diff --git a/arch/csky/include/asm/syscall.h b/arch/csky/include/asm/syscall.h
index 850b694a463e..8278658e74f9 100644
--- a/arch/csky/include/asm/syscall.h
+++ b/arch/csky/include/asm/syscall.h
@@ -16,6 +16,13 @@ syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
 	return regs_syscallid(regs);
 }
 
+static inline void
+syscall_set_nr(struct task_struct *task, struct pt_regs *regs,
+	       int sysno)
+{
+	regs_syscallid(regs) = sysno;
+}
+
 static inline void
 syscall_rollback(struct task_struct *task, struct pt_regs *regs)
 {
diff --git a/arch/csky/kernel/ptrace.c b/arch/csky/kernel/ptrace.c
index 91bc74bb569f..313623a19ecb 100644
--- a/arch/csky/kernel/ptrace.c
+++ b/arch/csky/kernel/ptrace.c
@@ -215,7 +215,8 @@ long arch_ptrace(struct task_struct *child, long request,
 asmlinkage void syscall_trace_enter(struct pt_regs *regs)
 {
 	if (test_thread_flag(TIF_SYSCALL_TRACE))
-		tracehook_report_syscall_entry(regs);
+		if (tracehook_report_syscall_entry(regs))
+			syscall_set_nr(current, regs, -1);
 
 	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 		trace_sys_enter(regs, syscall_get_nr(current, regs));