Preliminary support for systems which require changing JIT memory regions privilege from read / write to read / executable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56303 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/System/Memory.h

@@ -69,6 +69,11 @@ namespace sys {
     /// that has been emitted it must invalidate the instruction cache on some
     /// platforms.
     static void InvalidateInstructionCache(const void *Addr, size_t Len);
+
+    /// SetRXPrivilege - Before the JIT can run a block of code, it has to be
+    /// given read and executable privilege. Return true if it is already r-x
+    /// or the system is able to change its previlege.
+    static bool SetRXPrivilege(const void *Addr, size_t Size);
   };
 }
 }

lib/ExecutionEngine/ExecutionEngine.cpp

@@ -86,7 +86,8 @@ Function *ExecutionEngine::FindFunctionNamed(const char *FnName) {
 /// existing data in memory.
 void ExecutionEngine::addGlobalMapping(const GlobalValue *GV, void *Addr) {
   MutexGuard locked(lock);
-  
+
+  DOUT << "Map " << *GV << " to " << Addr << "\n";  
   void *&CurVal = state.getGlobalAddressMap(locked)[GV];
   assert((CurVal == 0 || Addr == 0) && "GlobalMapping already established!");
   CurVal = Addr;

lib/ExecutionEngine/JIT/JITEmitter.cpp

@@ -925,6 +925,9 @@ bool JITEmitter::finishFunction(MachineFunction &F) {
        << Relocations.size() << " relocations\n";
   Relocations.clear();
 
+  // Mark code region readable and executable if it's not so already.
+  sys::Memory::SetRXPrivilege(FnStart, FnEnd-FnStart);
+
 #ifndef NDEBUG
   {
   DOUT << std::hex;

lib/ExecutionEngine/JIT/JITMemoryManager.cpp

@@ -370,7 +370,11 @@ namespace {
 
 DefaultJITMemoryManager::DefaultJITMemoryManager() {
   // Allocate a 16M block of memory for functions.
+#if defined(__APPLE__) && defined(__arm__)
+  sys::MemoryBlock MemBlock = getNewMemoryBlock(4 << 20);
+#else
   sys::MemoryBlock MemBlock = getNewMemoryBlock(16 << 20);
+#endif
 
   unsigned char *MemBase = static_cast<unsigned char*>(MemBlock.base());
 

lib/System/Memory.cpp

@@ -58,3 +58,14 @@ void llvm::sys::Memory::InvalidateInstructionCache(const void *Addr,
 #endif  // end PPC
 
 }
+
+bool llvm::sys::Memory::SetRXPrivilege(const void *Addr, size_t Size) {
+#if defined(__APPLE__) && defined(__arm__)
+  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)Addr,
+                                (vm_size_t)Size, 0,
+                                VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
+  return KERN_SUCCESS == kr;
+#else
+  return true;
+#endif
+}

lib/System/Unix/Memory.inc

@@ -18,6 +18,10 @@
 #include <sys/mman.h>
 #endif
 
+#ifdef __APPLE__
+#include <mach/mach.h>
+#endif
+
 /// AllocateRWX - Allocate a slab of memory with read/write/execute
 /// permissions.  This is typically used for JIT applications where we want
 /// to emit code to the memory then jump to it.  Getting this type of memory
@@ -52,8 +56,13 @@ llvm::sys::Memory::AllocateRWX(unsigned NumBytes, const MemoryBlock* NearBlock,
   void* start = NearBlock ? (unsigned char*)NearBlock->base() + 
                             NearBlock->size() : 0;
 
+#if defined(__APPLE__) && defined(__arm__)
+  void *pa = ::mmap(start, pageSize*NumPages, PROT_READ|PROT_EXEC,
+                    flags, fd, 0);
+#else
   void *pa = ::mmap(start, pageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
                     flags, fd, 0);
+#endif
   if (pa == MAP_FAILED) {
     if (NearBlock) //Try again without a near hint
       return AllocateRWX(NumBytes, 0);
@@ -61,9 +70,29 @@ llvm::sys::Memory::AllocateRWX(unsigned NumBytes, const MemoryBlock* NearBlock,
     MakeErrMsg(ErrMsg, "Can't allocate RWX Memory");
     return MemoryBlock();
   }
+
+#if defined(__APPLE__) && defined(__arm__)
+  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)pa,
+                                (vm_size_t)(pageSize*NumPages), 0,
+                                VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
+  if (KERN_SUCCESS != kr) {
+    MakeErrMsg(ErrMsg, "vm_protect max RWX failed\n");
+    return sys::MemoryBlock();
+  }
+
+  kr = vm_protect(mach_task_self(), (vm_address_t)pa,
+                  (vm_size_t)(pageSize*NumPages), 0,
+                  VM_PROT_READ | VM_PROT_WRITE);
+  if (KERN_SUCCESS != kr) {
+    MakeErrMsg(ErrMsg, "vm_protect RW failed\n");
+    return sys::MemoryBlock();
+  }
+#endif
+
   MemoryBlock result;
   result.Address = pa;
   result.Size = NumPages*pageSize;
+
   return result;
 }