx later and we > keep the MODULE_STATE_COMING semantics. And if we're enforcing the > above module state meanings, I would also be OK with moving jump_label > and static_call out of the coming notifier chain and making them > explicit calls while the module is still writable. > > Sorry in advance if I missed anything above, I'm still trying to wrap > my head around which callers need what module state and what module > permissions :/ Sounds reasonable to me... BTW, instead of hard-coding the jump-label/static-call/ftrace calls, we could instead call notifiers with MODULE_STATE_UNFORMED. -- Josh
