On Thu, Jan 11, 2018 at 9:32 AM, Peter Zijlstra <pet...@infradead.org> wrote: > On Thu, Jan 11, 2018 at 02:28:32PM +0000, David Woodhouse wrote: >> On Thu, 2018-01-11 at 08:20 -0600, Josh Poimboeuf wrote: >> > >> > This seems weird. I liked v1 a lot better. What's the problem with >> > patching in the whole thing? >> > >> > Also, if you go back to v1, it should be an easy objtool fix, just add >> > ANNOTATE_NOSPEC_ALTERNATIVE in front of it. >> >> The objection was that I was patching in a fairly long set of >> instructions. I confess I don't actually know why that's a problem, > > You get a giant string of NOPs, a single jmp should be faster.
That could be handled in add_nops(), where if over a certain threshold it changes to a JMP. -- Brian Gerst