selftests/harness: Display signed values correctly

Since forever the harness output for signed value tests have reported
unsigned values to avoid casting. Instead, actually test the variable
types and perform the correct casts and choose the correct format
specifiers.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/kselftest_harness.h

@@ -679,17 +679,49 @@
 	if (_metadata->passed && _metadata->step < 255) \
 		_metadata->step++;
 
+#define is_signed_type(var)       (!!(((__typeof__(var))(-1)) < (__typeof__(var))1))
+
 #define __EXPECT(_expected, _expected_str, _seen, _seen_str, _t, _assert) do { \
 	/* Avoid multiple evaluation of the cases */ \
 	__typeof__(_expected) __exp = (_expected); \
 	__typeof__(_seen) __seen = (_seen); \
 	if (_assert) __INC_STEP(_metadata); \
 	if (!(__exp _t __seen)) { \
-		unsigned long long __exp_print = (uintptr_t)__exp; \
-		unsigned long long __seen_print = (uintptr_t)__seen; \
-		__TH_LOG("Expected %s (%llu) %s %s (%llu)", \
-			 _expected_str, __exp_print, #_t, \
-			 _seen_str, __seen_print); \
+		/* Report with actual signedness to avoid weird output. */ \
+		switch (is_signed_type(__exp) * 2 + is_signed_type(__seen)) { \
+		case 0: { \
+			unsigned long long __exp_print = (uintptr_t)__exp; \
+			unsigned long long __seen_print = (uintptr_t)__seen; \
+			__TH_LOG("Expected %s (%llu) %s %s (%llu)", \
+				 _expected_str, __exp_print, #_t, \
+				 _seen_str, __seen_print); \
+			break; \
+			} \
+		case 1: { \
+			unsigned long long __exp_print = (uintptr_t)__exp; \
+			long long __seen_print = (intptr_t)__seen; \
+			__TH_LOG("Expected %s (%llu) %s %s (%lld)", \
+				 _expected_str, __exp_print, #_t, \
+				 _seen_str, __seen_print); \
+			break; \
+			} \
+		case 2: { \
+			long long __exp_print = (intptr_t)__exp; \
+			unsigned long long __seen_print = (uintptr_t)__seen; \
+			__TH_LOG("Expected %s (%lld) %s %s (%llu)", \
+				 _expected_str, __exp_print, #_t, \
+				 _seen_str, __seen_print); \
+			break; \
+			} \
+		case 3: { \
+			long long __exp_print = (intptr_t)__exp; \
+			long long __seen_print = (intptr_t)__seen; \
+			__TH_LOG("Expected %s (%lld) %s %s (%lld)", \
+				 _expected_str, __exp_print, #_t, \
+				 _seen_str, __seen_print); \
+			break; \
+			} \
+		} \
 		_metadata->passed = 0; \
 		/* Ensure the optional handler is triggered */ \
 		_metadata->trigger = 1; \