Andy Lutomirski <[email protected]> writes: >> On Jun 12, 2020, at 2:01 AM, Thomas Gleixner <[email protected]> wrote: >> There is no IST on 32bit, never was. We do software stack switching for >> device interrupts, but that's a different story. >> > > DEFINE_IDTENTRY does the idtentry_enter_cond_rcu() dance, which isn’t > intended to be safe from NMI context. It should probably map to > DEFINE_IDTENTRY_RAW() instead. The specific issue is that NMI ends up > there, and at least DEFINE_IDTENTRY_NMI should be raw.
Yes, you are right. That's clearly broken. > I haven’t tried this at all, nor have I dug through all the users of > these macros to check what they expect. Perhaps we should not have > the _IST one defined at all on 32 bit and rename it to > DEFINE_IDTENTRY_IST_RAW on 64 bit to make it more clear what’s going > on when reading the C code. Let me go over it with a fine comb. > Or maybe I’m too sleepy and I’m nuts. But I don’t think I am. /me politely refrains from commenting
