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

[Akihiko Odaki]

On 2025/07/01 22:55, Dave Martin wrote:
> 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

For the whole series:
Reviewed-by: Akihiko Odaki <odaki at rsg.ci.i.u-tokyo.ac.jp>

Regards,
Akihiko Odaki