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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed, 4 May 2022 11:00:00 -0700
Message-ID: <CAHk-=wgb_eBdjM_mzEvXfRG2EhrSK5MHNGyAj7=4vxvN4U9Rug@mail.gmail.com>
Subject: Re: [PATCH v2] hex2bin: make the function hex_to_bin constant-time
To:     "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc:     Andy Shevchenko <andriy.shevchenko@intel.com>,
        Stafford Horne <shorne@gmail.com>,
        Mikulas Patocka <mpatocka@redhat.com>,
        Andy Shevchenko <andy@kernel.org>,
        device-mapper development <dm-devel@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Mike Snitzer <msnitzer@redhat.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
        Milan Broz <gmazyland@gmail.com>
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On Wed, May 4, 2022 at 3:15 AM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> > Alignment? Compiler bug? HW issue?
>
> Probably one of those, yea. Removing the instruction addresses, the only
> difference between the two compiles is: https://xn--4db.cc/Rrn8usaX/diff#=
line-440

Well, that address doesn't work for me at all. It turns into =D7=90.cc.

I'd love to see the compiler problem, since I find those fascinating
(mainly because they scare the hell out of me), but those web
addresses you use are not working for me.

It most definitely looks like an OpenRISC compiler bug - that code
doesn't look like it does anything remotely undefined (and with the
"unsigned char", nothing implementation-defined either).

             Linus