[PATCH 00/20] powerpc: Define eligible functions as __init

Nick Child nnac123 at gmail.com
Thu Dec 16 03:12:23 AEDT 2021


Hello all,

This patchset focuses on redefining/declaring functions that could be 
labeled with the macro `__init`. From my understanding, an initialization 
function is one which is only needed during the initial phases of booting, 
after which it's resources can be freed. I figure that any function which is 
only called by other initialization functions may also be labeled as an 
initialization function. There are several (mostly static) functions which 
can and should be labeled as `__init`. I created some scripts to help 
identify these functions. It scans all functions defined in `arch/powerpc` 
and, if it is only called by functions with the `__init` attribute, it will 
go on to adjust the prototype and definition to include the `__init` 
declaration.

Some notes about the scripts:
  1. Trying to handle things like functions assigned to macros and function
      pointers proved to be a bit too complicated to track. I ended up just
      halting the investigation of these functions. In the future, I would 
      like to be able to attempt to `__init` them but for now we leave them 
      alone.

  2. The proper syntax for adding the `__init` macro is followed as it is 
      defined in `include/linux/init.h`. 

  3. There are some odd looking functions that look something like: 
      `char *__init foo(...`. I have found that this happens in many other 
      places in the kernel source prior to running the scripts. Additionally,
      after running the scripts. I have successfully built all powerpc 
      defconfigs without error. For these reasons, I assume the odd syntax is
      valid but I am interested in other opinions on this.

  5. I have run my scripts on the 12/3/2021 `merge` branch (specifically
      78e00acdd35c)

After running my script for 3 rounds, they have identified about 250
functions so I tried to break the patches up into related platforms and
subdirectories. There are only two functions with a prototype outside of 
`arch/powerpc`, these are `find_via_cuda` and `find_via_pmu`. I put those in 
their own patch.

Other than building all the ppc defconfigs, I have tested the changes by 
building kernels with and without the patches using defconfigs ppc64le_guest, 
powernv and pseries_le. There were no size differences reported in the boot 
logs. However, when using `readelf -t` we see the following differences in 
the size of the .text section:
  ppc64le_guest -> .text decreased in size by 12.8k, init.text unchanged
  powernv -> .text decreased in size by 7.7k, init.text unchanged
  pseries_le -> .text decreased in size by 9.6k, init.text increased 65.5k

I figured the size differences (or lack of) in .init.text might have something
to do with the requirement that the .init.text "section ends on a page
boundary", as described in `arch/powerpc/kernel/vmlinux.lds.S`. 

I am excited to say this is my first attempt at kernel development. I know
this patchset is in no way important but I figured it was a good starting
point. Please let me know if there is anything I am doing wrong or if I can 
do anything to help meet the kernel contribution guidelines.

Special thanks to Daniel Axtens for mentoring me and helping me get my first
patchset out!

Nick Child (20):
  powerpc/kernel: Add __init attribute to eligible functions
  powerpc/lib: Add __init attribute to eligible functions
  powerpc/mm: Add __init attribute to eligible functions
  powerpc/perf: Add __init attribute to eligible functions
  powerpc/sysdev: Add __init attribute to eligible functions
  powerpc/xmon: Add __init attribute to eligible functions
  powerpc/cell: Add __init attribute to eligible functions
  powerpc/chrp: Add __init attribute to eligible functions
  powerpc/pasemi: Add __init attribute to eligible functions
  powerpc/powermac: Add __init attribute to eligible functions
  powerpc/powernv: Add __init attribute to eligible functions
  powerpc/pseries: Add __init attribute to eligible functions
  powerpc/ps3: Add __init attribute to eligible functions
  powerpc/4xx: Add __init attribute to eligible functions
  powerpc/44x: Add __init attribute to eligible functions
  powerpc/embedded6xx: Add __init attribute to eligible functions
  powerpc/83xx: Add __init attribute to eligible functions
  powerpc/85xx: Add __init attribute to eligible functions
  powerpc/512x: Add __init attribute to eligible functions
  cuda/pmu: Make find_via_cuda/pmu init functions

 arch/powerpc/include/asm/book3s/64/mmu.h      |  2 +-
 arch/powerpc/include/asm/btext.h              | 10 ++--
 arch/powerpc/include/asm/cpm2.h               |  6 +--
 arch/powerpc/include/asm/cpuidle.h            |  2 +-
 arch/powerpc/include/asm/eeh.h                |  2 +-
 arch/powerpc/include/asm/fadump-internal.h    |  6 +--
 arch/powerpc/include/asm/hugetlb.h            |  2 +-
 arch/powerpc/include/asm/i8259.h              |  2 +-
 arch/powerpc/include/asm/iommu.h              |  2 +-
 arch/powerpc/include/asm/ipic.h               |  2 +-
 arch/powerpc/include/asm/kexec.h              |  2 +-
 arch/powerpc/include/asm/kvm_guest.h          |  2 +-
 arch/powerpc/include/asm/mmu_context.h        |  2 +-
 arch/powerpc/include/asm/mpic.h               |  2 +-
 arch/powerpc/include/asm/opal.h               |  2 +-
 arch/powerpc/include/asm/pci.h                |  2 +-
 arch/powerpc/include/asm/perf_event_server.h  |  2 +-
 arch/powerpc/include/asm/setup.h              |  8 +--
 arch/powerpc/include/asm/smu.h                |  2 +-
 arch/powerpc/include/asm/udbg.h               | 10 ++--
 arch/powerpc/include/asm/xics.h               |  4 +-
 arch/powerpc/include/asm/xmon.h               |  2 +-
 arch/powerpc/kernel/btext.c                   | 12 ++---
 arch/powerpc/kernel/dt_cpu_ftrs.c             |  2 +-
 arch/powerpc/kernel/eeh_cache.c               |  2 +-
 arch/powerpc/kernel/fadump.c                  | 18 +++----
 arch/powerpc/kernel/nvram_64.c                |  6 +--
 arch/powerpc/kernel/pci-common.c              |  2 +-
 arch/powerpc/kernel/pci_32.c                  |  4 +-
 arch/powerpc/kernel/prom.c                    |  4 +-
 arch/powerpc/kernel/prom_init.c               | 12 ++---
 arch/powerpc/kernel/rtasd.c                   |  6 +--
 arch/powerpc/kernel/security.c                |  4 +-
 arch/powerpc/kernel/setup_64.c                |  2 +-
 arch/powerpc/kernel/smp.c                     |  4 +-
 arch/powerpc/kernel/sysfs.c                   | 10 ++--
 arch/powerpc/kernel/udbg_16550.c              | 10 ++--
 arch/powerpc/kexec/core.c                     |  2 +-
 arch/powerpc/lib/code-patching.c              |  2 +-
 arch/powerpc/lib/feature-fixups.c             | 26 +++++-----
 arch/powerpc/mm/book3s32/mmu.c                |  2 +-
 arch/powerpc/mm/book3s64/hash_hugetlbpage.c   |  2 +-
 arch/powerpc/mm/book3s64/hash_utils.c         |  6 +--
 arch/powerpc/mm/book3s64/mmu_context.c        |  2 +-
 arch/powerpc/mm/book3s64/pkeys.c              |  2 +-
 arch/powerpc/mm/book3s64/radix_pgtable.c      |  4 +-
 arch/powerpc/mm/nohash/44x.c                  |  4 +-
 arch/powerpc/mm/nohash/fsl_book3e.c           |  2 +-
 arch/powerpc/mm/nohash/tlb.c                  |  4 +-
 arch/powerpc/mm/numa.c                        |  6 +--
 arch/powerpc/mm/ptdump/ptdump.c               |  2 +-
 arch/powerpc/perf/core-book3s.c               |  2 +-
 arch/powerpc/perf/generic-compat-pmu.c        |  2 +-
 arch/powerpc/perf/internal.h                  | 18 +++----
 arch/powerpc/perf/power10-pmu.c               |  2 +-
 arch/powerpc/perf/power5+-pmu.c               |  2 +-
 arch/powerpc/perf/power5-pmu.c                |  2 +-
 arch/powerpc/perf/power6-pmu.c                |  2 +-
 arch/powerpc/perf/power7-pmu.c                |  2 +-
 arch/powerpc/perf/power8-pmu.c                |  2 +-
 arch/powerpc/perf/power9-pmu.c                |  2 +-
 arch/powerpc/perf/ppc970-pmu.c                |  2 +-
 arch/powerpc/platforms/44x/fsp2.c             |  4 +-
 arch/powerpc/platforms/4xx/cpm.c              |  4 +-
 arch/powerpc/platforms/4xx/pci.c              |  2 +-
 arch/powerpc/platforms/512x/clock-commonclk.c | 52 +++++++++----------
 arch/powerpc/platforms/512x/mpc512x.h         |  4 +-
 arch/powerpc/platforms/512x/mpc512x_shared.c  |  4 +-
 arch/powerpc/platforms/83xx/km83xx.c          |  2 +-
 arch/powerpc/platforms/83xx/mpc834x_mds.c     |  2 +-
 arch/powerpc/platforms/83xx/mpc837x_mds.c     |  2 +-
 arch/powerpc/platforms/83xx/mpc837x_rdb.c     |  2 +-
 arch/powerpc/platforms/83xx/mpc83xx.h         |  6 +--
 arch/powerpc/platforms/83xx/usb.c             |  6 +--
 arch/powerpc/platforms/85xx/ge_imp3a.c        |  2 +-
 arch/powerpc/platforms/85xx/mpc85xx_cds.c     |  2 +-
 .../platforms/85xx/socrates_fpga_pic.c        |  2 +-
 .../platforms/85xx/socrates_fpga_pic.h        |  2 +-
 arch/powerpc/platforms/85xx/xes_mpc85xx.c     |  4 +-
 arch/powerpc/platforms/cell/cbe_regs.c        |  2 +-
 arch/powerpc/platforms/cell/iommu.c           | 14 ++---
 arch/powerpc/platforms/cell/spu_base.c        |  6 +--
 arch/powerpc/platforms/cell/spu_manage.c      | 16 +++---
 arch/powerpc/platforms/cell/spufs/inode.c     |  2 +-
 arch/powerpc/platforms/chrp/pegasos_eth.c     |  2 +-
 arch/powerpc/platforms/embedded6xx/hlwd-pic.c |  4 +-
 arch/powerpc/platforms/embedded6xx/hlwd-pic.h |  2 +-
 arch/powerpc/platforms/embedded6xx/holly.c    |  2 +-
 .../platforms/embedded6xx/usbgecko_udbg.c     |  4 +-
 arch/powerpc/platforms/embedded6xx/wii.c      |  2 +-
 arch/powerpc/platforms/pasemi/msi.c           |  2 +-
 arch/powerpc/platforms/pasemi/pasemi.h        |  2 +-
 arch/powerpc/platforms/pasemi/pci.c           |  2 +-
 arch/powerpc/platforms/pasemi/setup.c         |  2 +-
 arch/powerpc/platforms/powermac/feature.c     |  2 +-
 arch/powerpc/platforms/powermac/nvram.c       |  2 +-
 arch/powerpc/platforms/powermac/pfunc_base.c  |  6 +--
 arch/powerpc/platforms/powermac/setup.c       |  6 +--
 arch/powerpc/platforms/powermac/smp.c         |  4 +-
 arch/powerpc/platforms/powermac/udbg_scc.c    |  2 +-
 arch/powerpc/platforms/powernv/idle.c         |  6 +--
 arch/powerpc/platforms/powernv/opal-core.c    |  6 +--
 arch/powerpc/platforms/powernv/opal-fadump.c  |  2 +-
 arch/powerpc/platforms/powernv/opal-msglog.c  |  4 +-
 arch/powerpc/platforms/powernv/opal-power.c   |  2 +-
 .../powerpc/platforms/powernv/opal-powercap.c |  2 +-
 arch/powerpc/platforms/powernv/opal-rtc.c     |  2 +-
 .../platforms/powernv/opal-sensor-groups.c    |  4 +-
 arch/powerpc/platforms/powernv/opal.c         |  8 +--
 arch/powerpc/platforms/powernv/pci-ioda.c     |  4 +-
 arch/powerpc/platforms/powernv/powernv.h      |  4 +-
 arch/powerpc/platforms/powernv/rng.c          |  2 +-
 arch/powerpc/platforms/powernv/setup.c        |  6 +--
 arch/powerpc/platforms/ps3/gelic_udbg.c       |  2 +-
 arch/powerpc/platforms/ps3/mm.c               |  4 +-
 arch/powerpc/platforms/ps3/os-area.c          |  4 +-
 arch/powerpc/platforms/ps3/platform.h         | 14 ++---
 arch/powerpc/platforms/ps3/repository.c       | 20 +++----
 arch/powerpc/platforms/ps3/smp.c              |  2 +-
 arch/powerpc/platforms/ps3/spu.c              |  2 +-
 .../powerpc/platforms/pseries/event_sources.c |  2 +-
 arch/powerpc/platforms/pseries/iommu.c        |  2 +-
 arch/powerpc/platforms/pseries/lpar.c         |  6 +--
 arch/powerpc/platforms/pseries/pseries.h      |  2 +-
 arch/powerpc/platforms/pseries/rtas-fadump.c  |  6 +--
 arch/powerpc/platforms/pseries/setup.c        |  4 +-
 arch/powerpc/platforms/pseries/vas.c          |  2 +-
 arch/powerpc/platforms/pseries/vio.c          |  6 +--
 arch/powerpc/sysdev/cpm2.c                    |  6 +--
 arch/powerpc/sysdev/dart_iommu.c              |  2 +-
 arch/powerpc/sysdev/fsl_mpic_err.c            |  4 +-
 arch/powerpc/sysdev/fsl_pci.c                 |  2 +-
 arch/powerpc/sysdev/fsl_pci.h                 |  2 +-
 arch/powerpc/sysdev/i8259.c                   |  2 +-
 arch/powerpc/sysdev/ipic.c                    |  2 +-
 arch/powerpc/sysdev/mpic.c                    |  2 +-
 arch/powerpc/sysdev/mpic.h                    | 10 ++--
 arch/powerpc/sysdev/mpic_msi.c                |  6 +--
 arch/powerpc/sysdev/mpic_timer.c              |  6 +--
 arch/powerpc/sysdev/mpic_u3msi.c              |  2 +-
 arch/powerpc/sysdev/tsi108_pci.c              |  2 +-
 arch/powerpc/sysdev/udbg_memcons.c            |  2 +-
 arch/powerpc/sysdev/xics/icp-hv.c             |  2 +-
 arch/powerpc/sysdev/xics/icp-opal.c           |  2 +-
 arch/powerpc/sysdev/xics/xics-common.c        |  2 +-
 arch/powerpc/sysdev/xive/native.c             |  4 +-
 arch/powerpc/sysdev/xive/spapr.c              |  6 +--
 arch/powerpc/xmon/xmon.c                      |  2 +-
 include/linux/cuda.h                          |  2 +-
 include/linux/pmu.h                           |  2 +-
 150 files changed, 334 insertions(+), 334 deletions(-)

-- 
2.25.1



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