linux-kernel - Re: [PATCH 20/22] pstore: %pF is only for function pointers

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Message-ID: <20150616223700.GA26982@d1stkfactory>
Date:	Tue, 16 Jun 2015 15:37:00 -0700
From:	Anton Vorontsov <anton@...msg.org>
To:	Kees Cook <keescook@...omium.org>
Cc:	trivial@...nel.org, LKML <linux-kernel@...r.kernel.org>,
	Colin Cross <ccross@...roid.com>,
	Tony Luck <tony.luck@...el.com>,
	Scott Wood <scottwood@...escale.com>
Subject: Re: [PATCH 20/22] pstore: %pF is only for function pointers

On Tue, Jun 16, 2015 at 03:02:50PM -0700, Kees Cook wrote:
> On Wed, Mar 11, 2015 at 8:13 PM, Scott Wood <scottwood@...escale.com> wrote:
> > Use %pS for actual addresses, otherwise you'll get bad output
> > on arches like ppc64 where %pF expects a function descriptor.
> >
> > Signed-off-by: Scott Wood <scottwood@...escale.com>
...
> > -       seq_printf(s, "%d %08lx  %08lx  %pf <- %pF\n",
> > +       seq_printf(s, "%d %08lx  %08lx  %ps <- %pS\n",
...
> Anton, does this look okay to you? (i.e. switching from function
> pointer to direct pointer?) vsprintf docs say:
>  * Note: The difference between 'S' and 'F' is that on ia64 and ppc64
>  * function pointers are really function descriptors, which contain a
>  * pointer to the real address.
> 
> So this seems correct to me.
> 
> Reviewed-by: Kees Cook <keescook@...omium.org>

Without questioning the confusing behaviour of "%pF", yes, sure... ack. :)

(However, intuitively I'd expect %pF to behave like %pS... but this surely not
going to change...)

Thanks!

Anton
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