x86: Fix JNI function 64-bit return values on 32-bit

This patch fixes edx clobbering issue with 64-bit JNI function return values.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

arch/x86/jni.S

@@ -22,10 +22,16 @@ jni_trampoline:
 	addl	$0x4, %esp
 	subl	$0x4, %esp		# new return address
 
-	pushl	%eax			# save return value
+	# save return value
+	pushl	%eax
+	pushl	%edx
+
 	call	vm_leave_jni
-	movl	%eax, 0x4(%esp)		# override return address
-	popl	%eax			# restore return value
+	movl	%eax, 0x8(%esp)		# override return address
+
+	# restore return value
+	popl	%edx
+	popl	%eax
 
 	ret
 error:

test/functional/java/lang/JNITest.java

@@ -120,7 +120,9 @@ public static void testReturnPassedInt() {
 
   public static void testReturnPassedLong() {
     assertEquals(42l, staticReturnPassedLong(42l));
+    assertEquals(0xdeadbeefcafebabeL, staticReturnPassedLong(0xdeadbeefcafebabeL));
     assertEquals(42l, jniTest.returnPassedLong(42l));
+    assertEquals(0xdeadbeefcafebabeL, jniTest.returnPassedLong(0xdeadbeefcafebabeL));
     assertEquals(42l, staticReturnPassedLongArray(new long[]{42l})[0]);
     assertEquals(42l, jniTest.returnPassedLongArray(new long[]{42l})[0]);
   }