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Date:   Sat, 26 Feb 2022 12:48:47 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Masami Hiramatsu <mhiramat@kernel.org>
Cc:     x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com,
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        mark.rutland@arm.com, alyssa.milburn@intel.com, mbenes@suse.cz,
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Subject: Re: [PATCH v2 15/39] x86/ibt,kprobes: Fix more +0 assumptions
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On Sat, Feb 26, 2022 at 11:10:40AM +0900, Masami Hiramatsu wrote:

> > The alternative 'hack' I've been contemplating is (ab)using
> > INT_MIN/INT_MAX offset for __fentry__ and __fexit__ points (that latter
> > is something we'll probably have to grow when CET-SHSTK or backward-edge
> > CFI gets to be done, because then ROP tricks as used by function-graph
> > and kretprobes are out the window).
> > 
> > That way sym+[0..size) is still a valid reference to the actual
> > instruction in the symbol, but sym+INT_MIN will hard map to __fentry__
> > while sym+INT_MAX will get us __fexit__.
> 
> Interesting, is that done by another series?

Not yet, that was just a crazy idea I had ;-)