On January 11, 2019 11:34:34 AM PST, Linus Torvalds <torva...@linux-foundation.org> wrote: >On Fri, Jan 11, 2019 at 11:24 AM <h...@zytor.com> wrote: >> >> I still don't see why can't simply spin in the #BP handler until the >patch is complete. > >So here's at least one problem: > >text_poke_bp() > text_poke(addr, &int3, sizeof(int3)); > *interrupt* > interrupt has a static call > *BP* > poke_int3_handler > *BOOM* > >Note how at BOOM we cannot just spin (or return) to wait for the >'int3' to be switched back. Becuase it never will. Because we are >interrupting the thing that would do that switch-back. > >So we'd have to do the 'text_poke_bp()' sequence with interrupts >disabled. Which we can't do right now at least, because part of that >sequence involves that on_each_cpu(do_sync_core) thing, which needs >interrupts enabled. > >See? > >Or am I missing something? > > Linus
Ok, I was thinking far more about spinning with an IRET and letting the exception be delivered. Patching with interrupts disabled have other problems... -- Sent from my Android device with K-9 Mail. Please excuse my brevity.
