Index: lldb/source/Plugins/Process/OpenBSDKernel/RegisterContextOpenBSDKernel_x86_64.cpp
--- lldb/source/Plugins/Process/OpenBSDKernel/RegisterContextOpenBSDKernel_x86_64.cpp.orig
+++ lldb/source/Plugins/Process/OpenBSDKernel/RegisterContextOpenBSDKernel_x86_64.cpp
@@ -0,0 +1,110 @@
+//===-- RegisterContextOpenBSDKernel_x86_64.cpp ---------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#if defined(__OpenBSD__)
+#include <sys/types.h>
+#include <sys/time.h>
+#define _KERNEL
+#include <machine/cpu.h>
+#undef _KERNEL
+#include <machine/pcb.h>
+#include <frame.h>
+#endif
+
+#include "RegisterContextOpenBSDKernel_x86_64.h"
+
+#include "lldb/Target/Process.h"
+#include "lldb/Target/Thread.h"
+#include "lldb/Utility/RegisterValue.h"
+#include "llvm/Support/Endian.h"
+
+using namespace lldb;
+using namespace lldb_private;
+
+RegisterContextOpenBSDKernel_x86_64::RegisterContextOpenBSDKernel_x86_64(
+    Thread &thread, RegisterInfoInterface *register_info,
+    lldb::addr_t pcb)
+  : RegisterContextPOSIX_x86(thread, 0, register_info),
+    m_pcb_addr(pcb) {
+}
+
+bool RegisterContextOpenBSDKernel_x86_64::ReadGPR() { return true; }
+
+bool RegisterContextOpenBSDKernel_x86_64::ReadFPR() { return true; }
+
+bool RegisterContextOpenBSDKernel_x86_64::WriteGPR() {
+  assert(0);
+  return false;
+}
+
+bool RegisterContextOpenBSDKernel_x86_64::WriteFPR() {
+  assert(0);
+  return false;
+}
+
+bool RegisterContextOpenBSDKernel_x86_64::ReadRegister(
+    const RegisterInfo *reg_info, RegisterValue &value) {
+  Status error;
+
+  if (m_pcb_addr == LLDB_INVALID_ADDRESS)
+    return false;
+
+#ifdef __amd64__
+  struct pcb pcb;
+  size_t rd = m_thread.GetProcess()->ReadMemory(m_pcb_addr, &pcb, sizeof(pcb),
+						error);
+  if (rd != sizeof(pcb))
+    return false;
+
+  /*
+    Usually pcb is written in `cpu_switchto` function. This function writes
+    registers as same as the structure of  `swichframe`  in the stack.
+    We read the frame if it is.
+   */
+  struct switchframe sf;
+  rd = m_thread.GetProcess()->ReadMemory(pcb.pcb_rsp, &sf, sizeof(sf), error);
+  if (rd != sizeof(sf))
+    return false;
+
+  uint32_t reg = reg_info->kinds[lldb::eRegisterKindLLDB];
+  if (pcb.pcb_rbp == (u_int64_t)sf.sf_rbp) {
+#define SFREG(x)				\
+    case lldb_##x##_x86_64:			\
+      value = (u_int64_t)sf.sf_##x;		\
+      return true;
+#define PCBREG(x, offset)			\
+    case lldb_##x##_x86_64:			\
+      value = pcb.pcb_##x + (offset);		\
+      return true;
+    switch (reg) {
+      SFREG(r15);
+      SFREG(r14);
+      SFREG(r13);
+      SFREG(r12);
+      SFREG(rbp);
+      SFREG(rbx);
+      SFREG(rip);
+      PCBREG(rsp, sizeof(sf));
+    }
+  } else {
+    switch (reg) {
+      PCBREG(rbp, 0);
+      PCBREG(rsp, 8);
+    case lldb_rip_x86_64:
+      value = m_thread.GetProcess()->ReadPointerFromMemory(pcb.pcb_rbp, error);
+      return true;
+    }
+  }
+#endif
+  return false;
+}
+
+bool RegisterContextOpenBSDKernel_x86_64::WriteRegister(
+    const RegisterInfo *reg_info, const RegisterValue &value) {
+  return false;
+}
