Write protect executable pages in the VM.

runtime/vm/debugger.cc

Index: runtime/vm/debugger.cc
diff --git a/runtime/vm/debugger.cc b/runtime/vm/debugger.cc
index f84dc2e0db20743b28b4ea1770331414d26bbc2e..d182aa6c8fcf9533f499f2aa3ebe07c6c05583b1 100644
--- a/runtime/vm/debugger.cc
+++ b/runtime/vm/debugger.cc
@@ -753,40 +753,40 @@ intptr_t CodeBreakpoint::LineNumber() {
 
 void CodeBreakpoint::PatchCode() {
   ASSERT(!is_enabled_);
-  switch (breakpoint_kind_) {
-    case PcDescriptors::kIcCall: {
-      const Code& code =
-          Code::Handle(Function::Handle(function_).unoptimized_code());
-      saved_bytes_.target_address_ =
-          CodePatcher::GetInstanceCallAt(pc_, code, NULL);
-      CodePatcher::PatchInstanceCallAt(pc_, code,
-                                       StubCode::BreakpointDynamicEntryPoint());
-      break;
-    }
-    case PcDescriptors::kUnoptStaticCall: {
-      const Code& code =
-          Code::Handle(Function::Handle(function_).unoptimized_code());
-      saved_bytes_.target_address_ =
-          CodePatcher::GetStaticCallTargetAt(pc_, code);
-      CodePatcher::PatchStaticCallAt(pc_, code,
-                                     StubCode::BreakpointStaticEntryPoint());
-      break;
-    }
-    case PcDescriptors::kRuntimeCall:
-    case PcDescriptors::kClosureCall: {
-      const Code& code =
-          Code::Handle(Function::Handle(function_).unoptimized_code());
-      saved_bytes_.target_address_ =
-          CodePatcher::GetStaticCallTargetAt(pc_, code);
-      CodePatcher::PatchStaticCallAt(pc_, code,
-                                     StubCode::BreakpointRuntimeEntryPoint());
-      break;
+  const Code& code =
+      Code::Handle(Function::Handle(function_).unoptimized_code());
+  const Instructions& instrs = Instructions::Handle(code.instructions());
+  {
+    WritableInstructionsScope writable(instrs.EntryPoint(), instrs.size());
+    switch (breakpoint_kind_) {
+      case PcDescriptors::kIcCall: {
+        saved_bytes_.target_address_ =
+            CodePatcher::GetInstanceCallAt(pc_, code, NULL);
+        CodePatcher::PatchInstanceCallAt(
+            pc_, code, StubCode::BreakpointDynamicEntryPoint());
+        break;
+      }
+      case PcDescriptors::kUnoptStaticCall: {
+        saved_bytes_.target_address_ =
+            CodePatcher::GetStaticCallTargetAt(pc_, code);
+        CodePatcher::PatchStaticCallAt(pc_, code,
+                                       StubCode::BreakpointStaticEntryPoint());
+        break;
+      }
+      case PcDescriptors::kRuntimeCall:
+      case PcDescriptors::kClosureCall: {
+        saved_bytes_.target_address_ =
+            CodePatcher::GetStaticCallTargetAt(pc_, code);
+        CodePatcher::PatchStaticCallAt(pc_, code,
+                                       StubCode::BreakpointRuntimeEntryPoint());
+        break;
+      }
+      case PcDescriptors::kReturn:
+        PatchFunctionReturn();
+        break;
+      default:
+        UNREACHABLE();
     }
-    case PcDescriptors::kReturn:
-      PatchFunctionReturn();
-      break;
-    default:
-      UNREACHABLE();
   }
   is_enabled_ = true;
 }
@@ -794,28 +794,32 @@ void CodeBreakpoint::PatchCode() {
 
 void CodeBreakpoint::RestoreCode() {
   ASSERT(is_enabled_);
-  switch (breakpoint_kind_) {
-    case PcDescriptors::kIcCall: {
-      const Code& code =
-          Code::Handle(Function::Handle(function_).unoptimized_code());
-      CodePatcher::PatchInstanceCallAt(pc_, code,
+  const Code& code =
+      Code::Handle(Function::Handle(function_).unoptimized_code());
+  const Instructions& instrs = Instructions::Handle(code.instructions());
+  {
+    WritableInstructionsScope writable(instrs.EntryPoint(), instrs.size());
+    switch (breakpoint_kind_) {
+      case PcDescriptors::kIcCall: {
+        CodePatcher::PatchInstanceCallAt(pc_, code,
+                                         saved_bytes_.target_address_);
+        break;
+      }
+      case PcDescriptors::kUnoptStaticCall:
+      case PcDescriptors::kClosureCall:
+      case PcDescriptors::kRuntimeCall: {
+        const Code& code =
+            Code::Handle(Function::Handle(function_).unoptimized_code());
+        CodePatcher::PatchStaticCallAt(pc_, code,
                                        saved_bytes_.target_address_);
-      break;
-    }
-    case PcDescriptors::kUnoptStaticCall:
-    case PcDescriptors::kClosureCall:
-    case PcDescriptors::kRuntimeCall: {
-      const Code& code =
-          Code::Handle(Function::Handle(function_).unoptimized_code());
-      CodePatcher::PatchStaticCallAt(pc_, code,
-                                     saved_bytes_.target_address_);
-      break;
+        break;
+      }
+      case PcDescriptors::kReturn:
+        RestoreFunctionReturn();
+        break;
+      default:
+        UNREACHABLE();
     }
-    case PcDescriptors::kReturn:
-      RestoreFunctionReturn();
-      break;
-    default:
-      UNREACHABLE();
   }
   is_enabled_ = false;
 }