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()

[srinivas pandruvada <srinivas.pandruvada@linux.intel.com>]

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


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