On Sun, Jun 04, 2023 at 10:52:44PM -0400, Steven Rostedt wrote: > On Thu, 1 Jun 2023 16:54:36 -0700 > Nadav Amit <nadav.amit@xxxxxxxxx> wrote: > > > > The way text_poke() is used here, it is creating a new writable alias > > > and flushing it for *each* write to the module (like for each write of > > > an individual relocation, etc). I was just thinking it might warrant > > > some batching or something. > > I am not advocating to do so, but if you want to have many efficient > > writes, perhaps you can just disable CR0.WP. Just saying that if you > > are about to write all over the memory, text_poke() does not provide > > too much security for the poking thread. Heh, this is definitely and easier hack to implement :) > Batching does exist, which is what the text_poke_queue() thing does. For module loading text_poke_queue() will still be much slower than a bunch of memset()s for no good reason because we don't need all the complexity of text_poke_bp_batch() for module initialization because we are sure we are not patching live code. What we'd need here is a new batching mode that will create a writable alias mapping at the beginning of apply_relocate_*() and module_finalize(), then it will use memcpy() to that writable alias and will tear the mapping down in the end. Another option is to teach alternatives to update a writable copy rather than do in place changes like Song suggested. My feeling is that it will be more intrusive change though. > -- Steve > -- Sincerely yours, Mike.
