10 files changed, 484 insertions, 200 deletions

diff --git a/scripts/gendwarfksyms/cache.c b/scripts/gendwarfksyms/cache.c
index c9c19b86a686..1c640db93db3 100644
--- a/scripts/gendwarfksyms/cache.c
+++ b/scripts/gendwarfksyms/cache.c
@@ -15,7 +15,7 @@ void cache_set(struct cache *cache, unsigned long key, int value)
 {
 	struct cache_item *ci;
 
-	ci = xmalloc(sizeof(struct cache_item));
+	ci = xmalloc(sizeof(*ci));
 	ci->key = key;
 	ci->value = value;
 	hash_add(cache->cache, &ci->hash, hash_32(key));
diff --git a/scripts/gendwarfksyms/die.c b/scripts/gendwarfksyms/die.c
index 66bd4c9bc952..052f7a3f975a 100644
--- a/scripts/gendwarfksyms/die.c
+++ b/scripts/gendwarfksyms/die.c
@@ -6,7 +6,7 @@
 #include <string.h>
 #include "gendwarfksyms.h"
 
-#define DIE_HASH_BITS 15
+#define DIE_HASH_BITS 16
 
 /* {die->addr, state} -> struct die * */
 static HASHTABLE_DEFINE(die_map, 1 << DIE_HASH_BITS);
@@ -33,7 +33,7 @@ static struct die *create_die(Dwarf_Die *die, enum die_state state)
 {
 	struct die *cd;
 
-	cd = xmalloc(sizeof(struct die));
+	cd = xmalloc(sizeof(*cd));
 	init_die(cd);
 	cd->addr = (uintptr_t)die->addr;
 
@@ -123,7 +123,7 @@ static struct die_fragment *append_item(struct die *cd)
 {
 	struct die_fragment *df;
 
-	df = xmalloc(sizeof(struct die_fragment));
+	df = xmalloc(sizeof(*df));
 	df->type = FRAGMENT_EMPTY;
 	list_add_tail(&df->list, &cd->fragments);
 	return df;
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
index 534d9aa7c114..3538a7d9cb07 100644
--- a/scripts/gendwarfksyms/dwarf.c
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2024 Google LLC
  */
 
+#define _GNU_SOURCE
 #include <assert.h>
 #include <inttypes.h>
 #include <stdarg.h>
@@ -193,79 +194,17 @@ static void process_fmt(struct die *cache, const char *fmt, ...)
 	va_end(args);
 }
 
-#define MAX_FQN_SIZE 64
-
-/* Get a fully qualified name from DWARF scopes */
-static char *get_fqn(Dwarf_Die *die)
+static void update_fqn(struct die *cache, Dwarf_Die *die)
 {
-	const char *list[MAX_FQN_SIZE];
-	Dwarf_Die *scopes = NULL;
-	bool has_name = false;
-	char *fqn = NULL;
-	char *p;
-	int count = 0;
-	int len = 0;
-	int res;
-	int i;
-
-	res = checkp(dwarf_getscopes_die(die, &scopes));
-	if (!res) {
-		list[count] = get_name_attr(die);
-
-		if (!list[count])
-			return NULL;
-
-		len += strlen(list[count]);
-		count++;
-
-		goto done;
-	}
-
-	for (i = res - 1; i >= 0 && count < MAX_FQN_SIZE; i--) {
-		if (dwarf_tag(&scopes[i]) == DW_TAG_compile_unit)
-			continue;
+	struct die *fqn;
 
-		list[count] = get_name_attr(&scopes[i]);
-
-		if (list[count]) {
-			has_name = true;
-		} else {
-			list[count] = "<anonymous>";
-			has_name = false;
-		}
-
-		len += strlen(list[count]);
-		count++;
-
-		if (i > 0) {
-			list[count++] = "::";
-			len += 2;
-		}
+	if (!cache->fqn) {
+		if (!__die_map_get((uintptr_t)die->addr, DIE_FQN, &fqn) &&
+		    *fqn->fqn)
+			cache->fqn = xstrdup(fqn->fqn);
+		else
+			cache->fqn = "";
 	}
-
-	free(scopes);
-
-	if (count == MAX_FQN_SIZE)
-		warn("increase MAX_FQN_SIZE: reached the maximum");
-
-	/* Consider the DIE unnamed if the last scope doesn't have a name */
-	if (!has_name)
-		return NULL;
-done:
-	fqn = xmalloc(len + 1);
-	*fqn = '\0';
-
-	p = fqn;
-	for (i = 0; i < count; i++)
-		p = stpcpy(p, list[i]);
-
-	return fqn;
-}
-
-static void update_fqn(struct die *cache, Dwarf_Die *die)
-{
-	if (!cache->fqn)
-		cache->fqn = get_fqn(die) ?: "";
 }
 
 static void process_fqn(struct die *cache, Dwarf_Die *die)
@@ -289,12 +228,24 @@ static void process_fqn(struct die *cache, Dwarf_Die *die)
 DEFINE_PROCESS_UDATA_ATTRIBUTE(accessibility)
 DEFINE_PROCESS_UDATA_ATTRIBUTE(alignment)
 DEFINE_PROCESS_UDATA_ATTRIBUTE(bit_size)
-DEFINE_PROCESS_UDATA_ATTRIBUTE(byte_size)
 DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding)
 DEFINE_PROCESS_UDATA_ATTRIBUTE(data_bit_offset)
 DEFINE_PROCESS_UDATA_ATTRIBUTE(data_member_location)
 DEFINE_PROCESS_UDATA_ATTRIBUTE(discr_value)
 
+static void process_byte_size_attr(struct die *cache, Dwarf_Die *die)
+{
+	Dwarf_Word value;
+	unsigned long override;
+
+	if (get_udata_attr(die, DW_AT_byte_size, &value)) {
+		if (stable && kabi_get_byte_size(cache->fqn, &override))
+			value = override;
+
+		process_fmt(cache, " byte_size(%" PRIu64 ")", value);
+	}
+}
+
 /* Match functions -- die_match_callback_t */
 #define DEFINE_MATCH(type)                                     \
 	static bool match_##type##_type(Dwarf_Die *die)        \
@@ -683,7 +634,7 @@ static int get_union_kabi_status(Dwarf_Die *die, Dwarf_Die *placeholder,
 	 * Note that the user of this feature is responsible for ensuring
 	 * that the structure actually remains ABI compatible.
 	 */
-	memset(&state.kabi, 0, sizeof(struct kabi_state));
+	memset(&state.kabi, 0, sizeof(state.kabi));
 
 	res = checkp(process_die_container(&state, NULL, die,
 					   check_union_member_kabi_status,
@@ -1148,8 +1099,81 @@ static void process_symbol_ptr(struct symbol *sym, void *arg)
 	cache_free(&state.expansion_cache);
 }
 
+static int resolve_fqns(struct state *parent, struct die *unused,
+			Dwarf_Die *die)
+{
+	struct state state;
+	struct die *cache;
+	const char *name;
+	bool use_prefix;
+	char *prefix = NULL;
+	char *fqn = "";
+	int tag;
+
+	if (!__die_map_get((uintptr_t)die->addr, DIE_FQN, &cache))
+		return 0;
+
+	tag = dwarf_tag(die);
+
+	/*
+	 * Only namespaces and structures need to pass a prefix to the next
+	 * scope.
+	 */
+	use_prefix = tag == DW_TAG_namespace || tag == DW_TAG_class_type ||
+		     tag == DW_TAG_structure_type;
+
+	state.expand.current_fqn = NULL;
+	name = get_name_attr(die);
+
+	if (parent && parent->expand.current_fqn && (use_prefix || name)) {
+		/*
+		 * The fqn for the current DIE, and if needed, a prefix for the
+		 * next scope.
+		 */
+		if (asprintf(&prefix, "%s::%s", parent->expand.current_fqn,
+			     name ? name : "<anonymous>") < 0)
+			error("asprintf failed");
+
+		if (use_prefix)
+			state.expand.current_fqn = prefix;
+
+		/*
+		 * Use fqn only if the DIE has a name. Otherwise fqn will
+		 * remain empty.
+		 */
+		if (name) {
+			fqn = prefix;
+			/* prefix will be freed by die_map. */
+			prefix = NULL;
+		}
+	} else if (name) {
+		/* No prefix from the previous scope. Use only the name. */
+		fqn = xstrdup(name);
+
+		if (use_prefix)
+			state.expand.current_fqn = fqn;
+	}
+
+	/* If the DIE has a non-empty name, cache it. */
+	if (*fqn) {
+		cache = die_map_get(die, DIE_FQN);
+		/* Move ownership of fqn to die_map. */
+		cache->fqn = fqn;
+		cache->state = DIE_FQN;
+	}
+
+	check(process_die_container(&state, NULL, die, resolve_fqns,
+				    match_all));
+
+	free(prefix);
+	return 0;
+}
+
 void process_cu(Dwarf_Die *cudie)
 {
+	check(process_die_container(NULL, NULL, cudie, resolve_fqns,
+				    match_all));
+
 	check(process_die_container(NULL, NULL, cudie, process_exported_symbols,
 				    match_all));
 
diff --git a/scripts/gendwarfksyms/examples/kabi.h b/scripts/gendwarfksyms/examples/kabi.h
index 97a5669b083d..170733a3fba4 100644
--- a/scripts/gendwarfksyms/examples/kabi.h
+++ b/scripts/gendwarfksyms/examples/kabi.h
@@ -37,11 +37,14 @@
 #define __stringify(x...) __stringify_1(x)
 #endif
 
-#define __KABI_RULE(hint, target, value)                             \
+#define ___KABI_RULE(hint, target, value)                            \
 	static const char __PASTE(__gendwarfksyms_rule_,             \
 				  __COUNTER__)[] __used __aligned(1) \
 		__section(".discard.gendwarfksyms.kabi_rules") =     \
-			"1\0" #hint "\0" #target "\0" #value
+			"1\0" #hint "\0" target "\0" value
+
+#define __KABI_RULE(hint, target, value) \
+	___KABI_RULE(hint, #target, #value)
 
 #define __KABI_NORMAL_SIZE_ALIGN(_orig, _new)                                             \
 	union {                                                                           \
@@ -90,6 +93,20 @@
 	__KABI_RULE(enumerator_value, fqn field, value)
 
 /*
+ * KABI_BYTE_SIZE(fqn, value)
+ *   Set the byte_size attribute for the struct/union/enum fqn to
+ *   value bytes.
+ */
+#define KABI_BYTE_SIZE(fqn, value) __KABI_RULE(byte_size, fqn, value)
+
+/*
+ * KABI_TYPE_STRING(type, str)
+ *   For the given type, override the type string used in symtypes
+ *   output and version calculation with str.
+ */
+#define KABI_TYPE_STRING(type, str) ___KABI_RULE(type_string, type, str)
+
+/*
  * KABI_RESERVE
  *   Reserve some "padding" in a structure for use by LTS backports.
  *   This is normally placed at the end of a structure.
diff --git a/scripts/gendwarfksyms/examples/kabi_ex.c b/scripts/gendwarfksyms/examples/kabi_ex.c
index 0b7ffd830541..1f799eb7c756 100644
--- a/scripts/gendwarfksyms/examples/kabi_ex.c
+++ b/scripts/gendwarfksyms/examples/kabi_ex.c
@@ -28,3 +28,10 @@ struct ex2c ex2c;
 struct ex3a ex3a;
 struct ex3b ex3b;
 struct ex3c ex3c;
+
+struct ex4a ex4a;
+
+struct ex5a ex5a;
+struct ex5b ex5b;
+
+int ex6a;
diff --git a/scripts/gendwarfksyms/examples/kabi_ex.h b/scripts/gendwarfksyms/examples/kabi_ex.h
index 1736e0f65208..785b211d9c58 100644
--- a/scripts/gendwarfksyms/examples/kabi_ex.h
+++ b/scripts/gendwarfksyms/examples/kabi_ex.h
@@ -21,6 +21,12 @@
  * 	./gendwarfksyms --stable --dump-dies \
  * 		examples/kabi_ex.o 2>&1 >/dev/null | \
  * 	FileCheck examples/kabi_ex.h --check-prefix=STABLE
+
+ * $ nm examples/kabi_ex.o | awk '{ print $NF }' | \
+ * 	./gendwarfksyms --stable --dump-versions \
+ * 		examples/kabi_ex.o 2>&1 >/dev/null | \
+ * 	sort | \
+ * 	FileCheck examples/kabi_ex.h --check-prefix=VERSIONS
  */
 
 #ifndef __KABI_EX_H__
@@ -170,7 +176,7 @@ struct ex2a {
 /*
  * STABLE:      variable structure_type ex2a {
  * STABLE-NEXT:   member base_type int byte_size(4) encoding(5) a data_member_location(0) ,
- * STABLE-NEXT:   member base_type [[ULONG:long unsigned int|unsigned long]] byte_size(8) encoding(7) b data_member_location(8)
+ * STABLE-NEXT:   member base_type [[ULONG]] byte_size(8) encoding(7) b data_member_location(8)
  * STABLE-NEXT:   member base_type int byte_size(4) encoding(5) c data_member_location(16) ,
  * STABLE-NEXT:   member base_type [[ULONG]] byte_size(8) encoding(7) d data_member_location(24)
  * STABLE-NEXT: } byte_size(32)
@@ -227,7 +233,7 @@ struct ex3a {
 
 /*
  * STABLE:      variable structure_type ex3a {
- * STABLE-NEXT:   member base_type [[ULONG:long unsigned int|unsigned long]] byte_size(8) encoding(7) a data_member_location(0)
+ * STABLE-NEXT:   member base_type [[ULONG]] byte_size(8) encoding(7) a data_member_location(0)
  * STABLE-NEXT:   member base_type [[ULONG]] byte_size(8) encoding(7) unused data_member_location(8)
  * STABLE-NEXT: } byte_size(16)
  */
@@ -260,4 +266,95 @@ _Static_assert(sizeof(struct ex3a) == sizeof(struct ex3c), "ex3a size doesn't ma
  * STABLE-NEXT: } byte_size(16)
  */
 
+/*
+ * Example: An ignored field added to an end of a partially opaque struct,
+ * while keeping the byte_size attribute unchanged.
+ */
+
+struct ex4a {
+	unsigned long a;
+	KABI_IGNORE(0, unsigned long b);
+};
+
+/*
+ * This may be safe if the structure allocation is managed by the core kernel
+ * and the layout remains unchanged except for appended new members.
+ */
+KABI_BYTE_SIZE(ex4a, 8);
+
+/*
+ * STABLE:      variable structure_type ex4a {
+ * STABLE-NEXT:   member base_type [[ULONG]] byte_size(8) encoding(7) a data_member_location(0)
+ * STABLE-NEXT: } byte_size(8)
+ */
+
+/*
+ * Example: A type string override.
+ */
+
+struct ex5a {
+	unsigned long a;
+};
+
+/*
+ * This may be safe if the structure is fully opaque to modules, even though
+ * its definition has inadvertently become part of the ABI.
+ */
+KABI_TYPE_STRING(
+	"s#ex5a",
+	"structure_type ex5a { member pointer_type { s#ex4a } byte_size(8) p data_member_location(0) } byte_size(8)");
+
+/*
+ * Make sure the fully expanded type string includes ex4a.
+ *
+ * VERSIONS:      ex5a variable structure_type ex5a {
+ * VERSIONS-SAME:   member pointer_type {
+ * VERSIONS-SAME:     structure_type ex4a {
+ * VERSIONS-SAME:       member base_type [[ULONG:long unsigned int|unsigned long]] byte_size(8) encoding(7) a data_member_location(0)
+ * VERSIONS-SAME:     } byte_size(8)
+ * VERSIONS-SAME:   } byte_size(8) p data_member_location(0)
+ * VERSIONS-SAME: } byte_size(8)
+ */
+
+/*
+ * Example: A type string definition for a non-existent type.
+ */
+
+struct ex5b {
+	unsigned long a;
+};
+
+/* Replace the type string for struct ex5b */
+KABI_TYPE_STRING(
+	"s#ex5b",
+	"structure_type ex5b { member pointer_type { s#ex5c } byte_size(8) p data_member_location(0) } byte_size(8)");
+
+/* Define a type string for a non-existent struct ex5c */
+KABI_TYPE_STRING(
+	"s#ex5c",
+	"structure_type ex5c { member base_type int byte_size(4) encoding(5) n data_member_location(0) } byte_size(8)");
+
+/*
+ * Make sure the fully expanded type string includes the definition for ex5c.
+ *
+ * VERSIONS:      ex5b variable structure_type ex5b {
+ * VERSIONS-SAME:   member pointer_type {
+ * VERSIONS-SAME:     structure_type ex5c {
+ * VERSIONS-SAME:       member base_type int byte_size(4) encoding(5) n data_member_location(0)
+ * VERSIONS-SAME:     } byte_size(8)
+ * VERSIONS-SAME:   } byte_size(8) p data_member_location(0)
+ * VERSIONS-SAME: } byte_size(8)
+ */
+
+/*
+ * Example: A type string override for a symbol.
+ */
+
+KABI_TYPE_STRING("ex6a", "variable s#ex5c");
+
+/*
+ * VERSIONS:      ex6a variable structure_type ex5c {
+ * VERSIONS-SAME:   member base_type int byte_size(4) encoding(5) n data_member_location(0)
+ * VERSIONS-SAME: } byte_size(8)
+ */
 #endif /* __KABI_EX_H__ */
diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h
index 197a1a8123c6..d9c06d2cb1df 100644
--- a/scripts/gendwarfksyms/gendwarfksyms.h
+++ b/scripts/gendwarfksyms/gendwarfksyms.h
@@ -139,6 +139,7 @@ void symbol_free(void);
 
 enum die_state {
 	DIE_INCOMPLETE,
+	DIE_FQN,
 	DIE_UNEXPANDED,
 	DIE_COMPLETE,
 	DIE_SYMBOL,
@@ -170,6 +171,7 @@ static inline const char *die_state_name(enum die_state state)
 {
 	switch (state) {
 	CASE_CONST_TO_STR(DIE_INCOMPLETE)
+	CASE_CONST_TO_STR(DIE_FQN)
 	CASE_CONST_TO_STR(DIE_UNEXPANDED)
 	CASE_CONST_TO_STR(DIE_COMPLETE)
 	CASE_CONST_TO_STR(DIE_SYMBOL)
@@ -214,24 +216,14 @@ int cache_get(struct cache *cache, unsigned long key);
 void cache_init(struct cache *cache);
 void cache_free(struct cache *cache);
 
-static inline void __cache_mark_expanded(struct cache *cache, uintptr_t addr)
-{
-	cache_set(cache, addr, 1);
-}
-
-static inline bool __cache_was_expanded(struct cache *cache, uintptr_t addr)
-{
-	return cache_get(cache, addr) == 1;
-}
-
 static inline void cache_mark_expanded(struct cache *cache, void *addr)
 {
-	__cache_mark_expanded(cache, (uintptr_t)addr);
+	cache_set(cache, (unsigned long)addr, 1);
 }
 
 static inline bool cache_was_expanded(struct cache *cache, void *addr)
 {
-	return __cache_was_expanded(cache, (uintptr_t)addr);
+	return cache_get(cache, (unsigned long)addr) == 1;
 }
 
 /*
@@ -285,10 +277,12 @@ void generate_symtypes_and_versions(FILE *file);
  * kabi.c
  */
 
+bool kabi_get_byte_size(const char *fqn, unsigned long *value);
 bool kabi_is_enumerator_ignored(const char *fqn, const char *field);
 bool kabi_get_enumerator_value(const char *fqn, const char *field,
 			       unsigned long *value);
 bool kabi_is_declonly(const char *fqn);
+bool kabi_get_type_string(const char *type, const char **str);
 
 void kabi_read_rules(int fd);
 void kabi_free(void);
diff --git a/scripts/gendwarfksyms/kabi.c b/scripts/gendwarfksyms/kabi.c
index 66f01fcd1607..e3c2a3ccf51a 100644
--- a/scripts/gendwarfksyms/kabi.c
+++ b/scripts/gendwarfksyms/kabi.c
@@ -54,11 +54,27 @@
  */
 #define KABI_RULE_TAG_ENUMERATOR_VALUE "enumerator_value"
 
+/*
+ * Rule: byte_size
+ * - For the fqn_field in the target field, set the byte_size
+ *   attribute to the value in the value field.
+ */
+#define KABI_RULE_TAG_BYTE_SIZE "byte_size"
+
+/*
+ * Rule: type_string
+ * - For the type reference in the fqn field, use the type string
+ *   in the value field.
+ */
+#define KABI_RULE_TAG_TYPE_STRING "type_string"
+
 enum kabi_rule_type {
 	KABI_RULE_TYPE_UNKNOWN,
 	KABI_RULE_TYPE_DECLONLY,
 	KABI_RULE_TYPE_ENUMERATOR_IGNORE,
 	KABI_RULE_TYPE_ENUMERATOR_VALUE,
+	KABI_RULE_TYPE_BYTE_SIZE,
+	KABI_RULE_TYPE_TYPE_STRING,
 };
 
 #define RULE_HASH_BITS 7
@@ -127,6 +143,14 @@ void kabi_read_rules(int fd)
 			.type = KABI_RULE_TYPE_ENUMERATOR_VALUE,
 			.tag = KABI_RULE_TAG_ENUMERATOR_VALUE,
 		},
+		{
+			.type = KABI_RULE_TYPE_BYTE_SIZE,
+			.tag = KABI_RULE_TAG_BYTE_SIZE,
+		},
+		{
+			.type = KABI_RULE_TYPE_TYPE_STRING,
+			.tag = KABI_RULE_TAG_TYPE_STRING,
+		},
 	};
 
 	if (!stable)
@@ -204,7 +228,7 @@ void kabi_read_rules(int fd)
 		if (type == KABI_RULE_TYPE_UNKNOWN)
 			error("unsupported kABI rule type: '%s'", field);
 
-		rule = xmalloc(sizeof(struct rule));
+		rule = xmalloc(sizeof(*rule));
 
 		rule->type = type;
 		rule->target = xstrdup(get_rule_field(&rule_str, &left));
@@ -222,33 +246,55 @@ void kabi_read_rules(int fd)
 	check(elf_end(elf));
 }
 
-bool kabi_is_declonly(const char *fqn)
+static char *get_enumerator_target(const char *fqn, const char *field)
+{
+	char *target = NULL;
+
+	if (asprintf(&target, "%s %s", fqn, field) < 0)
+		error("asprintf failed for '%s %s'", fqn, field);
+
+	return target;
+}
+
+static struct rule *find_rule(enum kabi_rule_type type, const char *target)
 {
 	struct rule *rule;
 
 	if (!stable)
-		return false;
-	if (!fqn || !*fqn)
-		return false;
+		return NULL;
+	if (!target || !*target)
+		return NULL;
 
 	hash_for_each_possible(rules, rule, hash,
-			       rule_values_hash(KABI_RULE_TYPE_DECLONLY, fqn)) {
-		if (rule->type == KABI_RULE_TYPE_DECLONLY &&
-		    !strcmp(fqn, rule->target))
-			return true;
+			       rule_values_hash(type, target)) {
+		if (rule->type == type && !strcmp(target, rule->target))
+			return rule;
 	}
 
-	return false;
+	return NULL;
 }
 
-static char *get_enumerator_target(const char *fqn, const char *field)
+static struct rule *find_enumerator_rule(enum kabi_rule_type type,
+					 const char *fqn, const char *field)
 {
-	char *target = NULL;
+	struct rule *rule;
+	char *target;
 
-	if (asprintf(&target, "%s %s", fqn, field) < 0)
-		error("asprintf failed for '%s %s'", fqn, field);
+	if (!stable)
+		return NULL;
+	if (!fqn || !*fqn || !field || !*field)
+		return NULL;
 
-	return target;
+	target = get_enumerator_target(fqn, field);
+	rule = find_rule(type, target);
+
+	free(target);
+	return rule;
+}
+
+bool kabi_is_declonly(const char *fqn)
+{
+	return !!find_rule(KABI_RULE_TYPE_DECLONLY, fqn);
 }
 
 static unsigned long get_ulong_value(const char *value)
@@ -267,58 +313,49 @@ static unsigned long get_ulong_value(const char *value)
 
 bool kabi_is_enumerator_ignored(const char *fqn, const char *field)
 {
-	bool match = false;
-	struct rule *rule;
-	char *target;
-
-	if (!stable)
-		return false;
-	if (!fqn || !*fqn || !field || !*field)
-		return false;
+	return !!find_enumerator_rule(KABI_RULE_TYPE_ENUMERATOR_IGNORE, fqn,
+				      field);
+}
 
-	target = get_enumerator_target(fqn, field);
+bool kabi_get_enumerator_value(const char *fqn, const char *field,
+			       unsigned long *value)
+{
+	struct rule *rule;
 
-	hash_for_each_possible(
-		rules, rule, hash,
-		rule_values_hash(KABI_RULE_TYPE_ENUMERATOR_IGNORE, target)) {
-		if (rule->type == KABI_RULE_TYPE_ENUMERATOR_IGNORE &&
-		    !strcmp(target, rule->target)) {
-			match = true;
-			break;
-		}
+	rule = find_enumerator_rule(KABI_RULE_TYPE_ENUMERATOR_VALUE, fqn,
+				    field);
+	if (rule) {
+		*value = get_ulong_value(rule->value);
+		return true;
 	}
 
-	free(target);
-	return match;
+	return false;
 }
 
-bool kabi_get_enumerator_value(const char *fqn, const char *field,
-			       unsigned long *value)
+bool kabi_get_byte_size(const char *fqn, unsigned long *value)
 {
-	bool match = false;
 	struct rule *rule;
-	char *target;
 
-	if (!stable)
-		return false;
-	if (!fqn || !*fqn || !field || !*field)
-		return false;
+	rule = find_rule(KABI_RULE_TYPE_BYTE_SIZE, fqn);
+	if (rule) {
+		*value = get_ulong_value(rule->value);
+		return true;
+	}
 
-	target = get_enumerator_target(fqn, field);
+	return false;
+}
 
-	hash_for_each_possible(rules, rule, hash,
-			       rule_values_hash(KABI_RULE_TYPE_ENUMERATOR_VALUE,
-						target)) {
-		if (rule->type == KABI_RULE_TYPE_ENUMERATOR_VALUE &&
-		    !strcmp(target, rule->target)) {
-			*value = get_ulong_value(rule->value);
-			match = true;
-			break;
-		}
+bool kabi_get_type_string(const char *type, const char **str)
+{
+	struct rule *rule;
+
+	rule = find_rule(KABI_RULE_TYPE_TYPE_STRING, type);
+	if (rule) {
+		*str = rule->value;
+		return true;
 	}
 
-	free(target);
-	return match;
+	return false;
 }
 
 void kabi_free(void)
diff --git a/scripts/gendwarfksyms/symbols.c b/scripts/gendwarfksyms/symbols.c
index 327f87389c34..35ed594f0749 100644
--- a/scripts/gendwarfksyms/symbols.c
+++ b/scripts/gendwarfksyms/symbols.c
@@ -146,7 +146,7 @@ void symbol_read_exports(FILE *file)
 			continue;
 		}
 
-		sym = xcalloc(1, sizeof(struct symbol));
+		sym = xcalloc(1, sizeof(*sym));
 		sym->name = name;
 		sym->addr.section = SHN_UNDEF;
 		sym->state = SYMBOL_UNPROCESSED;
diff --git a/scripts/gendwarfksyms/types.c b/scripts/gendwarfksyms/types.c
index 6c03265f4d10..9c3b053bf061 100644
--- a/scripts/gendwarfksyms/types.c
+++ b/scripts/gendwarfksyms/types.c
@@ -6,6 +6,8 @@
 #define _GNU_SOURCE
 #include <inttypes.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 #include <zlib.h>
 
 #include "gendwarfksyms.h"
@@ -43,7 +45,7 @@ static int type_list_append(struct list_head *list, const char *s, void *owned)
 	if (!s)
 		return 0;
 
-	entry = xmalloc(sizeof(struct type_list_entry));
+	entry = xmalloc(sizeof(*entry));
 	entry->str = s;
 	entry->owned = owned;
 	list_add_tail(&entry->list, list);
@@ -100,7 +102,7 @@ static void type_expansion_append(struct type_expansion *type, const char *s,
 #define TYPE_HASH_BITS 12
 static HASHTABLE_DEFINE(type_map, 1 << TYPE_HASH_BITS);
 
-static int type_map_get(const char *name, struct type_expansion **res)
+static int __type_map_get(const char *name, struct type_expansion **res)
 {
 	struct type_expansion *e;
 
@@ -114,12 +116,13 @@ static int type_map_get(const char *name, struct type_expansion **res)
 	return -1;
 }
 
-static void type_map_add(const char *name, struct type_expansion *type)
+static struct type_expansion *type_map_add(const char *name,
+					   struct type_expansion *type)
 {
 	struct type_expansion *e;
 
-	if (type_map_get(name, &e)) {
-		e = xmalloc(sizeof(struct type_expansion));
+	if (__type_map_get(name, &e)) {
+		e = xmalloc(sizeof(*e));
 		type_expansion_init(e);
 		e->name = xstrdup(name);
 
@@ -130,7 +133,7 @@ static void type_map_add(const char *name, struct type_expansion *type)
 	} else {
 		/* Use the longest available expansion */
 		if (type->len <= e->len)
-			return;
+			return e;
 
 		type_list_free(&e->expanded);
 
@@ -148,22 +151,71 @@ static void type_map_add(const char *name, struct type_expansion *type)
 		type_list_write(&e->expanded, stderr);
 		checkp(fputs("\n", stderr));
 	}
+
+	return e;
+}
+
+static void type_parse(const char *name, const char *str,
+		       struct type_expansion *type);
+
+static int type_map_get(const char *name, struct type_expansion **res)
+{
+	struct type_expansion type;
+	const char *override;
+
+	if (!__type_map_get(name, res))
+		return 0;
+
+	/*
+	 * If die_map didn't contain a type, we might still have
+	 * a type_string kABI rule that defines it.
+	 */
+	if (stable && kabi_get_type_string(name, &override)) {
+		type_expansion_init(&type);
+		type_parse(name, override, &type);
+		*res = type_map_add(name, &type);
+		type_expansion_free(&type);
+		return 0;
+	}
+
+	return -1;
+}
+
+static int cmp_expansion_name(const void *p1, const void *p2)
+{
+	struct type_expansion *const *e1 = p1;
+	struct type_expansion *const *e2 = p2;
+
+	return strcmp((*e1)->name, (*e2)->name);
 }
 
 static void type_map_write(FILE *file)
 {
 	struct type_expansion *e;
 	struct hlist_node *tmp;
+	struct type_expansion **es;
+	size_t count = 0;
+	size_t i = 0;
 
 	if (!file)
 		return;
 
-	hash_for_each_safe(type_map, e, tmp, hash) {
-		checkp(fputs(e->name, file));
+	hash_for_each_safe(type_map, e, tmp, hash)
+		++count;
+	es = xmalloc(count * sizeof(*es));
+	hash_for_each_safe(type_map, e, tmp, hash)
+		es[i++] = e;
+
+	qsort(es, count, sizeof(*es), cmp_expansion_name);
+
+	for (i = 0; i < count; ++i) {
+		checkp(fputs(es[i]->name, file));
 		checkp(fputs(" ", file));
-		type_list_write(&e->expanded, file);
+		type_list_write(&es[i]->expanded, file);
 		checkp(fputs("\n", file));
 	}
+
+	free(es);
 }
 
 static void type_map_free(void)
@@ -248,7 +300,7 @@ static char *get_type_name(struct die *cache)
 		warn("found incomplete cache entry: %p", cache);
 		return NULL;
 	}
-	if (cache->state == DIE_SYMBOL)
+	if (cache->state == DIE_SYMBOL || cache->state == DIE_FQN)
 		return NULL;
 	if (!cache->fqn || !*cache->fqn)
 		return NULL;
@@ -267,15 +319,18 @@ static char *get_type_name(struct die *cache)
 	return name;
 }
 
-static void __calculate_version(struct version *version, struct list_head *list)
+static void __calculate_version(struct version *version,
+				struct type_expansion *type)
 {
 	struct type_list_entry *entry;
 	struct type_expansion *e;
 
 	/* Calculate a CRC over an expanded type string */
-	list_for_each_entry(entry, list, list) {
+	list_for_each_entry(entry, &type->expanded, list) {
 		if (is_type_prefix(entry->str)) {
-			check(type_map_get(entry->str, &e));
+			if (type_map_get(entry->str, &e))
+				error("unknown type reference to '%s' when expanding '%s'",
+				      entry->str, type->name);
 
 			/*
 			 * It's sufficient to expand each type reference just
@@ -285,7 +340,7 @@ static void __calculate_version(struct version *version, struct list_head *list)
 				version_add(version, entry->str);
 			} else {
 				cache_mark_expanded(&expansion_cache, e);
-				__calculate_version(version, &e->expanded);
+				__calculate_version(version, e);
 			}
 		} else {
 			version_add(version, entry->str);
@@ -293,44 +348,19 @@ static void __calculate_version(struct version *version, struct list_head *list)
 	}
 }
 
-static void calculate_version(struct version *version, struct list_head *list)
+static void calculate_version(struct version *version,
+			      struct type_expansion *type)
 {
 	version_init(version);
-	__calculate_version(version, list);
+	__calculate_version(version, type);
 	cache_free(&expansion_cache);
 }
 
-static void __type_expand(struct die *cache, struct type_expansion *type,
-			  bool recursive);
-
-static void type_expand_child(struct die *cache, struct type_expansion *type,
-			      bool recursive)
-{
-	struct type_expansion child;
-	char *name;
-
-	name = get_type_name(cache);
-	if (!name) {
-		__type_expand(cache, type, recursive);
-		return;
-	}
-
-	if (recursive && !__cache_was_expanded(&expansion_cache, cache->addr)) {
-		__cache_mark_expanded(&expansion_cache, cache->addr);
-		type_expansion_init(&child);
-		__type_expand(cache, &child, true);
-		type_map_add(name, &child);
-		type_expansion_free(&child);
-	}
-
-	type_expansion_append(type, name, name);
-}
-
-static void __type_expand(struct die *cache, struct type_expansion *type,
-			  bool recursive)
+static void __type_expand(struct die *cache, struct type_expansion *type)
 {
 	struct die_fragment *df;
 	struct die *child;
+	char *name;
 
 	list_for_each_entry(df, &cache->fragments, list) {
 		switch (df->type) {
@@ -346,7 +376,12 @@ static void __type_expand(struct die *cache, struct type_expansion *type,
 				error("unknown child: %" PRIxPTR,
 				      df->data.addr);
 
-			type_expand_child(child, type, recursive);
+			name = get_type_name(child);
+			if (name)
+				type_expansion_append(type, name, name);
+			else
+				__type_expand(child, type);
+
 			break;
 		case FRAGMENT_LINEBREAK:
 			/*
@@ -364,12 +399,85 @@ static void __type_expand(struct die *cache, struct type_expansion *type,
 	}
 }
 
-static void type_expand(struct die *cache, struct type_expansion *type,
-			bool recursive)
+static void type_expand(const char *name, struct die *cache,
+			struct type_expansion *type)
 {
+	const char *override;
+
 	type_expansion_init(type);
-	__type_expand(cache, type, recursive);
-	cache_free(&expansion_cache);
+
+	if (stable && kabi_get_type_string(name, &override))
+		type_parse(name, override, type);
+	else
+		__type_expand(cache, type);
+}
+
+static void type_parse(const char *name, const char *str,
+		       struct type_expansion *type)
+{
+	char *fragment;
+	size_t start = 0;
+	size_t end;
+	size_t pos;
+
+	if (!*str)
+		error("empty type string override for '%s'", name);
+
+	for (pos = 0; str[pos]; ++pos) {
+		bool empty;
+		char marker = ' ';
+
+		if (!is_type_prefix(&str[pos]))
+			continue;
+
+		end = pos + 2;
+
+		/*
+		 * Find the end of the type reference. If the type name contains
+		 * spaces, it must be in single quotes.
+		 */
+		if (str[end] == '\'') {
+			marker = '\'';
+			++end;
+		}
+		while (str[end] && str[end] != marker)
+			++end;
+
+		/* Check that we have a non-empty type name */
+		if (marker == '\'') {
+			if (str[end] != marker)
+				error("incomplete %c# type reference for '%s' (string : '%s')",
+				      str[pos], name, str);
+			empty = end == pos + 3;
+			++end;
+		} else {
+			empty = end == pos + 2;
+		}
+		if (empty)
+			error("empty %c# type name for '%s' (string: '%s')",
+			      str[pos], name, str);
+
+		/* Append the part of the string before the type reference */
+		if (pos > start) {
+			fragment = xstrndup(&str[start], pos - start);
+			type_expansion_append(type, fragment, fragment);
+		}
+
+		/*
+		 * Append the type reference -- note that if the reference
+		 * is invalid, i.e. points to a non-existent type, we will
+		 * print out an error when calculating versions.
+		 */
+		fragment = xstrndup(&str[pos], end - pos);
+		type_expansion_append(type, fragment, fragment);
+
+		start = end;
+		pos = end - 1;
+	}
+
+	/* Append the rest of the type string, if there's any left */
+	if (str[start])
+		type_expansion_append(type, &str[start], NULL);
 }
 
 static void expand_type(struct die *cache, void *arg)
@@ -399,9 +507,9 @@ static void expand_type(struct die *cache, void *arg)
 		return;
 
 	debug("%s", name);
-	type_expand(cache, &type, true);
-	type_map_add(name, &type);
 
+	type_expand(name, cache, &type);
+	type_map_add(name, &type);
 	type_expansion_free(&type);
 	free(name);
 }
@@ -423,11 +531,11 @@ static void expand_symbol(struct symbol *sym, void *arg)
 	if (__die_map_get(sym->die_addr, DIE_SYMBOL, &cache))
 		return; /* We'll warn about missing CRCs later. */
 
-	type_expand(cache, &type, false);
+	type_expand(sym->name, cache, &type);
 
 	/* If the symbol already has a version, don't calculate it again. */
 	if (sym->state != SYMBOL_PROCESSED) {
-		calculate_version(&version, &type.expanded);
+		calculate_version(&version, &type);
 		symbol_set_crc(sym, version.crc);
 		debug("%s = %lx", sym->name, version.crc);