[lldb][AArch64] Add memory-tagging qSupported feature

This feature "memory-tagging+" indicates that lldb-server
supports memory tagging packets. (added in a later patch)

We check HWCAP2_MTE to decide whether to enable this
feature for Linux.

Reviewed By: omjavaid

Differential Revision: https://reviews.llvm.org/D97282

Author: DavidSpickett

lldb/include/lldb/Host/common/NativeProcessProtocol.h

@@ -243,8 +243,9 @@ class NativeProcessProtocol {
     pass_signals = (1u << 3),
     auxv = (1u << 4),
     libraries_svr4 = (1u << 5),
+    memory_tagging = (1u << 6),
 
-    LLVM_MARK_AS_BITMASK_ENUM(libraries_svr4)
+    LLVM_MARK_AS_BITMASK_ENUM(memory_tagging)
   };
 
   class Factory {

lldb/include/lldb/Target/Process.h

@@ -2721,6 +2721,13 @@ void PruneThreadPlans();
   ///     false.
   bool RouteAsyncStructuredData(const StructuredData::ObjectSP object_sp);
 
+  /// Check whether the process supports memory tagging.
+  ///
+  /// \return
+  ///     true if the process supports memory tagging,
+  ///     false otherwise.
+  virtual bool SupportsMemoryTagging() { return false; }
+
   // Type definitions
   typedef std::map<lldb::LanguageType, lldb::LanguageRuntimeSP>
       LanguageRuntimeCollection;

lldb/packages/Python/lldbsuite/test/tools/lldb-server/gdbremote_testcase.py

@@ -858,6 +858,7 @@ def add_qSupported_packets(self, client_features=[]):
         "multiprocess",
         "fork-events",
         "vfork-events",
+        "memory-tagging",
     ]
 
     def parse_qSupported_response(self, context):

lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp

@@ -53,11 +53,20 @@
 #include <sys/user.h>
 #include <sys/wait.h>
 
+#ifdef __aarch64__
+#include <asm/hwcap.h>
+#include <sys/auxv.h>
+#endif
+
 // Support hardware breakpoints in case it has not been defined
 #ifndef TRAP_HWBKPT
 #define TRAP_HWBKPT 4
 #endif
 
+#ifndef HWCAP2_MTE
+#define HWCAP2_MTE (1 << 18)
+#endif
+
 using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::process_linux;
@@ -283,8 +292,17 @@ NativeProcessLinux::Factory::Attach(
 
 NativeProcessLinux::Extension
 NativeProcessLinux::Factory::GetSupportedExtensions() const {
-  return Extension::multiprocess | Extension::fork | Extension::vfork |
-         Extension::pass_signals | Extension::auxv | Extension::libraries_svr4;
+  NativeProcessLinux::Extension supported =
+      Extension::multiprocess | Extension::fork | Extension::vfork |
+      Extension::pass_signals | Extension::auxv | Extension::libraries_svr4;
+
+#ifdef __aarch64__
+  // At this point we do not have a process so read auxv directly.
+  if ((getauxval(AT_HWCAP2) & HWCAP2_MTE))
+    supported |= Extension::memory_tagging;
+#endif
+
+  return supported;
 }
 
 // Public Instance Methods

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp

@@ -311,6 +311,7 @@ void GDBRemoteCommunicationClient::GetRemoteQSupported() {
   m_supports_multiprocess = eLazyBoolNo;
   m_supports_qEcho = eLazyBoolNo;
   m_supports_QPassSignals = eLazyBoolNo;
+  m_supports_memory_tagging = eLazyBoolNo;
 
   m_max_packet_size = UINT64_MAX; // It's supposed to always be there, but if
                                   // not, we assume no limit
@@ -356,6 +357,8 @@ void GDBRemoteCommunicationClient::GetRemoteQSupported() {
         m_supports_QPassSignals = eLazyBoolYes;
       else if (x == "multiprocess+")
         m_supports_multiprocess = eLazyBoolYes;
+      else if (x == "memory-tagging+")
+        m_supports_memory_tagging = eLazyBoolYes;
       // Look for a list of compressions in the features list e.g.
       // qXfer:features:read+;PacketSize=20000;qEcho+;SupportedCompressions=zlib-
       // deflate,lzma
@@ -576,6 +579,13 @@ bool GDBRemoteCommunicationClient::GetSharedCacheInfoSupported() {
   return m_supports_jGetSharedCacheInfo;
 }
 
+bool GDBRemoteCommunicationClient::GetMemoryTaggingSupported() {
+  if (m_supports_memory_tagging == eLazyBoolCalculate) {
+    GetRemoteQSupported();
+  }
+  return m_supports_memory_tagging == eLazyBoolYes;
+}
+
 bool GDBRemoteCommunicationClient::GetxPacketSupported() {
   if (m_supports_x == eLazyBoolCalculate) {
     StringExtractorGDBRemote response;

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h

@@ -451,6 +451,8 @@ class GDBRemoteCommunicationClient : public GDBRemoteClientBase {
 
   bool GetSharedCacheInfoSupported();
 
+  bool GetMemoryTaggingSupported();
+
   /// Use qOffsets to query the offset used when relocating the target
   /// executable. If successful, the returned structure will contain at least
   /// one value in the offsets field.
@@ -558,6 +560,7 @@ class GDBRemoteCommunicationClient : public GDBRemoteClientBase {
   LazyBool m_supports_QPassSignals = eLazyBoolCalculate;
   LazyBool m_supports_error_string_reply = eLazyBoolCalculate;
   LazyBool m_supports_multiprocess = eLazyBoolCalculate;
+  LazyBool m_supports_memory_tagging = eLazyBoolCalculate;
 
   bool m_supports_qProcessInfoPID : 1, m_supports_qfProcessInfo : 1,
       m_supports_qUserName : 1, m_supports_qGroupName : 1,

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp

@@ -3608,6 +3608,8 @@ std::vector<std::string> GDBRemoteCommunicationServerLLGS::HandleFeatures(
     ret.push_back("qXfer:auxv:read+");
   if (bool(plugin_features & Extension::libraries_svr4))
     ret.push_back("qXfer:libraries-svr4:read+");
+  if (bool(plugin_features & Extension::memory_tagging))
+    ret.push_back("memory-tagging+");
 
   // check for client features
   m_extensions_supported = {};

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

@@ -2767,6 +2767,10 @@ size_t ProcessGDBRemote::DoReadMemory(addr_t addr, void *buf, size_t size,
   return 0;
 }
 
+bool ProcessGDBRemote::SupportsMemoryTagging() {
+  return m_gdb_comm.GetMemoryTaggingSupported();
+}
+
 Status ProcessGDBRemote::WriteObjectFile(
     std::vector<ObjectFile::LoadableData> entries) {
   Status error;

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h

@@ -235,6 +235,8 @@ class ProcessGDBRemote : public Process,
   friend class GDBRemoteCommunicationClient;
   friend class GDBRemoteRegisterContext;
 
+  bool SupportsMemoryTagging() override;
+
   /// Broadcaster event bits definitions.
   enum {
     eBroadcastBitAsyncContinue = (1 << 0),

lldb/test/API/tools/lldb-server/TestLldbGdbServer.py

@@ -1025,6 +1025,14 @@ def test_qSupported_vfork_events_without_multiprocess(self):
         self.assertEqual(supported_dict.get('fork-events', '-'), '-')
         self.assertEqual(supported_dict.get('vfork-events', '-'), '-')
 
+    # We need to be able to self.runCmd to get cpuinfo,
+    # which is not possible when using a remote platform.
+    @skipIfRemote
+    def test_qSupported_memory_tagging(self):
+        supported_dict = self.get_qSupported_dict()
+        self.assertEqual(supported_dict.get("memory-tagging", '-'),
+                         '+' if self.isAArch64MTE() else '-')
+
     @skipIfWindows # No pty support to test any inferior output
     def test_written_M_content_reads_back_correctly(self):
         self.build()