Fix singlefile on OSX ARM64 (#68845)

* Same alignment in the bundle on OSX as on Linux

* Extra VA gap between section in casse we run from sf bundle

* Rename prevSectionEnd -> prevSectionEndAligned and make it aligned.

* Suppress assert for now on OSX

src/coreclr/pal/src/map/map.cpp

@@ -2394,8 +2394,9 @@ void * MAPMapPEFile(HANDLE hFile, off_t offset)
         goto doneReleaseMappingCriticalSection;
     }
 
-    void* prevSectionEnd;
-    prevSectionEnd = (char*)loadedHeader + headerSize; // the first "section" for our purposes is the header
+    void* prevSectionEndAligned;
+    // the first "section" for our purposes is the header
+    prevSectionEndAligned = ALIGN_UP((char*)loadedHeader + headerSize, GetVirtualPageSize());
 
     for (unsigned i = 0; i < numSections; ++i)
     {
@@ -2412,7 +2413,7 @@ void * MAPMapPEFile(HANDLE hFile, off_t offset)
         if (   (sectionBase < loadedHeader)                                                           // Did computing the section base overflow?
             || ((char*)sectionBase + currentHeader.SizeOfRawData < (char*)sectionBase)              // Does the section overflow?
             || ((char*)sectionBase + currentHeader.SizeOfRawData > (char*)loadedHeader + virtualSize) // Does the section extend past the end of the image as the header stated?
-            || (prevSectionEnd > sectionBase)                                                       // Does this section overlap the previous one?
+            || (prevSectionEndAligned > sectionBase)                                                       // Does this section overlap the previous one?
             )
         {
             ERROR_(LOADER)( "section %d is corrupt\n", i );
@@ -2435,12 +2436,12 @@ void * MAPMapPEFile(HANDLE hFile, off_t offset)
         }
 
         // Is there space between the previous section and this one? If so, add a PROT_NONE mapping to cover it.
-        if (prevSectionEnd < sectionBaseAligned)
+        if (prevSectionEndAligned < sectionBaseAligned)
         {
             palError = MAPRecordMapping(pFileObject,
                             loadedBase,
-                            prevSectionEnd,
-                            (char*)sectionBaseAligned - (char*)prevSectionEnd,
+                            prevSectionEndAligned,
+                            (char*)sectionBaseAligned - (char*)prevSectionEndAligned,
                             PROT_NONE);
             if (NO_ERROR != palError)
             {
@@ -2488,18 +2489,18 @@ void * MAPMapPEFile(HANDLE hFile, off_t offset)
         }
 #endif // _DEBUG
 
-        prevSectionEnd = ALIGN_UP((char*)sectionBase + currentHeader.SizeOfRawData, GetVirtualPageSize()); // round up to page boundary
+        prevSectionEndAligned = ALIGN_UP((char*)sectionBase + currentHeader.SizeOfRawData, GetVirtualPageSize()); // round up to page boundary
     }
 
     // Is there space after the last section and before the end of the mapped image? If so, add a PROT_NONE mapping to cover it.
     char* imageEnd;
     imageEnd = (char*)loadedBase + virtualSize; // actually, points just after the mapped end
-    if (prevSectionEnd < imageEnd)
+    if (prevSectionEndAligned < imageEnd)
     {
         palError = MAPRecordMapping(pFileObject,
                         loadedBase,
-                        prevSectionEnd,
-                        offset + (char*)imageEnd - (char*)prevSectionEnd,
+                        prevSectionEndAligned,
+                        offset + (char*)imageEnd - (char*)prevSectionEndAligned,
                         PROT_NONE);
         if (NO_ERROR != palError)
         {

src/coreclr/tools/aot/ILCompiler.ReadyToRun/ObjectWriter/R2RPEBuilder.cs

@@ -599,12 +599,19 @@ protected override BlobBuilder SerializeSection(string name, SectionLocation loc
 
             if (!_target.IsWindows)
             {
+                const int RVAAlign = 1 << RVABitsToMatchFilePos;
                 if (outputSectionIndex > 0)
                 {
                     sectionStartRva = Math.Max(sectionStartRva, _sectionRVAs[outputSectionIndex - 1] + _sectionRawSizes[outputSectionIndex - 1]);
+
+                    // when assembly is stored in a singlefile bundle, an additional skew is introduced
+                    // as the streams inside the bundle are not necessarily page aligned as we do not 
+                    // know the actual page size on the target system. 
+                    // We may need one page gap of unused VA space before the next section starts.
+                    // We will assume the page size is <= RVAAlign
+                    sectionStartRva += RVAAlign;
                 }
 
-                const int RVAAlign = 1 << RVABitsToMatchFilePos;
                 sectionStartRva = AlignmentHelper.AlignUp(sectionStartRva, RVAAlign);
 
                 int rvaAdjust = (location.PointerToRawData - sectionStartRva) & (RVAAlign - 1);

src/coreclr/vm/peimagelayout.cpp

@@ -79,7 +79,9 @@ PEImageLayout* PEImageLayout::LoadConverted(PEImage* pOwner)
     if (pFlat == NULL || !pFlat->CheckILOnlyFormat())
         EEFileLoadException::Throw(pOwner->GetPathForErrorMessages(), COR_E_BADIMAGEFORMAT);
 
-#ifdef TARGET_UNIX
+// TODO: enable on OSX eventually
+//       right now we have binaries that will trigger this in a singlefile bundle.
+#ifdef TARGET_LINUX 
     // we should not see R2R files here on Unix.
     // ConvertedImageLayout may be able to handle them, but the fact that we were unable to
     // load directly implies that MAPMapPEFile could not consume what crossgen produced.

src/installer/managed/Microsoft.NET.HostModel/Bundle/TargetInfo.cs

@@ -57,17 +57,17 @@ public TargetInfo(OSPlatform? os, Architecture? arch, Version targetFrameworkVer
                 throw new ArgumentException($"Invalid input: Unsupported Target Framework Version {targetFrameworkVersion}");
             }
 
-            if (IsLinux && Arch == Architecture.Arm64)
+            if (IsWindows)
             {
-                // We align assemblies in the bundle at 4K so that we can use mmap on Linux without changing the page alignment of ARM64 R2R code.
+                // We align assemblies in the bundle at 4K - per requirements of memory mapping API (MapViewOfFile3, et al).
                 // This is only necessary for R2R assemblies, but we do it for all assemblies for simplicity.
-                // See https://github.com/dotnet/runtime/issues/41832.
                 AssemblyAlignment = 4096;
             }
-            else if (IsWindows)
+            else if (Arch == Architecture.Arm64)
             {
-                // We align assemblies in the bundle at 4K - per requirements of memory mapping API (MapViewOfFile3, et al).
+                // We align assemblies in the bundle at 4K so that we can use mmap on Unix without changing the page alignment of ARM64 R2R code.
                 // This is only necessary for R2R assemblies, but we do it for all assemblies for simplicity.
+                // See https://github.com/dotnet/runtime/issues/41832.
                 AssemblyAlignment = 4096;
             }
             else