csky: Fixup perf probe -x hungup

case:
 # perf probe -x /lib/libc-2.28.9000.so memcpy
 # perf record -e probe_libc:memcpy -aR sleep 1

System hangup and cpu get in trap_c loop, because our hardware
singlestep state could still get interrupt signal. When we get in
uprobe_xol singlestep slot, we should disable irq in pt_regs->psr.

And is_swbp_insn() need a csky arch implementation with a low 16bit
mask.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>

arch/csky/kernel/probes/uprobes.c

@@ -11,6 +11,11 @@
 
 #define UPROBE_TRAP_NR	UINT_MAX
 
+bool is_swbp_insn(uprobe_opcode_t *insn)
+{
+	return (*insn & 0xffff) == UPROBE_SWBP_INSN;
+}
+
 unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
 {
 	return instruction_pointer(regs);

arch/csky/kernel/ptrace.c

@@ -41,6 +41,9 @@ static void singlestep_disable(struct task_struct *tsk)
 
 	regs = task_pt_regs(tsk);
 	regs->sr = (regs->sr & TRACE_MODE_MASK) | TRACE_MODE_RUN;
+
+	/* Enable irq */
+	regs->sr |= BIT(6);
 }
 
 static void singlestep_enable(struct task_struct *tsk)
@@ -49,6 +52,9 @@ static void singlestep_enable(struct task_struct *tsk)
 
 	regs = task_pt_regs(tsk);
 	regs->sr = (regs->sr & TRACE_MODE_MASK) | TRACE_MODE_SI;
+
+	/* Disable irq */
+	regs->sr &= ~BIT(6);
 }
 
 /*