Added indirect branch protection to function abstraction

* Adds a new entry to FuncAttributes
  * Adds a new API to FuncFrame

src/asmjit/arm/a64emithelper.cpp

@@ -312,6 +312,12 @@ ASMJIT_FAVOR_SIZE Error EmitHelper::emitProlog(const FuncFrame& frame) {
     { Inst::kIdStr_v, Inst::kIdStp_v }
   }};
 
+  // Emit: 'bti' (indirect branch protection).
+  if (frame.hasIndirectBranchProtection()) {
+    // TODO: The instruction is not available at the moment (would be ABI break).
+    // ASMJIT_PROPAGATE(emitter->bti());
+  }
+
   uint32_t adjustInitialOffset = pei.sizeTotal;
 
   for (RegGroup group : Support::EnumValues<RegGroup, RegGroup::kGp, RegGroup::kVec>{}) {

src/asmjit/core/builder.h

@@ -546,7 +546,7 @@ public:
     uint8_t _reserved1;
   };
 
-  //! Data that can have different meaning dependning on \ref NodeType.
+  //! Data that can have different meaning depending on \ref NodeType.
   union {
     //! Data useful by any node type.
     AnyData _any;
@@ -694,8 +694,9 @@ public:
 
   //! Returns user data casted to `T*`.
   //!
-  //! User data is decicated to be used only by AsmJit users and not touched by the library. The data has a pointer
-  //! size so you can either store a pointer or `intptr_t` value through `setUserDataAsIntPtr()`.
+  //! User data is dedicated to be used only by AsmJit users and not touched by the library. The data is of a pointer
+  //! size so you can either store a pointer or `int64_t` value through `setUserDataAsPtr()`, `setUserDataAsInt64()`
+  //! and `setUserDataAsUInt64()`.
   template<typename T>
   ASMJIT_INLINE_NODEBUG T* userDataAsPtr() const noexcept { return static_cast<T*>(_userDataPtr); }
   //! Returns user data casted to `int64_t`.

src/asmjit/core/func.h

@@ -717,6 +717,11 @@ enum class FuncAttributes : uint32_t {
   kHasFuncCalls = 0x00000020u,
   //! Function has aligned save/restore of vector registers.
   kAlignedVecSR = 0x00000040u,
+  //! Function must begin with an instruction that marks a start of a branch or function.
+  //!
+  //!   * `ENDBR32/ENDBR64` instruction is inserted at the beginning of the function (X86, X86_64).
+  //!   * `BTI` instruction is inserted at the beginning of the function (AArch64)
+  kIndirectBranchProtection = 0x00000080u,
   //! FuncFrame is finalized and can be used by prolog/epilog inserter (PEI).
   kIsFinalized = 0x00000800u,
 
@@ -1072,11 +1077,18 @@ public:
 
   //! Tests whether the function calls other functions.
   ASMJIT_INLINE_NODEBUG bool hasFuncCalls() const noexcept { return hasAttribute(FuncAttributes::kHasFuncCalls); }
-  //! Sets `kFlagHasCalls` to true.
+  //! Sets `FuncAttributes::kHasFuncCalls` to true.
   ASMJIT_INLINE_NODEBUG void setFuncCalls() noexcept { addAttributes(FuncAttributes::kHasFuncCalls); }
-  //! Sets `kFlagHasCalls` to false.
+  //! Sets `FuncAttributes::kHasFuncCalls` to false.
   ASMJIT_INLINE_NODEBUG void resetFuncCalls() noexcept { clearAttributes(FuncAttributes::kHasFuncCalls); }
 
+  //! Tests whether the function uses indirect branch protection, see \ref FuncAttributes::kIndirectBranchProtection.
+  ASMJIT_INLINE_NODEBUG bool hasIndirectBranchProtection() const noexcept { return hasAttribute(FuncAttributes::kIndirectBranchProtection); }
+  //! Enabled indirect branch protection (sets `FuncAttributes::kIndirectBranchProtection` attribute to true).
+  ASMJIT_INLINE_NODEBUG void setIndirectBranchProtection() noexcept { addAttributes(FuncAttributes::kIndirectBranchProtection); }
+  //! Disables indirect branch protection (sets `FuncAttributes::kIndirectBranchProtection` attribute to false).
+  ASMJIT_INLINE_NODEBUG void resetIndirectBranchProtection() noexcept { clearAttributes(FuncAttributes::kIndirectBranchProtection); }
+
   //! Tests whether the function has AVX enabled.
   ASMJIT_INLINE_NODEBUG bool isAvxEnabled() const noexcept { return hasAttribute(FuncAttributes::kX86_AVXEnabled); }
   //! Enables AVX use.

src/asmjit/x86/x86emithelper.cpp

@@ -425,6 +425,12 @@ ASMJIT_FAVOR_SIZE Error EmitHelper::emitProlog(const FuncFrame& frame) {
   Gp gpReg = zsp;            // General purpose register (temporary).
   Gp saReg = zsp;            // Stack-arguments base pointer.
 
+  // Emit: 'endbr32' or 'endbr64' (indirect branch protection).
+  if (frame.hasIndirectBranchProtection()) {
+    InstId instId = emitter->is32Bit() ? Inst::kIdEndbr32 : Inst::kIdEndbr64;
+    ASMJIT_PROPAGATE(emitter->emit(instId));
+  }
+
   // Emit: 'push zbp'
   //       'mov  zbp, zsp'.
   if (frame.hasPreservedFP()) {

test/asmjit_test_compiler_x86.cpp

@@ -238,8 +238,8 @@ public:
   }
 };
 
-// x86::Compiler - X86Test_AlignNone
-// =================================
+// x86::Compiler - X86Test_NoAlign
+// ===============================
 
 class X86Test_NoAlign : public X86TestCase {
 public:
@@ -267,6 +267,35 @@ public:
   }
 };
 
+// x86::Compiler - X86Test_IndirectBranchProtection
+// ================================================
+
+class X86Test_IndirectBranchProtection : public X86TestCase {
+public:
+  X86Test_IndirectBranchProtection() : X86TestCase("IndirectBranchProtection") {}
+
+  static void add(TestApp& app) {
+    app.add(new X86Test_IndirectBranchProtection());
+  }
+
+  virtual void compile(x86::Compiler& cc) {
+    FuncNode* func = cc.addFunc(FuncSignatureT<void>(CallConvId::kHost));
+    func->addAttributes(FuncAttributes::kIndirectBranchProtection);
+    cc.endFunc();
+  }
+
+  virtual bool run(void* _func, String& result, String& expect) {
+    DebugUtils::unused(result, expect);
+
+    typedef void (*Func)(void);
+    Func func = ptr_as_func<Func>(_func);
+
+    func();
+    return true;
+  }
+};
+
+
 // x86::Compiler - X86Test_JumpMerge
 // =================================
 
@@ -4362,6 +4391,7 @@ void compiler_add_x86_tests(TestApp& app) {
   // Base tests.
   app.addT<X86Test_NoCode>();
   app.addT<X86Test_NoAlign>();
+  app.addT<X86Test_IndirectBranchProtection>();
   app.addT<X86Test_AlignBase>();
 
   // Jump tests.