Merge pull request #7104 from theresa-m/fix_5988

Round maxRequiredSize to match romSize calculation
eclipse-openj9 · Sep 19, 2019 · 217b85d · 217b85d
2 parents 1b35e0a + e3156d2
commit 217b85d
Showing 1 changed file with 9 additions and 37 deletions.
diff --git a/runtime/bcutil/ROMClassBuilder.cpp b/runtime/bcutil/ROMClassBuilder.cpp
@@ -478,9 +478,7 @@ ROMClassBuilder::prepareAndLaydown( BufferManager *bufferManager, ClassFileParse
 	if (isLambda) {
 		/* calculate the romSize to compare the ROM sizes in the compareROMClassForEquality method for lambda classes */
 		romSize = U_32(sizeInformation.rcWithOutUTF8sSize + sizeInformation.utf8sSize + sizeInformation.rawClassDataSize + sizeInformation.varHandleMethodTypeLookupTableSize);
-		/* round up to sizeof(U_64) */
-		romSize += (sizeof(U_64) - 1);
-		romSize &= ~(sizeof(U_64) - 1);
+		romSize = ROUND_UP_TO_POWEROF2(romSize, sizeof(U_64));
 	}
 
 	if ( context->shouldCompareROMClassForEquality() ) {
@@ -599,17 +597,13 @@ ROMClassBuilder::prepareAndLaydown( BufferManager *bufferManager, ClassFileParse
 			sizeRequirements.romClassMinimalSize =
 					U_32(sizeInformation.rcWithOutUTF8sSize
 					+ sizeInformation.utf8sSize + sizeInformation.rawClassDataSize + sizeInformation.varHandleMethodTypeLookupTableSize);
-			/* round up to sizeof(U_64) */
-			sizeRequirements.romClassMinimalSize += (sizeof(U_64) - 1);
-			sizeRequirements.romClassMinimalSize &= ~(sizeof(U_64) - 1);
+			sizeRequirements.romClassMinimalSize = ROUND_UP_TO_POWEROF2(sizeRequirements.romClassMinimalSize, sizeof(U_64));
 
 			sizeRequirements.romClassSizeFullSize =
 					U_32(sizeRequirements.romClassMinimalSize
 					+ sizeInformation.lineNumberSize
 					+ sizeInformation.variableInfoSize);
-			/* round up to sizeof(U_64) */
-			sizeRequirements.romClassSizeFullSize += (sizeof(U_64) - 1);
-			sizeRequirements.romClassSizeFullSize &= ~(sizeof(U_64)-1);
+			sizeRequirements.romClassSizeFullSize = ROUND_UP_TO_POWEROF2(sizeRequirements.romClassSizeFullSize, sizeof(U_64));
 
 
 			sizeRequirements.lineNumberTableSize = U_32(sizeInformation.lineNumberSize);
@@ -701,31 +695,11 @@ ROMClassBuilder::prepareAndLaydown( BufferManager *bufferManager, ClassFileParse
 		lineNumberBuffer = allocatedBuffers.lineNumberBuffer;
 		variableInfoBuffer = allocatedBuffers.variableInfoBuffer;
 	} else {
-		if (countDebugDataOutOfLine) {
-			/* Pad maxRequiredSize to the size to sizeof(U_64) in order to prevent memory corruption.  
-			 * 
-			 * In rare cases it is possible that maxRequiredSize is 2 bytes too small, due to
-			 * counting the data 'out-of-line', and then writing the debug data 'in-line' with 
-			 * padding U_64 adjustments. The extra 2 bytes is a result of a switch from U_16
-			 * alignment for debug data (when writing out of line), to U_32 alignment (when 
-			 * writing inline). It should also be noted that these extra 2 bytes are only 
-			 * visible when only one method with debug data exists. If there are more, then the removal 
-			 * of 'SRPs to debug data' from each method will hide the extra padding for in-line 
-			 * debug data.
-			 * 
-			 * Without this padding any new segment returned by the below call to allocate could be 
-			 * too small to contain the rom class that is about to be written.
-			 * 
-			 * Note: When the problem described above occurs maxRequiredSize will not be U_64 aligned 
-			 *       until the below code runs.
-			 */
-			UDATA alignmentBits = (sizeof (U_64) - 1);
-			UDATA adjustedCount = (maxRequiredSize + alignmentBits) & ~alignmentBits;
-			UDATA bytesToPad = adjustedCount - maxRequiredSize;
-			if (0 != bytesToPad) {
-				maxRequiredSize += bytesToPad;
-			}
-		}
+		/* Pad maxRequiredSize to the size to sizeof(U_64) in order to prevent memory corruption. 
+		* This mirrors ROM class padding in finishPrepareAndLaydown when the final ROM class size 
+		* is calculated.
+		*/
+		maxRequiredSize = ROUND_UP_TO_POWEROF2(maxRequiredSize, sizeof(U_64));
 		romClassBuffer = context->allocationStrategy()->allocate(maxRequiredSize);
 	}
 	if ( romClassBuffer == NULL ) {
@@ -1041,9 +1015,7 @@ ROMClassBuilder::finishPrepareAndLaydown(
 	 * Record the romSize as the final size of the ROMClass with interned strings space removed.
 	 */
 	U_32 romSize = U_32(sizeInformation->rcWithOutUTF8sSize + sizeInformation->utf8sSize + sizeInformation->rawClassDataSize + sizeInformation->varHandleMethodTypeLookupTableSize);
-	/* round up to sizeof(U_64) */
-	romSize += (sizeof(U_64) - 1);
-	romSize &= ~(sizeof(U_64) - 1);
+	romSize = ROUND_UP_TO_POWEROF2(romSize, sizeof(U_64));
 
 	/*
 	 * update the SRP Offset Table with the base addresses for main ROMClass section (RC_TAG),