linux-kernel - Re: [RFC PATCH] ARM: Use logical or instead of addition for badr address calculation

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Message-ID: <20180619172422.GB16846@roeck-us.net>
Date:   Tue, 19 Jun 2018 10:24:22 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     Russell King <linux@...linux.org.uk>,
        Mark Rutland <mark.rutland@....com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Arnd Bergmann <arnd@...db.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] ARM: Use logical or instead of addition for badr
 address calculation

On Tue, Jun 19, 2018 at 03:35:07PM +0200, Ard Biesheuvel wrote:
> >>
> >> +       /* this needs to be a separate macro or \@ does not work correctly
> >> */
> >> +       .macro  __badr, c, rd, sym
> >> +       .eqv    .Lsym\@, \sym
> >> +       adr\c   \rd, .Lsym\@ + 1
> >
> >
> > Wild shot, but the following works for me.
> >
> >         .eqv    .Lsym\@, \sym + 1
> >         adr\c   \rd, .Lsym\@
> >
> > Does it make sense ?
> >
> 
> Interesting. Do you mean this works with your 2.30 binutils that
> triggers the original issue?
> 

Yes, it does. It is also the solution used for some graphics libraries,
though of course now I don't find the link anymore.

Guess this is going nowhere given Russell's response, so I'll just
live with it, like obviously everyone else does already. I built
a toolchain using gcc 7.3.0 and binutils 2.28.1 which "solves"
the problem for me.

Guenter