8219993: AArch64: Compiled CI stubs are unsafely modified

Reviewed-by: adinn

src/hotspot/cpu/aarch64/c1_LIRAssembler_aarch64.cpp

@@ -34,6 +34,7 @@
 #include "c1/c1_ValueStack.hpp"
 #include "ci/ciArrayKlass.hpp"
 #include "ci/ciInstance.hpp"
+#include "code/compiledIC.hpp"
 #include "gc/shared/barrierSet.hpp"
 #include "gc/shared/cardTableBarrierSet.hpp"
 #include "gc/shared/collectedHeap.hpp"
@@ -2063,11 +2064,10 @@ void LIR_Assembler::emit_static_call_stub() {
   int start = __ offset();
 
   __ relocate(static_stub_Relocation::spec(call_pc));
-  __ mov_metadata(rmethod, (Metadata*)NULL);
+  __ emit_static_call_stub();
-  __ movptr(rscratch1, 0);
-  __ br(rscratch1);
 
-  assert(__ offset() - start <= call_stub_size(), "stub too big");
+  assert(__ offset() - start + CompiledStaticCall::to_trampoline_stub_size()
+        <= call_stub_size(), "stub too big");
   __ end_a_stub();
 }
 

src/hotspot/cpu/aarch64/c1_LIRAssembler_aarch64.hpp

@@ -69,7 +69,9 @@ friend class ArrayCopyStub;
   void deoptimize_trap(CodeEmitInfo *info);
 
   enum {
-    _call_stub_size = 12 * NativeInstruction::instruction_size,
+    // call stub: CompiledStaticCall::to_interp_stub_size() +
+    //            CompiledStaticCall::to_trampoline_stub_size()
+    _call_stub_size = 13 * NativeInstruction::instruction_size,
     _call_aot_stub_size = 0,
     _exception_handler_size = DEBUG_ONLY(1*K) NOT_DEBUG(175),
     _deopt_handler_size = 7 * NativeInstruction::instruction_size

src/hotspot/cpu/aarch64/compiledIC_aarch64.cpp

@@ -61,15 +61,15 @@ address CompiledStaticCall::emit_to_interp_stub(CodeBuffer &cbuf, address mark)
   // Don't create a Metadata reloc if we're generating immutable PIC.
   if (cbuf.immutable_PIC()) {
     __ movptr(rmethod, 0);
-  } else {
-    __ mov_metadata(rmethod, (Metadata*)NULL);
-  }
-#else
-  __ mov_metadata(rmethod, (Metadata*)NULL);
-#endif
     __ movptr(rscratch1, 0);
     __ br(rscratch1);
 
+  } else
+#endif
+  {
+    __ emit_static_call_stub();
+  }
+
   assert((__ offset() - offset) <= (int)to_interp_stub_size(), "stub too big");
   __ end_a_stub();
   return base;
@@ -77,7 +77,8 @@ address CompiledStaticCall::emit_to_interp_stub(CodeBuffer &cbuf, address mark)
 #undef __
 
 int CompiledStaticCall::to_interp_stub_size() {
-  return 7 * NativeInstruction::instruction_size;
+  // isb; movk; movz; movz; movk; movz; movz; br
+  return 8 * NativeInstruction::instruction_size;
 }
 
 int CompiledStaticCall::to_trampoline_stub_size() {
@@ -159,7 +160,8 @@ void CompiledDirectStaticCall::set_to_interpreted(const methodHandle& callee, ad
   }
 
   // Creation also verifies the object.
-  NativeMovConstReg* method_holder = nativeMovConstReg_at(stub);
+  NativeMovConstReg* method_holder
+    = nativeMovConstReg_at(stub + NativeInstruction::instruction_size);
 #ifndef PRODUCT
   NativeGeneralJump* jump = nativeGeneralJump_at(method_holder->next_instruction_address());
 
@@ -184,7 +186,8 @@ void CompiledDirectStaticCall::set_stub_to_clean(static_stub_Relocation* static_
   assert(stub != NULL, "stub not found");
   assert(CompiledICLocker::is_safe(stub), "mt unsafe call");
   // Creation also verifies the object.
-  NativeMovConstReg* method_holder = nativeMovConstReg_at(stub);
+  NativeMovConstReg* method_holder
+    = nativeMovConstReg_at(stub + NativeInstruction::instruction_size);
   method_holder->set_data(0);
 }
 
@@ -201,7 +204,8 @@ void CompiledDirectStaticCall::verify() {
   address stub = find_stub(false /* is_aot */);
   assert(stub != NULL, "no stub found for static call");
   // Creation also verifies the object.
-  NativeMovConstReg* method_holder = nativeMovConstReg_at(stub);
+  NativeMovConstReg* method_holder
+    = nativeMovConstReg_at(stub + NativeInstruction::instruction_size);
   NativeJump* jump = nativeJump_at(method_holder->next_instruction_address());
 
   // Verify state.

src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp

@@ -812,6 +812,18 @@ address MacroAssembler::emit_trampoline_stub(int insts_call_instruction_offset,
   return stub_start_addr;
 }
 
+void MacroAssembler::emit_static_call_stub() {
+  // CompiledDirectStaticCall::set_to_interpreted knows the
+  // exact layout of this stub.
+
+  isb();
+  mov_metadata(rmethod, (Metadata*)NULL);
+
+  // Jump to the entry point of the i2c stub.
+  movptr(rscratch1, 0);
+  br(rscratch1);
+}
+
 void MacroAssembler::c2bool(Register x) {
   // implements x == 0 ? 0 : 1
   // note: must only look at least-significant byte of x

src/hotspot/cpu/aarch64/macroAssembler_aarch64.hpp

@@ -607,6 +607,7 @@ public:
   static int patch_narrow_klass(address insn_addr, narrowKlass n);
 
   address emit_trampoline_stub(int insts_call_instruction_offset, address target);
+  void emit_static_call_stub();
 
   // The following 4 methods return the offset of the appropriate move instruction
 

src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp

@@ -232,7 +232,11 @@ void NativeCall::insert(address code_pos, address entry) { Unimplemented(); }
 //-------------------------------------------------------------------
 
 void NativeMovConstReg::verify() {
-  // make sure code pattern is actually mov reg64, imm64 instructions
+  if (! (nativeInstruction_at(instruction_address())->is_movz() ||
+        is_adrp_at(instruction_address()) ||
+        is_ldr_literal_at(instruction_address())) ) {
+    fatal("should be MOVZ or ADRP or LDR (literal)");
+  }
 }