[Lldb-commits] [lldb] [lldb][AArch64] Add register fields for Guarded Control Stack registers (PR #124295)

via lldb-commits lldb-commits at lists.llvm.org
Fri Jan 24 07:51:05 PST 2025


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lldb

Author: David Spickett (DavidSpickett)

<details>
<summary>Changes</summary>

The features and locked registers hold the same bits, the latter
is a lock for the former. Tested with core files and live processes.

I thought about setting a non-zero lock register in the core file,
however:
* We can be pretty sure it's reading correctly because its between
  the 2 other GCS registers in the same core file note.
* I can't make the test case modify lock bits because userspace
  can't clear them and we don't know what the libc has locked
  (probably all feature bits).

---

Patch is 42.40 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/124295.diff


15 Files Affected:

- (modified) lldb/source/Plugins/ABI/AArch64/ABISysV_arm64.cpp (+75) 
- (modified) lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.cpp (+104) 
- (modified) lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.h (+16) 
- (modified) lldb/source/Plugins/Process/Utility/RegisterContextPOSIX_arm64.cpp (+4) 
- (modified) lldb/source/Plugins/Process/Utility/RegisterContextPOSIX_arm64.h (+1) 
- (modified) lldb/source/Plugins/Process/Utility/RegisterFlagsDetector_arm64.cpp (+16) 
- (modified) lldb/source/Plugins/Process/Utility/RegisterFlagsDetector_arm64.h (+4-1) 
- (modified) lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.cpp (+38-1) 
- (modified) lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.h (+7) 
- (modified) lldb/source/Plugins/Process/elf-core/RegisterContextPOSIXCore_arm64.cpp (+17) 
- (modified) lldb/source/Plugins/Process/elf-core/RegisterContextPOSIXCore_arm64.h (+1) 
- (modified) lldb/source/Plugins/Process/elf-core/RegisterUtilities.h (+4) 
- (modified) lldb/test/API/linux/aarch64/gcs/TestAArch64LinuxGCS.py (+323) 
- (added) lldb/test/API/linux/aarch64/gcs/corefile () 
- (modified) lldb/test/API/linux/aarch64/gcs/main.c (+57-5) 


``````````diff
diff --git a/lldb/source/Plugins/ABI/AArch64/ABISysV_arm64.cpp b/lldb/source/Plugins/ABI/AArch64/ABISysV_arm64.cpp
index 93b8141e97ef86..74047ea65788cf 100644
--- a/lldb/source/Plugins/ABI/AArch64/ABISysV_arm64.cpp
+++ b/lldb/source/Plugins/ABI/AArch64/ABISysV_arm64.cpp
@@ -60,6 +60,69 @@ ABISysV_arm64::CreateInstance(lldb::ProcessSP process_sp, const ArchSpec &arch)
   return ABISP();
 }
 
+static Status PushToLinuxGuardedControlStack(addr_t return_addr,
+                                             RegisterContext *reg_ctx,
+                                             Thread &thread) {
+  Status err;
+
+  // If the Guarded Control Stack extension is present we may need to put the
+  // return address onto that stack.
+  const RegisterInfo *gcs_features_enabled_info =
+      reg_ctx->GetRegisterInfoByName("gcs_features_enabled");
+  if (!gcs_features_enabled_info)
+    return err;
+
+  uint64_t gcs_features_enabled = reg_ctx->ReadRegisterAsUnsigned(
+      gcs_features_enabled_info, LLDB_INVALID_ADDRESS);
+  if (gcs_features_enabled == LLDB_INVALID_ADDRESS)
+    return Status("Could not read GCS features enabled register.");
+
+  // Only attempt this if GCS is enabled. If it's not enabled then gcspr_el0
+  // may point to unmapped memory.
+  if ((gcs_features_enabled & 1) == 0)
+    return err;
+
+  const RegisterInfo *gcspr_el0_info =
+      reg_ctx->GetRegisterInfoByName("gcspr_el0");
+  if (!gcspr_el0_info)
+    return Status("Could not get register info for gcspr_el0.");
+
+  uint64_t gcspr_el0 =
+      reg_ctx->ReadRegisterAsUnsigned(gcspr_el0_info, LLDB_INVALID_ADDRESS);
+  if (gcspr_el0 == LLDB_INVALID_ADDRESS)
+    return Status("Could not read gcspr_el0.");
+
+  // A link register entry on the GCS is 8 bytes.
+  gcspr_el0 -= 8;
+  if (!reg_ctx->WriteRegisterFromUnsigned(gcspr_el0_info, gcspr_el0))
+    return Status(
+        "Attempted to decrement gcspr_el0, but could not write to it.");
+
+  Status error;
+  size_t wrote = thread.GetProcess()->WriteMemory(gcspr_el0, &return_addr,
+                                                  sizeof(return_addr), error);
+  if ((wrote != sizeof(return_addr) || error.Fail())) {
+    // When PrepareTrivialCall fails, the register context is not restored,
+    // unlike when an expression fails to execute. This is arguably a bug,
+    // see https://github.com/llvm/llvm-project/issues/124269.
+    // For now we are handling this here specifically. We can assume this
+    // write will work as the one to decrement the register did.
+    reg_ctx->WriteRegisterFromUnsigned(gcspr_el0_info, gcspr_el0 + 8);
+    return Status("Failed to write new Guarded Control Stack entry.");
+  }
+
+  Log *log = GetLog(LLDBLog::Expressions);
+  LLDB_LOGF(log,
+            "Pushed return address 0x%" PRIx64 " to Guarded Control Stack. "
+            "gcspr_el0 was 0%" PRIx64 ", is now 0x%" PRIx64 ".",
+            return_addr, gcspr_el0 - 8, gcspr_el0);
+
+  // gcspr_el0 will be restored to the original value by lldb-server after
+  // the call has finished, which serves as the "pop".
+
+  return err;
+}
+
 bool ABISysV_arm64::PrepareTrivialCall(Thread &thread, addr_t sp,
                                        addr_t func_addr, addr_t return_addr,
                                        llvm::ArrayRef<addr_t> args) const {
@@ -87,6 +150,18 @@ bool ABISysV_arm64::PrepareTrivialCall(Thread &thread, addr_t sp,
   if (args.size() > 8)
     return false;
 
+  // Do this first, as it's got the most chance of failing (though still very
+  // low).
+  if (GetProcessSP()->GetTarget().GetArchitecture().GetTriple().isOSLinux()) {
+    Status err = PushToLinuxGuardedControlStack(return_addr, reg_ctx, thread);
+    // If we could not manage the GCS, the expression will certainly fail,
+    // and if we just carried on, that failure would be a lot more cryptic.
+    if (err.Fail()) {
+      LLDB_LOGF(log, "Failed to setup Guarded Call Stack: %s", err.AsCString());
+      return false;
+    }
+  }
+
   for (size_t i = 0; i < args.size(); ++i) {
     const RegisterInfo *reg_info = reg_ctx->GetRegisterInfo(
         eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG1 + i);
diff --git a/lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.cpp b/lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.cpp
index 6056f3001fed6e..884c7d4b9e3590 100644
--- a/lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.cpp
+++ b/lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.cpp
@@ -64,8 +64,14 @@
 #define NT_ARM_FPMR 0x40e /* Floating point mode register */
 #endif
 
+#ifndef NT_ARM_GCS
+#define NT_ARM_GCS 0x410 /* Guarded Control Stack control registers */
+#endif
+
 #define HWCAP_PACA (1 << 30)
 
+#define HWCAP_GCS (1UL << 32)
+
 #define HWCAP2_MTE (1 << 18)
 
 #define HWCAP2_FPMR (1UL << 48)
@@ -150,6 +156,8 @@ NativeRegisterContextLinux::CreateHostNativeRegisterContextLinux(
         opt_regsets.Set(RegisterInfoPOSIX_arm64::eRegsetMaskMTE);
       if (*auxv_at_hwcap2 & HWCAP2_FPMR)
         opt_regsets.Set(RegisterInfoPOSIX_arm64::eRegsetMaskFPMR);
+      if (*auxv_at_hwcap & HWCAP_GCS)
+        opt_regsets.Set(RegisterInfoPOSIX_arm64::eRegsetMaskGCS);
     }
 
     opt_regsets.Set(RegisterInfoPOSIX_arm64::eRegsetMaskTLS);
@@ -193,6 +201,7 @@ NativeRegisterContextLinux_arm64::NativeRegisterContextLinux_arm64(
   ::memset(&m_pac_mask, 0, sizeof(m_pac_mask));
   ::memset(&m_tls_regs, 0, sizeof(m_tls_regs));
   ::memset(&m_sme_pseudo_regs, 0, sizeof(m_sme_pseudo_regs));
+  ::memset(&m_gcs_regs, 0, sizeof(m_gcs_regs));
   std::fill(m_zt_reg.begin(), m_zt_reg.end(), 0);
 
   m_mte_ctrl_reg = 0;
@@ -213,6 +222,7 @@ NativeRegisterContextLinux_arm64::NativeRegisterContextLinux_arm64(
   m_tls_is_valid = false;
   m_zt_buffer_is_valid = false;
   m_fpmr_is_valid = false;
+  m_gcs_is_valid = false;
 
   // SME adds the tpidr2 register
   m_tls_size = GetRegisterInfo().IsSSVEPresent() ? sizeof(m_tls_regs)
@@ -433,6 +443,14 @@ NativeRegisterContextLinux_arm64::ReadRegister(const RegisterInfo *reg_info,
     offset = reg_info->byte_offset - GetRegisterInfo().GetFPMROffset();
     assert(offset < GetFPMRBufferSize());
     src = (uint8_t *)GetFPMRBuffer() + offset;
+  } else if (IsGCS(reg)) {
+    error = ReadGCS();
+    if (error.Fail())
+      return error;
+
+    offset = reg_info->byte_offset - GetRegisterInfo().GetGCSOffset();
+    assert(offset < GetGCSBufferSize());
+    src = (uint8_t *)GetGCSBuffer() + offset;
   } else
     return Status::FromErrorString(
         "failed - register wasn't recognized to be a GPR or an FPR, "
@@ -657,6 +675,17 @@ Status NativeRegisterContextLinux_arm64::WriteRegister(
     ::memcpy(dst, reg_value.GetBytes(), reg_info->byte_size);
 
     return WriteFPMR();
+  } else if (IsGCS(reg)) {
+    error = ReadGCS();
+    if (error.Fail())
+      return error;
+
+    offset = reg_info->byte_offset - GetRegisterInfo().GetGCSOffset();
+    assert(offset < GetGCSBufferSize());
+    dst = (uint8_t *)GetGCSBuffer() + offset;
+    ::memcpy(dst, reg_value.GetBytes(), reg_info->byte_size);
+
+    return WriteGCS();
   }
 
   return Status::FromErrorString("Failed to write register value");
@@ -672,6 +701,7 @@ enum RegisterSetType : uint32_t {
   SME,  // ZA only, because SVCR and SVG are pseudo registers.
   SME2, // ZT only.
   FPMR,
+  GCS, // Guarded Control Stack registers.
 };
 
 static uint8_t *AddRegisterSetType(uint8_t *dst,
@@ -759,6 +789,13 @@ NativeRegisterContextLinux_arm64::CacheAllRegisters(uint32_t &cached_size) {
       return error;
   }
 
+  if (GetRegisterInfo().IsGCSPresent()) {
+    cached_size += sizeof(RegisterSetType) + GetGCSBufferSize();
+    error = ReadGCS();
+    if (error.Fail())
+      return error;
+  }
+
   // tpidr is always present but tpidr2 depends on SME.
   cached_size += sizeof(RegisterSetType) + GetTLSBufferSize();
   error = ReadTLS();
@@ -867,6 +904,11 @@ Status NativeRegisterContextLinux_arm64::ReadAllRegisterValues(
                             GetFPMRBufferSize());
   }
 
+  if (GetRegisterInfo().IsGCSPresent()) {
+    dst = AddSavedRegisters(dst, RegisterSetType::GCS, GetGCSBuffer(),
+                            GetGCSBufferSize());
+  }
+
   dst = AddSavedRegisters(dst, RegisterSetType::TLS, GetTLSBuffer(),
                           GetTLSBufferSize());
 
@@ -1020,6 +1062,29 @@ Status NativeRegisterContextLinux_arm64::WriteAllRegisterValues(
           GetFPMRBuffer(), &src, GetFPMRBufferSize(), m_fpmr_is_valid,
           std::bind(&NativeRegisterContextLinux_arm64::WriteFPMR, this));
       break;
+    case RegisterSetType::GCS:
+      // It is not permitted to enable GCS via ptrace. We can disable it, but
+      // to keep things simple we will not revert any change to the
+      // PR_SHADOW_STACK_ENABLE bit. Instead patch in the current enable bit
+      // into the registers we are about to restore.
+      m_gcs_is_valid = false;
+      error = ReadGCS();
+      if (error.Fail())
+        return error;
+
+      uint64_t enable_bit = m_gcs_regs.features_enabled & 1UL;
+      gcs_regs new_gcs_regs = *reinterpret_cast<const gcs_regs *>(src);
+      new_gcs_regs.features_enabled =
+          (new_gcs_regs.features_enabled & ~1UL) | enable_bit;
+
+      const uint8_t *new_gcs_src =
+          reinterpret_cast<const uint8_t *>(&new_gcs_regs);
+      error = RestoreRegisters(
+          GetGCSBuffer(), &new_gcs_src, GetGCSBufferSize(), m_gcs_is_valid,
+          std::bind(&NativeRegisterContextLinux_arm64::WriteGCS, this));
+      src += GetGCSBufferSize();
+
+      break;
     }
 
     if (error.Fail())
@@ -1067,6 +1132,10 @@ bool NativeRegisterContextLinux_arm64::IsFPMR(unsigned reg) const {
   return GetRegisterInfo().IsFPMRReg(reg);
 }
 
+bool NativeRegisterContextLinux_arm64::IsGCS(unsigned reg) const {
+  return GetRegisterInfo().IsGCSReg(reg);
+}
+
 llvm::Error NativeRegisterContextLinux_arm64::ReadHardwareDebugInfo() {
   if (!m_refresh_hwdebug_info) {
     return llvm::Error::success();
@@ -1215,6 +1284,7 @@ void NativeRegisterContextLinux_arm64::InvalidateAllRegisters() {
   m_tls_is_valid = false;
   m_zt_buffer_is_valid = false;
   m_fpmr_is_valid = false;
+  m_gcs_is_valid = false;
 
   // Update SVE and ZA registers in case there is change in configuration.
   ConfigureRegisterContext();
@@ -1400,6 +1470,40 @@ Status NativeRegisterContextLinux_arm64::WriteTLS() {
   return WriteRegisterSet(&ioVec, GetTLSBufferSize(), NT_ARM_TLS);
 }
 
+Status NativeRegisterContextLinux_arm64::ReadGCS() {
+  Status error;
+
+  if (m_gcs_is_valid)
+    return error;
+
+  struct iovec ioVec;
+  ioVec.iov_base = GetGCSBuffer();
+  ioVec.iov_len = GetGCSBufferSize();
+
+  error = ReadRegisterSet(&ioVec, GetGCSBufferSize(), NT_ARM_GCS);
+
+  if (error.Success())
+    m_gcs_is_valid = true;
+
+  return error;
+}
+
+Status NativeRegisterContextLinux_arm64::WriteGCS() {
+  Status error;
+
+  error = ReadGCS();
+  if (error.Fail())
+    return error;
+
+  struct iovec ioVec;
+  ioVec.iov_base = GetGCSBuffer();
+  ioVec.iov_len = GetGCSBufferSize();
+
+  m_gcs_is_valid = false;
+
+  return WriteRegisterSet(&ioVec, GetGCSBufferSize(), NT_ARM_GCS);
+}
+
 Status NativeRegisterContextLinux_arm64::ReadZAHeader() {
   Status error;
 
diff --git a/lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.h b/lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.h
index 16190b5492582b..7ed0da85034969 100644
--- a/lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.h
+++ b/lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.h
@@ -92,6 +92,7 @@ class NativeRegisterContextLinux_arm64
   bool m_pac_mask_is_valid;
   bool m_tls_is_valid;
   size_t m_tls_size;
+  bool m_gcs_is_valid;
 
   struct user_pt_regs m_gpr_arm64; // 64-bit general purpose registers.
 
@@ -136,6 +137,12 @@ class NativeRegisterContextLinux_arm64
 
   uint64_t m_fpmr_reg;
 
+  struct gcs_regs {
+    uint64_t features_enabled;
+    uint64_t features_locked;
+    uint64_t gcspr_e0;
+  } m_gcs_regs;
+
   bool IsGPR(unsigned reg) const;
 
   bool IsFPR(unsigned reg) const;
@@ -166,6 +173,10 @@ class NativeRegisterContextLinux_arm64
 
   Status WriteZA();
 
+  Status ReadGCS();
+
+  Status WriteGCS();
+
   // No WriteZAHeader because writing only the header will disable ZA.
   // Instead use WriteZA and ensure you have the correct ZA buffer size set
   // beforehand if you wish to disable it.
@@ -187,6 +198,7 @@ class NativeRegisterContextLinux_arm64
   bool IsMTE(unsigned reg) const;
   bool IsTLS(unsigned reg) const;
   bool IsFPMR(unsigned reg) const;
+  bool IsGCS(unsigned reg) const;
 
   uint64_t GetSVERegVG() { return m_sve_header.vl / 8; }
 
@@ -212,6 +224,8 @@ class NativeRegisterContextLinux_arm64
 
   void *GetFPMRBuffer() { return &m_fpmr_reg; }
 
+  void *GetGCSBuffer() { return &m_gcs_regs; }
+
   size_t GetSVEHeaderSize() { return sizeof(m_sve_header); }
 
   size_t GetPACMaskSize() { return sizeof(m_pac_mask); }
@@ -234,6 +248,8 @@ class NativeRegisterContextLinux_arm64
 
   size_t GetFPMRBufferSize() { return sizeof(m_fpmr_reg); }
 
+  size_t GetGCSBufferSize() { return sizeof(m_gcs_regs); }
+
   llvm::Error ReadHardwareDebugInfo() override;
 
   llvm::Error WriteHardwareDebugRegs(DREGType hwbType) override;
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextPOSIX_arm64.cpp b/lldb/source/Plugins/Process/Utility/RegisterContextPOSIX_arm64.cpp
index 575e9c8c81cbf5..0233837f99d097 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextPOSIX_arm64.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextPOSIX_arm64.cpp
@@ -63,6 +63,10 @@ bool RegisterContextPOSIX_arm64::IsFPMR(unsigned reg) const {
   return m_register_info_up->IsFPMRReg(reg);
 }
 
+bool RegisterContextPOSIX_arm64::IsGCS(unsigned reg) const {
+  return m_register_info_up->IsGCSReg(reg);
+}
+
 RegisterContextPOSIX_arm64::RegisterContextPOSIX_arm64(
     lldb_private::Thread &thread,
     std::unique_ptr<RegisterInfoPOSIX_arm64> register_info)
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextPOSIX_arm64.h b/lldb/source/Plugins/Process/Utility/RegisterContextPOSIX_arm64.h
index 35ad56c98a7aed..de46c628d836d8 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextPOSIX_arm64.h
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextPOSIX_arm64.h
@@ -59,6 +59,7 @@ class RegisterContextPOSIX_arm64 : public lldb_private::RegisterContext {
   bool IsSME(unsigned reg) const;
   bool IsMTE(unsigned reg) const;
   bool IsFPMR(unsigned reg) const;
+  bool IsGCS(unsigned reg) const;
 
   bool IsSVEZ(unsigned reg) const { return m_register_info_up->IsSVEZReg(reg); }
   bool IsSVEP(unsigned reg) const { return m_register_info_up->IsSVEPReg(reg); }
diff --git a/lldb/source/Plugins/Process/Utility/RegisterFlagsDetector_arm64.cpp b/lldb/source/Plugins/Process/Utility/RegisterFlagsDetector_arm64.cpp
index 9f82c935c0e7ed..1438a45f37d724 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterFlagsDetector_arm64.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterFlagsDetector_arm64.cpp
@@ -17,6 +17,7 @@
 #define HWCAP_ASIMDHP (1ULL << 10)
 #define HWCAP_DIT (1ULL << 24)
 #define HWCAP_SSBS (1ULL << 28)
+#define HWCAP_GCS (1UL << 32)
 
 #define HWCAP2_BTI (1ULL << 17)
 #define HWCAP2_MTE (1ULL << 18)
@@ -50,6 +51,21 @@ Arm64RegisterFlagsDetector::DetectFPMRFields(uint64_t hwcap, uint64_t hwcap2) {
   };
 }
 
+Arm64RegisterFlagsDetector::Fields
+Arm64RegisterFlagsDetector::DetectGCSFeatureFields(uint64_t hwcap,
+                                                   uint64_t hwcap2) {
+  (void)hwcap2;
+
+  if (!(hwcap & HWCAP_GCS))
+    return {};
+
+  return {
+      {"PUSH", 2},
+      {"WRITE", 1},
+      {"ENABLE", 0},
+  };
+}
+
 Arm64RegisterFlagsDetector::Fields
 Arm64RegisterFlagsDetector::DetectSVCRFields(uint64_t hwcap, uint64_t hwcap2) {
   (void)hwcap;
diff --git a/lldb/source/Plugins/Process/Utility/RegisterFlagsDetector_arm64.h b/lldb/source/Plugins/Process/Utility/RegisterFlagsDetector_arm64.h
index 0f3d53d93892bd..7daebcc71db044 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterFlagsDetector_arm64.h
+++ b/lldb/source/Plugins/Process/Utility/RegisterFlagsDetector_arm64.h
@@ -61,6 +61,7 @@ class Arm64RegisterFlagsDetector {
   static Fields DetectMTECtrlFields(uint64_t hwcap, uint64_t hwcap2);
   static Fields DetectSVCRFields(uint64_t hwcap, uint64_t hwcap2);
   static Fields DetectFPMRFields(uint64_t hwcap, uint64_t hwcap2);
+  static Fields DetectGCSFeatureFields(uint64_t hwcap, uint64_t hwcap2);
 
   struct RegisterEntry {
     RegisterEntry(llvm::StringRef name, unsigned size, DetectorFn detector)
@@ -70,13 +71,15 @@ class Arm64RegisterFlagsDetector {
     llvm::StringRef m_name;
     RegisterFlags m_flags;
     DetectorFn m_detector;
-  } m_registers[6] = {
+  } m_registers[8] = {
       RegisterEntry("cpsr", 4, DetectCPSRFields),
       RegisterEntry("fpsr", 4, DetectFPSRFields),
       RegisterEntry("fpcr", 4, DetectFPCRFields),
       RegisterEntry("mte_ctrl", 8, DetectMTECtrlFields),
       RegisterEntry("svcr", 8, DetectSVCRFields),
       RegisterEntry("fpmr", 8, DetectFPMRFields),
+      RegisterEntry("gcs_features_enabled", 8, DetectGCSFeatureFields),
+      RegisterEntry("gcs_features_locked", 8, DetectGCSFeatureFields),
   };
 
   // Becomes true once field detection has been run for all registers.
diff --git a/lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.cpp b/lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.cpp
index f51a93e1b2dcbd..c004c0f3c3cf52 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterInfoPOSIX_arm64.cpp
@@ -97,6 +97,10 @@ static lldb_private::RegisterInfo g_register_infos_sme2[] = {
 static lldb_private::RegisterInfo g_register_infos_fpmr[] = {
     DEFINE_EXTENSION_REG(fpmr)};
 
+static lldb_private::RegisterInfo g_register_infos_gcs[] = {
+    DEFINE_EXTENSION_REG(gcs_features_enabled),
+    DEFINE_EXTENSION_REG(gcs_features_locked), DEFINE_EXTENSION_REG(gcspr_el0)};
+
 // Number of register sets provided by this context.
 enum {
   k_num_gpr_registers = gpr_w28 - gpr_x0 + 1,
@@ -109,6 +113,7 @@ enum {
   // only for SME1 registers.
   k_num_sme_register = 3,
   k_num_fpmr_register = 1,
+  k_num_gcs_register = 3,
   k_num_register_sets_default = 2,
   k_num_register_sets = 3
 };
@@ -221,6 +226,9 @@ static const lldb_private::RegisterSet g_reg_set_sme_arm64 = {
 static const lldb_private::RegisterSet g_reg_set_fpmr_arm64 = {
     "Floating Point Mode Register", "fpmr", k_num_fpmr_register, nullptr};
 
+static const lldb_private::RegisterSet g_reg_set_gcs_arm64 = {
+    "Guarded Control Stack Registers", "gcs", k_num_gcs_register, nullptr};
+
 RegisterInfoPOSIX_arm64::RegisterInfoPOSIX_arm64(
     const lldb_private::ArchSpec &target_arch, lldb_private::Flags opt_regsets)
     : lldb_private::RegisterInfoAndSetInterface(target_arch),
@@ -273,6 +281,9 @@ RegisterInfoPOSIX_arm64::RegisterInfoPOSIX_arm64(
       if (m_opt_regsets.AllSet(eRegsetMaskFPMR))
         AddRegSetFPMR();
 
+      if (m_opt_regsets.AllSet(eRegsetMaskGCS))
+        AddRegSetGCS();
+
       m_register_info_count = m_dynamic_reg_infos.size();
       m_register_info_p = m_dynamic_reg_infos.data();
       m_register_set_p = m_dynamic_reg_sets.data();
@@ -434,6 +445,24 @@ void RegisterInfoPOSIX_arm64::AddRegSetFPMR() {
   m_dynamic_reg_sets.back().registers = m_fpmr_regnum_collection.data();
 }
 
+void RegisterInfoPOSIX_arm64::AddRegSetGCS() {
+  uint32_t gcs_regnum = m_dynamic_reg_infos.size();
+  for (uint32_t i = 0; i < k_num_gcs_register; i++) {
+    m_gcs_regnum_collection.push_back(gcs_regnum + i);
+    m_dynamic_reg_infos.push_back(g_register_infos_gcs[i]);
+    m_dynamic_reg_infos[gcs_regnum + i].byte_offset =
+        m_dynamic_reg_infos[gcs_regnum + i - 1].byte_offset +
+        m_dynamic_reg_infos[gcs_regnum + i - 1].byte_size;
+    m_dynamic_reg_infos[gcs_regnum + i].kinds[lldb::eRegisterKindLLDB] =
+        gcs_regnum + i;
+  }
+
+  m_per_regset_regnum_range[m_register_set_count] =
+      std::make_pair(gcs_regnum, m_dynamic_reg_infos.size());
+  m_dynamic_reg_sets.push_back(g_reg_set_gcs_arm64);
+  m_dynamic_reg_sets.back().registers = m_gcs_regnum_collection.data();
+}
+
 uint32_t RegisterInfoPOSIX_arm64::ConfigureVectorLengthSVE(uint32_t sve_vq) {
   // sve_vq contains SVE Quad vector length in context of AArch64 SVE.
   // SVE register info...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/124295


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