On Fri, May 2, 2014 at 2:01 PM, Linus Torvalds <torva...@linux-foundation.org> wrote: > On Fri, May 2, 2014 at 1:30 PM, Thomas Gleixner <t...@linutronix.de> wrote: >> >> So what about manipulating the stack so that the popf does not enable >> interrupts and do an explicit sti to get the benefit of the >> one-instruction shadow ? > > That's what I already suggested in the original "I don't think popf > works" email. > > It does get more complex since you now have to test things (there are > very much cases where we get page faults and other exceptions with > interrupts disabled), but it shouldn't be much worse. > > Btw, Andy, why did you do "popq %rsp"? That just looks crazy. If the > stack isn't contiguous, the subsequent "popf" couldn't have worked > anyway. And I bet it screws with the stack engine. So you should just > have done something like "addq $16,%rsp" or whatever the constant ends > up being.
Because otherwise I'd have to keep track of whether it's a zeroentry or an errorentry. I can't stuff the offset in a register without even more stack hackery, since there are no available registers there. I could split the whole thing into two code paths, I guess. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/