MIPS: fix uretprobe implementation

arch_uretprobe_hijack_return_addr should replace the return address for
a call with a trampoline address.

Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Fixes: 40e084a506 ('MIPS: Add uprobes support.')
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14298/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/uprobes.c

@@ -257,7 +257,7 @@ unsigned long arch_uretprobe_hijack_return_addr(
 	ra = regs->regs[31];
 
 	/* Replace the return address with the trampoline address */
-	regs->regs[31] = ra;
+	regs->regs[31] = trampoline_vaddr;
 
 	return ra;
 }