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

On Mon, Sep 01, 2025 at 03:09:49PM +0200, Simon Schuster via B4 Relay wrote:
> This series adds support for the clone3 system call to the nios2
> architecture. This addresses the build-time warning "warning: clone3()

I did not expect that to happen or matter but fine.

> 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.

I've reworked copy_thread()/copy_thread_tls() a few years ago but I
don't remember why I didn't switch to a u64 for them. Probably because
only CLONE_VM and CLONE_SETTLS mattered. Thanks for doing that.

> 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 [email protected] 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 <[email protected]>
> ---
> Changes in v2:
> - Introduce "Fixes:" and "Cc: [email protected]" 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 <[email protected]>
> 
>