xlat_tables_v2: print xlat tables without recursion

This patch uses an array on stack to save parent xlat table information when
traversing the xlat tables. It keeps exactly same xlat table traversal
order compared to recursive version.

fixes arm-software/tf-issues#664

Signed-off-by: David Pu <dpu@nvidia.com>

lib/xlat_tables_v2/xlat_tables_utils.c

@@ -109,7 +109,7 @@ static const char *invalid_descriptors_ommited =
 		"%s(%d invalid descriptors omitted)\n";
 
 /*
- * Recursive function that reads the translation tables passed as an argument
+ * Function that reads the translation tables passed as an argument
  * and prints their status.
  */
 static void xlat_tables_print_internal(xlat_ctx_t *ctx, uintptr_t table_base_va,
@@ -118,10 +118,23 @@ static void xlat_tables_print_internal(xlat_ctx_t *ctx, uintptr_t table_base_va,
 {
 	assert(level <= XLAT_TABLE_LEVEL_MAX);
 
-	uint64_t desc;
-	uintptr_t table_idx_va = table_base_va;
+	/*
+	 * data structure to track DESC_TABLE entry before iterate into subtable
+	 * of next translation level. it will be restored after return from
+	 * subtable iteration.
+	 */
+	struct desc_table {
+		const uint64_t *table_base;
+		uintptr_t table_idx_va;
+		unsigned int idx;
+	} desc_tables[XLAT_TABLE_LEVEL_MAX + 1] = {
+		{NULL, 0U, XLAT_TABLE_ENTRIES}, };
+	unsigned int this_level = level;
+	const uint64_t *this_base = table_base;
+	unsigned int max_entries = table_entries;
+	size_t level_size = XLAT_BLOCK_SIZE(this_level);
 	unsigned int table_idx = 0U;
-	size_t level_size = XLAT_BLOCK_SIZE(level);
+	uintptr_t table_idx_va = table_base_va;
 
 	/*
 	 * Keep track of how many invalid descriptors are counted in a row.
@@ -131,67 +144,110 @@ static void xlat_tables_print_internal(xlat_ctx_t *ctx, uintptr_t table_base_va,
 	 */
 	int invalid_row_count = 0;
 
-	while (table_idx < table_entries) {
+	while (this_base != NULL) {
+		/* finish current xlat level */
+		if (table_idx >= max_entries) {
+			if (invalid_row_count > 1) {
+				printf(invalid_descriptors_ommited,
+					  level_spacers[this_level],
+					  invalid_row_count - 1);
+			}
+			invalid_row_count = 0;
 
-		desc = table_base[table_idx];
+			/* no parent level to iterate. */
+			if (this_level <= level) {
+				this_base = NULL;
+				table_idx = max_entries + 1;
+			} else {
+				/* retore previous DESC_TABLE entry and start
+				 * to iterate.
+				 */
+				this_level--;
+				level_size = XLAT_BLOCK_SIZE(this_level);
+				this_base = desc_tables[this_level].table_base;
+				table_idx = desc_tables[this_level].idx;
+				table_idx_va =
+					desc_tables[this_level].table_idx_va;
+				if (this_level == level) {
+					max_entries = table_entries;
+				} else {
+					max_entries = XLAT_TABLE_ENTRIES;
+				}
 
-		if ((desc & DESC_MASK) == INVALID_DESC) {
+				assert(this_base != NULL);
+			}
+		} else {
+			uint64_t desc = this_base[table_idx];
 
+			if ((desc & DESC_MASK) == INVALID_DESC) {
 				if (invalid_row_count == 0) {
 					printf("%sVA:0x%lx size:0x%zx\n",
-				       level_spacers[level],
+						  level_spacers[this_level],
 						  table_idx_va, level_size);
 				}
 				invalid_row_count++;
-
+				table_idx++;
+				table_idx_va += level_size;
 			} else {
-
 				if (invalid_row_count > 1) {
 					printf(invalid_descriptors_ommited,
-				       level_spacers[level],
+						  level_spacers[this_level],
 						  invalid_row_count - 1);
 				}
 				invalid_row_count = 0;
-
 				/*
-			 * Check if this is a table or a block. Tables are only
-			 * allowed in levels other than 3, but DESC_PAGE has the
-			 * same value as DESC_TABLE, so we need to check.
+				 * Check if this is a table or a block. Tables
+				 * are only allowed in levels other than 3, but
+				 * DESC_PAGE has the same value as DESC_TABLE,
+				 * so we need to check.
 				 */
+
 				if (((desc & DESC_MASK) == TABLE_DESC) &&
-					(level < XLAT_TABLE_LEVEL_MAX)) {
+				    (this_level < XLAT_TABLE_LEVEL_MAX)) {
+					uintptr_t addr_inner;
+
 					/*
-				 * Do not print any PA for a table descriptor,
-				 * as it doesn't directly map physical memory
-				 * but instead points to the next translation
+					 * Do not print any PA for a table
+					 * descriptor, as it doesn't directly
+					 * map physical memory but instead
+					 * points to the next translation
 					 * table in the translation table walk.
 					 */
 					printf("%sVA:0x%lx size:0x%zx\n",
-				       level_spacers[level],
+					       level_spacers[this_level],
 					       table_idx_va, level_size);
 
-				uintptr_t addr_inner = desc & TABLE_ADDR_MASK;
-
-				xlat_tables_print_internal(ctx, table_idx_va,
-					(uint64_t *)addr_inner,
-					XLAT_TABLE_ENTRIES, level + 1U);
+					addr_inner = desc & TABLE_ADDR_MASK;
+					/* save current xlat level */
+					desc_tables[this_level].table_base =
+						this_base;
+					desc_tables[this_level].idx =
+						table_idx + 1;
+					desc_tables[this_level].table_idx_va =
+						table_idx_va + level_size;
+
+					/* start iterating next level entries */
+					this_base = (uint64_t *)addr_inner;
+					max_entries = XLAT_TABLE_ENTRIES;
+					this_level++;
+					level_size =
+						XLAT_BLOCK_SIZE(this_level);
+					table_idx = 0U;
 				} else {
 					printf("%sVA:0x%lx PA:0x%llx size:0x%zx ",
-				       level_spacers[level], table_idx_va,
+					       level_spacers[this_level],
+					       table_idx_va,
 					       (uint64_t)(desc & TABLE_ADDR_MASK),
 					       level_size);
 					xlat_desc_print(ctx, desc);
 					printf("\n");
-			}
-		}
 
 					table_idx++;
 					table_idx_va += level_size;
-	}
 
-	if (invalid_row_count > 1) {
-		printf(invalid_descriptors_ommited,
-		       level_spacers[level], invalid_row_count - 1);
+				}
+			}
+		}
 	}
 }