lwn.git/arch/m68k/kernel/process.c, branch docs-next

arch: copy_thread: pass clone_flags as u64

2025-09-01T13:31:34+00:00

With the introduction of clone3 in commit 7f192e3cd316 ("fork: add clone3") the effective bit width of clone_flags on all architectures was increased from 32-bit to 64-bit, with a new type of u64 for the flags. However, for most consumers of clone_flags the interface was not changed from the previous type of unsigned long. While this works fine as long as none of the new 64-bit flag bits (CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still undesirable in terms of the principle of least surprise. Thus, this commit fixes all relevant interfaces of the copy_thread function that is called from copy_process to consistently pass clone_flags as u64, so that no truncation to 32-bit integers occurs on 32-bit architectures. Signed-off-by: Simon Schuster Link: https://lore.kernel.org/20250901-nios2-implement-clone3-v2-3-53fcf5577d57@siemens-energy.com Fixes: c5febea0956fd387 ("fork: Pass struct kernel_clone_args into copy_thread") Acked-by: Guo Ren (Alibaba Damo Academy) Acked-by: Andreas Larsson # sparc Acked-by: David Hildenbrand Acked-by: Geert Uytterhoeven # m68k Reviewed-by: Arnd Bergmann Signed-off-by: Christian Brauner

m68k: Fix kernel_clone_args.flags in m68k_clone()

2024-08-26T08:24:34+00:00

Stan Johnson recently reported a failure from the 'dump' command: DUMP: Date of this level 0 dump: Fri Aug 9 23:37:15 2024 DUMP: Dumping /dev/sda (an unlisted file system) to /dev/null DUMP: Label: none DUMP: Writing 10 Kilobyte records DUMP: mapping (Pass I) [regular files] DUMP: mapping (Pass II) [directories] DUMP: estimated 3595695 blocks. DUMP: Context save fork fails in parent 671 The dump program uses the clone syscall with the CLONE_IO flag, that is, flags == 0x80000000. When that value is promoted from long int to u64 by m68k_clone(), it undergoes sign-extension. The new value includes CLONE_INTO_CGROUP so the validation in cgroup_css_set_fork() fails and the syscall returns -EBADF. Avoid sign-extension by casting to u32. Reported-by: Stan Johnson Closes: https://lists.debian.org/debian-68k/2024/08/msg00000.html Fixes: 6aabc1facdb2 ("m68k: Implement copy_thread_tls()") Signed-off-by: Finn Thain Reviewed-by: Geert Uytterhoeven Link: https://lore.kernel.org/3463f1e5d4e95468dc9f3368f2b78ffa7b72199b.1723335149.git.fthain@linux-m68k.org Signed-off-by: Geert Uytterhoeven

m68k: kernel: Add and use "process.h"

2023-10-06T08:03:01+00:00

When building with W=1: arch/m68k/kernel/process.c:115:16: warning: no previous prototype for ‘m68k_clone’ [-Wmissing-prototypes] 115 | asmlinkage int m68k_clone(struct pt_regs *regs) | ^~~~~~~~~~ arch/m68k/kernel/process.c:136:16: warning: no previous prototype for ‘m68k_clone3’ [-Wmissing-prototypes] 136 | asmlinkage int m68k_clone3(struct pt_regs *regs) | ^~~~~~~~~~~ Fix this by introducing a new header file "process.h" for holding the prototypes of functions implemented in arch/m68k/kernel/process.c. Signed-off-by: Geert Uytterhoeven Acked-by: Arnd Bergmann Link: https://lore.kernel.org/r/5e50257d8fcae3eb202ce5f439dc29c09cb6c44f.1694613528.git.geert@linux-m68k.org

[elf][non-regset] uninline elf_core_copy_task_fpregs() (and lose pt_regs argument)

2022-11-25T04:24:23+00:00

Don't bother with pointless macros - we are not sharing it with aout coredumps anymore. Just convert the underlying functions to the same arguments (nobody uses regs, actually) and call them elf_core_copy_task_fpregs(). And unexport the entire bunch, while we are at it. [added missing includes in arch/{csky,m68k,um}/kernel/process.c to avoid extra warnings about the lack of externs getting added to huge piles for those files. Pointless, but...] Signed-off-by: Al Viro

Merge tag 'kthread-cleanups-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2022-06-03T23:03:05+00:00

Pull kthread updates from Eric Biederman: "This updates init and user mode helper tasks to be ordinary user mode tasks. Commit 40966e316f86 ("kthread: Ensure struct kthread is present for all kthreads") caused init and the user mode helper threads that call kernel_execve to have struct kthread allocated for them. This struct kthread going away during execve in turned made a use after free of struct kthread possible. Here, commit 343f4c49f243 ("kthread: Don't allocate kthread_struct for init and umh") is enough to fix the use after free and is simple enough to be backportable. The rest of the changes pass struct kernel_clone_args to clean things up and cause the code to make sense. In making init and the user mode helpers tasks purely user mode tasks I ran into two complications. The function task_tick_numa was detecting tasks without an mm by testing for the presence of PF_KTHREAD. The initramfs code in populate_initrd_image was using flush_delayed_fput to ensuere the closing of all it's file descriptors was complete, and flush_delayed_fput does not work in a userspace thread. I have looked and looked and more complications and in my code review I have not found any, and neither has anyone else with the code sitting in linux-next" * tag 'kthread-cleanups-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: sched: Update task_tick_numa to ignore tasks without an mm fork: Stop allowing kthreads to call execve fork: Explicitly set PF_KTHREAD init: Deal with the init process being a user mode process fork: Generalize PF_IO_WORKER handling fork: Explicity test for idle tasks in copy_thread fork: Pass struct kernel_clone_args into copy_thread kthread: Don't allocate kthread_struct for init and umh

m68k: Switch to new sys-off handler API

2022-05-19T17:30:30+00:00

Kernel now supports chained power-off handlers. Use register_power_off_handler() that registers power-off handlers and do_kernel_power_off() that invokes chained power-off handlers. Legacy pm_power_off() will be removed once all drivers will be converted to the new sys-off API. Normally arch code should adopt only the do_kernel_power_off() at first, but m68k is a special case because it uses pm_power_off() "inside out", i.e. pm_power_off() invokes machine_power_off() [in fact it does nothing], while it's machine_power_off() that should invoke the pm_power_off(), and thus, we can't convert platforms to the new API separately. There are only two platforms changed here, so it's not a big deal. Acked-by: Geert Uytterhoeven Reviewed-by: Michał Mirosław Signed-off-by: Dmitry Osipenko Signed-off-by: Rafael J. Wysocki

fork: Generalize PF_IO_WORKER handling

2022-05-07T14:01:59+00:00

Add fn and fn_arg members into struct kernel_clone_args and test for them in copy_thread (instead of testing for PF_KTHREAD | PF_IO_WORKER). This allows any task that wants to be a user space task that only runs in kernel mode to use this functionality. The code on x86 is an exception and still retains a PF_KTHREAD test because x86 unlikely everything else handles kthreads slightly differently than user space tasks that start with a function. The functions that created tasks that start with a function have been updated to set ".fn" and ".fn_arg" instead of ".stack" and ".stack_size". These functions are fork_idle(), create_io_thread(), kernel_thread(), and user_mode_thread(). Link: https://lkml.kernel.org/r/20220506141512.516114-4-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman"

fork: Pass struct kernel_clone_args into copy_thread

2022-05-07T14:01:48+00:00

With io_uring we have started supporting tasks that are for most purposes user space tasks that exclusively run code in kernel mode. The kernel task that exec's init and tasks that exec user mode helpers are also user mode tasks that just run kernel code until they call kernel execve. Pass kernel_clone_args into copy_thread so these oddball tasks can be supported more cleanly and easily. v2: Fix spelling of kenrel_clone_args on h8300 Link: https://lkml.kernel.org/r/20220506141512.516114-2-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman"

sched: Add wrapper for get_wchan() to keep task blocked

2021-10-15T09:25:14+00:00

Having a stable wchan means the process must be blocked and for it to stay that way while performing stack unwinding. Suggested-by: Peter Zijlstra Signed-off-by: Kees Cook Signed-off-by: Peter Zijlstra (Intel) Acked-by: Geert Uytterhoeven Acked-by: Russell King (Oracle) [arm] Tested-by: Mark Rutland [arm64] Link: https://lkml.kernel.org/r/20211008111626.332092234@infradead.org

m68k: Remove set_fs()

2021-09-24T11:35:07+00:00

Add a m68k-only set_fc helper to set the SFC and DFC registers for the few places that need to override it for special MM operations, but disconnect that from the deprecated kernel-wide set_fs() API. Note that the SFC/DFC registers are context switched, so there is no need to disable preemption. Partially based on an earlier patch from Linus Torvalds . Signed-off-by: Christoph Hellwig Reviewed-by: Michael Schmitz Tested-by: Michael Schmitz Link: https://lore.kernel.org/r/20210916070405.52750-7-hch@lst.de Signed-off-by: Geert Uytterhoeven