[PATCH] mips: vdso: fix DWARF2 warning

[PATCH] mips: vdso: fix DWARF2 warning

[Anders Roxell]

When building mips tinyconifg the following warning show up

make --silent --keep-going --jobs=8 O=/home/anders/src/kernel/next/out/builddir ARCH=mips CROSS_COMPILE=mips-linux-gnu- HOSTCC=clang CC=clang
/srv/src/kernel/next/arch/mips/vdso/elf.S:14:1: warning: DWARF2 only supports one section per compilation unit
.pushsection .note.Linux, "a",@note ; .balign 4 ; .long 2f - 1f ; .long 4484f - 3f ; .long 0 ; 1:.asciz "Linux" ; 2:.balign 4 ; 3:
^
/srv/src/kernel/next/arch/mips/vdso/elf.S:34:2: warning: DWARF2 only supports one section per compilation unit
 .section .mips_abiflags, "a"
 ^

Rework so the mips vdso Makefile adds flag '-no-integrated-as' unless
LLVM_IAS is defined.

Link: https://github.com/ClangBuiltLinux/linux/issues/1256
Cc: stable@vger.kernel.org # v4.19+
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 arch/mips/vdso/Makefile | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
index 5810cc12bc1d..83e8cf216ac8 100644
--- a/arch/mips/vdso/Makefile
+++ b/arch/mips/vdso/Makefile
@@ -26,6 +26,10 @@ ifdef CONFIG_CC_IS_CLANG
 ccflags-vdso += $(filter --target=%,$(KBUILD_CFLAGS))
 endif
 
+ifneq ($(LLVM_IAS),1)
+ccflags-vdso += -no-integrated-as
+endif
+
 #
 # The -fno-jump-tables flag only prevents the compiler from generating
 # jump tables but does not prevent the compiler from emitting absolute
-- 
2.29.2

Re: [PATCH] mips: vdso: fix DWARF2 warning

[Nathan Chancellor]

On Fri, Jan 15, 2021 at 08:13:30PM +0100, Anders Roxell wrote:
> When building mips tinyconifg the following warning show up
> 
> make --silent --keep-going --jobs=8 O=/home/anders/src/kernel/next/out/builddir ARCH=mips CROSS_COMPILE=mips-linux-gnu- HOSTCC=clang CC=clang
> /srv/src/kernel/next/arch/mips/vdso/elf.S:14:1: warning: DWARF2 only supports one section per compilation unit
> .pushsection .note.Linux, "a",@note ; .balign 4 ; .long 2f - 1f ; .long 4484f - 3f ; .long 0 ; 1:.asciz "Linux" ; 2:.balign 4 ; 3:
> ^
> /srv/src/kernel/next/arch/mips/vdso/elf.S:34:2: warning: DWARF2 only supports one section per compilation unit
>  .section .mips_abiflags, "a"
>  ^
> 
> Rework so the mips vdso Makefile adds flag '-no-integrated-as' unless
> LLVM_IAS is defined.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1256
> Cc: stable@vger.kernel.org # v4.19+
> Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>

I believe this is the better solution:

https://lore.kernel.org/r/20210115192622.3828545-1-natechancellor@gmail.com/

Cheers,
Nathan

Re: [PATCH] mips: vdso: fix DWARF2 warning

[Anders Roxell]

On Fri, 15 Jan 2021 at 20:28, Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> On Fri, Jan 15, 2021 at 08:13:30PM +0100, Anders Roxell wrote:
> > When building mips tinyconifg the following warning show up
> >
> > make --silent --keep-going --jobs=8 O=/home/anders/src/kernel/next/out/builddir ARCH=mips CROSS_COMPILE=mips-linux-gnu- HOSTCC=clang CC=clang
> > /srv/src/kernel/next/arch/mips/vdso/elf.S:14:1: warning: DWARF2 only supports one section per compilation unit
> > .pushsection .note.Linux, "a",@note ; .balign 4 ; .long 2f - 1f ; .long 4484f - 3f ; .long 0 ; 1:.asciz "Linux" ; 2:.balign 4 ; 3:
> > ^
> > /srv/src/kernel/next/arch/mips/vdso/elf.S:34:2: warning: DWARF2 only supports one section per compilation unit
> >  .section .mips_abiflags, "a"
> >  ^
> >
> > Rework so the mips vdso Makefile adds flag '-no-integrated-as' unless
> > LLVM_IAS is defined.
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1256
> > Cc: stable@vger.kernel.org # v4.19+
> > Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
> > Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
>
> I believe this is the better solution:
>
> https://lore.kernel.org/r/20210115192622.3828545-1-natechancellor@gmail.com/

Yes, I agree.

Cheers,
Anders

Re: [PATCH] mips: vdso: fix DWARF2 warning

[Fangrui Song]

On 2021-01-15, Anders Roxell wrote:
>On Fri, 15 Jan 2021 at 20:28, Nathan Chancellor
><natechancellor@gmail.com> wrote:
>>
>> On Fri, Jan 15, 2021 at 08:13:30PM +0100, Anders Roxell wrote:
>> > When building mips tinyconifg the following warning show up
>> >
>> > make --silent --keep-going --jobs=8 O=/home/anders/src/kernel/next/out/builddir ARCH=mips CROSS_COMPILE=mips-linux-gnu- HOSTCC=clang CC=clang
>> > /srv/src/kernel/next/arch/mips/vdso/elf.S:14:1: warning: DWARF2 only supports one section per compilation unit
>> > .pushsection .note.Linux, "a",@note ; .balign 4 ; .long 2f - 1f ; .long 4484f - 3f ; .long 0 ; 1:.asciz "Linux" ; 2:.balign 4 ; 3:
>> > ^
>> > /srv/src/kernel/next/arch/mips/vdso/elf.S:34:2: warning: DWARF2 only supports one section per compilation unit
>> >  .section .mips_abiflags, "a"
>> >  ^
>> >
>> > Rework so the mips vdso Makefile adds flag '-no-integrated-as' unless
>> > LLVM_IAS is defined.
>> >
>> > Link: https://github.com/ClangBuiltLinux/linux/issues/1256
>> > Cc: stable@vger.kernel.org # v4.19+
>> > Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
>> > Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
>>
>> I believe this is the better solution:
>>
>> https://lore.kernel.org/r/20210115192622.3828545-1-natechancellor@gmail.com/
>
>Yes, I agree.
>
>Cheers,
>Anders

http://lore.kernel.org/r/20201202010850.jibrjpyu6xgkff5p@google.com
Personally I'd drop DWARF v2 as an option.

Re: [PATCH] mips: vdso: fix DWARF2 warning

[Nick Desaulniers]

On Fri, Jan 15, 2021 at 12:13 PM Fangrui Song <maskray@google.com> wrote:
>
> http://lore.kernel.org/r/20201202010850.jibrjpyu6xgkff5p@google.com
> Personally I'd drop DWARF v2 as an option.

WIP :P

-- 
Thanks,
~Nick Desaulniers

Re: [PATCH] mips: vdso: fix DWARF2 warning

[kernel test robot]

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Hi Anders,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v5.11-rc3 next-20210115]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Anders-Roxell/mips-vdso-fix-DWARF2-warning/20210116-031903
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5ee88057889bbca5f5bb96031b62b3756b33e164
config: mips-cavium_octeon_defconfig (attached as .config)
compiler: mips64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/242da1138d05b84d92be2e0a06d6e3fb40c752de
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Anders-Roxell/mips-vdso-fix-DWARF2-warning/20210116-031903
        git checkout 242da1138d05b84d92be2e0a06d6e3fb40c752de
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> mips64-linux-gcc: error: unrecognized command line option '-no-integrated-as'; did you mean '-no-integrated-cpp'?

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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Re: [PATCH] mips: vdso: fix DWARF2 warning

[kernel test robot]

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Hi Anders,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v5.11-rc3 next-20210115]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Anders-Roxell/mips-vdso-fix-DWARF2-warning/20210116-031903
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5ee88057889bbca5f5bb96031b62b3756b33e164
config: mips-randconfig-p001-20210115 (attached as .config)
compiler: mips-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/242da1138d05b84d92be2e0a06d6e3fb40c752de
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Anders-Roxell/mips-vdso-fix-DWARF2-warning/20210116-031903
        git checkout 242da1138d05b84d92be2e0a06d6e3fb40c752de
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> mips-linux-gcc: error: unrecognized command line option '-no-integrated-as'; did you mean '-no-integrated-cpp'?

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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