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Date:   Thu, 14 Apr 2022 17:38:01 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Alexander Potapenko <glider@google.com>
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
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Subject: Re: [PATCH v2 38/48] objtool: kmsan: list KMSAN API functions as
 uaccess-safe
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References: <20220329124017.737571-1-glider@google.com>
 <20220329124017.737571-39-glider@google.com>
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 <CAG_fn=UzshCuwbq7pZ93v7+eVUgFq1dZ4L_9nEWhYnotmyZtJg@mail.gmail.com>
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On Thu, Apr 14, 2022 at 05:30:34PM +0200, Alexander Potapenko wrote:
> On Wed, Mar 30, 2022 at 10:46 AM Peter Zijlstra <peterz@infradead.org>
> wrote:
> 
> > On Tue, Mar 29, 2022 at 02:40:07PM +0200, Alexander Potapenko wrote:
> > > KMSAN inserts API function calls in a lot of places (function entries
> > > and exits, local variables, memory accesses), so they may get called
> > > from the uaccess regions as well.
> >
> > That's insufficient. Explain how you did the right thing and made these
> > functions actually safe to be called in this context.
> >

> As a result, none of KMSAN API functions perform userspace accesses, but
> since they might be called from UACCESS regions they
> use user_access_save/restore().

^ That.. very good.

Thanks!