Re: [linux-next:master 8353/12793] drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.o: warning: objtool: map_partition_power_domain_id() falls through to next function get_instance()

[Yujie Liu <yujie.liu@intel.com>]

On Tue, May 14, 2024 at 11:00:50AM -0700, srinivas pandruvada wrote:
> On Tue, 2024-05-14 at 14:05 +0800, kernel test robot wrote:
> > tree:  
> > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git m
> > aster
> > head:   6ba6c795dc73c22ce2c86006f17c4aa802db2a60
> > commit: 9d1d36268f3d8276aefd1fad4e0a415dc8c36edd [8353/12793]
> > platform/x86: ISST: Support partitioned systems
> > config: x86_64-randconfig-101-20240514
> > (https://download.01.org/0day-ci/archive/20240514/202405141321.RQmski
> > Tj-lkp@intel.com/config)
> > compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0

[...]

> > reproduce (this is a W=1 build):
> > (https://download.01.org/0day-ci/archive/20240514/202405141321.RQmski
> > Tj-lkp@intel.com/reproduce)
> > 
> > If you fix the issue in a separate patch/commit (i.e. not just a new
> > version of
> > the same patch/commit), kindly add following tags
> > > Reported-by: kernel test robot <lkp@intel.com>
> > > Closes:
> > > https://lore.kernel.org/oe-kbuild-all/202405141321.RQmskiTj-lkp@intel.com/
> > 
> > All warnings (new ones prefixed by >>):
> > 
> > > > drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.o:
> > > > warning: objtool: map_partition_power_domain_id() falls through
> > > > to next function get_instance()
> > 
> 
> Not able to reproduce on two gcc versions on Fedora and Ubuntu
> distribution.
> gcc --version
> gcc (GCC) 13.2.1 20240316 (Red Hat 13.2.1-7)
> 
> gcc --version
> gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0

We tried various versions of gcc on Ubuntu distribution and found
that only "gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0" can reproduce it, while
other newer versions cannot, so this may be a gcc-7 bug. Please ignore
it and we will configure the bot to skip this particular "function falls
through" warning for gcc-7.

Thanks,
Yujie

> 
> 
> The documentation for this error:
> https://elixir.bootlin.com/linux/latest/source/tools/objtool/Documentation/objtool.txt
> 
> "
> 8. file.o: warning: objtool: funcA() falls through to next function
> funcB()
> 
>  This means that funcA() doesn't end with a return instruction or an
>   unconditional jump, and that objtool has determined that the function
>    can fall through into the next function.
> 
> "
> 
> This function ends with " return -EINVAL;"
> 
> Also the three reasons in the documentation is also not met.
> 
> 
> 
> make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash
> make[1]: Entering directory '/home/spandruv/development/linux-
> next/build_dir'
>   GEN     Makefile
>   CALL    ../scripts/checksyscalls.sh
>   DESCEND objtool
>   INSTALL libsubcmd_headers
>   DESCEND bpf/resolve_btfids
>   INSTALL libsubcmd_headers
>   CHK     kernel/kheaders_data.tar.xz
>   CC [M]  drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.o
>   MODPOST Module.symvers
> ...
> 
>   TEST    posttest
> arch/x86/tools/insn_decoder_test: success: Decoded and checked 8715543
> instructions
>   TEST    posttest
> arch/x86/tools/insn_sanity: Success: decoded and checked 1000000 random
> instructions with 0 errors (seed:0x5e80fa20)
> Kernel: arch/x86/boot/bzImage is ready  (#1)
>   LD [M]  drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.ko
>   BTF [M] drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.ko
> ..
> make[1]: Leaving directory '/home/spandruv/development/linux-
> next/build_dir'
> 
> 
> Thanks,
> Srinivas
> 
>