8286711: AArch64: serviceability agent tests fail with PAC enabled

Reviewed-by: dholmes, cjplummer

src/hotspot/cpu/aarch64/pauth_aarch64.hpp

@@ -25,6 +25,10 @@
 #ifndef CPU_AARCH64_PAUTH_AARCH64_HPP
 #define CPU_AARCH64_PAUTH_AARCH64_HPP
 
+#include "runtime/vm_version.hpp"
+#include "utilities/globalDefinitions.hpp"
+#include "utilities/macros.hpp"
+
 #include OS_CPU_HEADER_INLINE(pauth)
 
 // Support for ROP Protection in VM code.

src/hotspot/cpu/aarch64/vmStructs_aarch64.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2022, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2014, Red Hat Inc. All rights reserved. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -31,9 +31,12 @@
 // referenced by vmStructs.cpp.
 
 #define VM_STRUCTS_CPU(nonstatic_field, static_field, unchecked_nonstatic_field, volatile_nonstatic_field, nonproduct_nonstatic_field, c2_nonstatic_field, unchecked_c1_static_field, unchecked_c2_static_field) \
-  volatile_nonstatic_field(JavaFrameAnchor, _last_Java_fp, intptr_t*)
+  volatile_nonstatic_field(JavaFrameAnchor, _last_Java_fp,   intptr_t*) \
+              static_field(VM_Version,      _rop_protection, bool)      \
+              static_field(VM_Version,      _pac_mask,       uintptr_t)
 
-#define VM_TYPES_CPU(declare_type, declare_toplevel_type, declare_oop_type, declare_integer_type, declare_unsigned_integer_type, declare_c1_toplevel_type, declare_c2_type, declare_c2_toplevel_type)
+#define VM_TYPES_CPU(declare_type, declare_toplevel_type, declare_oop_type, declare_integer_type, declare_unsigned_integer_type, declare_c1_toplevel_type, declare_c2_type, declare_c2_toplevel_type) \
+  declare_toplevel_type(VM_Version)
 
 #define VM_INT_CONSTANTS_CPU(declare_constant, declare_preprocessor_constant, declare_c1_constant, declare_c2_constant, declare_c2_preprocessor_constant)
 

src/hotspot/cpu/aarch64/vm_version_aarch64.cpp

@@ -24,6 +24,7 @@
  */
 
 #include "precompiled.hpp"
+#include "pauth_aarch64.hpp"
 #include "runtime/arguments.hpp"
 #include "runtime/globals_extension.hpp"
 #include "runtime/java.hpp"
@@ -46,6 +47,7 @@ int VM_Version::_dcache_line_size;
 int VM_Version::_icache_line_size;
 int VM_Version::_initial_sve_vector_length;
 bool VM_Version::_rop_protection;
+uintptr_t VM_Version::_pac_mask;
 
 SpinWait VM_Version::_spin_wait;
 
@@ -444,8 +446,12 @@ void VM_Version::initialize() {
     vm_exit_during_initialization(err_msg("Unsupported UseBranchProtection: %s", UseBranchProtection));
   }
 
-  // The frame pointer must be preserved for ROP protection.
   if (_rop_protection == true) {
+    // Determine the mask of address bits used for PAC. Clear bit 55 of
+    // the input to make it look like a user address.
+    _pac_mask = (uintptr_t)pauth_strip_pointer((address)~(UINT64_C(1) << 55));
+
+    // The frame pointer must be preserved for ROP protection.
     if (FLAG_IS_DEFAULT(PreserveFramePointer) == false && PreserveFramePointer == false ) {
       vm_exit_during_initialization(err_msg("PreserveFramePointer cannot be disabled for ROP-protection"));
     }

src/hotspot/cpu/aarch64/vm_version_aarch64.hpp

@@ -31,6 +31,7 @@
 #include "utilities/sizes.hpp"
 
 class VM_Version : public Abstract_VM_Version {
+  friend class VMStructs;
   friend class JVMCIVMStructs;
 
 protected:
@@ -46,6 +47,7 @@ protected:
   static int _icache_line_size;
   static int _initial_sve_vector_length;
   static bool _rop_protection;
+  static uintptr_t _pac_mask;
 
   static SpinWait _spin_wait;
 

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/aarch64/AARCH64Frame.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2022, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2015, 2019, Red Hat Inc.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -70,6 +70,9 @@ public class AARCH64Frame extends Frame {
   // Native frames
   private static final int NATIVE_FRAME_INITIAL_PARAM_OFFSET =  2;
 
+  private static CIntegerField ropProtectionField;
+  private static CIntegerField pacMaskField;
+
   private static VMReg fp = new VMReg(29 << 1);
 
   static {
@@ -90,8 +93,11 @@ public class AARCH64Frame extends Frame {
     INTERPRETER_FRAME_INITIAL_SP_OFFSET           = INTERPRETER_FRAME_BCX_OFFSET - 1;
     INTERPRETER_FRAME_MONITOR_BLOCK_TOP_OFFSET    = INTERPRETER_FRAME_INITIAL_SP_OFFSET;
     INTERPRETER_FRAME_MONITOR_BLOCK_BOTTOM_OFFSET = INTERPRETER_FRAME_INITIAL_SP_OFFSET;
-  }
 
+    Type vmVersion = db.lookupType("VM_Version");
+    ropProtectionField = vmVersion.getCIntegerField("_rop_protection");
+    pacMaskField = vmVersion.getCIntegerField("_pac_mask");
+  }
 
   // an additional field beyond sp and pc:
   Address raw_fp; // frame pointer
@@ -391,7 +397,7 @@ public class AARCH64Frame extends Frame {
     Address senderSP = getUnextendedSP().addOffsetTo(cb.getFrameSize());
 
     // The return_address is always the word on the stack
-    Address senderPC = senderSP.getAddressAt(-1 * VM.getVM().getAddressSize());
+    Address senderPC = stripPAC(senderSP.getAddressAt(-1 * VM.getVM().getAddressSize()));
 
     // This is the saved value of FP which may or may not really be an FP.
     // It is only an FP if the sender is an interpreter frame.
@@ -445,7 +451,19 @@ public class AARCH64Frame extends Frame {
 
   // Return address:
   public Address getSenderPCAddr() { return addressOfStackSlot(RETURN_ADDR_OFFSET); }
-  public Address getSenderPC()     { return getSenderPCAddr().getAddressAt(0);      }
+  public Address getSenderPC()     { return stripPAC(getSenderPCAddr().getAddressAt(0)); }
+
+  // Remove any embedded pointer authentication code from an address.
+  private Address stripPAC(Address addr) {
+    // Really we should use the XPACI instruction to do this but we
+    // can't access that from Java so rely on the mask of PAC bits
+    // calculated by vm_version_aarch64.cpp on startup.
+    if (ropProtectionField.getValue() != 0) {
+      return addr.andWithMask(pacMaskField.getValue());
+    } else {
+      return addr;
+    }
+  }
 
   // return address of param, zero origin index.
   public Address getNativeParamAddr(int idx) {