Interface changes to allow RuntimeDyld memory managers to set memory permissions after an object has been loaded.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168114 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 24 insertions, 3 deletions

diff --git a/lib/ExecutionEngine/JIT/JITMemoryManager.cpp b/lib/ExecutionEngine/JIT/JITMemoryManager.cpp
index 61bc119..bd0519e 100644
--- a/lib/ExecutionEngine/JIT/JITMemoryManager.cpp
+++ b/lib/ExecutionEngine/JIT/JITMemoryManager.cpp
@@ -501,10 +501,14 @@ namespace {
 
     /// allocateDataSection - Allocate memory for a data section.
     uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
-                                 unsigned SectionID) {
+                                 unsigned SectionID, bool IsReadOnly) {
       return (uint8_t*)DataAllocator.Allocate(Size, Alignment);
     }
 
+    bool applyPermissions(std::string *ErrMsg) {
+      return false;
+    }
+
     /// startExceptionTable - Use startFunctionBody to allocate memory for the
     /// function's exception table.
     uint8_t* startExceptionTable(const Function* F, uintptr_t &ActualSize) {
diff --git a/lib/ExecutionEngine/MCJIT/MCJIT.cpp b/lib/ExecutionEngine/MCJIT/MCJIT.cpp
index 752c5b7..d72e563 100644
--- a/lib/ExecutionEngine/MCJIT/MCJIT.cpp
+++ b/lib/ExecutionEngine/MCJIT/MCJIT.cpp
@@ -118,17 +118,26 @@ void MCJIT::emitObject(Module *m) {
 
 // FIXME: Add a parameter to identify which object is being finalized when
 // MCJIT supports multiple modules.
+// FIXME: Provide a way to separate code emission, relocations and page 
+// protection in the interface.
 void MCJIT::finalizeObject() {
   // If the module hasn't been compiled, just do that.
   if (!isCompiled) {
     // If the call to Dyld.resolveRelocations() is removed from emitObject()
     // we'll need to do that here.
     emitObject(M);
+
+    // Set page permissions.
+    MemMgr->applyPermissions();
+
     return;
   }
 
   // Resolve any relocations.
   Dyld.resolveRelocations();
+
+  // Set page permissions.
+  MemMgr->applyPermissions();
 }
 
 void *MCJIT::getPointerToBasicBlock(BasicBlock *BB) {
diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
index f6dccb1..4118e8a 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
@@ -182,7 +182,7 @@ void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
   // Allocate memory for the section
   unsigned SectionID = Sections.size();
   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
-                                              SectionID);
+                                              SectionID, false);
   if (!Addr)
     report_fatal_error("Unable to allocate memory for common symbols!");
   uint64_t Offset = 0;
@@ -237,11 +237,13 @@ unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
   bool IsRequired;
   bool IsVirtual;
   bool IsZeroInit;
+  bool IsReadOnly;
   uint64_t DataSize;
   StringRef Name;
   Check(Section.isRequiredForExecution(IsRequired));
   Check(Section.isVirtual(IsVirtual));
   Check(Section.isZeroInit(IsZeroInit));
+  Check(Section.isReadOnlyData(IsReadOnly));
   Check(Section.getSize(DataSize));
   Check(Section.getName(Name));
 
@@ -256,7 +258,7 @@ unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
     Allocate = DataSize + StubBufSize;
     Addr = IsCode
       ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
-      : MemMgr->allocateDataSection(Allocate, Alignment, SectionID);
+      : MemMgr->allocateDataSection(Allocate, Alignment, SectionID, IsReadOnly);
     if (!Addr)
       report_fatal_error("Unable to allocate section memory!");
 
@@ -451,6 +453,12 @@ void RuntimeDyldImpl::resolveExternalSymbols() {
 //===----------------------------------------------------------------------===//
 // RuntimeDyld class implementation
 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
+  // FIXME: There's a potential issue lurking here if a single instance of
+  // RuntimeDyld is used to load multiple objects.  The current implementation
+  // associates a single memory manager with a RuntimeDyld instance.  Even
+  // though the public class spawns a new 'impl' instance for each load,
+  // they share a single memory manager.  This can become a problem when page
+  // permissions are applied.
   Dyld = 0;
   MM = mm;
 }