1 files changed, 96 insertions, 0 deletions
diff --git a/src/vm/arm64/cgencpu.h b/src/vm/arm64/cgencpu.h
index 7d01f9d6ff..ea5fe7b4fc 100644
--- a/src/vm/arm64/cgencpu.h
+++ b/src/vm/arm64/cgencpu.h
@@ -48,6 +48,8 @@ extern PCODE GetPreStubEntryPoint();
 #define HAS_RELATIVE_FIXUP_PRECODE              1
 #endif
 
+#define HAS_RELATIVE_STUB_PRECODE               1
+
 // ThisPtrRetBufPrecode one is necessary for closed delegates over static methods with return buffer
 #define HAS_THISPTR_RETBUF_PRECODE              1
 
@@ -627,6 +629,15 @@ struct StubPrecode {
             (LONGLONG*)&m_pTarget, (TADDR)target, (TADDR)expected) == expected;
     }
 
+    static BOOL IsStubPrecodeByASM(PCODE addr)
+    {
+        PTR_DWORD pInstr = dac_cast<PTR_DWORD>(PCODEToPINSTR(addr));
+        return
+            (pInstr[0] == 0x10000089) &&
+            (pInstr[1] == 0xA940312A) &&
+            (pInstr[2] == 0xD61F0140);
+    }
+
 #ifdef FEATURE_PREJIT
     void Fixup(DataImage *image);
 #endif
@@ -634,6 +645,91 @@ struct StubPrecode {
 typedef DPTR(StubPrecode) PTR_StubPrecode;
 
 
+struct RelativeStubPrecode {
+
+    static const int Type = 0xC9;
+
+    // adr x9, #24
+    // ldp x10,x12,[x9]        ; =m_pTargetOffset,m_pMethodDescOffset
+    // add x12,x12,x9
+    // add x10,x10,x9
+    // br x10
+    // 4 byte padding for 8 byte allignement
+    // dcd m_pTargetOffset     ; m_pTargetOffset is relative to itself
+    // dcd m_pMethodDescOffset ; m_pMethodDescOffset is relative to location of m_pTargetOffset
+
+    DWORD   m_rgCode[6];
+    TADDR   m_pTargetOffset;
+    TADDR   m_pMethodDescOffset;
+
+    void Init(MethodDesc* pMD, LoaderAllocator *pLoaderAllocator);
+
+    static TADDR GetTargetOffset()
+    {
+        LIMITED_METHOD_DAC_CONTRACT;
+        return offsetof(RelativeStubPrecode, m_pTargetOffset);
+    }
+
+    TADDR GetMethodDesc()
+    {
+        LIMITED_METHOD_DAC_CONTRACT;
+        return dac_cast<TADDR>(this) + GetTargetOffset() + m_pMethodDescOffset;
+    }
+
+    PCODE GetTarget()
+    {
+        LIMITED_METHOD_DAC_CONTRACT;
+        return dac_cast<TADDR>(this) + GetTargetOffset() + m_pTargetOffset;
+    }
+
+    void ResetTargetInterlocked()
+    {
+        CONTRACTL
+        {
+            THROWS;
+            GC_NOTRIGGER;
+        }
+        CONTRACTL_END;
+
+        EnsureWritableExecutablePages(&m_pTargetOffset);
+        TADDR addr = (TADDR)GetPreStubEntryPoint() - (TADDR)(this) - GetTargetOffset();
+        InterlockedExchange64((LONGLONG*)&m_pTargetOffset, addr);
+    }
+
+    BOOL SetTargetInterlocked(TADDR target, TADDR expected)
+    {
+        CONTRACTL
+        {
+            THROWS;
+            GC_NOTRIGGER;
+        }
+        CONTRACTL_END;
+
+        EnsureWritableExecutablePages(&m_pTargetOffset);
+        TADDR addrExpected = expected - (TADDR)(this) - GetTargetOffset();
+        TADDR addrTarget = target - (TADDR)(this) - GetTargetOffset();
+        return (TADDR)InterlockedCompareExchange64(
+            (LONGLONG*)&m_pTargetOffset, addrTarget, addrExpected) == addrExpected;
+    }
+
+    static BOOL IsRelativeStubPrecodeByASM(PCODE addr)
+    {
+        PTR_DWORD pInstr = dac_cast<PTR_DWORD>(PCODEToPINSTR(addr));
+        return
+            (pInstr[0] == 0x100000C9) &&
+            (pInstr[1] == 0xA940312A) &&
+            (pInstr[2] == 0x8B09018C) &&
+            (pInstr[3] == 0x8B09014A) &&
+            (pInstr[4] == 0xD61F0140);
+    }
+
+#ifdef FEATURE_PREJIT
+    void Fixup(DataImage *image);
+#endif
+};
+typedef DPTR(RelativeStubPrecode) PTR_RelativeStubPrecode;
+
+
 struct NDirectImportPrecode {
 
     static const int Type = 0x8B;