> On Nov 29, 2018, at 9:50 AM, Linus Torvalds <torva...@linux-foundation.org> > wrote: > >> On Thu, Nov 29, 2018 at 9:44 AM Steven Rostedt <rost...@goodmis.org> wrote: >> >> Well, the current method (as Jiri mentioned) did get the OK from at >> least Intel (and that was with a lot of arm twisting to do so). > > Guys, when the comparison is to: > > - create a huge honking security hole by screwing up the stack frame > > or > > - corrupt random registers because we "know" they aren't in use
For C calls, we do indeed know that. But I guess there could be asm calls. > > then it really sounds pretty safe to just say "ok, just make it > aligned and update the instruction with an atomic cmpxchg or > something". And how do we do that? With a gcc plugin and some asm magic? > > Of course, another option is to just say "we don't do the inline case, > then", and only ever do a call to a stub that does a "jmp" > instruction. That’s not a terrible idea. > > Problem solved, at the cost of some I$. Emulating a "jmp" is trivial, > in ways emulating a "call" is not. > >
