Re: [PATCH 5.12 000/677] 5.12.4-rc1 review

[Nathan Chancellor]

On 5/12/2021 11:51 AM, Greg Kroah-Hartman wrote:
> On Thu, May 13, 2021 at 12:18:32AM +0530, Naresh Kamboju wrote:
> > On Wed, 12 May 2021 at 23:26, Greg Kroah-Hartman
> > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> > > On Wed, May 12, 2021 at 10:53:04PM +0530, Naresh Kamboju wrote:
> > > > On Wed, 12 May 2021 at 21:27, Greg Kroah-Hartman
> > > > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> > > > > This is the start of the stable review cycle for the 5.12.4 release.
> > > > > There are 677 patches in this series, all will be posted as a response
> > > > > to this one.  If anyone has any issues with these being applied, please
> > > > > let me know.
> > > > >
> > > > > Responses should be made by Fri, 14 May 2021 14:47:09 +0000.
> > > > > Anything received after that time might be too late.
> > > > >
> > > > > The whole patch series can be found in one patch at:
> > > > >          https://www.kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.12.4-rc1.gz
> > > > > or in the git tree and branch at:
> > > > >          git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.12.y
> > > > > and the diffstat can be found below.
> > > > >
> > > > > thanks,
> > > > >
> > > > > greg k-h
> > > >
> > > >
> > > > MIPS Clang build regression detected.
> > > > MIPS gcc-10,9 and 8 build PASS.
> > > >
> > > > > Maciej W. Rozycki <macro@xxxxxxxxxxx>
> > > > >      MIPS: Reinstate platform `__div64_32' handler
> > > >
> > > > mips clang build breaks on stable rc 5.4 .. 5.12 due to below warnings / errors
> > > >   - mips (defconfig) with clang-12
> > > >   - mips (tinyconfig) with clang-12
> > > >   - mips (allnoconfig) with clang-12
> > > >
> > > > make --silent --keep-going --jobs=8
> > > > O=/home/tuxbuild/.cache/tuxmake/builds/current ARCH=mips
> > > > CROSS_COMPILE=mips-linux-gnu- 'HOSTCC=sccache clang' 'CC=sccache
> > > > clang'
> > > > kernel/time/hrtimer.c:318:2: error: couldn't allocate output register
> > > > for constraint 'x'
> > > >          do_div(tmp, (u32) div);
> > > >          ^
> > > > include/asm-generic/div64.h:243:11: note: expanded from macro 'do_div'
> > > >                  __rem = __div64_32(&(n), __base);       \
> > > >                          ^
> > > > arch/mips/include/asm/div64.h:74:11: note: expanded from macro '__div64_32'
> > > >                  __asm__("divu   $0, %z1, %z2"                           \
> > > >                          ^
> > > > 1 error generated.
> > >
> > > Does this also show up in Linus's tree?  The same MIPS patch is there as
> > > well from what I can tell.
> >
> > No.
> > Linus's tree builds MIPS clang successfully.
>
> Ick, ok, I'll go drop this and let a MIPS developer send us the correct
> thing.
>
> thanks!
>
> greg k-h

I think you just need to grab commits c1d337d45ec0 ("MIPS: Avoid DIVU in 
`__div64_32' is result would be zero") and 25ab14cbe9d1 ("MIPS: Avoid 
handcoded DIVU in `__div64_32' altogether") to fix this up.

Cheers,
Nathan