[lldb] [Process/FreeBSDRemote] Introduce arm64 support

[mgorny]

Summary

Introduce arm64 support in the FreeBSDRemote plugin. The code
is roughly based on Linux and reuses the same POSIX RegisterInfos
(but the buffers need to be a few bytes larger due to stricter struct
member alignment in FreeBSD structures -- luckily, they do not affect
the actual member offsets). It supports reading and writing
general-purpose and FPU registers. SVE and hardware watchpoint support
is missing due to the limitations of FreeBSD ptrace(2) API.

[mgorny]

Removed unused REG_CONTEXT_SIZE.

[mgorny]

Remove unused copy-pasted class method declarations.

[krytarowski]

@clayborg please have a look!

[clayborg]

Is this code used by lldb-server or the native Free BSD plug-in?

[mgorny]

In D95297#2531752, @clayborg wrote:

Is this code used by lldb-server or the native Free BSD plug-in?

lldb-server. We're aiming towards removing the native plug-in soon.

[emaste]

In D95297#2532026, @mgorny wrote:

lldb-server. We're aiming towards removing the native plug-in soon.

To add a little background, the FreeBSD Foundation is funding this effort to move all FreeBSD targets to lldb-server; amd64 and arm64 are our primary targets of interest while other supported FreeBSD architectures (32-bit arm, 32- and 64-bit mips, 32- and 64-bit powerpc, 64-bit risc-v) are intended to be handled on a best-effort basis, depending in part on whether FreeBSD folks with an interest in those platforms are available to help test.

[labath]

This looks fine to me (and sorry about the delay). There are some defensive checks that I think could be upgraded to asserts (or even deleted), but these are consistent with the other register contexts, so I am not going to make a fuss about it.

lldb/source/Plugins/Platform/FreeBSD/PlatformFreeBSD.cpp

 }
 
 bool PlatformFreeBSD::CanDebugProcess() {
   if (IsHost()) {
     llvm::Triple host_triple{llvm::sys::getProcessTriple()};
     bool use_legacy_plugin;
 
     switch (host_triple.getArch()) {
+      case llvm::Triple::aarch64:
       case llvm::Triple::x86:
       case llvm::Triple::x86_64:
-        // FreeBSDRemote plugin supports x86 only at the moment
         use_legacy_plugin = !!getenv("FREEBSD_LEGACY_PLUGIN");
         break;
       default:
         use_legacy_plugin = true;
     }
 
     return !use_legacy_plugin;
   } else {

lldb/source/Plugins/Process/FreeBSDRemote/CMakeLists.txt

 add_lldb_library(lldbPluginProcessFreeBSDRemote
   NativeProcessFreeBSD.cpp
   NativeRegisterContextFreeBSD.cpp
+  NativeRegisterContextFreeBSD_arm64.cpp
   NativeRegisterContextFreeBSD_x86_64.cpp
   NativeThreadFreeBSD.cpp
 
   LINK_LIBS
     lldbHost
     lldbSymbol
     lldbTarget
     lldbUtility
     lldbPluginProcessPOSIX
     lldbPluginProcessUtility
   LINK_COMPONENTS
     Support
   )

lldb/source/Plugins/Process/FreeBSDRemote/NativeRegisterContextFreeBSD_arm64.h

+//===-- NativeRegisterContextFreeBSD_arm64.h --------------------*- C++ -*-===//
+//
+// 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(__aarch64__)
+
+#ifndef lldb_NativeRegisterContextFreeBSD_arm64_h
+#define lldb_NativeRegisterContextFreeBSD_arm64_h
+
+// clang-format off
+#include <sys/types.h>
+#include <machine/reg.h>
+// clang-format on
+
+#include "Plugins/Process/FreeBSDRemote/NativeRegisterContextFreeBSD.h"
+#include "Plugins/Process/Utility/RegisterInfoPOSIX_arm64.h"
+
+#include <array>
+
+namespace lldb_private {
+namespace process_freebsd {
+
+class NativeProcessFreeBSD;
+
+class NativeRegisterContextFreeBSD_arm64 : public NativeRegisterContextFreeBSD {
+public:
+  NativeRegisterContextFreeBSD_arm64(const ArchSpec &target_arch,
+                                     NativeThreadProtocol &native_thread);
+
+  uint32_t GetRegisterSetCount() const override;
+
+  uint32_t GetUserRegisterCount() const override;
+
+  const RegisterSet *GetRegisterSet(uint32_t set_index) const override;
+
+  Status ReadRegister(const RegisterInfo *reg_info,
+                      RegisterValue &reg_value) override;
+
+  Status WriteRegister(const RegisterInfo *reg_info,
+                       const RegisterValue &reg_value) override;
+
+  Status ReadAllRegisterValues(lldb::DataBufferSP &data_sp) override;
+
+  Status WriteAllRegisterValues(const lldb::DataBufferSP &data_sp) override;
+
+  llvm::Error
+  CopyHardwareWatchpointsFrom(NativeRegisterContextFreeBSD &source) override;
+
+private:
+  // Due to alignment, FreeBSD reg/fpreg are a few bytes larger than
+  // LLDB's GPR/FPU structs.  However, all fields have matching offsets
+  // and sizes, so we do not have to worry about these (and we have
+  // a unittest to assert that).
+  std::array<uint8_t, sizeof(reg) + sizeof(fpreg)> m_reg_data;
+
+  Status ReadRegisterSet(uint32_t set);
+  Status WriteRegisterSet(uint32_t set);
+
+  RegisterInfoPOSIX_arm64 &GetRegisterInfo() const;
+};
+
+} // namespace process_freebsd
+} // namespace lldb_private
+
+#endif // #ifndef lldb_NativeRegisterContextFreeBSD_arm64_h
+
+#endif // defined (__aarch64__)

lldb/source/Plugins/Process/FreeBSDRemote/NativeRegisterContextFreeBSD_arm64.cpp

+//===-- NativeRegisterContextFreeBSD_arm64.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(__aarch64__)
+
+#include "NativeRegisterContextFreeBSD_arm64.h"
+
+#include "lldb/Utility/DataBufferHeap.h"
+#include "lldb/Utility/RegisterValue.h"
+#include "lldb/Utility/Status.h"
+
+#include "Plugins/Process/FreeBSDRemote/NativeProcessFreeBSD.h"
+#include "Plugins/Process/Utility/RegisterInfoPOSIX_arm64.h"
+
+// clang-format off
+#include <sys/param.h>
+#include <sys/ptrace.h>
+#include <sys/types.h>
+// clang-format on
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::process_freebsd;
+
+NativeRegisterContextFreeBSD *
+NativeRegisterContextFreeBSD::CreateHostNativeRegisterContextFreeBSD(
+    const ArchSpec &target_arch, NativeThreadProtocol &native_thread) {
+  return new NativeRegisterContextFreeBSD_arm64(target_arch, native_thread);
+}
+
+NativeRegisterContextFreeBSD_arm64::NativeRegisterContextFreeBSD_arm64(
+    const ArchSpec &target_arch, NativeThreadProtocol &native_thread)
+    : NativeRegisterContextRegisterInfo(
+          native_thread, new RegisterInfoPOSIX_arm64(target_arch)) {
+  GetRegisterInfo().ConfigureVectorRegisterInfos(
+      RegisterInfoPOSIX_arm64::eVectorQuadwordAArch64);
+}
+
+RegisterInfoPOSIX_arm64 &
+NativeRegisterContextFreeBSD_arm64::GetRegisterInfo() const {
+  return static_cast<RegisterInfoPOSIX_arm64 &>(*m_register_info_interface_up);
+}
+
+uint32_t NativeRegisterContextFreeBSD_arm64::GetRegisterSetCount() const {
+  return GetRegisterInfo().GetRegisterSetCount();
+}
+
+const RegisterSet *
+NativeRegisterContextFreeBSD_arm64::GetRegisterSet(uint32_t set_index) const {
+  return GetRegisterInfo().GetRegisterSet(set_index);
+}
+
+uint32_t NativeRegisterContextFreeBSD_arm64::GetUserRegisterCount() const {
+  uint32_t count = 0;
+  for (uint32_t set_index = 0; set_index < GetRegisterSetCount(); ++set_index)
+    count += GetRegisterSet(set_index)->num_registers;
+  return count;
+}
+
+Status NativeRegisterContextFreeBSD_arm64::ReadRegisterSet(uint32_t set) {
+  switch (set) {
+  case RegisterInfoPOSIX_arm64::GPRegSet:
+    return NativeProcessFreeBSD::PtraceWrapper(PT_GETREGS, m_thread.GetID(),
+                                               m_reg_data.data());
+  case RegisterInfoPOSIX_arm64::FPRegSet:
+    return NativeProcessFreeBSD::PtraceWrapper(
+        PT_GETFPREGS, m_thread.GetID(),
+        m_reg_data.data() + sizeof(RegisterInfoPOSIX_arm64::GPR));
+  case RegisterInfoPOSIX_arm64::SVERegSet:
+    return Status("not supported");
+  }
+  llvm_unreachable("NativeRegisterContextFreeBSD_arm64::ReadRegisterSet");
+}
+
+Status NativeRegisterContextFreeBSD_arm64::WriteRegisterSet(uint32_t set) {
+  switch (set) {
+  case RegisterInfoPOSIX_arm64::GPRegSet:
+    return NativeProcessFreeBSD::PtraceWrapper(PT_SETREGS, m_thread.GetID(),
+                                               m_reg_data.data());
+  case RegisterInfoPOSIX_arm64::FPRegSet:
+    return NativeProcessFreeBSD::PtraceWrapper(
+        PT_SETFPREGS, m_thread.GetID(),
+        m_reg_data.data() + sizeof(RegisterInfoPOSIX_arm64::GPR));
+  case RegisterInfoPOSIX_arm64::SVERegSet:
+    return Status("not supported");
+  }
+  llvm_unreachable("NativeRegisterContextFreeBSD_arm64::WriteRegisterSet");
+}
+
+Status
+NativeRegisterContextFreeBSD_arm64::ReadRegister(const RegisterInfo *reg_info,
+                                                 RegisterValue &reg_value) {
+  Status error;
+
+  if (!reg_info) {
+    error.SetErrorString("reg_info NULL");
+    return error;
+  }
+
+  const uint32_t reg = reg_info->kinds[lldb::eRegisterKindLLDB];
+
+  if (reg == LLDB_INVALID_REGNUM)
+    return Status("no lldb regnum for %s", reg_info && reg_info->name
+                                               ? reg_info->name
+                                               : "<unknown register>");
+
+  uint32_t set = GetRegisterInfo().GetRegisterSetFromRegisterIndex(reg);
+  error = ReadRegisterSet(set);
+  if (error.Fail())
+    return error;
+
+  assert(reg_info->byte_offset + reg_info->byte_size <= m_reg_data.size());
+  reg_value.SetBytes(m_reg_data.data() + reg_info->byte_offset,
+                     reg_info->byte_size, endian::InlHostByteOrder());
+  return error;
+}
+
+Status NativeRegisterContextFreeBSD_arm64::WriteRegister(
+    const RegisterInfo *reg_info, const RegisterValue &reg_value) {
+  Status error;
+
+  if (!reg_info)
+    return Status("reg_info NULL");
+
+  const uint32_t reg = reg_info->kinds[lldb::eRegisterKindLLDB];
+
+  if (reg == LLDB_INVALID_REGNUM)
+    return Status("no lldb regnum for %s", reg_info && reg_info->name
+                                               ? reg_info->name
+                                               : "<unknown register>");
+
+  uint32_t set = GetRegisterInfo().GetRegisterSetFromRegisterIndex(reg);
+  error = ReadRegisterSet(set);
+  if (error.Fail())
+    return error;
+
+  assert(reg_info->byte_offset + reg_info->byte_size <= m_reg_data.size());
+  ::memcpy(m_reg_data.data() + reg_info->byte_offset, reg_value.GetBytes(),
+           reg_info->byte_size);
+
+  return WriteRegisterSet(set);
+}
+
+Status NativeRegisterContextFreeBSD_arm64::ReadAllRegisterValues(
+    lldb::DataBufferSP &data_sp) {
+  Status error;
+
+  error = ReadRegisterSet(RegisterInfoPOSIX_arm64::GPRegSet);
+  if (error.Fail())
+    return error;
+
+  error = ReadRegisterSet(RegisterInfoPOSIX_arm64::FPRegSet);
+  if (error.Fail())
+    return error;
+
+  data_sp.reset(new DataBufferHeap(m_reg_data.size(), 0));
+  uint8_t *dst = data_sp->GetBytes();
+  ::memcpy(dst, m_reg_data.data(), m_reg_data.size());
+
+  return error;
+}
+
+Status NativeRegisterContextFreeBSD_arm64::WriteAllRegisterValues(
+    const lldb::DataBufferSP &data_sp) {
+  Status error;
+
+  if (!data_sp) {
+    error.SetErrorStringWithFormat(
+        "NativeRegisterContextFreeBSD_arm64::%s invalid data_sp provided",
+        __FUNCTION__);
+    return error;
+  }
+
+  if (data_sp->GetByteSize() != m_reg_data.size()) {
+    error.SetErrorStringWithFormat(
+        "NativeRegisterContextFreeBSD_arm64::%s data_sp contained mismatched "
+        "data size, expected %" PRIu64 ", actual %" PRIu64,
+        __FUNCTION__, m_reg_data.size(), data_sp->GetByteSize());
+    return error;
+  }
+
+  uint8_t *src = data_sp->GetBytes();
+  if (src == nullptr) {
+    error.SetErrorStringWithFormat("NativeRegisterContextFreeBSD_arm64::%s "
+                                   "DataBuffer::GetBytes() returned a null "
+                                   "pointer",
+                                   __FUNCTION__);
+    return error;
+  }
+  ::memcpy(m_reg_data.data(), src, m_reg_data.size());
+
+  error = WriteRegisterSet(RegisterInfoPOSIX_arm64::GPRegSet);
+  if (error.Fail())
+    return error;
+
+  return WriteRegisterSet(RegisterInfoPOSIX_arm64::FPRegSet);
+}
+
+llvm::Error NativeRegisterContextFreeBSD_arm64::CopyHardwareWatchpointsFrom(
+    NativeRegisterContextFreeBSD &source) {
+  return llvm::Error::success();
+}
+
+#endif // defined (__aarch64__)

lldb/unittests/Process/Utility/RegisterContextFreeBSDTest.cpp

 // clang-format on
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
 #include "Plugins/Process/Utility/lldb-x86-register-enums.h"
 #include "Plugins/Process/Utility/RegisterContextFreeBSD_i386.h"
 #include "Plugins/Process/Utility/RegisterContextFreeBSD_x86_64.h"
+#include "Plugins/Process/Utility/RegisterInfoPOSIX_arm64.h"
+#include "Plugins/Process/Utility/lldb-arm64-register-enums.h"
 
 using namespace lldb;
 using namespace lldb_private;
 
 std::pair<size_t, size_t> GetRegParams(RegisterInfoInterface &ctx,
                                        uint32_t reg) {
   const RegisterInfo &info = ctx.GetRegisterInfo()[reg];
   return {info.byte_offset, info.byte_size};
#endif
   EXPECT_DBR_I386(3);
   EXPECT_DBR_I386(4);
   EXPECT_DBR_I386(5);
   EXPECT_DBR_I386(6);
   EXPECT_DBR_I386(7);
 }
 
 #endif // defined(__i386__) || defined(__x86_64__)
+
+#if defined(__aarch64__)
+
+#define EXPECT_GPR_ARM64(lldb_reg, fbsd_reg)                                   \
+  EXPECT_THAT(GetRegParams(reg_ctx, gpr_##lldb_reg##_arm64),                   \
+              ::testing::Pair(offsetof(reg, fbsd_reg), sizeof(reg::fbsd_reg)))
+#define EXPECT_FPU_ARM64(lldb_reg, fbsd_reg)                                   \
+  EXPECT_THAT(GetRegParams(reg_ctx, fpu_##lldb_reg##_arm64),                   \
+              ::testing::Pair(offsetof(fpreg, fbsd_reg) + base_offset,         \
+                              sizeof(fpreg::fbsd_reg)))
+
+TEST(RegisterContextFreeBSDTest, arm64) {
+  ArchSpec arch{"aarch64-unknown-freebsd"};
+  RegisterInfoPOSIX_arm64 reg_ctx{arch};
+
+  EXPECT_GPR_ARM64(x0, x[0]);
+  EXPECT_GPR_ARM64(x1, x[1]);
+  EXPECT_GPR_ARM64(x2, x[2]);
+  EXPECT_GPR_ARM64(x3, x[3]);
+  EXPECT_GPR_ARM64(x4, x[4]);
+  EXPECT_GPR_ARM64(x5, x[5]);
+  EXPECT_GPR_ARM64(x6, x[6]);
+  EXPECT_GPR_ARM64(x7, x[7]);
+  EXPECT_GPR_ARM64(x8, x[8]);
+  EXPECT_GPR_ARM64(x9, x[9]);
+  EXPECT_GPR_ARM64(x10, x[10]);
+  EXPECT_GPR_ARM64(x11, x[11]);
+  EXPECT_GPR_ARM64(x12, x[12]);
+  EXPECT_GPR_ARM64(x13, x[13]);
+  EXPECT_GPR_ARM64(x14, x[14]);
+  EXPECT_GPR_ARM64(x15, x[15]);
+  EXPECT_GPR_ARM64(x16, x[16]);
+  EXPECT_GPR_ARM64(x17, x[17]);
+  EXPECT_GPR_ARM64(x18, x[18]);
+  EXPECT_GPR_ARM64(x19, x[19]);
+  EXPECT_GPR_ARM64(x20, x[20]);
+  EXPECT_GPR_ARM64(x21, x[21]);
+  EXPECT_GPR_ARM64(x22, x[22]);
+  EXPECT_GPR_ARM64(x23, x[23]);
+  EXPECT_GPR_ARM64(x24, x[24]);
+  EXPECT_GPR_ARM64(x25, x[25]);
+  EXPECT_GPR_ARM64(x26, x[26]);
+  EXPECT_GPR_ARM64(x27, x[27]);
+  EXPECT_GPR_ARM64(x28, x[28]);
+  EXPECT_GPR_ARM64(fp, x[29]);
+  EXPECT_GPR_ARM64(lr, lr);
+  EXPECT_GPR_ARM64(sp, sp);
+  EXPECT_GPR_ARM64(pc, elr);
+  EXPECT_GPR_ARM64(cpsr, spsr);
+
+  size_t base_offset = reg_ctx.GetRegisterInfo()[fpu_v0_arm64].byte_offset;
+
+  EXPECT_FPU_ARM64(v0, fp_q[0]);
+  EXPECT_FPU_ARM64(v1, fp_q[1]);
+  EXPECT_FPU_ARM64(v2, fp_q[2]);
+  EXPECT_FPU_ARM64(v3, fp_q[3]);
+  EXPECT_FPU_ARM64(v4, fp_q[4]);
+  EXPECT_FPU_ARM64(v5, fp_q[5]);
+  EXPECT_FPU_ARM64(v6, fp_q[6]);
+  EXPECT_FPU_ARM64(v7, fp_q[7]);
+  EXPECT_FPU_ARM64(v8, fp_q[8]);
+  EXPECT_FPU_ARM64(v9, fp_q[9]);
+  EXPECT_FPU_ARM64(v10, fp_q[10]);
+  EXPECT_FPU_ARM64(v11, fp_q[11]);
+  EXPECT_FPU_ARM64(v12, fp_q[12]);
+  EXPECT_FPU_ARM64(v13, fp_q[13]);
+  EXPECT_FPU_ARM64(v14, fp_q[14]);
+  EXPECT_FPU_ARM64(v15, fp_q[15]);
+  EXPECT_FPU_ARM64(v16, fp_q[16]);
+  EXPECT_FPU_ARM64(v17, fp_q[17]);
+  EXPECT_FPU_ARM64(v18, fp_q[18]);
+  EXPECT_FPU_ARM64(v19, fp_q[19]);
+  EXPECT_FPU_ARM64(v20, fp_q[20]);
+  EXPECT_FPU_ARM64(v21, fp_q[21]);
+  EXPECT_FPU_ARM64(v22, fp_q[22]);
+  EXPECT_FPU_ARM64(v23, fp_q[23]);
+  EXPECT_FPU_ARM64(v24, fp_q[24]);
+  EXPECT_FPU_ARM64(v25, fp_q[25]);
+  EXPECT_FPU_ARM64(v26, fp_q[26]);
+  EXPECT_FPU_ARM64(v27, fp_q[27]);
+  EXPECT_FPU_ARM64(v28, fp_q[28]);
+  EXPECT_FPU_ARM64(v29, fp_q[29]);
+  EXPECT_FPU_ARM64(v30, fp_q[30]);
+  EXPECT_FPU_ARM64(v31, fp_q[31]);
+  EXPECT_FPU_ARM64(fpsr, fp_sr);
+  EXPECT_FPU_ARM64(fpcr, fp_cr);
+}
+
+#endif // defined(__aarch64__)