[lldb] Introduce Process::FixAnyAddressPreservingAuthentication

lldb/include/lldb/Target/ABI.h

@@ -141,6 +141,10 @@ class ABI : public PluginInterface {
     return FixDataAddress(pc);
   }
 
+  virtual lldb::addr_t FixAnyAddressPreservingAuthentication(lldb::addr_t pc) {
+    return FixAnyAddress(pc);
+  }
+
   llvm::MCRegisterInfo &GetMCRegisterInfo() { return *m_mc_register_info_up; }
 
   virtual void

lldb/include/lldb/Target/Process.h

@@ -1464,6 +1464,11 @@ class Process : public std::enable_shared_from_this<Process>,
   /// platforms where there is a difference (only Arm Thumb at this time).
   lldb::addr_t FixAnyAddress(lldb::addr_t pc);
 
+  /// Strip pointer metadata except for the bits necessary to authenticate a
+  /// memory access. This is useful, for example, if `address` requires
+  /// authentication and it is going to be consumed in JITed code.
+  lldb::addr_t FixAnyAddressPreservingAuthentication(lldb::addr_t address);
+
   /// Get the Modification ID of the process.
   ///
   /// \return

lldb/source/Expression/IRMemoryMap.cpp

@@ -647,7 +647,7 @@ void IRMemoryMap::WritePointerToMemory(lldb::addr_t process_address,
   if (it == m_allocations.end() ||
       it->second.m_policy != AllocationPolicy::eAllocationPolicyHostOnly)
     if (auto process_sp = GetProcessWP().lock())
-      pointer = process_sp->FixAnyAddress(pointer);
+      pointer = process_sp->FixAnyAddressPreservingAuthentication(pointer);
 
   Scalar scalar(pointer);
 

lldb/source/Plugins/ABI/AArch64/ABIMacOSX_arm64.cpp

@@ -792,6 +792,15 @@ addr_t ABIMacOSX_arm64::FixDataAddress(addr_t addr) {
   return DoFixAddr(addr, false /*is_code*/, GetProcessSP());
 }
 
+addr_t ABIMacOSX_arm64::FixAnyAddressPreservingAuthentication(addr_t addr) {
+  // Save the old MTE tag and restore it later.
+  constexpr addr_t mte_mask = 0x0f00000000000000ULL;
+  addr_t old_mte_tag = addr & mte_mask;
+
+  addr_t fixed_addr = FixDataAddress(addr);
+  return old_mte_tag | (fixed_addr & (~mte_mask));
+}
+
 void ABIMacOSX_arm64::Initialize() {
   PluginManager::RegisterPlugin(GetPluginNameStatic(), pluginDesc,
                                 CreateInstance);

lldb/source/Plugins/ABI/AArch64/ABIMacOSX_arm64.h

@@ -59,6 +59,7 @@ class ABIMacOSX_arm64 : public ABIAArch64 {
 
   lldb::addr_t FixCodeAddress(lldb::addr_t pc) override;
   lldb::addr_t FixDataAddress(lldb::addr_t pc) override;
+  lldb::addr_t FixAnyAddressPreservingAuthentication(lldb::addr_t pc) override;
 
   // Static Functions
 

lldb/source/Target/Process.cpp

@@ -5971,6 +5971,12 @@ addr_t Process::FixAnyAddress(addr_t addr) {
   return addr;
 }
 
+addr_t Process::FixAnyAddressPreservingAuthentication(addr_t addr) {
+  if (ABISP abi_sp = GetABI())
+    addr = abi_sp->FixAnyAddressPreservingAuthentication(addr);
+  return addr;
+}
+
 void Process::DidExec() {
   Log *log = GetLog(LLDBLog::Process);
   LLDB_LOGF(log, "Process::%s()", __FUNCTION__);

lldb/test/API/pointer-nonaddressable-bits/TestArmPointerMetadataStripping.py

@@ -41,8 +41,15 @@ def test(self):
         symbols_file = self.create_symbols_file()
         self.runCmd(f"target module add {symbols_file}")
 
+        # The address of myglobal_json is: 0x1200AAAAAAAB1014
         # The high order bits should be stripped.
-        self.expect_expr("get_high_bits(&myglobal_json)", result_value="0")
+        # On Darwin platforms, the lower nibble of the most significant byte is preserved.
+        if platform.system() == "Darwin":
+            expected_value = str(0x200000000000000)
+        else:
+            expected_value = "0"
+
+        self.expect_expr("get_high_bits(&myglobal_json)", result_value=expected_value)
 
         # Mark all bits as used for addresses and ensure bits are no longer stripped.
         self.runCmd("settings set target.process.virtual-addressable-bits 64")