Re: [PATCH v5 22/34] x86/fred: FRED initialization code

Peter Zijlstra
2023-03-20T17:51:32Z

On Sat, Mar 18, 2023 at 02:33:30PM +0800, Lai Jiangshan wrote:
> If there is no other concrete reason other than overflowing for
> assigning NMI and #DB with a stack level > 0, #VE should also
> be assigned with a stack level > 0, and #BP too. #VE can happen
> anytime and anywhere, so it is subject to overflowing too.

So #BP needs the stack-gap (redzone) for text_poke_bp().

#BP can end up in kprobes which can then end up in ftrace/perf,
depending on how it's all wired up.

#VE is currently a trainwreck vs NMI/MCE, but I think FRED solves the
worst of that. I'm not exactly sure how deep the #VE handler goes.