unicore32: switch to generic clone(2)

Signed-off-by: Al Viro <[e-mail]>

arch/unicore32/include/uapi/asm/unistd.h

···
 /* Use the standard ABI for syscalls. */
 #include <asm-generic/unistd.h>
 #define __ARCH_WANT_SYS_EXECVE
+#define __ARCH_WANT_SYS_CLONE

arch/unicore32/kernel/entry.S

···
 #endif
 	.ltorg
 
-ENTRY(sys_clone)
-		add	ip, sp, #S_OFF
-		stw	ip, [sp+], #4
-		b	__sys_clone
-ENDPROC(sys_clone)
-
 ENTRY(sys_rt_sigreturn)
 		add	r0, sp, #S_OFF
 		mov	why, #0		@ prevent syscall restart handling

arch/unicore32/kernel/process.c

···
 
 int
 copy_thread(unsigned long clone_flags, unsigned long stack_start,
-	    unsigned long stk_sz, struct task_struct *p, struct pt_regs *regs)
+	    unsigned long stk_sz, struct task_struct *p, struct pt_regs *unused)
 {
 	struct thread_info *thread = task_thread_info(p);
 	struct pt_regs *childregs = task_pt_regs(p);
 
 	memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
 	thread->cpu_context.sp = (unsigned long)childregs;
-	if (unlikely(!regs)) {
+	if (unlikely(p->flags & PF_KTHREAD)) {
 		thread->cpu_context.pc = (unsigned long)ret_from_kernel_thread;
 		thread->cpu_context.r4 = stack_start;
 		thread->cpu_context.r5 = stk_sz;
 		memset(childregs, 0, sizeof(struct pt_regs));
 	} else {
 		thread->cpu_context.pc = (unsigned long)ret_from_fork;
-		*childregs = *regs;
+		*childregs = *current_pt_regs();
 		childregs->UCreg_00 = 0;
-		childregs->UCreg_sp = stack_start;
+		if (stack_start)
+			childregs->UCreg_sp = stack_start;
 
 		if (clone_flags & CLONE_SETTLS)
-			childregs->UCreg_16 = regs->UCreg_03;
+			childregs->UCreg_16 = childregs->UCreg_03;
 	}
 	return 0;
 }

arch/unicore32/kernel/sys.c

···
 #include <asm/syscalls.h>
 #include <asm/cacheflush.h>
 
-/* Clone a task - this clones the calling program thread.
- * This is called indirectly via a small wrapper
- */
-asmlinkage long __sys_clone(unsigned long clone_flags, unsigned long newsp,
-			 void __user *parent_tid, void __user *child_tid,
-			 struct pt_regs *regs)
-{
-	if (!newsp)
-		newsp = regs->UCreg_sp;
-
-	return do_fork(clone_flags, newsp, regs, 0,
-			parent_tid, child_tid);
-}
-
 /* Note: used by the compat code even in 64-bit Linux. */
 SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
 		unsigned long, prot, unsigned long, flags,