kmsan: avoid false reports while processing NMIs
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Authored by chs on Thu, Sep 24, 12:09 AM.

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Summary

The NMI asm path needs two KMSAN hooks to avoid false reports:

KMSAN_INIT_ARG clears the parameter shadow for calling an instrumented C function from asm code
KMSAN_MARK_TRAPFRAME marks a trapframe that was initialized in asm code as initialized.

Sponsored by: Netflix
Assisted-By: Claude Code - Opus 5 (1M context)

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rG FreeBSD src repository

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Buildable 77233
Build 74116: arc lint + arc unit

chs requested review of this revision.Thu, Sep 24, 12:09 AM

chs created this revision.

sys/amd64/amd64/exception.S
879	Why are we doing this here? We're either about to return back to the interrupted context via iret, or we're going to call pmc_hook. In the latter case, the trapframe has already been marked by the trap() call above.