[PATCH 00/23] binfmt_elf,arch/*: Use elf.h for coredump note names
From: Dave Martin <Dave.Martin@arm.com>
Date: 2025-07-01 13:56:34
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