Hi Ludwig, On Mon, 2026-01-19 at 15:47 +0100, Ludwig Rydberg wrote: > Add support for the clone3 system call to the SPARC architectures. > > The implementation follows the pattern of the original clone syscall. > However, instead of explicitly calling kernel_clone, the clone3 > handler calls the generic sys_clone3 handler in kernel/fork. > In case no stack is provided, the parents stack is reused. > > The return value convention for clone3 follows the regular kernel return > value convention (in contrast to the original clone/fork on SPARC). > > Closes: https://github.com/sparclinux/issues/issues/10 > Signed-off-by: Ludwig Rydberg <[email protected]> > --- > arch/sparc/include/asm/syscalls.h | 1 + > arch/sparc/include/asm/unistd.h | 2 -- > arch/sparc/kernel/entry.S | 15 ++++++++++++++ > arch/sparc/kernel/kernel.h | 1 + > arch/sparc/kernel/process.c | 14 +++++++++++++ > arch/sparc/kernel/process_32.c | 23 ++++++++++++++++------ > arch/sparc/kernel/process_64.c | 27 ++++++++++++++++++++------ > arch/sparc/kernel/syscalls.S | 8 ++++++++ > arch/sparc/kernel/syscalls/syscall.tbl | 2 +- > 9 files changed, 78 insertions(+), 15 deletions(-) > > diff --git a/arch/sparc/include/asm/syscalls.h > b/arch/sparc/include/asm/syscalls.h > index 35575fbfb9dc..282e62b66518 100644 > --- a/arch/sparc/include/asm/syscalls.h > +++ b/arch/sparc/include/asm/syscalls.h > @@ -7,5 +7,6 @@ struct pt_regs; > asmlinkage long sparc_fork(struct pt_regs *regs); > asmlinkage long sparc_vfork(struct pt_regs *regs); > asmlinkage long sparc_clone(struct pt_regs *regs); > +asmlinkage long sparc_clone3(struct pt_regs *regs); > > #endif /* _SPARC64_SYSCALLS_H */ > diff --git a/arch/sparc/include/asm/unistd.h b/arch/sparc/include/asm/unistd.h > index 3380411a4537..d6bc76706a7a 100644 > --- a/arch/sparc/include/asm/unistd.h > +++ b/arch/sparc/include/asm/unistd.h > @@ -49,8 +49,6 @@ > #define __ARCH_WANT_COMPAT_STAT > #endif > > -#define __ARCH_BROKEN_SYS_CLONE3 > - > #ifdef __32bit_syscall_numbers__ > /* Sparc 32-bit only has the "setresuid32", "getresuid32" variants, > * it never had the plain ones and there is no value to adding those > diff --git a/arch/sparc/kernel/entry.S b/arch/sparc/kernel/entry.S > index a3fdee4cd6fa..ea51ef52c952 100644 > --- a/arch/sparc/kernel/entry.S > +++ b/arch/sparc/kernel/entry.S > @@ -907,6 +907,21 @@ flush_patch_four: > jmpl %l1 + %lo(sparc_vfork), %g0 > add %sp, STACKFRAME_SZ, %o0 > > + .globl __sys_clone3, flush_patch_five > +__sys_clone3: > + mov %o7, %l5 > +flush_patch_five: > + FLUSH_ALL_KERNEL_WINDOWS; > + ld [%curptr + TI_TASK], %o4 > + rd %psr, %g4 > + WRITE_PAUSE > + rd %wim, %g5 > + WRITE_PAUSE > + std %g4, [%o4 + AOFF_task_thread + AOFF_thread_fork_kpsr] > + add %sp, STACKFRAME_SZ, %o0 > + call sparc_clone3 > + mov %l5, %o7 > + > .align 4 > linux_sparc_ni_syscall: > sethi %hi(sys_ni_syscall), %l7 > diff --git a/arch/sparc/kernel/kernel.h b/arch/sparc/kernel/kernel.h > index 8328a3b78a44..4ee85051521a 100644 > --- a/arch/sparc/kernel/kernel.h > +++ b/arch/sparc/kernel/kernel.h > @@ -18,6 +18,7 @@ extern int ncpus_probed; > asmlinkage long sparc_clone(struct pt_regs *regs); > asmlinkage long sparc_fork(struct pt_regs *regs); > asmlinkage long sparc_vfork(struct pt_regs *regs); > +asmlinkage long sparc_clone3(struct pt_regs *regs); > > #ifdef CONFIG_SPARC64 > /* setup_64.c */ > diff --git a/arch/sparc/kernel/process.c b/arch/sparc/kernel/process.c > index 7d69877511fa..d72fa0665943 100644 > --- a/arch/sparc/kernel/process.c > +++ b/arch/sparc/kernel/process.c > @@ -12,6 +12,7 @@ > #include <linux/sched/task.h> > #include <linux/sched/task_stack.h> > #include <linux/signal.h> > +#include <linux/syscalls.h> > > #include "kernel.h" > > @@ -118,3 +119,16 @@ asmlinkage long sparc_clone(struct pt_regs *regs) > > return ret; > } > + > +asmlinkage long sparc_clone3(struct pt_regs *regs) > +{ > + unsigned long sz; > + struct clone_args __user *cl_args; > + > + synchronize_user_stack(); > + > + cl_args = (struct clone_args __user *)regs->u_regs[UREG_I0]; > + sz = regs->u_regs[UREG_I1]; > + > + return sys_clone3(cl_args, sz); > +} > diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c > index 5a28c0e91bf1..dd8c6c02b0f1 100644 > --- a/arch/sparc/kernel/process_32.c > +++ b/arch/sparc/kernel/process_32.c > @@ -247,6 +247,8 @@ clone_stackframe(struct sparc_stackf __user *dst, > * Parent --> %o0 == childs pid, %o1 == 0 > * Child --> %o0 == parents pid, %o1 == 1 > * > + * clone3() - Uses regular kernel return value conventions > + * > * NOTE: We have a separate fork kpsr/kwim because > * the parent could change these values between > * sys_fork invocation and when we reach here > @@ -261,11 +263,11 @@ extern void ret_from_kernel_thread(void); > int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) > { > u64 clone_flags = args->flags; > - unsigned long sp = args->stack; > unsigned long tls = args->tls; > struct thread_info *ti = task_thread_info(p); > struct pt_regs *childregs, *regs = current_pt_regs(); > char *new_stack; > + unsigned long sp = args->stack ? args->stack : regs->u_regs[UREG_FP]; > > #ifndef CONFIG_SMP > if(last_task_used_math == current) { > @@ -350,13 +352,22 @@ int copy_thread(struct task_struct *p, const struct > kernel_clone_args *args) > childregs->psr &= ~PSR_EF; > clear_tsk_thread_flag(p, TIF_USEDFPU); > #endif > + /* Handle return value conventions */ > + if (regs->u_regs[UREG_G1] == __NR_clone3) { > + /* clone3() - use regular kernel return value convention */ > + > + /* Set the return value for the child. */ > + childregs->u_regs[UREG_I0] = 0; > + } else { > + /* clone()/fork() - use SunOS return value convention */ > > - /* Set the return value for the child. */ > - childregs->u_regs[UREG_I0] = current->pid; > - childregs->u_regs[UREG_I1] = 1; > + /* Set the return value for the child. */ > + childregs->u_regs[UREG_I0] = current->pid; > + childregs->u_regs[UREG_I1] = 1; > > - /* Set the return value for the parent. */ > - regs->u_regs[UREG_I1] = 0; > + /* Set the return value for the parent. */ > + regs->u_regs[UREG_I1] = 0; > + } > > if (clone_flags & CLONE_SETTLS) > childregs->u_regs[UREG_G7] = tls; > diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c > index 25781923788a..e889da8e4835 100644 > --- a/arch/sparc/kernel/process_64.c > +++ b/arch/sparc/kernel/process_64.c > @@ -564,17 +564,19 @@ void fault_in_user_windows(struct pt_regs *regs) > * under SunOS are nothing short of bletcherous: > * Parent --> %o0 == childs pid, %o1 == 0 > * Child --> %o0 == parents pid, %o1 == 1 > + * > + * clone3() - Uses regular kernel return value conventions > */ > int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) > { > u64 clone_flags = args->flags; > - unsigned long sp = args->stack; > unsigned long tls = args->tls; > struct thread_info *t = task_thread_info(p); > struct pt_regs *regs = current_pt_regs(); > struct sparc_stackf *parent_sf; > unsigned long child_stack_sz; > char *child_trap_frame; > + unsigned long sp = args->stack ? args->stack : regs->u_regs[UREG_FP]; > > /* Calculate offset to stack_frame & pt_regs */ > child_stack_sz = (STACKFRAME_SZ + TRACEREG_SZ); > @@ -616,12 +618,25 @@ int copy_thread(struct task_struct *p, const struct > kernel_clone_args *args) > if (t->utraps) > t->utraps[0]++; > > - /* Set the return value for the child. */ > - t->kregs->u_regs[UREG_I0] = current->pid; > - t->kregs->u_regs[UREG_I1] = 1; > + /* Handle return value conventions */ > + if (regs->u_regs[UREG_G1] == __NR_clone3) { > + /* clone3() - use regular kernel return value convention */ > + > + /* Set the return value for the child. */ > + t->kregs->u_regs[UREG_I0] = 0; > + > + /* Clear g1 to indicate user thread */ > + t->kregs->u_regs[UREG_G1] = 0; > + } else { > + /* clone()/fork() - use SunOS return value convention */ > + > + /* Set the return value for the child. */ > + t->kregs->u_regs[UREG_I0] = current->pid; > + t->kregs->u_regs[UREG_I1] = 1; > > - /* Set the second return value for the parent. */ > - regs->u_regs[UREG_I1] = 0; > + /* Set the second return value for the parent. */ > + regs->u_regs[UREG_I1] = 0; > + } > > if (clone_flags & CLONE_SETTLS) > t->kregs->u_regs[UREG_G7] = tls; > diff --git a/arch/sparc/kernel/syscalls.S b/arch/sparc/kernel/syscalls.S > index 0e8ab0602c36..96fe8763d70c 100644 > --- a/arch/sparc/kernel/syscalls.S > +++ b/arch/sparc/kernel/syscalls.S > @@ -103,6 +103,12 @@ sys_clone: > ba,pt %xcc, sparc_clone > add %sp, PTREGS_OFF, %o0 > > + .align 32 > +__sys_clone3: > + flushw > + ba,pt %xcc, sparc_clone3 > + add %sp, PTREGS_OFF, %o0 > + > .globl ret_from_fork > ret_from_fork: > /* Clear current_thread_info()->new_child. */ > @@ -113,6 +119,8 @@ ret_from_fork: > brnz,pt %o0, ret_sys_call > ldx [%g6 + TI_FLAGS], %l0 > ldx [%sp + PTREGS_OFF + PT_V9_G1], %l1 > + brz,pt %l1, ret_sys_call > + nop > call %l1 > ldx [%sp + PTREGS_OFF + PT_V9_G2], %o0 > ba,pt %xcc, ret_sys_call > diff --git a/arch/sparc/kernel/syscalls/syscall.tbl > b/arch/sparc/kernel/syscalls/syscall.tbl > index 39aa26b6a50b..c0307bb09892 100644 > --- a/arch/sparc/kernel/syscalls/syscall.tbl > +++ b/arch/sparc/kernel/syscalls/syscall.tbl > @@ -480,7 +480,7 @@ > 432 common fsmount sys_fsmount > 433 common fspick sys_fspick > 434 common pidfd_open sys_pidfd_open > -# 435 reserved for clone3 > +435 common clone3 __sys_clone3 > 436 common close_range sys_close_range > 437 common openat2 sys_openat2 > 438 common pidfd_getfd sys_pidfd_getfd
I can confirm that this patch passes both the clone3 selftest from within the kernel sources in ./tools/testing/selftests/clone3: root@raverin:/usr/src/linux/tools/testing/selftests/clone3# uname -a Linux raverin 6.19.0-rc6+ #21 Tue Jan 20 12:41:03 UTC 2026 sparc64 GNU/Linux root@raverin:/usr/src/linux/tools/testing/selftests/clone3# ./clone3 TAP version 13 1..19 # clone3() syscall supported # Running test 'simple clone3()' # [1495] Trying clone3() with flags 0 (size 0) # I am the parent (1495). My child's pid is 1496 # I am the child, my PID is 1496 # [1495] clone3() with flags says: 0 expected 0 ok 1 simple clone3() # Running test 'clone3() in a new PID_NS' # [1495] Trying clone3() with flags 0x20000000 (size 0) # I am the parent (1495). My child's pid is 1497 # I am the child, my PID is 1 # [1495] clone3() with flags says: 0 expected 0 ok 2 clone3() in a new PID_NS # Running test 'CLONE_ARGS_SIZE_VER0' # [1495] Trying clone3() with flags 0 (size 64) # I am the parent (1495). My child's pid is 1498 # I am the child, my PID is 1498 # [1495] clone3() with flags says: 0 expected 0 ok 3 CLONE_ARGS_SIZE_VER0 # Running test 'CLONE_ARGS_SIZE_VER0 - 8' # [1495] Trying clone3() with flags 0 (size 56) # Invalid argument - Failed to create new process # [1495] clone3() with flags says: -22 expected -22 ok 4 CLONE_ARGS_SIZE_VER0 - 8 # Running test 'sizeof(struct clone_args) + 8' # [1495] Trying clone3() with flags 0 (size 96) # I am the parent (1495). My child's pid is 1499 # I am the child, my PID is 1499 # [1495] clone3() with flags says: 0 expected 0 ok 5 sizeof(struct clone_args) + 8 # Running test 'exit_signal with highest 32 bits non-zero' # [1495] Trying clone3() with flags 0 (size 0) # Invalid argument - Failed to create new process # [1495] clone3() with flags says: -22 expected -22 ok 6 exit_signal with highest 32 bits non-zero # Running test 'negative 32-bit exit_signal' # [1495] Trying clone3() with flags 0 (size 0) # Invalid argument - Failed to create new process # [1495] clone3() with flags says: -22 expected -22 ok 7 negative 32-bit exit_signal # Running test 'exit_signal not fitting into CSIGNAL mask' # [1495] Trying clone3() with flags 0 (size 0) # Invalid argument - Failed to create new process # [1495] clone3() with flags says: -22 expected -22 ok 8 exit_signal not fitting into CSIGNAL mask # Running test 'NSIG < exit_signal < CSIG' # [1495] Trying clone3() with flags 0 (size 0) # Invalid argument - Failed to create new process # [1495] clone3() with flags says: -22 expected -22 ok 9 NSIG < exit_signal < CSIG # Running test 'Arguments sizeof(struct clone_args) + 8' # [1495] Trying clone3() with flags 0 (size 96) # I am the parent (1495). My child's pid is 1500 # I am the child, my PID is 1500 # [1495] clone3() with flags says: 0 expected 0 ok 10 Arguments sizeof(struct clone_args) + 8 # Running test 'Arguments sizeof(struct clone_args) + 16' # [1495] Trying clone3() with flags 0 (size 104) # Argument list too long - Failed to create new process # [1495] clone3() with flags says: -7 expected -7 ok 11 Arguments sizeof(struct clone_args) + 16 # Running test 'Arguments sizeof(struct clone_arg) * 2' # [1495] Trying clone3() with flags 0 (size 104) # Argument list too long - Failed to create new process # [1495] clone3() with flags says: -7 expected -7 ok 12 Arguments sizeof(struct clone_arg) * 2 # Running test 'Arguments > page size' # [1495] Trying clone3() with flags 0 (size 8200) # Argument list too long - Failed to create new process # [1495] clone3() with flags says: -7 expected -7 ok 13 Arguments > page size # Running test 'CLONE_ARGS_SIZE_VER0 in a new PID NS' # [1495] Trying clone3() with flags 0x20000000 (size 64) # I am the parent (1495). My child's pid is 1501 # I am the child, my PID is 1 # [1495] clone3() with flags says: 0 expected 0 ok 14 CLONE_ARGS_SIZE_VER0 in a new PID NS # Running test 'CLONE_ARGS_SIZE_VER0 - 8 in a new PID NS' # [1495] Trying clone3() with flags 0x20000000 (size 56) # Invalid argument - Failed to create new process # [1495] clone3() with flags says: -22 expected -22 ok 15 CLONE_ARGS_SIZE_VER0 - 8 in a new PID NS # Running test 'sizeof(struct clone_args) + 8 in a new PID NS' # [1495] Trying clone3() with flags 0x20000000 (size 96) # I am the parent (1495). My child's pid is 1502 # I am the child, my PID is 1 # [1495] clone3() with flags says: 0 expected 0 ok 16 sizeof(struct clone_args) + 8 in a new PID NS # Running test 'Arguments > page size in a new PID NS' # [1495] Trying clone3() with flags 0x20000000 (size 8200) # Argument list too long - Failed to create new process # [1495] clone3() with flags says: -7 expected -7 ok 17 Arguments > page size in a new PID NS # Time namespaces are not supported ok 18 # SKIP New time NS # Running test 'exit signal (SIGCHLD) in flags' # [1495] Trying clone3() with flags 0x14 (size 0) # Invalid argument - Failed to create new process # [1495] clone3() with flags says: -22 expected -22 ok 19 exit signal (SIGCHLD) in flags # 1 skipped test(s) detected. Consider enabling relevant config options to improve coverage. # Totals: pass:18 fail:0 xfail:0 xpass:0 skip:1 error:0 root@raverin:/usr/src/linux/tools/testing/selftests/clone3# and the libcamera build and testsuite: Ok: 38 Expected Fail: 1 Fail: 0 Skipped: 31 Tested-by: John Paul Adrian Glaubitz <[email protected]> Adrian -- .''`. John Paul Adrian Glaubitz : :' : Debian Developer `. `' Physicist `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
