xlat v2: Clean debug xlat tables descriptor print

The previous debug output for EL1&0 translation regimes was too verbose,
which makes it hard to read and hides the intent behind the parameters
assigned to each region. This patch simplifies this output and makes the
outputs for EL3 and EL1&0 mostly the same. The difference is that in
EL1&0 it is specified whether the region is exclusively accessible from
EL1 (PRIV) or both EL0 and EL1 (USER).

For example:

    MEM-RW(PRIV)-NOACCESS(USER)-XN(PRIV)-XN(USER)-S
    MEM-RO(PRIV)-NOACCESS(USER)-EXEC(PRIV)-EXEC(USER)-S

After the change, it becomes this:

    MEM-RW-XN-PRIV-S
    MEM-RO-EXEC-PRIV-S

Change-Id: I15f4b99058429d42107fbf89e15f4838a9b559a5
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

lib/xlat_tables_v2/xlat_tables_utils.c

@@ -60,47 +60,36 @@ static void xlat_desc_print(const xlat_ctx_t *ctx, uint64_t desc)
 		tf_printf("DEV");
 	}
 
-	const char *priv_str = "(PRIV)";
-	const char *user_str = "(USER)";
-
-	/*
-	 * Showing Privileged vs Unprivileged only makes sense for EL1&0
-	 * mappings
-	 */
-	const char *ro_str = "-RO";
-	const char *rw_str = "-RW";
-	const char *no_access_str = "-NOACCESS";
-
 	if (xlat_regime == EL3_REGIME) {
-		/* For EL3, the AP[2] bit is all what matters */
-		tf_printf("%s", (desc & LOWER_ATTRS(AP_RO)) ? ro_str : rw_str);
+		/* For EL3 only check the AP[2] and XN bits. */
+		tf_printf((desc & LOWER_ATTRS(AP_RO)) ? "-RO" : "-RW");
+		tf_printf((desc & UPPER_ATTRS(XN)) ? "-XN" : "-EXEC");
 	} else {
-		const char *ap_str = (desc & LOWER_ATTRS(AP_RO)) ? ro_str : rw_str;
-		tf_printf("%s", ap_str);
-		tf_printf("%s", priv_str);
+		assert(xlat_regime == EL1_EL0_REGIME);
 		/*
-		 * EL0 can only have the same permissions as EL1 or no
-		 * permissions at all.
+		 * For EL0 and EL1:
+		 * - In AArch64 PXN and UXN can be set independently but in
+		 *   AArch32 there is no UXN (XN affects both privilege levels).
+		 *   For consistency, we set them simultaneously in both cases.
+		 * - RO and RW permissions must be the same in EL1 and EL0. If
+		 *   EL0 can access that memory region, so can EL1, with the
+		 *   same permissions.
 		 */
-		tf_printf("%s",
-			  (desc & LOWER_ATTRS(AP_ACCESS_UNPRIVILEGED))
-			  ? ap_str : no_access_str);
-		tf_printf("%s", user_str);
-	}
-
-	const char *xn_str = "-XN";
-	const char *exec_str = "-EXEC";
+#if ENABLE_ASSERTIONS
+		uint64_t xn_mask = xlat_arch_regime_get_xn_desc(EL1_EL0_REGIME);
+		uint64_t xn_perm = desc & xn_mask;
 
-	if (xlat_regime == EL3_REGIME) {
-		/* For EL3, the XN bit is all what matters */
-		tf_printf("%s", (UPPER_ATTRS(XN) & desc) ? xn_str : exec_str);
-	} else {
-		/* For EL0 and EL1, we need to know who has which rights */
-		tf_printf("%s", (UPPER_ATTRS(PXN) & desc) ? xn_str : exec_str);
-		tf_printf("%s", priv_str);
-
-		tf_printf("%s", (UPPER_ATTRS(UXN) & desc) ? xn_str : exec_str);
-		tf_printf("%s", user_str);
+		assert((xn_perm == xn_mask) || (xn_perm == 0ULL));
+#endif
+		tf_printf((desc & LOWER_ATTRS(AP_RO)) ? "-RO" : "-RW");
+		/* Only check one of PXN and UXN, the other one is the same. */
+		tf_printf((desc & UPPER_ATTRS(PXN)) ? "-XN" : "-EXEC");
+		/*
+		 * Privileged regions can only be accessed from EL1, user
+		 * regions can be accessed from EL1 and EL0.
+		 */
+		tf_printf((desc & LOWER_ATTRS(AP_ACCESS_UNPRIVILEGED))
+			  ? "-USER" : "-PRIV");
 	}
 
 	tf_printf(LOWER_ATTRS(NS) & desc ? "-NS" : "-S");