[PATCH v2 0/4] nios2: Add architecture support for clone3

Simon Schuster via B4 Relay
2025-09-01T13:10:49Z

This series adds support for the clone3 system call to the nios2
architecture. This addresses the build-time warning "warning: clone3()
entry point is missing, please fix" introduced in 505d66d1abfb9
("clone3: drop __ARCH_WANT_SYS_CLONE3 macro"). The implementation passes
the relevant clone3 tests of kselftest when applied on top of
next-20250815:

./run_kselftest.sh
TAP version 13
1..4
# selftests: clone3: clone3
ok 1 selftests: clone3: clone3
# selftests: clone3: clone3_clear_sighand
ok 2 selftests: clone3: clone3_clear_sighand
# selftests: clone3: clone3_set_tid
ok 3 selftests: clone3: clone3_set_tid
# selftests: clone3: clone3_cap_checkpoint_restore
ok 4 selftests: clone3: clone3_cap_checkpoint_restore

The series also includes a small patch to kernel/fork.c that ensures
that clone_flags are passed correctly on architectures where unsigned
long is insufficient to store the u64 clone_flags. It is marked as a fix
for stable backporting.

As requested, in v2, this series now further tries to correct this type
error throughout the whole code base. Thus, it now touches a larger
number of subsystems and all architectures.

Therefore, another test was performed for ARCH=x86_64 (as a
representative for 64-bit architectures). Here, the series builds cleanly
without warnings on defconfig with CONFIG_SECURITY_APPARMOR=y and
CONFIG_SECURITY_TOMOYO=y (to compile-check the LSM-related changes).
The build further successfully passes testing/selftests/clone3 (with the
patch from 20241105062948.1037011-1-zhouyuhang1010@163.com to prepare
clone3_cap_checkpoint_restore for compatibility with the newer libcap
version on my system).

Is there any option to further preflight check this patch series via
lkp/KernelCI/etc. for a broader test across architectures, or is this
degree of testing sufficient to eventually get the series merged?

N.B.: The series is not checkpatch clean right now:
- include/linux/cred.h, include/linux/mnt_namespace.h:
function definition arguments without identifier name
- include/trace/events/task.h:
space prohibited after that open parenthesis

I did not fix these warnings to keep my changes minimal and reviewable,
as the issues persist throughout the files and they were not introduced
by me; I only followed the existing code style and just replaced the
types. If desired, I'd be happy to make the changes in a potential v3,
though.

Signed-off-by: Simon Schuster <schuster.simon@siemens-energy.com>
---
Changes in v2:
- Introduce "Fixes:" and "Cc: stable@vger.kernel.org" where necessary
- Factor out "Fixes:" when adapting the datatype of clone_flags for
easier backports
- Fix additional instances where `unsigned long` clone_flags is used
- Reword commit message to make it clearer that any 32-bit arch is
affected by this bug
- Link to v1: https://lore.kernel.org/r/20250821-nios2-implement-clone3-v1-0-1bb24017376a@siemens-energy.com

---
Simon Schuster (4):
copy_sighand: Handle architectures where sizeof(unsigned long) < sizeof(u64)
copy_process: pass clone_flags as u64 across calltree
arch: copy_thread: pass clone_flags as u64
nios2: implement architecture-specific portion of sys_clone3

arch/alpha/kernel/process.c | 2 +-
arch/arc/kernel/process.c | 2 +-
arch/arm/kernel/process.c | 2 +-
arch/arm64/kernel/process.c | 2 +-
arch/csky/kernel/process.c | 2 +-
arch/hexagon/kernel/process.c | 2 +-
arch/loongarch/kernel/process.c | 2 +-
arch/m68k/kernel/process.c | 2 +-
arch/microblaze/kernel/process.c | 2 +-
arch/mips/kernel/process.c | 2 +-
arch/nios2/include/asm/syscalls.h | 1 +
arch/nios2/include/asm/unistd.h | 2 --
arch/nios2/kernel/entry.S | 6 ++++++
arch/nios2/kernel/process.c | 2 +-
arch/nios2/kernel/syscall_table.c | 1 +
arch/openrisc/kernel/process.c | 2 +-
arch/parisc/kernel/process.c | 2 +-
arch/powerpc/kernel/process.c | 2 +-
arch/riscv/kernel/process.c | 2 +-
arch/s390/kernel/process.c | 2 +-
arch/sh/kernel/process_32.c | 2 +-
arch/sparc/kernel/process_32.c | 2 +-
arch/sparc/kernel/process_64.c | 2 +-
arch/um/kernel/process.c | 2 +-
arch/x86/include/asm/fpu/sched.h | 2 +-
arch/x86/include/asm/shstk.h | 4 ++--
arch/x86/kernel/fpu/core.c | 2 +-
arch/x86/kernel/process.c | 2 +-
arch/x86/kernel/shstk.c | 2 +-
arch/xtensa/kernel/process.c | 2 +-
block/blk-ioc.c | 2 +-
fs/namespace.c | 2 +-
include/linux/cgroup.h | 4 ++--
include/linux/cred.h | 2 +-
include/linux/iocontext.h | 6 +++---
include/linux/ipc_namespace.h | 4 ++--
include/linux/lsm_hook_defs.h | 2 +-
include/linux/mnt_namespace.h | 2 +-
include/linux/nsproxy.h | 2 +-
include/linux/pid_namespace.h | 4 ++--
include/linux/rseq.h | 4 ++--
include/linux/sched/task.h | 2 +-
include/linux/security.h | 4 ++--
include/linux/sem.h | 4 ++--
include/linux/time_namespace.h | 4 ++--
include/linux/uprobes.h | 4 ++--
include/linux/user_events.h | 4 ++--
include/linux/utsname.h | 4 ++--
include/net/net_namespace.h | 4 ++--
include/trace/events/task.h | 6 +++---
ipc/namespace.c | 2 +-
ipc/sem.c | 2 +-
kernel/cgroup/namespace.c | 2 +-
kernel/cred.c | 2 +-
kernel/events/uprobes.c | 2 +-
kernel/fork.c | 10 +++++-----
kernel/nsproxy.c | 4 ++--
kernel/pid_namespace.c | 2 +-
kernel/sched/core.c | 4 ++--
kernel/sched/fair.c | 2 +-
kernel/sched/sched.h | 4 ++--
kernel/time/namespace.c | 2 +-
kernel/utsname.c | 2 +-
net/core/net_namespace.c | 2 +-
security/apparmor/lsm.c | 2 +-
security/security.c | 2 +-
security/selinux/hooks.c | 2 +-
security/tomoyo/tomoyo.c | 2 +-
68 files changed, 95 insertions(+), 89 deletions(-)
---
base-commit: 1357b2649c026b51353c84ddd32bc963e8999603
change-id: 20250818-nios2-implement-clone3-7f252c20860b

Best regards,
--
Simon Schuster <schuster.simon@siemens-energy.com>