[PATCH 2/3] sparc: Add architecture support for clone3
From: Ludwig Rydberg
Date: Fri Jan 16 2026 - 10:30:59 EST
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 call conventions for clone on SPARC are kept for clone3:
Parent --> %o0 == child's pid, %o1 == 0
Child --> %o0 == parent's pid, %o1 == 1
Closes: https://github.com/sparclinux/issues/issues/10
Signed-off-by: Ludwig Rydberg <ludwig.rydberg@xxxxxxxxxxx>
---
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 | 25 +++++++++++++++++++++++++
arch/sparc/kernel/process_32.c | 2 +-
arch/sparc/kernel/process_64.c | 2 +-
arch/sparc/kernel/syscalls.S | 6 ++++++
arch/sparc/kernel/syscalls/syscall.tbl | 2 +-
9 files changed, 51 insertions(+), 5 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..b8e23295db69 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 +119,27 @@ asmlinkage long sparc_clone(struct pt_regs *regs)
return ret;
}
+
+asmlinkage long sparc_clone3(struct pt_regs *regs)
+{
+ unsigned long sz;
+ long ret;
+ 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];
+
+ ret = sys_clone3(cl_args, sz);
+
+ /* If we get an error and potentially restart the system
+ * call, we're screwed because copy_thread() clobbered
+ * the parent's %o1. So detect that case and restore it
+ * here.
+ */
+ if ((unsigned long)ret >= -ERESTART_RESTARTBLOCK)
+ regs->u_regs[UREG_I1] = sz;
+
+ return ret;
+}
diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index 5a28c0e91bf1..216c07971c81 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -261,11 +261,11 @@ 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) {
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 25781923788a..885d617ba29d 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -568,13 +568,13 @@ void fault_in_user_windows(struct pt_regs *regs)
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);
diff --git a/arch/sparc/kernel/syscalls.S b/arch/sparc/kernel/syscalls.S
index 0e8ab0602c36..c8d374a37f98 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. */
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
--
2.35.3