1 files changed, 1159 insertions, 0 deletions
diff --git a/scripts/gendwarfksyms/dwarf.c b/scripts/gendwarfksyms/dwarf.c
new file mode 100644
index 000000000000..534d9aa7c114
--- /dev/null
+++ b/scripts/gendwarfksyms/dwarf.c
@@ -0,0 +1,1159 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Google LLC
+ */
+
+#include <assert.h>
+#include <inttypes.h>
+#include <stdarg.h>
+#include "gendwarfksyms.h"
+
+/* See get_union_kabi_status */
+#define KABI_PREFIX "__kabi_"
+#define KABI_PREFIX_LEN (sizeof(KABI_PREFIX) - 1)
+#define KABI_RESERVED_PREFIX "reserved"
+#define KABI_RESERVED_PREFIX_LEN (sizeof(KABI_RESERVED_PREFIX) - 1)
+#define KABI_RENAMED_PREFIX "renamed"
+#define KABI_RENAMED_PREFIX_LEN (sizeof(KABI_RENAMED_PREFIX) - 1)
+#define KABI_IGNORED_PREFIX "ignored"
+#define KABI_IGNORED_PREFIX_LEN (sizeof(KABI_IGNORED_PREFIX) - 1)
+
+static inline bool is_kabi_prefix(const char *name)
+{
+	return name && !strncmp(name, KABI_PREFIX, KABI_PREFIX_LEN);
+}
+
+enum kabi_status {
+	/* >0 to stop DIE processing */
+	KABI_NORMAL = 1,
+	KABI_RESERVED,
+	KABI_IGNORED,
+};
+
+static bool do_linebreak;
+static int indentation_level;
+
+/* Line breaks and indentation for pretty-printing */
+static void process_linebreak(struct die *cache, int n)
+{
+	indentation_level += n;
+	do_linebreak = true;
+	die_map_add_linebreak(cache, n);
+}
+
+#define DEFINE_GET_ATTR(attr, type)                                    \
+	static bool get_##attr##_attr(Dwarf_Die *die, unsigned int id, \
+				      type *value)                     \
+	{                                                              \
+		Dwarf_Attribute da;                                    \
+		return dwarf_attr(die, id, &da) &&                     \
+		       !dwarf_form##attr(&da, value);                  \
+	}
+
+DEFINE_GET_ATTR(flag, bool)
+DEFINE_GET_ATTR(udata, Dwarf_Word)
+
+static bool get_ref_die_attr(Dwarf_Die *die, unsigned int id, Dwarf_Die *value)
+{
+	Dwarf_Attribute da;
+
+	/* dwarf_formref_die returns a pointer instead of an error value. */
+	return dwarf_attr(die, id, &da) && dwarf_formref_die(&da, value);
+}
+
+#define DEFINE_GET_STRING_ATTR(attr)                         \
+	static const char *get_##attr##_attr(Dwarf_Die *die) \
+	{                                                    \
+		Dwarf_Attribute da;                          \
+		if (dwarf_attr(die, DW_AT_##attr, &da))      \
+			return dwarf_formstring(&da);        \
+		return NULL;                                 \
+	}
+
+DEFINE_GET_STRING_ATTR(name)
+DEFINE_GET_STRING_ATTR(linkage_name)
+
+static const char *get_symbol_name(Dwarf_Die *die)
+{
+	const char *name;
+
+	/* rustc uses DW_AT_linkage_name for exported symbols */
+	name = get_linkage_name_attr(die);
+	if (!name)
+		name = get_name_attr(die);
+
+	return name;
+}
+
+static bool match_export_symbol(struct state *state, Dwarf_Die *die)
+{
+	Dwarf_Die *source = die;
+	Dwarf_Die origin;
+
+	/* If the DIE has an abstract origin, use it for type information. */
+	if (get_ref_die_attr(die, DW_AT_abstract_origin, &origin))
+		source = &origin;
+
+	state->sym = symbol_get(get_symbol_name(die));
+
+	/* Look up using the origin name if there are no matches. */
+	if (!state->sym && source != die)
+		state->sym = symbol_get(get_symbol_name(source));
+
+	state->die = *source;
+	return !!state->sym;
+}
+
+/* DW_AT_decl_file -> struct srcfile */
+static struct cache srcfile_cache;
+
+static bool is_definition_private(Dwarf_Die *die)
+{
+	Dwarf_Word filenum;
+	Dwarf_Files *files;
+	Dwarf_Die cudie;
+	const char *s;
+	int res;
+
+	/*
+	 * Definitions in .c files cannot change the public ABI,
+	 * so consider them private.
+	 */
+	if (!get_udata_attr(die, DW_AT_decl_file, &filenum))
+		return false;
+
+	res = cache_get(&srcfile_cache, filenum);
+	if (res >= 0)
+		return !!res;
+
+	if (!dwarf_cu_die(die->cu, &cudie, NULL, NULL, NULL, NULL, NULL, NULL))
+		error("dwarf_cu_die failed: '%s'", dwarf_errmsg(-1));
+
+	if (dwarf_getsrcfiles(&cudie, &files, NULL))
+		error("dwarf_getsrcfiles failed: '%s'", dwarf_errmsg(-1));
+
+	s = dwarf_filesrc(files, filenum, NULL, NULL);
+	if (!s)
+		error("dwarf_filesrc failed: '%s'", dwarf_errmsg(-1));
+
+	s = strrchr(s, '.');
+	res = s && !strcmp(s, ".c");
+	cache_set(&srcfile_cache, filenum, res);
+
+	return !!res;
+}
+
+static bool is_kabi_definition(struct die *cache, Dwarf_Die *die)
+{
+	bool value;
+
+	if (get_flag_attr(die, DW_AT_declaration, &value) && value)
+		return false;
+
+	if (kabi_is_declonly(cache->fqn))
+		return false;
+
+	return !is_definition_private(die);
+}
+
+/*
+ * Type string processing
+ */
+static void process(struct die *cache, const char *s)
+{
+	s = s ?: "<null>";
+
+	if (dump_dies && do_linebreak) {
+		fputs("\n", stderr);
+		for (int i = 0; i < indentation_level; i++)
+			fputs("  ", stderr);
+		do_linebreak = false;
+	}
+	if (dump_dies)
+		fputs(s, stderr);
+
+	if (cache)
+		die_debug_r("cache %p string '%s'", cache, s);
+	die_map_add_string(cache, s);
+}
+
+#define MAX_FMT_BUFFER_SIZE 128
+
+static void process_fmt(struct die *cache, const char *fmt, ...)
+{
+	char buf[MAX_FMT_BUFFER_SIZE];
+	va_list args;
+
+	va_start(args, fmt);
+
+	if (checkp(vsnprintf(buf, sizeof(buf), fmt, args)) >= sizeof(buf))
+		error("vsnprintf overflow: increase MAX_FMT_BUFFER_SIZE");
+
+	process(cache, buf);
+	va_end(args);
+}
+
+#define MAX_FQN_SIZE 64
+
+/* Get a fully qualified name from DWARF scopes */
+static char *get_fqn(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;
+
+		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;
+		}
+	}
+
+	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)
+{
+	update_fqn(cache, die);
+	if (*cache->fqn)
+		process(cache, " ");
+	process(cache, cache->fqn);
+}
+
+#define DEFINE_PROCESS_UDATA_ATTRIBUTE(attribute)                          \
+	static void process_##attribute##_attr(struct die *cache,          \
+					       Dwarf_Die *die)             \
+	{                                                                  \
+		Dwarf_Word value;                                          \
+		if (get_udata_attr(die, DW_AT_##attribute, &value))        \
+			process_fmt(cache, " " #attribute "(%" PRIu64 ")", \
+				    value);                                \
+	}
+
+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)
+
+/* Match functions -- die_match_callback_t */
+#define DEFINE_MATCH(type)                                     \
+	static bool match_##type##_type(Dwarf_Die *die)        \
+	{                                                      \
+		return dwarf_tag(die) == DW_TAG_##type##_type; \
+	}
+
+DEFINE_MATCH(enumerator)
+DEFINE_MATCH(formal_parameter)
+DEFINE_MATCH(member)
+DEFINE_MATCH(subrange)
+
+bool match_all(Dwarf_Die *die)
+{
+	return true;
+}
+
+int process_die_container(struct state *state, struct die *cache,
+			  Dwarf_Die *die, die_callback_t func,
+			  die_match_callback_t match)
+{
+	Dwarf_Die current;
+	int res;
+
+	/* Track the first item in lists. */
+	if (state)
+		state->first_list_item = true;
+
+	res = checkp(dwarf_child(die, &current));
+	while (!res) {
+		if (match(&current)) {
+			/* <0 = error, 0 = continue, >0 = stop */
+			res = checkp(func(state, cache, &current));
+			if (res)
+				goto out;
+		}
+
+		res = checkp(dwarf_siblingof(&current, &current));
+	}
+
+	res = 0;
+out:
+	if (state)
+		state->first_list_item = false;
+
+	return res;
+}
+
+static int process_type(struct state *state, struct die *parent,
+			Dwarf_Die *die);
+
+static void process_type_attr(struct state *state, struct die *cache,
+			      Dwarf_Die *die)
+{
+	Dwarf_Die type;
+
+	if (get_ref_die_attr(die, DW_AT_type, &type)) {
+		check(process_type(state, cache, &type));
+		return;
+	}
+
+	/* Compilers can omit DW_AT_type -- print out 'void' to clarify */
+	process(cache, "base_type void");
+}
+
+static void process_list_comma(struct state *state, struct die *cache)
+{
+	if (state->first_list_item) {
+		state->first_list_item = false;
+	} else {
+		process(cache, " ,");
+		process_linebreak(cache, 0);
+	}
+}
+
+/* Comma-separated with DW_AT_type */
+static void __process_list_type(struct state *state, struct die *cache,
+				Dwarf_Die *die, const char *type)
+{
+	const char *name = get_name_attr(die);
+
+	if (stable) {
+		if (is_kabi_prefix(name))
+			name = NULL;
+		state->kabi.orig_name = NULL;
+	}
+
+	process_list_comma(state, cache);
+	process(cache, type);
+	process_type_attr(state, cache, die);
+
+	if (stable && state->kabi.orig_name)
+		name = state->kabi.orig_name;
+	if (name) {
+		process(cache, " ");
+		process(cache, name);
+	}
+
+	process_accessibility_attr(cache, die);
+	process_bit_size_attr(cache, die);
+	process_data_bit_offset_attr(cache, die);
+	process_data_member_location_attr(cache, die);
+}
+
+#define DEFINE_PROCESS_LIST_TYPE(type)                                       \
+	static void process_##type##_type(struct state *state,               \
+					  struct die *cache, Dwarf_Die *die) \
+	{                                                                    \
+		__process_list_type(state, cache, die, #type " ");           \
+	}
+
+DEFINE_PROCESS_LIST_TYPE(formal_parameter)
+DEFINE_PROCESS_LIST_TYPE(member)
+
+/* Container types with DW_AT_type */
+static void __process_type(struct state *state, struct die *cache,
+			   Dwarf_Die *die, const char *type)
+{
+	process(cache, type);
+	process_fqn(cache, die);
+	process(cache, " {");
+	process_linebreak(cache, 1);
+	process_type_attr(state, cache, die);
+	process_linebreak(cache, -1);
+	process(cache, "}");
+	process_byte_size_attr(cache, die);
+	process_alignment_attr(cache, die);
+}
+
+#define DEFINE_PROCESS_TYPE(type)                                            \
+	static void process_##type##_type(struct state *state,               \
+					  struct die *cache, Dwarf_Die *die) \
+	{                                                                    \
+		__process_type(state, cache, die, #type "_type");            \
+	}
+
+DEFINE_PROCESS_TYPE(atomic)
+DEFINE_PROCESS_TYPE(const)
+DEFINE_PROCESS_TYPE(immutable)
+DEFINE_PROCESS_TYPE(packed)
+DEFINE_PROCESS_TYPE(pointer)
+DEFINE_PROCESS_TYPE(reference)
+DEFINE_PROCESS_TYPE(restrict)
+DEFINE_PROCESS_TYPE(rvalue_reference)
+DEFINE_PROCESS_TYPE(shared)
+DEFINE_PROCESS_TYPE(template_type_parameter)
+DEFINE_PROCESS_TYPE(volatile)
+DEFINE_PROCESS_TYPE(typedef)
+
+static void process_subrange_type(struct state *state, struct die *cache,
+				  Dwarf_Die *die)
+{
+	Dwarf_Word count = 0;
+
+	if (get_udata_attr(die, DW_AT_count, &count))
+		process_fmt(cache, "[%" PRIu64 "]", count);
+	else if (get_udata_attr(die, DW_AT_upper_bound, &count))
+		process_fmt(cache, "[%" PRIu64 "]", count + 1);
+	else
+		process(cache, "[]");
+}
+
+static void process_array_type(struct state *state, struct die *cache,
+			       Dwarf_Die *die)
+{
+	process(cache, "array_type");
+	/* Array size */
+	check(process_die_container(state, cache, die, process_type,
+				    match_subrange_type));
+	process(cache, " {");
+	process_linebreak(cache, 1);
+	process_type_attr(state, cache, die);
+	process_linebreak(cache, -1);
+	process(cache, "}");
+}
+
+static void __process_subroutine_type(struct state *state, struct die *cache,
+				      Dwarf_Die *die, const char *type)
+{
+	process(cache, type);
+	process(cache, " (");
+	process_linebreak(cache, 1);
+	/* Parameters */
+	check(process_die_container(state, cache, die, process_type,
+				    match_formal_parameter_type));
+	process_linebreak(cache, -1);
+	process(cache, ")");
+	process_linebreak(cache, 0);
+	/* Return type */
+	process(cache, "-> ");
+	process_type_attr(state, cache, die);
+}
+
+static void process_subroutine_type(struct state *state, struct die *cache,
+				    Dwarf_Die *die)
+{
+	__process_subroutine_type(state, cache, die, "subroutine_type");
+}
+
+static void process_variant_type(struct state *state, struct die *cache,
+				 Dwarf_Die *die)
+{
+	process_list_comma(state, cache);
+	process(cache, "variant {");
+	process_linebreak(cache, 1);
+	check(process_die_container(state, cache, die, process_type,
+				    match_member_type));
+	process_linebreak(cache, -1);
+	process(cache, "}");
+	process_discr_value_attr(cache, die);
+}
+
+static void process_variant_part_type(struct state *state, struct die *cache,
+				      Dwarf_Die *die)
+{
+	process_list_comma(state, cache);
+	process(cache, "variant_part {");
+	process_linebreak(cache, 1);
+	check(process_die_container(state, cache, die, process_type,
+				    match_all));
+	process_linebreak(cache, -1);
+	process(cache, "}");
+}
+
+static int get_kabi_status(Dwarf_Die *die, const char **suffix)
+{
+	const char *name = get_name_attr(die);
+
+	if (suffix)
+		*suffix = NULL;
+
+	if (is_kabi_prefix(name)) {
+		name += KABI_PREFIX_LEN;
+
+		if (!strncmp(name, KABI_RESERVED_PREFIX,
+			     KABI_RESERVED_PREFIX_LEN))
+			return KABI_RESERVED;
+		if (!strncmp(name, KABI_IGNORED_PREFIX,
+			     KABI_IGNORED_PREFIX_LEN))
+			return KABI_IGNORED;
+
+		if (!strncmp(name, KABI_RENAMED_PREFIX,
+			     KABI_RENAMED_PREFIX_LEN)) {
+			if (suffix) {
+				name += KABI_RENAMED_PREFIX_LEN;
+				*suffix = name;
+			}
+			return KABI_RESERVED;
+		}
+	}
+
+	return KABI_NORMAL;
+}
+
+static int check_struct_member_kabi_status(struct state *state,
+					   struct die *__unused, Dwarf_Die *die)
+{
+	int res;
+
+	assert(dwarf_tag(die) == DW_TAG_member_type);
+
+	/*
+	 * If the union member is a struct, expect the __kabi field to
+	 * be the first member of the structure, i.e..:
+	 *
+	 * union {
+	 * 	type new_member;
+	 * 	struct {
+	 * 		type __kabi_field;
+	 * 	}
+	 * };
+	 */
+	res = get_kabi_status(die, &state->kabi.orig_name);
+
+	if (res == KABI_RESERVED &&
+	    !get_ref_die_attr(die, DW_AT_type, &state->kabi.placeholder))
+		error("structure member missing a type?");
+
+	return res;
+}
+
+static int check_union_member_kabi_status(struct state *state,
+					  struct die *__unused, Dwarf_Die *die)
+{
+	Dwarf_Die type;
+	int res;
+
+	assert(dwarf_tag(die) == DW_TAG_member_type);
+
+	if (!get_ref_die_attr(die, DW_AT_type, &type))
+		error("union member missing a type?");
+
+	/*
+	 * We expect a union with two members. Check if either of them
+	 * has a __kabi name prefix, i.e.:
+	 *
+	 * union {
+	 * 	...
+	 * 	type memberN; // <- type, N = {0,1}
+	 *	...
+	 * };
+	 *
+	 * The member can also be a structure type, in which case we'll
+	 * check the first structure member.
+	 *
+	 * In any case, stop processing after we've seen two members.
+	 */
+	res = get_kabi_status(die, &state->kabi.orig_name);
+
+	if (res == KABI_RESERVED)
+		state->kabi.placeholder = type;
+	if (res != KABI_NORMAL)
+		return res;
+
+	if (dwarf_tag(&type) == DW_TAG_structure_type)
+		res = checkp(process_die_container(
+			state, NULL, &type, check_struct_member_kabi_status,
+			match_member_type));
+
+	if (res <= KABI_NORMAL && ++state->kabi.members < 2)
+		return 0; /* Continue */
+
+	return res;
+}
+
+static int get_union_kabi_status(Dwarf_Die *die, Dwarf_Die *placeholder,
+				 const char **orig_name)
+{
+	struct state state;
+	int res;
+
+	if (!stable)
+		return KABI_NORMAL;
+
+	/*
+	 * To maintain a stable kABI, distributions may choose to reserve
+	 * space in structs for later use by adding placeholder members,
+	 * for example:
+	 *
+	 * struct s {
+	 * 	u32 a;
+	 *	// an 8-byte placeholder for future use
+	 * 	u64 __kabi_reserved_0;
+	 * };
+	 *
+	 * When the reserved member is taken into use, the type change
+	 * would normally cause the symbol version to change as well, but
+	 * if the replacement uses the following convention, gendwarfksyms
+	 * continues to use the placeholder type for versioning instead,
+	 * thus maintaining the same symbol version:
+	 *
+	 * struct s {
+	 * 	u32 a;
+	 *	union {
+	 * 		// placeholder replaced with a new member `b`
+	 * 		struct t b;
+	 * 		struct {
+	 * 			// the placeholder type that is still
+	 *			// used for versioning
+	 * 			u64 __kabi_reserved_0;
+	 * 		};
+	 * 	};
+	 * };
+	 *
+	 * I.e., as long as the replaced member is in a union, and the
+	 * placeholder has a __kabi_reserved name prefix, we'll continue
+	 * to use the placeholder type (here u64) for version calculation
+	 * instead of the union type.
+	 *
+	 * It's also possible to ignore new members from versioning if
+	 * they've been added to alignment holes, for example, by
+	 * including them in a union with another member that uses the
+	 * __kabi_ignored name prefix:
+	 *
+	 * struct s {
+	 * 	u32 a;
+	 *	// an alignment hole is used to add `n`
+	 * 	union {
+	 * 		u32 n;
+	 *		// hide the entire union member from versioning
+	 * 		u8 __kabi_ignored_0;
+	 * 	};
+	 * 	u64 b;
+	 * };
+	 *
+	 * 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));
+
+	res = checkp(process_die_container(&state, NULL, die,
+					   check_union_member_kabi_status,
+					   match_member_type));
+
+	if (res == KABI_RESERVED) {
+		if (placeholder)
+			*placeholder = state.kabi.placeholder;
+		if (orig_name)
+			*orig_name = state.kabi.orig_name;
+	}
+
+	return res;
+}
+
+static bool is_kabi_ignored(Dwarf_Die *die)
+{
+	Dwarf_Die type;
+
+	if (!stable)
+		return false;
+
+	if (!get_ref_die_attr(die, DW_AT_type, &type))
+		error("member missing a type?");
+
+	return dwarf_tag(&type) == DW_TAG_union_type &&
+	       checkp(get_union_kabi_status(&type, NULL, NULL)) == KABI_IGNORED;
+}
+
+static int ___process_structure_type(struct state *state, struct die *cache,
+				     Dwarf_Die *die)
+{
+	switch (dwarf_tag(die)) {
+	case DW_TAG_member:
+		if (is_kabi_ignored(die))
+			return 0;
+		return check(process_type(state, cache, die));
+	case DW_TAG_variant_part:
+		return check(process_type(state, cache, die));
+	case DW_TAG_class_type:
+	case DW_TAG_enumeration_type:
+	case DW_TAG_structure_type:
+	case DW_TAG_template_type_parameter:
+	case DW_TAG_union_type:
+	case DW_TAG_subprogram:
+		/* Skip non-member types, including member functions */
+		return 0;
+	default:
+		error("unexpected structure_type child: %x", dwarf_tag(die));
+	}
+}
+
+static void __process_structure_type(struct state *state, struct die *cache,
+				     Dwarf_Die *die, const char *type,
+				     die_callback_t process_func,
+				     die_match_callback_t match_func)
+{
+	bool expand;
+
+	process(cache, type);
+	process_fqn(cache, die);
+	process(cache, " {");
+	process_linebreak(cache, 1);
+
+	expand = state->expand.expand && is_kabi_definition(cache, die);
+
+	if (expand) {
+		state->expand.current_fqn = cache->fqn;
+		check(process_die_container(state, cache, die, process_func,
+					    match_func));
+	}
+
+	process_linebreak(cache, -1);
+	process(cache, "}");
+
+	if (expand) {
+		process_byte_size_attr(cache, die);
+		process_alignment_attr(cache, die);
+	}
+}
+
+#define DEFINE_PROCESS_STRUCTURE_TYPE(structure)                        \
+	static void process_##structure##_type(                         \
+		struct state *state, struct die *cache, Dwarf_Die *die) \
+	{                                                               \
+		__process_structure_type(state, cache, die,             \
+					 #structure "_type",            \
+					 ___process_structure_type,     \
+					 match_all);                    \
+	}
+
+DEFINE_PROCESS_STRUCTURE_TYPE(class)
+DEFINE_PROCESS_STRUCTURE_TYPE(structure)
+
+static void process_union_type(struct state *state, struct die *cache,
+			       Dwarf_Die *die)
+{
+	Dwarf_Die placeholder;
+
+	int res = checkp(get_union_kabi_status(die, &placeholder,
+					       &state->kabi.orig_name));
+
+	if (res == KABI_RESERVED)
+		check(process_type(state, cache, &placeholder));
+	if (res > KABI_NORMAL)
+		return;
+
+	__process_structure_type(state, cache, die, "union_type",
+				 ___process_structure_type, match_all);
+}
+
+static void process_enumerator_type(struct state *state, struct die *cache,
+				    Dwarf_Die *die)
+{
+	bool overridden = false;
+	Dwarf_Word value;
+
+	if (stable) {
+		/* Get the fqn before we process anything */
+		update_fqn(cache, die);
+
+		if (kabi_is_enumerator_ignored(state->expand.current_fqn,
+					       cache->fqn))
+			return;
+
+		overridden = kabi_get_enumerator_value(
+			state->expand.current_fqn, cache->fqn, &value);
+	}
+
+	process_list_comma(state, cache);
+	process(cache, "enumerator");
+	process_fqn(cache, die);
+
+	if (overridden || get_udata_attr(die, DW_AT_const_value, &value)) {
+		process(cache, " = ");
+		process_fmt(cache, "%" PRIu64, value);
+	}
+}
+
+static void process_enumeration_type(struct state *state, struct die *cache,
+				     Dwarf_Die *die)
+{
+	__process_structure_type(state, cache, die, "enumeration_type",
+				 process_type, match_enumerator_type);
+}
+
+static void process_base_type(struct state *state, struct die *cache,
+			      Dwarf_Die *die)
+{
+	process(cache, "base_type");
+	process_fqn(cache, die);
+	process_byte_size_attr(cache, die);
+	process_encoding_attr(cache, die);
+	process_alignment_attr(cache, die);
+}
+
+static void process_unspecified_type(struct state *state, struct die *cache,
+				     Dwarf_Die *die)
+{
+	/*
+	 * These can be emitted for stand-alone assembly code, which means we
+	 * might run into them in vmlinux.o.
+	 */
+	process(cache, "unspecified_type");
+}
+
+static void process_cached(struct state *state, struct die *cache,
+			   Dwarf_Die *die)
+{
+	struct die_fragment *df;
+	Dwarf_Die child;
+
+	list_for_each_entry(df, &cache->fragments, list) {
+		switch (df->type) {
+		case FRAGMENT_STRING:
+			die_debug_b("cache %p STRING '%s'", cache,
+				    df->data.str);
+			process(NULL, df->data.str);
+			break;
+		case FRAGMENT_LINEBREAK:
+			process_linebreak(NULL, df->data.linebreak);
+			break;
+		case FRAGMENT_DIE:
+			if (!dwarf_die_addr_die(dwarf_cu_getdwarf(die->cu),
+						(void *)df->data.addr, &child))
+				error("dwarf_die_addr_die failed");
+			die_debug_b("cache %p DIE addr %" PRIxPTR " tag %x",
+				    cache, df->data.addr, dwarf_tag(&child));
+			check(process_type(state, NULL, &child));
+			break;
+		default:
+			error("empty die_fragment");
+		}
+	}
+}
+
+static void state_init(struct state *state)
+{
+	state->expand.expand = true;
+	state->expand.current_fqn = NULL;
+	cache_init(&state->expansion_cache);
+}
+
+static void expansion_state_restore(struct expansion_state *state,
+				    struct expansion_state *saved)
+{
+	state->expand = saved->expand;
+	state->current_fqn = saved->current_fqn;
+}
+
+static void expansion_state_save(struct expansion_state *state,
+				 struct expansion_state *saved)
+{
+	expansion_state_restore(saved, state);
+}
+
+static bool is_expanded_type(int tag)
+{
+	return tag == DW_TAG_class_type || tag == DW_TAG_structure_type ||
+	       tag == DW_TAG_union_type || tag == DW_TAG_enumeration_type;
+}
+
+#define PROCESS_TYPE(type)                                \
+	case DW_TAG_##type##_type:                        \
+		process_##type##_type(state, cache, die); \
+		break;
+
+static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
+{
+	enum die_state want_state = DIE_COMPLETE;
+	struct die *cache;
+	struct expansion_state saved;
+	int tag = dwarf_tag(die);
+
+	expansion_state_save(&state->expand, &saved);
+
+	/*
+	 * Structures and enumeration types are expanded only once per
+	 * exported symbol. This is sufficient for detecting ABI changes
+	 * within the structure.
+	 */
+	if (is_expanded_type(tag)) {
+		if (cache_was_expanded(&state->expansion_cache, die->addr))
+			state->expand.expand = false;
+
+		if (state->expand.expand)
+			cache_mark_expanded(&state->expansion_cache, die->addr);
+		else
+			want_state = DIE_UNEXPANDED;
+	}
+
+	/*
+	 * If we have want_state already cached, use it instead of walking
+	 * through DWARF.
+	 */
+	cache = die_map_get(die, want_state);
+
+	if (cache->state == want_state) {
+		die_debug_g("cached addr %p tag %x -- %s", die->addr, tag,
+			    die_state_name(cache->state));
+
+		process_cached(state, cache, die);
+		die_map_add_die(parent, cache);
+
+		expansion_state_restore(&state->expand, &saved);
+		return 0;
+	}
+
+	die_debug_g("addr %p tag %x -- %s -> %s", die->addr, tag,
+		    die_state_name(cache->state), die_state_name(want_state));
+
+	switch (tag) {
+	/* Type modifiers */
+	PROCESS_TYPE(atomic)
+	PROCESS_TYPE(const)
+	PROCESS_TYPE(immutable)
+	PROCESS_TYPE(packed)
+	PROCESS_TYPE(pointer)
+	PROCESS_TYPE(reference)
+	PROCESS_TYPE(restrict)
+	PROCESS_TYPE(rvalue_reference)
+	PROCESS_TYPE(shared)
+	PROCESS_TYPE(volatile)
+	/* Container types */
+	PROCESS_TYPE(class)
+	PROCESS_TYPE(structure)
+	PROCESS_TYPE(union)
+	PROCESS_TYPE(enumeration)
+	/* Subtypes */
+	PROCESS_TYPE(enumerator)
+	PROCESS_TYPE(formal_parameter)
+	PROCESS_TYPE(member)
+	PROCESS_TYPE(subrange)
+	PROCESS_TYPE(template_type_parameter)
+	PROCESS_TYPE(variant)
+	PROCESS_TYPE(variant_part)
+	/* Other types */
+	PROCESS_TYPE(array)
+	PROCESS_TYPE(base)
+	PROCESS_TYPE(subroutine)
+	PROCESS_TYPE(typedef)
+	PROCESS_TYPE(unspecified)
+	default:
+		error("unexpected type: %x", tag);
+	}
+
+	die_debug_r("parent %p cache %p die addr %p tag %x", parent, cache,
+		    die->addr, tag);
+
+	/* Update cache state and append to the parent (if any) */
+	cache->tag = tag;
+	cache->state = want_state;
+	die_map_add_die(parent, cache);
+
+	expansion_state_restore(&state->expand, &saved);
+	return 0;
+}
+
+/*
+ * Exported symbol processing
+ */
+static struct die *get_symbol_cache(struct state *state, Dwarf_Die *die)
+{
+	struct die *cache;
+
+	cache = die_map_get(die, DIE_SYMBOL);
+
+	if (cache->state != DIE_INCOMPLETE)
+		return NULL; /* We already processed a symbol for this DIE */
+
+	cache->tag = dwarf_tag(die);
+	return cache;
+}
+
+static void process_symbol(struct state *state, Dwarf_Die *die,
+			   die_callback_t process_func)
+{
+	struct die *cache;
+
+	symbol_set_die(state->sym, die);
+
+	cache = get_symbol_cache(state, die);
+	if (!cache)
+		return;
+
+	debug("%s", state->sym->name);
+	check(process_func(state, cache, die));
+	cache->state = DIE_SYMBOL;
+	if (dump_dies)
+		fputs("\n", stderr);
+}
+
+static int __process_subprogram(struct state *state, struct die *cache,
+				Dwarf_Die *die)
+{
+	__process_subroutine_type(state, cache, die, "subprogram");
+	return 0;
+}
+
+static void process_subprogram(struct state *state, Dwarf_Die *die)
+{
+	process_symbol(state, die, __process_subprogram);
+}
+
+static int __process_variable(struct state *state, struct die *cache,
+			      Dwarf_Die *die)
+{
+	process(cache, "variable ");
+	process_type_attr(state, cache, die);
+	return 0;
+}
+
+static void process_variable(struct state *state, Dwarf_Die *die)
+{
+	process_symbol(state, die, __process_variable);
+}
+
+static void save_symbol_ptr(struct state *state)
+{
+	Dwarf_Die ptr_type;
+	Dwarf_Die type;
+
+	if (!get_ref_die_attr(&state->die, DW_AT_type, &ptr_type) ||
+	    dwarf_tag(&ptr_type) != DW_TAG_pointer_type)
+		error("%s must be a pointer type!",
+		      get_symbol_name(&state->die));
+
+	if (!get_ref_die_attr(&ptr_type, DW_AT_type, &type))
+		error("%s pointer missing a type attribute?",
+		      get_symbol_name(&state->die));
+
+	/*
+	 * Save the symbol pointer DIE in case the actual symbol is
+	 * missing from the DWARF. Clang, for example, intentionally
+	 * omits external symbols from the debugging information.
+	 */
+	if (dwarf_tag(&type) == DW_TAG_subroutine_type)
+		symbol_set_ptr(state->sym, &type);
+	else
+		symbol_set_ptr(state->sym, &ptr_type);
+}
+
+static int process_exported_symbols(struct state *unused, struct die *cache,
+				    Dwarf_Die *die)
+{
+	int tag = dwarf_tag(die);
+
+	switch (tag) {
+	/* Possible containers of exported symbols */
+	case DW_TAG_namespace:
+	case DW_TAG_class_type:
+	case DW_TAG_structure_type:
+		return check(process_die_container(
+			NULL, cache, die, process_exported_symbols, match_all));
+
+	/* Possible exported symbols */
+	case DW_TAG_subprogram:
+	case DW_TAG_variable: {
+		struct state state;
+
+		if (!match_export_symbol(&state, die))
+			return 0;
+
+		state_init(&state);
+
+		if (is_symbol_ptr(get_symbol_name(&state.die)))
+			save_symbol_ptr(&state);
+		else if (tag == DW_TAG_subprogram)
+			process_subprogram(&state, &state.die);
+		else
+			process_variable(&state, &state.die);
+
+		cache_free(&state.expansion_cache);
+		return 0;
+	}
+	default:
+		return 0;
+	}
+}
+
+static void process_symbol_ptr(struct symbol *sym, void *arg)
+{
+	struct state state;
+	Dwarf *dwarf = arg;
+
+	if (sym->state != SYMBOL_UNPROCESSED || !sym->ptr_die_addr)
+		return;
+
+	debug("%s", sym->name);
+	state_init(&state);
+	state.sym = sym;
+
+	if (!dwarf_die_addr_die(dwarf, (void *)sym->ptr_die_addr, &state.die))
+		error("dwarf_die_addr_die failed for symbol ptr: '%s'",
+		      sym->name);
+
+	if (dwarf_tag(&state.die) == DW_TAG_subroutine_type)
+		process_subprogram(&state, &state.die);
+	else
+		process_variable(&state, &state.die);
+
+	cache_free(&state.expansion_cache);
+}
+
+void process_cu(Dwarf_Die *cudie)
+{
+	check(process_die_container(NULL, NULL, cudie, process_exported_symbols,
+				    match_all));
+
+	symbol_for_each(process_symbol_ptr, dwarf_cu_getdwarf(cudie->cu));
+
+	cache_free(&srcfile_cache);
+}