x86: Add NMI callback function.
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Authored by stevek on Mar 21 2024, 10:26 PM.

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Summary

Repurpose 'nmi_call_kdb_smp' function to be able to call a callback
function that is meant for safely handling a callback in SMP
environment. The function increments reference on 'nmi_kdb_lock'
atomically for one of the CPU cores. The rest of the CPU cores
execute ia32_pause(). On return from the NMI handler the ref count
on 'nmi_kdb_lock' is dropped and call made to resume the CPU cores.

Obtained from: Juniper Networks, Inc.

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rG FreeBSD src repository

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Buildable 56861
Build 53749: arc lint + arc unit

Event Timeline

stevek created this revision.Mar 21 2024, 10:26 PM

Herald added a subscriber: imp. · View Herald TranscriptMar 21 2024, 10:26 PM

stevek requested review of this revision.Mar 21 2024, 10:26 PM

Harbormaster completed remote builds in B56730: Diff 136052.Mar 21 2024, 10:26 PM

markj added inline comments.Mar 29 2024, 2:37 PM

sys/x86/x86/cpu_machdep.c
884	Doesn't this kind of check now logically belong in the parent? It's a bit odd for the kdb handler to implement this.
897–899	The non-SMP handler should be refactored similarly, no?

stevek added inline comments.Apr 1 2024, 6:51 PM

sys/x86/x86/cpu_machdep.c
884	Good point. It should be able to move to nmi_handle_intr(), since that's what is called from the trap handler.
897–899	I don't think there's anything that needs to be done for it. It doesn't need to do all the work that the SMP case needs to in a single CPU case (or unicast, not broadcast.)