Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Mon, 18 Oct 2021 16:42:04 -0400
From:   Rich Felker <dalias@libc.org>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     musl@lists.openwall.com, Takashi Iwai <tiwai@suse.de>,
        Michael Forney <mforney@mforney.org>,
        ALSA Development Mailing List <alsa-devel@alsa-project.org>,
        Takashi Iwai <tiwai@suse.com>,
        Baolin Wang <baolin.wang@linaro.org>,
        y2038 Mailman List <y2038@lists.linaro.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Mark Brown <broonie@kernel.org>,
        Baolin Wang <baolin.wang7@gmail.com>
Subject: Re: [musl] Re: [alsa-devel] [PATCH v7 8/9] ALSA: add new 32-bit
 layout for snd_pcm_mmap_status/control
Message-ID: <20211018204203.GM7074@brightrain.aerifal.cx>
References: <20211007165158.GC7074@brightrain.aerifal.cx>
 <s5h5yu79aab.wl-tiwai@suse.de>
 <CAK8P3a0qxNLv3_RcR5COcRGPcTnYMcfbOjdWKiT2hKdcof9WUg@mail.gmail.com>
 <s5hv9277oux.wl-tiwai@suse.de>
 <20211008120736.GF7074@brightrain.aerifal.cx>
 <s5hsfx95n99.wl-tiwai@suse.de>
 <20211018144259.GK7074@brightrain.aerifal.cx>
 <s5hlf2q4byc.wl-tiwai@suse.de>
 <20211018150824.GL7074@brightrain.aerifal.cx>
 <CAK8P3a1RAk5WRtMjqV6QZ1eHtFu_sxhSBJn0Uv-MhRA5WGiJqQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAK8P3a1RAk5WRtMjqV6QZ1eHtFu_sxhSBJn0Uv-MhRA5WGiJqQ@mail.gmail.com>
User-Agent: Mutt/1.5.21 (2010-09-15)
Precedence: bulk

On Mon, Oct 18, 2021 at 05:26:35PM +0200, Arnd Bergmann wrote:
> On Mon, Oct 18, 2021 at 5:08 PM Rich Felker <dalias@libc.org> wrote:
> > On Mon, Oct 18, 2021 at 04:58:03PM +0200, Takashi Iwai wrote:
> > > On Mon, 18 Oct 2021 16:43:00 +0200, Rich Felker wrote:
> >
> > No, I don't think so. The musl translator is to translate between the
> > time64 ioctl structures and the old time32 ones for the sake of
> > executing on an old kernel. Up til now, it has been broken comparably
> > to how 32-bit binaries running in compat mode on a 64-bit kernel were
> > broken: the code in musl translated the time64 structure to (and back
> > from) the time32 one assuming the intended padding. But the
> > application was using the actual kernel uapi struct where the padding
> > was (and still is) illogical. Thus, nothing was built with the wrong
> > ABI; it's only the musl-internal translation logic that was wrong (and
> > only pre-time64 kernels are affected).
> >
> > The attached patch should fix it, I think.
> >
> > + int adj = BYTE_ORDER==BIG_ENDIAN ? 4 : 0;
> > + if (dir==W) {
> > +     memcpy(old+68, new+72+adj, 4);
> > +     memcpy(old+72, new+72+4+2*adj, 4);
> 
> I think that should be "new+72+4+3*adj": the "2*adj" would
> be what the code does already for the originally intended
> format.

Well for little endian either would work (because adj is 0 :) but yes
there are 3 such paddings before the second member on big endian, so
it should be 3.

Rich