Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: Perf: WARNING: arch/x86/entry/common.c:624 idtentry_exit_cond_rcu+0x92/0xc0 | Date | Fri, 12 Jun 2020 12:34:18 +0200 |
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Andy Lutomirski <luto@amacapital.net> writes: >> On Jun 12, 2020, at 2:01 AM, Thomas Gleixner <tglx@linutronix.de> 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
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