[llvm] r192754 - Adding padding to the .eh_frame section in RuntimeDyld

[Andrew Kaylor]

Author: akaylor
Date: Tue Oct 15 19:32:24 2013
New Revision: 192754

URL: http://llvm.org/viewvc/llvm-project?rev=192754&view=rev
Log:
Adding padding to the .eh_frame section in RuntimeDyld

Modified:
    llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp

Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp?rev=192754&r1=192753&r2=192754&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp (original)
+++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp Tue Oct 15 19:32:24 2013
@@ -258,6 +258,7 @@ unsigned RuntimeDyldImpl::emitSection(Ob
   bool IsZeroInit;
   bool IsReadOnly;
   uint64_t DataSize;
+  unsigned PaddingSize = 0;
   StringRef Name;
   Check(Section.isRequiredForExecution(IsRequired));
   Check(Section.isVirtual(IsVirtual));
@@ -272,6 +273,12 @@ unsigned RuntimeDyldImpl::emitSection(Ob
       StubBufSize += StubAlignment - EndAlignment;
   }
 
+  // The .eh_frame section (at least on Linux) needs an extra four bytes padded
+  // with zeroes added at the end.  For MachO objects, this section has a
+  // slightly different name, so this won't have any effect for MachO objects.
+  if (Name == ".eh_frame")
+    PaddingSize = 4;
+
   unsigned Allocate;
   unsigned SectionID = Sections.size();
   uint8_t *Addr;
@@ -280,7 +287,7 @@ unsigned RuntimeDyldImpl::emitSection(Ob
   // Some sections, such as debug info, don't need to be loaded for execution.
   // Leave those where they are.
   if (IsRequired) {
-    Allocate = DataSize + StubBufSize;
+    Allocate = DataSize + PaddingSize + StubBufSize;
     Addr = IsCode
       ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID, Name)
       : MemMgr->allocateDataSection(Allocate, Alignment, SectionID, Name,
@@ -298,6 +305,13 @@ unsigned RuntimeDyldImpl::emitSection(Ob
     else
       memcpy(Addr, pData, DataSize);
 
+    // Fill in any extra bytes we allocated for padding
+    if (PaddingSize != 0) {
+      memset(Addr + DataSize, 0, PaddingSize);
+      // Update the DataSize variable so that the stub offset is set correctly.
+      DataSize += PaddingSize;
+    }
+
     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
                  << " Name: " << Name
                  << " obj addr: " << format("%p", pData)