openrisc: Add clone3 ABI wrapper

Like fork and clone the clone3 syscall needs a wrapper to save callee
saved registers, which is required by the OpenRISC ABI.  This came up
after auditing code following a discussion with Rob Landley and Arnd
Bergmann [0].

Tested with the clone3 kselftests and there were no issues.

[0] https://lore.kernel.org/all/41206fc7-f8ce-98aa-3718-ba3e1431e320@landley.net/T/#m9c0cdb2703813b9df4da04cf6b30de1f1aa89944

Fixes: 07e83df ("openrisc: Enable the clone3 syscall")
Cc: Rob Landley <rob@landley.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Stafford Horne <shorne@gmail.com>

Author: stffrdhrn

arch/openrisc/include/asm/syscalls.h

@@ -22,9 +22,11 @@ asmlinkage long sys_or1k_atomic(unsigned long type, unsigned long *v1,
 
 asmlinkage long __sys_clone(unsigned long clone_flags, unsigned long newsp,
 			void __user *parent_tid, void __user *child_tid, int tls);
+asmlinkage long __sys_clone3(struct clone_args __user *uargs, size_t size);
 asmlinkage long __sys_fork(void);
 
 #define sys_clone __sys_clone
+#define sys_clone3 __sys_clone3
 #define sys_fork __sys_fork
 
 #endif /* __ASM_OPENRISC_SYSCALLS_H */

arch/openrisc/kernel/entry.S

@@ -1165,6 +1165,11 @@ ENTRY(__sys_clone)
 	l.j	_fork_save_extra_regs_and_call
 	 l.ori	r29,r29,lo(sys_clone)
 
+ENTRY(__sys_clone3)
+	l.movhi	r29,hi(sys_clone3)
+	l.j	_fork_save_extra_regs_and_call
+	 l.ori	r29,r29,lo(sys_clone3)
+
 ENTRY(__sys_fork)
 	l.movhi	r29,hi(sys_fork)
 	l.j	_fork_save_extra_regs_and_call