On June 14, 2016 2:02:55 PM PDT, Borislav Petkov <[email protected]> wrote: >On Tue, Jun 14, 2016 at 01:54:25PM -0700, H. Peter Anvin wrote: >> There was that. It is still possible that we end up with NOP a JMP >> right before another JMP; we could perhaps make the patching code >> smarter and see if we have a JMP immediately after. > >Yeah, I still can't get reproduce that reliably - I remember seeing it >at some point but then dismissing it for another, higher-prio thing. >And >now the whole memory is hazy at best. > >But, you're giving me a great idea right now - I have this kernel >disassembler tool which dumps alternative sections already and I could >teach it to look for pathological cases around the patching sites and >scream. > >Something for my TODO list when I get a quiet moment. > >Thanks!
We talked with the GCC people about always bias asm goto toward the first label even if followed by __builtin_unreachable(). I don't know if that happened; if so we should probably insert the unreachable for those versions of gcc only. -- Sent from my Android device with K-9 Mail. Please excuse brevity and formatting.
