[PATCH 00/23] binfmt_elf,arch/*: Use elf.h for coredump note names

[Dave Martin]

This series aims to clean up an aspect of coredump generation:

ELF coredumps contain a set of notes describing the state of machine
registers and other information about the dumped process.

Notes are identified by a numeric identifier n_type and a "name"
string, although this terminology is somewhat misleading.  Officially,
the "name" of a note is really an "originator" or namespace identifier
that indicates how to interpret n_type [1], although in practice it is
often used more loosely.

Either way, each kind of note needs _both_ a specific "name" string and
a specific n_type to identify it robustly.

To centralise this knowledge in one place and avoid the need for ad-hoc
code to guess the correct name for a given note, commit 7da8e4ad4df0
("elf: Define note name macros") [2] added an explicit NN_<foo> #define
in elf.h to give the name corresponding to each named note type
NT_<foo>.

Now that the note name for each note is specified explicitly, the
remaining guesswork for determining the note name for common and
arch-specific regsets in ELF core dumps can be eliminated.

This series aims to do just that:

 * Patch 2 adds a user_regset field to specify the note name, and a
   helper macro to populate it correctly alongside the note type.

 * Patch 3 ports away the ad-hoc note names in the common coredump
   code.

 * Patches 4-22 make the arch-specific changes.  (This is pretty
   mechanical for most arches.)

 * The final patch adds a WARN() when no note name is specified,
   and simplifies the fallback guess.  This should only be applied
   when all arches have ported across.

See the individual patches for details.


Testing:

 * x86, arm64: Booted in a VM and triggered a core dump with no WARN(),
   and verified that the dumped notes are the same.

 * arm: Build-tested only (for now).

 * Other arches: not tested yet

Any help with testing is appreciated.  If the following generates the
same notes (as dumped by readelf -n core) and doesn't trigger a WARN,
then we are probably good.

$ sleep 60 &
$ kill -QUIT $!

(Register content might differ between runs, but it should be safe to
ignore that -- this series only deals with the note names and types.)

Cheers
---Dave


[1] System V Application Binary Interface, Edition 4.1,
Section 5 (Program Loading and Dynamic Linking) -> "Note Section"

https://refspecs.linuxfoundation.org/elf/gabi41.pdf

[2] elf: Define note name macros

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/uapi/linux/elf.h?id=7da8e4ad4df0dd12f37357af62ce1b63e75ae2e6


Dave Martin (23):
  regset: Fix kerneldoc for struct regset_get() in user_regset
  regset: Add explicit core note name in struct user_regset
  binfmt_elf: Dump non-arch notes with strictly matching name and type
  ARC: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  ARM: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  arm64: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note
    names
  csky: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  hexagon: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note
    names
  LoongArch: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note
    names
  m68k: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  MIPS: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  nios2: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note
    names
  openrisc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note
    names
  parisc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note
    names
  powerpc/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note
    names
  riscv: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note
    names
  s390/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  sh: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  sparc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note
    names
  x86/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  um: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names
  xtensa: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note
    names
  binfmt_elf: Warn on missing or suspicious regset note names

 arch/arc/kernel/ptrace.c                 |  4 +-
 arch/arm/kernel/ptrace.c                 |  6 +-
 arch/arm64/kernel/ptrace.c               | 52 ++++++++---------
 arch/csky/kernel/ptrace.c                |  4 +-
 arch/hexagon/kernel/ptrace.c             |  2 +-
 arch/loongarch/kernel/ptrace.c           | 16 ++---
 arch/m68k/kernel/ptrace.c                |  4 +-
 arch/mips/kernel/ptrace.c                | 20 +++----
 arch/nios2/kernel/ptrace.c               |  2 +-
 arch/openrisc/kernel/ptrace.c            |  4 +-
 arch/parisc/kernel/ptrace.c              |  8 +--
 arch/powerpc/kernel/ptrace/ptrace-view.c | 74 ++++++++++++------------
 arch/riscv/kernel/ptrace.c               | 12 ++--
 arch/s390/kernel/ptrace.c                | 42 +++++++-------
 arch/sh/kernel/ptrace_32.c               |  4 +-
 arch/sparc/kernel/ptrace_32.c            |  4 +-
 arch/sparc/kernel/ptrace_64.c            |  8 +--
 arch/x86/kernel/ptrace.c                 | 22 +++----
 arch/x86/um/ptrace.c                     | 10 ++--
 arch/xtensa/kernel/ptrace.c              |  4 +-
 fs/binfmt_elf.c                          | 36 +++++++-----
 fs/binfmt_elf_fdpic.c                    | 17 +++---
 include/linux/regset.h                   | 12 +++-
 23 files changed, 194 insertions(+), 173 deletions(-)


base-commit: 86731a2a651e58953fc949573895f2fa6d456841
-- 
2.34.1