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In-Reply-To: <17c91d37-7d9c-0df4-2438-2b30ca0b5777@collabora.com>
From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Mon, 15 May 2023 16:01:36 -0700
Message-ID: <CAKwvOdk4QO8x_bs64fFRCsMu__AjhXd4Ew2KfgzQOb9Q3FMqSA@mail.gmail.com>
Subject: Re: [PATCH v4] Makefile.compiler: replace cc-ifversion with
 compiler-specific macros
To:     Shreeya Patel <shreeya.patel@collabora.com>
Cc:     Michal Marek <michal.lkml@markovi.net>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        clang-built-linux <llvm@lists.linux.dev>,
        Bill Wendling <morbo@google.com>,
        Nathan Chancellor <nathan@kernel.org>,
        regressions@lists.linux.dev,
        "gustavo.padovan@collabora.com" <gustavo.padovan@collabora.com>,
        Guillaume Charles Tucker <guillaume.tucker@collabora.com>,
        denys.f@collabora.com, ricardo.canuelo@collabora.com,
        kernelci@lists.linux.dev
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On Wed, May 3, 2023 at 3:33=E2=80=AFPM Shreeya Patel
<shreeya.patel@collabora.com> wrote:
>
>
> On 04/05/23 02:45, Nick Desaulniers wrote:
> > On Wed, May 3, 2023 at 2:02=E2=80=AFPM Shreeya Patel
> > <shreeya.patel@collabora.com> wrote:
> >> Hi Nick,
> >>
> >> On 28/04/23 22:57, Nick Desaulniers wrote:
> >>> On Thu, Apr 27, 2023 at 4:54=E2=80=AFAM Shreeya Patel
> >>> <shreeya.patel@collabora.com> wrote:
> >>>> Hi Nick,
> >>>>
> >>>> On 19/09/22 22:38, Nick Desaulniers wrote:
> >>>>> cc-ifversion is GCC specific. Replace it with compiler specific
> >>>>> variants. Update the users of cc-ifversion to use these new macros.
> >>>>>
> >>>>> Link: https://github.com/ClangBuiltLinux/linux/issues/350
> >>>>> Link: https://lore.kernel.org/llvm/CAGG=3D3QWSAUakO42kubrCap8fp-gm1=
ERJJAYXTnP1iHk_wrH=3DBQ@mail.gmail.com/
> >>>>> Suggested-by: Bill Wendling <morbo@google.com>
> >>>>> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> >>>>> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> >>>> KernelCI found this patch causes a regression in the
> >>>> baseline.logintest on qemu_arm-virt-gicv3-uefi [1],
> >>>> see the bisection report for more details [2].
> >>>>
> >>>> Let me know if you have any questions.
> >>>>
> >>>>
> >>>> [1] https://linux.kernelci.org/test/case/id/644596a0beca2ead032e8669=
/
> >>> Hi Shreeya,
> >>> Thanks for the report.
> >>>
> >>> When I click the above link, then click `multi_v7_defconfig+debug` to
> >>> get the config necessary to reproduce, I get an HTTP 404.
> >>> https://storage.kernelci.org/mainline/master/v6.3/arm/multi_v7_defcon=
fig+debug/gcc-10/kernel.config
> >>>
> >>> Same for zImage
> >>> https://storage.kernelci.org/mainline/master/v6.3/arm/multi_v7_defcon=
fig+debug/gcc-10/zImage
> >> Apologies for the broken links. We will try to fix the important ones =
if
> >> we can but in the meantime,
> >> following is the correct link that you can refer.
> >>
> >> config :-
> >> https://storage.kernelci.org/mainline/master/v6.3/arm/multi_v7_defconf=
ig+debug/gcc-10/config/kernel.config
> >>
> >> zImage :-
> >> https://storage.kernelci.org/mainline/master/v6.3/arm/multi_v7_defconf=
ig+debug/gcc-10/kernel/zImage
> >>
> >> If you notice, they are present under the kernel directory and same wa=
y
> >> you can find links for other kernel
> >> builds if you'd like to check them out.
> >>
> >>> If I click on the log
> >>> https://storage.kernelci.org/mainline/master/v6.3/arm/multi_v7_defcon=
fig+debug/gcc-10/lab-collabora/baseline-qemu_arm-virt-gicv3-uefi.txt
> >>> It looks like the machine powered up, then powered off. Is the test
> >>> actually failing?
> >> I recommend checking the html logs from the kernelci dashboard.
> >> Also, FYI baseline.login test failure means that the device failed to
> >> boot which I think is causing by the issues that you pointed out.
> >>
> >> <3>[    0.417001][    T1] UBSAN: array-index-out-of-bounds in
> >> ../arch/arm/mach-sunxi/mc_smp.c:811:29
> >>
> >> And potentially another issue with ftrace
> >>
> >> <4>[    0.000000][    T0] WARNING: CPU: 0 PID: 0 at
> >> kernel/trace/ftrace.c:2176 ftrace_bug+0x340/0x3b4
> >>
> >>
> >> Let me know if you need more information from my side to reproduce thi=
s
> >> on your end.
> >>
> >>
> >> Thanks,
> >> Shreeya Patel
> > Hi Shreeya,
> > I may need your help to reproduce the failure.

Hi Shreeya,
Sorry for the delay, I was out traveling last week.  I still need help
reproducing. Trying this again from scratch, my VM is now failing to
boot regardless of whether I revert the patch in question or not.

Can you please help verify this failure by hand, and see if applying
https://github.com/ClangBuiltLinux/linux/commit/45c4fb6095d872785e077942da8=
96d65d87ab56b.patch
helps?  If you can repro; mind sharing your precise steps to reproduce?

> >
> > $ wget https://storage.kernelci.org/mainline/master/v6.3/arm/multi_v7_d=
efconfig+debug/gcc-10/config/kernel.config
> > -O .config
> > $ ARCH=3Darm CROSS_COMPILE=3Darm-linux-gnueabihf- make -j128 olddefconf=
ig all -s
> > <launch qemu>
> > / # mount -t proc /proc
> > / # cat /proc/version
> > Linux version 6.3.0 (root@61385772abae) (arm-linux-gnueabihf-gcc
> > (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian)
> > 2.35.2) #2 SMP Wed May  3 21:10:27 UTC 2023
> >
> > I was able to boot the resulting kernel to a command line.  Perhaps
> > there's something about the userspace image that tickles this? Can you
> > supply the rootfs that's used in testing?
>
>
> Following is the link to the rootfs for a different kernel build which
> has the same test case failing.
> http://storage.kernelci.org/images/rootfs/buildroot/buildroot-baseline/20=
230414.0/armel/rootfs.cpio.gz
>
>
> Lava job :-
> https://lava.collabora.dev/scheduler/job/10135631
>
> You can usually get the rootfs link and many more information through
> the "definition" present on Lava job dashboard.
>
> Kernelci test id for the above job :-
> https://linux.kernelci.org/test/case/id/64497865a4bab57def2e85e8/
>
>
> Thanks,
> Shreeya Patel
>
> >>> I was able to boot ARCH=3Darm defconfig with CC=3Darm-linux-gnueabihf=
-gcc
> >>> (Debian 10.2.1-6) in QEMU just fine.  So I'm going to need some more
> >>> information to help reproduce what specifically is failing.
> >>>
> >>> Linux version 6.3.0 (root@61385772abae) (arm-linux-gnueabihf-gcc
> >>> (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian)
> >>> 2.35.2) #1 SMP Fri Apr 28 17:19:59 UTC 2023
> >>>
> >>> ---
> >>>
> >>> It does look like UBSAN is flagging an array OOB:
> >>>
> >>> <3>[    0.417001][    T1] UBSAN: array-index-out-of-bounds in
> >>> ../arch/arm/mach-sunxi/mc_smp.c:811:29
> >>>
> >>> And potentially another issue with ftrace
> >>>
> >>> <4>[    0.000000][    T0] WARNING: CPU: 0 PID: 0 at
> >>> kernel/trace/ftrace.c:2176 ftrace_bug+0x340/0x3b4
> >>>
> >>>
> >>>
> >>>> [2] https://groups.io/g/kernelci-results/message/40804
> >>>>
> >>>>
> >>>> Thanks,
> >>>> Shreeya Patel
> >>>>
> >>>> #regzbot introduced: 88b61e3bff93
> >>>>
> >>>>> ---
> >>>>> Changes v3 -> v4:
> >>>>> * Split into its own patch again from series, as per Masahiro.
> >>>>> * Rebase on top of b0839b281c427e844143dba3893e25c83cdd6c17 and upd=
ate
> >>>>>      clang -Wformat logic in scripts/Makefile.extrawarn, as per Mas=
ahiro.
> >>>>>
> >>>>>     Documentation/kbuild/makefiles.rst          | 29 ++++++++++++--=
-------
> >>>>>     Makefile                                    |  6 ++---
> >>>>>     drivers/gpu/drm/amd/display/dc/dml/Makefile |  2 +-
> >>>>>     scripts/Makefile.compiler                   | 10 ++++---
> >>>>>     scripts/Makefile.extrawarn                  |  4 +--
> >>>>>     5 files changed, 29 insertions(+), 22 deletions(-)
> >>>>>
> >>>>> diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbu=
ild/makefiles.rst
> >>>>> index 11a296e52d68..ee7e3ea1fbe1 100644
> >>>>> --- a/Documentation/kbuild/makefiles.rst
> >>>>> +++ b/Documentation/kbuild/makefiles.rst
> >>>>> @@ -682,22 +682,27 @@ more details, with real examples.
> >>>>>         In the above example, -Wno-unused-but-set-variable will be =
added to
> >>>>>         KBUILD_CFLAGS only if gcc really accepts it.
> >>>>>
> >>>>> -    cc-ifversion
> >>>>> -     cc-ifversion tests the version of $(CC) and equals the fourth=
 parameter
> >>>>> -     if version expression is true, or the fifth (if given) if the=
 version
> >>>>> -     expression is false.
> >>>>> +    gcc-min-version
> >>>>> +     gcc-min-version tests if the value of $(CONFIG_GCC_VERSION) i=
s greater than
> >>>>> +     or equal to the provided value and evaluates to y if so.
> >>>>>
> >>>>>         Example::
> >>>>>
> >>>>> -             #fs/reiserfs/Makefile
> >>>>> -             ccflags-y :=3D $(call cc-ifversion, -lt, 0402, -O1)
> >>>>> +             cflags-$(call gcc-min-version, 70100) :=3D -foo
> >>>>>
> >>>>> -     In this example, ccflags-y will be assigned the value -O1 if =
the
> >>>>> -     $(CC) version is less than 4.2.
> >>>>> -     cc-ifversion takes all the shell operators:
> >>>>> -     -eq, -ne, -lt, -le, -gt, and -ge
> >>>>> -     The third parameter may be a text as in this example, but it =
may also
> >>>>> -     be an expanded variable or a macro.
> >>>>> +     In this example, cflags-y will be assigned the value -foo if =
$(CC) is gcc and
> >>>>> +     $(CONFIG_GCC_VERSION) is >=3D 7.1.
> >>>>> +
> >>>>> +    clang-min-version
> >>>>> +     clang-min-version tests if the value of $(CONFIG_CLANG_VERSIO=
N) is greater
> >>>>> +     than or equal to the provided value and evaluates to y if so.
> >>>>> +
> >>>>> +     Example::
> >>>>> +
> >>>>> +             cflags-$(call clang-min-version, 110000) :=3D -foo
> >>>>> +
> >>>>> +     In this example, cflags-y will be assigned the value -foo if =
$(CC) is clang
> >>>>> +     and $(CONFIG_CLANG_VERSION) is >=3D 11.0.0.
> >>>>>
> >>>>>         cc-cross-prefix
> >>>>>         cc-cross-prefix is used to check if there exists a $(CC) in=
 path with
> >>>>> diff --git a/Makefile b/Makefile
> >>>>> index 298f69060f10..411c8480b37e 100644
> >>>>> --- a/Makefile
> >>>>> +++ b/Makefile
> >>>>> @@ -790,7 +790,6 @@ KBUILD_CFLAGS +=3D $(stackp-flags-y)
> >>>>>
> >>>>>     KBUILD_CFLAGS-$(CONFIG_WERROR) +=3D -Werror
> >>>>>     KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) +=3D -Wno-array-boun=
ds
> >>>>> -KBUILD_CFLAGS +=3D $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHR=
OUGH)
> >>>>>
> >>>>>     ifdef CONFIG_CC_IS_CLANG
> >>>>>     KBUILD_CPPFLAGS +=3D -Qunused-arguments
> >>>>> @@ -972,7 +971,6 @@ ifdef CONFIG_CC_IS_GCC
> >>>>>     KBUILD_CFLAGS +=3D -Wno-maybe-uninitialized
> >>>>>     endif
> >>>>>
> >>>>> -ifdef CONFIG_CC_IS_GCC
> >>>>>     # The allocators already balk at large sizes, so silence the co=
mpiler
> >>>>>     # warnings for bounds checks involving those possible values. W=
hile
> >>>>>     # -Wno-alloc-size-larger-than would normally be used here, earl=
ier versions
> >>>>> @@ -984,8 +982,8 @@ ifdef CONFIG_CC_IS_GCC
> >>>>>     # ignored, continuing to default to PTRDIFF_MAX. So, left with =
no other
> >>>>>     # choice, we must perform a versioned check to disable this war=
ning.
> >>>>>     # https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auu=
g.org.au
> >>>>> -KBUILD_CFLAGS +=3D $(call cc-ifversion, -ge, 0901, -Wno-alloc-size=
-larger-than)
> >>>>> -endif
> >>>>> +KBUILD_CFLAGS-$(call gcc-min-version, 90100) +=3D -Wno-alloc-size-=
larger-than
> >>>>> +KBUILD_CFLAGS +=3D $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHR=
OUGH)
> >>>>>
> >>>>>     # disable invalid "can't wrap" optimizations for signed / point=
ers
> >>>>>     KBUILD_CFLAGS       +=3D -fno-strict-overflow
> >>>>> diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/=
gpu/drm/amd/display/dc/dml/Makefile
> >>>>> index cb81ed2fbd53..d70838edba80 100644
> >>>>> --- a/drivers/gpu/drm/amd/display/dc/dml/Makefile
> >>>>> +++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile
> >>>>> @@ -34,7 +34,7 @@ dml_ccflags :=3D -mhard-float -maltivec
> >>>>>     endif
> >>>>>
> >>>>>     ifdef CONFIG_CC_IS_GCC
> >>>>> -ifeq ($(call cc-ifversion, -lt, 0701, y), y)
> >>>>> +ifneq ($(call gcc-min-version, 70100),y)
> >>>>>     IS_OLD_GCC =3D 1
> >>>>>     endif
> >>>>>     endif
> >>>>> diff --git a/scripts/Makefile.compiler b/scripts/Makefile.compiler
> >>>>> index 94d0d40cddb3..9d18fb91890e 100644
> >>>>> --- a/scripts/Makefile.compiler
> >>>>> +++ b/scripts/Makefile.compiler
> >>>>> @@ -61,9 +61,13 @@ cc-option-yn =3D $(call try-run,\
> >>>>>     cc-disable-warning =3D $(call try-run,\
> >>>>>         $(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip=
 $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
> >>>>>
> >>>>> -# cc-ifversion
> >>>>> -# Usage:  EXTRA_CFLAGS +=3D $(call cc-ifversion, -lt, 0402, -O1)
> >>>>> -cc-ifversion =3D $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] &=
& echo $(3) || echo $(4))
> >>>>> +# gcc-min-version
> >>>>> +# Usage: cflags-$(call gcc-min-version, 70100) +=3D -foo
> >>>>> +gcc-min-version =3D $(shell [ $(CONFIG_GCC_VERSION) -ge $(1) ] && =
echo y)
> >>>>> +
> >>>>> +# clang-min-version
> >>>>> +# Usage: cflags-$(call clang-min-version, 110000) +=3D -foo
> >>>>> +clang-min-version =3D $(shell [ $(CONFIG_CLANG_VERSION) -ge $(1) ]=
 && echo y)
> >>>>>
> >>>>>     # ld-option
> >>>>>     # Usage: KBUILD_LDFLAGS +=3D $(call ld-option, -X, -Y)
> >>>>> diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawar=
n
> >>>>> index 6ae482158bc4..5769c1939d40 100644
> >>>>> --- a/scripts/Makefile.extrawarn
> >>>>> +++ b/scripts/Makefile.extrawarn
> >>>>> @@ -48,7 +48,7 @@ else
> >>>>>     ifdef CONFIG_CC_IS_CLANG
> >>>>>     KBUILD_CFLAGS +=3D -Wno-initializer-overrides
> >>>>>     # Clang before clang-16 would warn on default argument promotio=
ns.
> >>>>> -ifeq ($(shell [ $(CONFIG_CLANG_VERSION) -lt 160000 ] && echo y),y)
> >>>>> +ifneq ($(call clang-min-version, 160000),y)
> >>>>>     # Disable -Wformat
> >>>>>     KBUILD_CFLAGS +=3D -Wno-format
> >>>>>     # Then re-enable flags that were part of the -Wformat group tha=
t aren't
> >>>>> @@ -56,7 +56,7 @@ KBUILD_CFLAGS +=3D -Wno-format
> >>>>>     KBUILD_CFLAGS +=3D -Wformat-extra-args -Wformat-invalid-specifi=
er
> >>>>>     KBUILD_CFLAGS +=3D -Wformat-zero-length -Wnonnull
> >>>>>     # Requires clang-12+.
> >>>>> -ifeq ($(shell [ $(CONFIG_CLANG_VERSION) -ge 120000 ] && echo y),y)
> >>>>> +ifeq ($(call clang-min-version, 120000),y)
> >>>>>     KBUILD_CFLAGS +=3D -Wformat-insufficient-args
> >>>>>     endif
> >>>>>     endif
> >>>
> >
> >


--=20
Thanks,
~Nick Desaulniers