libctf: CTFv4: type opening

The majority of this commit rejigs the core type table opening
code for CTFv4: there are a few ancillary bits it drags in,
indicated below.

The internal definition of a child dict (that may not have type or string
lookups performed in it until ctf_open time) used to be 'has a
cth_parent_name', but since BTF doesn't have one of those at all, we add
an additional check: a dict the first byte of whose strtab is not 0 must
be a child.  (If *either* is true, this is a child dict, which allows for
the possibility of CTF dicts with non-deduplicated strtabs -- thus with
leading \0's -- to exist in future.)

The initial sweep through the type table in init_static_types (to size
the name-table lookup hashes) also now checks for various types which
indicate that this must be a CTF dict, in addition to being adjusted
to cater for new CTFv4 representations of things like forwards.  (At
this early stage, we cannot rely on the functions in ctf-type.c to
abstract over this for us.)

We make some new hashtables for new namespace-like things: datasecs
and type and decl tags.

The main name-population loop in init_static_types_names_internal
takes prefixes into account, looking for the name on the suffix type
(where the name is always found).  LSTRUCT handling is removed (they
no longer exist); ENUM64s, enum forwards, VARs, datasecs, and type
and decl tags get their names suitably populated.  Some buggy code
which tried to populate the name tables for cvr-quals (which are
nameless) was dropped.

We add an extra pass which traverses all datasecs and keeps track of which
datasec each var is instantiated in (if any) in a new ctf_var_datasecs hash
table.  (This uses a number of type-querying functions which don't yet
exist: they'll be added in the upcoming commits.)

We handle the type 0 == void case by pointing the first element of
ctf_txlate at a type read in named "void" (making type 0 an alias to it),
or, if one doesn't exist, creating a new one (outside the type table and dtd
arrays), and pointing type 0 at that.  Since it is numbered 0 and not in the
type table or dtd arrays, it will never be written out at serialization
time, but since it is *present*, libctf consumers who expect the void type
to have an integral definition rather than being a magic number will get
what they expect.

include/ctf-api.h

@@ -541,9 +541,10 @@ extern ctf_id_t ctf_lookup_by_symbol_name (ctf_dict_t *, const char *);
 extern ctf_id_t ctf_symbol_next (ctf_dict_t *, ctf_next_t **,
 				 const char **name, int functions);
 
-/* Look up a type by name: some simple C type parsing is done, but this is by no
-   means comprehensive.  Structures, unions and enums need "struct ", "union "
-   or "enum " on the front, as usual in C.  */
+/* Look up a type or variable by name: some simple C type parsing is done, but
+   this is by no means comprehensive.  Structures, unions and enums need "struct
+   ", "union " or "enum " on the front, as usual in C.  Some prefixes not seen
+   in C exist as well: datasecs use "datasec ". */
 
 extern ctf_id_t ctf_lookup_by_name (ctf_dict_t *, const char *);
 

libctf/ctf-create.c

@@ -106,14 +106,21 @@ ctf_grow_vlen (ctf_dict_t *fp, ctf_dtdef_t *dtd, size_t vlen)
 ctf_dict_t *
 ctf_create (int *errp)
 {
-  static const ctf_header_t hdr = { .cth_preamble = { CTF_MAGIC, CTF_VERSION, 0 } };
+  static ctf_header_t hdr =
+    {
+      .btf.bth_preamble = { CTF_BTF_MAGIC, CTF_BTF_VERSION, 0 },
+      .btf.bth_hdr_len = sizeof (ctf_btf_header_t),
+    };
 
   ctf_dynhash_t *structs = NULL, *unions = NULL, *enums = NULL, *names = NULL;
+  ctf_dynhash_t *datasecs = NULL, *tags = NULL;
   ctf_sect_t cts;
   ctf_dict_t *fp;
 
   libctf_init_debug();
 
+  hdr.cth_preamble.ctp_magic_version = (CTFv4_MAGIC << 16) | CTF_VERSION;
+
   structs = ctf_dynhash_create (ctf_hash_string, ctf_hash_eq_string,
 				NULL, NULL);
   unions = ctf_dynhash_create (ctf_hash_string, ctf_hash_eq_string,
@@ -122,7 +129,11 @@ ctf_create (int *errp)
 			      NULL, NULL);
   names = ctf_dynhash_create (ctf_hash_string, ctf_hash_eq_string,
 			      NULL, NULL);
-  if (!structs || !unions || !enums || !names)
+  datasecs = ctf_dynhash_create (ctf_hash_string, ctf_hash_eq_string,
+				 NULL, NULL);
+  tags = ctf_dynhash_create (ctf_hash_string, ctf_hash_eq_string,
+			     NULL, (ctf_hash_free_fun) ctf_dynset_destroy);
+  if (!structs || !unions || !enums || !names || !datasecs || !tags)
     {
       ctf_set_open_errno (errp, EAGAIN);
       goto err;
@@ -142,10 +153,14 @@ ctf_create (int *errp)
   ctf_dynhash_destroy (fp->ctf_unions);
   ctf_dynhash_destroy (fp->ctf_enums);
   ctf_dynhash_destroy (fp->ctf_names);
+  ctf_dynhash_destroy (fp->ctf_datasecs);
+  ctf_dynhash_destroy (fp->ctf_tags);
   fp->ctf_structs = structs;
   fp->ctf_unions = unions;
   fp->ctf_enums = enums;
   fp->ctf_names = names;
+  fp->ctf_datasecs = datasecs;
+  fp->ctf_tags = tags;
   fp->ctf_dtoldid = 0;
   fp->ctf_snapshot_lu = 0;
 
@@ -166,6 +181,8 @@ ctf_create (int *errp)
   ctf_dynhash_destroy (unions);
   ctf_dynhash_destroy (enums);
   ctf_dynhash_destroy (names);
+  ctf_dynhash_destroy (datasecs);
+  ctf_dynhash_destroy (tags);
   return NULL;
 }
 

libctf/ctf-hash.c

@@ -779,6 +779,12 @@ ctf_dynset_destroy (ctf_dynset_t *hp)
     htab_delete ((struct htab *) hp);
 }
 
+void
+ctf_dynset_destroy_arg (ctf_dynset_t *hp, void *unused _libctf_unused_)
+{
+  ctf_dynset_destroy (hp);
+}
+
 void *
 ctf_dynset_lookup (ctf_dynset_t *hp, const void *key)
 {

libctf/ctf-impl.h

@@ -385,9 +385,12 @@ struct ctf_dict
   ctf_dynhash_t *ctf_structs;	    /* Hash table of struct types.  */
   ctf_dynhash_t *ctf_unions;	    /* Hash table of union types.  */
   ctf_dynhash_t *ctf_enums;	    /* Hash table of enum types.  */
+  ctf_dynhash_t *ctf_datasecs;	    /* Hash table of datasecs.  */
+  ctf_dynhash_t *ctf_tags;	    /* Hash table of dynsets of type/decl tags.  */
   ctf_dynhash_t *ctf_names;	    /* Hash table of remaining types, plus
 				       enumeration constants.  */
-  ctf_lookup_t ctf_lookups[5];	    /* Pointers to nametabs for name lookup.  */
+  ctf_lookup_t ctf_lookups[6];	    /* Pointers to nametabs for name lookup.  */
+  ctf_dynhash_t *ctf_var_datasecs;  /* Variable -> datasec mappings.  */
   ctf_strs_t ctf_str[2];	    /* Array of string table base and bounds.  */
   ctf_strs_writable_t *ctf_dynstrtab; /* Dynamically allocated string table, if any. */
   ctf_dynhash_t *ctf_str_atoms;	  /* Hash table of ctf_str_atoms_t.  */
@@ -412,6 +415,8 @@ struct ctf_dict
   uint32_t *ctf_pptrtab;	  /* Parent types pointed to by child dicts.  */
   size_t ctf_pptrtab_len;	  /* Num types storable in pptrtab currently.  */
   uint32_t ctf_pptrtab_typemax;	  /* Max child type when pptrtab last updated.  */
+  ctf_type_t *ctf_void_type;	  /* void type, if dynamically constructed. (More
+				     space allocated, due to vlen.)  */
   ctf_dynset_t *ctf_conflicting_enums;	/* Tracks enum constants that conflict.  */
   uint32_t *ctf_funcidx_names;	  /* Name of each function symbol in symtypetab
 				     (if indexed).  */
@@ -707,6 +712,7 @@ extern int ctf_dynset_insert (ctf_dynset_t *, void *);
 extern void ctf_dynset_remove (ctf_dynset_t *, const void *);
 extern size_t ctf_dynset_elements (const ctf_dynset_t *);
 extern void ctf_dynset_destroy (ctf_dynset_t *);
+extern void ctf_dynset_destroy_arg (ctf_dynset_t *, void *unused);
 extern void *ctf_dynset_lookup (ctf_dynset_t *, const void *);
 extern int ctf_dynset_exists (ctf_dynset_t *, const void *key,
 			      const void **orig_key);

libctf/ctf-open.c

@@ -560,7 +560,7 @@ ctf_set_base (ctf_dict_t *fp, const ctf_header_t *hp, unsigned char *base)
 }
 
 static int
-init_static_types_names (ctf_dict_t *fp, ctf_header_t *cth);
+init_static_types_names (ctf_dict_t *fp, ctf_header_t *cth, int is_btf);
 
 /* Populate statically-defined types (those loaded from a saved buffer).
 
@@ -591,50 +591,105 @@ init_static_types (ctf_dict_t *fp, ctf_header_t *cth, int is_btf)
   fp->ctf_provtypemax = (uint32_t) -1;
 
   /* We determine whether the dict is a child or a parent based on the value of
-     cth_parname.  */
+     cth_parent_name: for BTF this is not enough, because there is no
+     cth_parent_name: instead, we can check the first byte of the strtab, which
+     is always 0 for parents and never 0 for children.  */
 
-  int child = cth->cth_parname != 0;
+  int child = (cth->cth_parent_name != 0
+	       || (fp->ctf_str[CTF_STRTAB_0].cts_len > 0
+		   && fp->ctf_str[CTF_STRTAB_0].cts_strs[0] != 0));
 
   if (fp->ctf_version < CTF_VERSION_4)
     {
+#if 0
       int err;
+
       if ((err = upgrade_types (fp, cth)) != 0)
 	return err;				/* Upgrade failed.  */
+#endif
+      ctf_err_warn (NULL, 0, ECTF_INTERNAL, "Implementation of backward-compatible CTF reading still underway\n");
+      return ECTF_INTERNAL;
     }
 
-  tbuf = (ctf_type_t *) (fp->ctf_buf + cth->cth_typeoff);
-  tend = (ctf_type_t *) (fp->ctf_buf + cth->cth_stroff);
+  tbuf = (ctf_type_t *) (fp->ctf_buf + cth->btf.bth_type_off);
+  tend = (ctf_type_t *) ((uintptr_t) tbuf + cth->btf.bth_type_len);
 
-  /* We make two passes through the entire type section, and one third pass
-     through part of it: but only the first is guaranteed to happen at this
-     stage.  The second and third passes require working string lookup, so in
-     child dicts can only happen at ctf_import time.
+  /* We make two passes through the entire type section, and more passes through
+     parts of it: but only the first is guaranteed to happen at this stage.  The
+     later passes require working string lookup, so in child dicts can only
+     happen at ctf_import time.
+
+     For prefixed kinds, we are interested in the thing we are prefixing:
+     that is the true type.
 
      In this first pass, we count the number of each type and type-like
      identifier (like enumerators) and the total number of types.  */
 
   for (tp = tbuf; tp < tend; typemax++)
     {
-      unsigned short kind = LCTF_INFO_KIND (fp, tp->ctt_info);
-      unsigned long vlen = LCTF_INFO_VLEN (fp, tp->ctt_info);
+      unsigned short kind = LCTF_INFO_UNPREFIXED_KIND (fp, tp->ctt_info);
+      size_t vlen = LCTF_VLEN (fp, tp);
+      int nonroot = 0;
       ssize_t size, increment, vbytes;
+      const ctf_type_t *suffix = tp;
 
       (void) ctf_get_ctt_size (fp, tp, &size, &increment);
-      vbytes = LCTF_VBYTES (fp, kind, size, vlen);
+
+      /* Go to the first unprefixed type, incrementing all prefixed types'
+	 popcounts along the way.  If we find a CTF_K_CONFLICTING, stop: these
+	 counts are used to increment identifier hashtab sizes, and conflicting
+	 types do not appear in identifier hashtabs.  */
+
+      while (LCTF_IS_PREFIXED_KIND (kind))
+	{
+	  if (is_btf)
+	    return ECTF_CORRUPT;
+
+	  pop[suffix->ctt_type]++;
+
+	  if (kind == CTF_K_CONFLICTING)
+	    {
+	      nonroot = 1;
+	      break;
+	    }
+
+	  suffix++;
+	  if (suffix >= tend)
+	    return ECTF_CORRUPT;
+
+	  kind = LCTF_INFO_UNPREFIXED_KIND (fp, suffix->ctt_info);
+	}
+
+      if (is_btf && kind > CTF_BTF_K_MAX)
+	return ECTF_CORRUPT;
+
+      vbytes = LCTF_VBYTES (fp, suffix, size);
 
       if (vbytes < 0)
 	return ECTF_CORRUPT;
 
-      /* For forward declarations, ctt_type is the CTF_K_* kind for the tag,
-	 so bump that population count too.  */
+      if (!nonroot)
+	{
+	  /* For forward declarations, the kflag indicates what type to use, so bump
+	     that population count too.  For enums, vlen 0 indicates a forward, so
+	     bump the forward population count.  */
 	  if (kind == CTF_K_FORWARD)
-	pop[tp->ctt_type]++;
+	    {
+	      if (CTF_INFO_KFLAG (suffix->ctt_info))
+		pop[CTF_K_UNION]++;
+	      else
+		pop[CTF_K_STRUCT]++;
+	    }
+	  else if (kind == CTF_K_ENUM && vlen == 0)
+	    pop[CTF_K_FORWARD]++;
+
+	  if (kind == CTF_K_ENUM || kind == CTF_K_ENUM64)
+	    pop_enumerators += vlen;
+
+	  pop[kind]++;
+	}
 
       tp = (ctf_type_t *) ((uintptr_t) tp + increment + vbytes);
-      pop[kind]++;
-
-      if (kind == CTF_K_ENUM)
-	pop_enumerators += vlen;
     }
 
   if (child)
@@ -666,11 +721,24 @@ init_static_types (ctf_dict_t *fp, ctf_header_t *cth, int is_btf)
 				   NULL, NULL, NULL)) == NULL)
     return ENOMEM;
 
+  if ((fp->ctf_datasecs
+       = ctf_dynhash_create_sized (pop[CTF_K_DATASEC], ctf_hash_string,
+				   ctf_hash_eq_string,
+				   NULL, NULL, NULL)) == NULL)
+    return ENOMEM;
+
+  if ((fp->ctf_tags
+       = ctf_dynhash_create_sized (pop[CTF_K_DECL_TAG] + pop [CTF_K_TYPE_TAG],
+				   ctf_hash_string, ctf_hash_eq_string,
+				   NULL, (ctf_hash_free_arg_fun) ctf_dynset_destroy_arg,
+				   NULL)) == NULL)
+    return ENOMEM;
+
   if ((fp->ctf_names
        = ctf_dynhash_create_sized (pop[CTF_K_UNKNOWN] +
 				   pop[CTF_K_INTEGER] +
 				   pop[CTF_K_FLOAT] +
-				   pop[CTF_K_FUNCTION] +
+				   pop[CTF_K_FUNC_LINKAGE] +
 				   pop[CTF_K_TYPEDEF] +
 				   pop_enumerators,
 				   ctf_hash_string,
@@ -678,6 +746,11 @@ init_static_types (ctf_dict_t *fp, ctf_header_t *cth, int is_btf)
 				   NULL, NULL, NULL)) == NULL)
     return ENOMEM;
 
+  if ((fp->ctf_var_datasecs
+       = ctf_dynhash_create (htab_hash_pointer, htab_eq_pointer, NULL, NULL))
+      == NULL)
+    return ENOMEM;
+
   if ((fp->ctf_conflicting_enums
        = ctf_dynset_create (htab_hash_string, htab_eq_string, NULL)) == NULL)
     return ENOMEM;
@@ -698,9 +771,7 @@ init_static_types (ctf_dict_t *fp, ctf_header_t *cth, int is_btf)
   if (fp->ctf_txlate == NULL || fp->ctf_ptrtab == NULL)
     return ENOMEM;		/* Memory allocation failed.  */
 
-  /* UPTODO: BTF is like v4 here: no string lookups in children, which blocks
-     almost all operations until after ctf_import.  */
-  if (child && cth->cth_parent_strlen != 0)
+  if (child || cth->cth_parent_strlen != 0)
     {
       fp->ctf_flags |= LCTF_NO_STR;
       return 0;
@@ -708,17 +779,17 @@ init_static_types (ctf_dict_t *fp, ctf_header_t *cth, int is_btf)
 
   ctf_dprintf ("%u types initialized (other than names)\n", fp->ctf_typemax);
 
-  return init_static_types_names (fp, cth);
+  return init_static_types_names (fp, cth, is_btf);
 }
 
 static int
-init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
+init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth, int is_btf,
 				  ctf_dynset_t *all_enums);
 
 /* A wrapper to simplify memory allocation.  */
 
 static int
-init_static_types_names (ctf_dict_t *fp, ctf_header_t *cth)
+init_static_types_names (ctf_dict_t *fp, ctf_header_t *cth, int is_btf)
 {
   ctf_dynset_t *all_enums;
   int err;
@@ -727,41 +798,43 @@ init_static_types_names (ctf_dict_t *fp, ctf_header_t *cth)
 				      NULL)) == NULL)
     return ENOMEM;
 
-  err = init_static_types_names_internal (fp, cth, all_enums);
+  err = init_static_types_names_internal (fp, cth, is_btf, all_enums);
   ctf_dynset_destroy (all_enums);
   return err;
 }
 
-/* Initialize the parts of the CTF dict whose initialization depends on name
-   lookup.  This happens at open time except for child dicts, when (for CTFv4+
-   dicts) it happens at ctf_import time instead, because before then the strtab
-   is truncated at the start.
+static int
+init_void (ctf_dict_t *fp);
+
+/* Initialize the parts of the CTF dict whose initialization depends on name or
+   type lookup.  This happens at open time except for child dicts, when (for
+   CTFv4+ dicts) it happens at ctf_import time instead, because before then the
+   strtab and type tables are truncated at the start.
 
    As a function largely called at open time, this function does not reliably
-   set the ctf_errno, but instead *returns* the error code.  */
+   set the ctf_errno, but instead returns a positive error code.  */
 
 static int
-init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
+init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth, int is_btf,
 				  ctf_dynset_t *all_enums)
 {
-  const ctf_type_t *tbuf;
-  const ctf_type_t *tend;
+  ctf_type_t *tbuf, *tend, *tp;
+  ctf_type_t **xp;
 
-  const ctf_type_t *tp;
   uint32_t id;
-  uint32_t *xp;
-
-  unsigned long typemax = fp->ctf_typemax;
+  ctf_id_t type;
 
   ctf_next_t *i = NULL;
   void *k;
   int err;
 
-  int child = cth->cth_parname != 0;
-  int nlstructs = 0, nlunions = 0;
+  /* See init_static_types.  */
+  int child = (cth->cth_parent_name != 0
+	       || (fp->ctf_str[CTF_STRTAB_0].cts_len > 0
+		   && fp->ctf_str[CTF_STRTAB_0].cts_strs[0] != 0));
 
-  tbuf = (ctf_type_t *) (fp->ctf_buf + cth->cth_typeoff);
-  tend = (ctf_type_t *) (fp->ctf_buf + cth->cth_stroff);
+  tbuf = (ctf_type_t *) (fp->ctf_buf + cth->btf.bth_type_off);
+  tend = (ctf_type_t *) ((uintptr_t) tbuf + cth->btf.bth_type_len);
 
   assert (!(fp->ctf_flags & LCTF_NO_STR));
 
@@ -770,30 +843,34 @@ init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
   /* In this second pass through the types, we fill in each entry of the type
      and pointer tables and add names to the appropriate hashes.
 
-     (Not all names are added in this pass, only type names.  See below.)
+     (Not all names are added in this pass, only type names.  See below.)  */
 
-     Reset ctf_typemax and bump it as we go, but keep it one higher than normal,
-     so that the type being read in is considered a valid type and it is at
-     least barely possible to run simple lookups on it: but higher types are
-     not, since their names are not yet known.  (It is kept at its standard
-     value before this function is called so that at least some type-related
-     operations work.  */
-
-  for (id = 1, fp->ctf_typemax = 1, tp = tbuf; tp < tend; xp++, id++, fp->ctf_typemax++)
+  for (id = 1, tp = tbuf; tp < tend; xp++, id++)
     {
-      unsigned short kind = LCTF_INFO_KIND (fp, tp->ctt_info);
+      unsigned short kind = LCTF_KIND (fp, tp);
       unsigned short isroot = LCTF_INFO_ISROOT (fp, tp->ctt_info);
-      unsigned long vlen = LCTF_INFO_VLEN (fp, tp->ctt_info);
+      size_t vlen = LCTF_VLEN (fp, tp);
       ssize_t size, increment, vbytes;
-
+      const ctf_type_t *suffix = tp;
       const char *name;
 
-      (void) ctf_get_ctt_size (fp, tp, &size, &increment);
-      name = ctf_strptr (fp, tp->ctt_name);
-      /* Cannot fail: shielded by call in loop above.  */
-      vbytes = LCTF_VBYTES (fp, kind, size, vlen);
+      /* Prefixed type: pull off the prefixes (for most purposes).  (We already
+	 know the prefixes cannot overflow.)  */
 
-      *xp = (uint32_t) ((uintptr_t) tp - (uintptr_t) fp->ctf_buf);
+      while (LCTF_IS_PREFIXED_INFO (suffix->ctt_info))
+	{
+	  if (is_btf)
+	    return ECTF_CORRUPT;
+
+	  suffix++;
+	}
+
+      (void) ctf_get_ctt_size (fp, tp, &size, &increment);
+      name = ctf_strptr (fp, suffix->ctt_name);
+      /* Cannot fail: shielded by call in init_static_types.  */
+      vbytes = LCTF_VBYTES (fp, suffix, size);
+
+      *xp = tp;
 
       switch (kind)
 	{
@@ -817,7 +894,10 @@ init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
 	       type as long as the new type is zero-offset and has a
 	       bit-width wider than the existing one, since the native type
 	       must necessarily have a bit-width at least as wide as any
-	       bitfield based on it. */
+	       bitfield based on it.
+
+	       BTF floats are more or less useless, having no encoding:
+	       the ctf_type_encoding check here suffices to replace them.  */
 
 	    if (((existing = ctf_dynhash_lookup_type (fp->ctf_names, name)) == 0)
 		|| ctf_type_encoding (fp, existing, &existing_en) != 0
@@ -828,40 +908,62 @@ init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
 	      {
 		err = ctf_dynhash_insert_type (fp, fp->ctf_names,
 					       ctf_index_to_type (fp, id),
-					       tp->ctt_name);
+					       suffix->ctt_name);
 		if (err != 0)
 		  return err * -1;
 	      }
 	    break;
 	  }
 
+	case CTF_K_BTF_FLOAT:
+	  {
+	    ctf_id_t existing;
+
+	    if (!isroot)
+	      break;
+
+	    /* Don't allow a float to be overwritten by a BTF float.  */
+
+	    if (((existing = ctf_dynhash_lookup_type (fp->ctf_names, name)) == 0)
+		&& ctf_type_kind (fp, existing) == CTF_K_FLOAT)
+	      break;
+
+	    err = ctf_dynhash_insert_type (fp, fp->ctf_names,
+					   ctf_index_to_type (fp, id),
+					   suffix->ctt_name);
+	    if (err != 0)
+	      return err * -1;
+	    break;
+	  }
+
 	  /* These kinds have no name, so do not need interning into any
 	     hashtables.  */
 	case CTF_K_ARRAY:
 	case CTF_K_SLICE:
+	case CTF_K_VOLATILE:
+	case CTF_K_CONST:
+	case CTF_K_RESTRICT:
+	case CTF_K_FUNCTION:
 	  break;
 
-	case CTF_K_FUNCTION:
+	case CTF_K_FUNC_LINKAGE:
 	  if (!isroot)
 	    break;
 
 	  err = ctf_dynhash_insert_type (fp, fp->ctf_names,
 					 ctf_index_to_type (fp, id),
-					 tp->ctt_name);
+					 suffix->ctt_name);
 	  if (err != 0)
 	    return err * -1;
 	  break;
 
 	case CTF_K_STRUCT:
-	  if (size >= CTF_LSTRUCT_THRESH)
-	    nlstructs++;
-
 	  if (!isroot)
 	    break;
 
 	  err = ctf_dynhash_insert_type (fp, fp->ctf_structs,
 					 ctf_index_to_type (fp, id),
-					 tp->ctt_name);
+					 suffix->ctt_name);
 
 	  if (err != 0)
 	    return err * -1;
@@ -869,38 +971,45 @@ init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
 	  break;
 
 	case CTF_K_UNION:
-	  if (size >= CTF_LSTRUCT_THRESH)
-	    nlunions++;
-
 	  if (!isroot)
 	    break;
 
 	  err = ctf_dynhash_insert_type (fp, fp->ctf_unions,
 					 ctf_index_to_type (fp, id),
-					 tp->ctt_name);
+					 suffix->ctt_name);
 
 	  if (err != 0)
 	    return err * -1;
 	  break;
 
 	case CTF_K_ENUM:
+	case CTF_K_ENUM64:
 	  {
 	    if (!isroot)
 	      break;
 
+	    /* Only insert forward types if the type is not already present.  */
+	    if (vlen == 0
+		&& ctf_dynhash_lookup_type (ctf_name_table (fp, kind),
+					    name) != 0)
+	      break;
+
 	    err = ctf_dynhash_insert_type (fp, fp->ctf_enums,
 					   ctf_index_to_type (fp, id),
-					   tp->ctt_name);
+					   suffix->ctt_name);
 
 	    if (err != 0)
 	      return err * -1;
 
-	    /* Remember all enums for later rescanning.  */
+	    /* Remember all non-forward enums for later rescanning.  */
 
+	    if (vlen != 0)
+	      {
 		err = ctf_dynset_insert (all_enums, (void *) (ptrdiff_t)
 					 ctf_index_to_type (fp, id));
 		if (err != 0)
 		  return err * -1;
+	      }
 	    break;
 	  }
 
@@ -910,14 +1019,56 @@ init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
 
 	  err = ctf_dynhash_insert_type (fp, fp->ctf_names,
 					 ctf_index_to_type (fp, id),
-					 tp->ctt_name);
+					 suffix->ctt_name);
 	  if (err != 0)
 	    return err * -1;
 	  break;
 
+	case CTF_K_VAR:
+	  if (!isroot)
+	    break;
+
+	  err = ctf_dynhash_insert_type (fp, fp->ctf_names,
+					 ctf_index_to_type (fp, id),
+					 suffix->ctt_name);
+	  if (err != 0)
+	    return err * -1;
+	  break;
+
+	case CTF_K_DATASEC:
+	  if (!isroot)
+	    break;
+
+	  err = ctf_dynhash_insert_type (fp, fp->ctf_datasecs,
+					 ctf_index_to_type (fp, id),
+					 suffix->ctt_name);
+	  if (err != 0)
+	    return err * -1;
+
+	  break;
+
+	case CTF_K_DECL_TAG:
+	case CTF_K_TYPE_TAG:
+	  {
+	    const char *str;
+
+	    if ((str = ctf_strptr_validate (fp, suffix->ctt_name)) == NULL)
+	      return ctf_errno (fp);
+
+	    if (!isroot)
+	      break;
+
+	    if (ctf_insert_type_decl_tag (fp, id, name, kind) < 0)
+	      return ctf_errno (fp);
+
+	    break;
+	  }
+
 	case CTF_K_FORWARD:
 	  {
-	    ctf_dynhash_t *h = ctf_name_table (fp, tp->ctt_type);
+	    int kflag = CTF_INFO_KFLAG (tp->ctt_info);
+	    ctf_dynhash_t *h = ctf_name_table (fp, kflag == 1
+					       ? CTF_K_UNION : CTF_K_STRUCT);
 
 	    if (!isroot)
 	      break;
@@ -927,7 +1078,7 @@ init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
 	    if (ctf_dynhash_lookup_type (h, name) == 0)
 	      {
 		err = ctf_dynhash_insert_type (fp, h, ctf_index_to_type (fp, id),
-					       tp->ctt_name);
+					       suffix->ctt_name);
 		if (err != 0)
 		  return err * -1;
 	      }
@@ -939,22 +1090,12 @@ init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
 	     store the index of the pointer type in fp->ctf_ptrtab[ index of
 	     referenced type ].  */
 
-	  if (ctf_type_ischild (fp, tp->ctt_type) == child
-	      && ctf_type_to_index (fp, tp->ctt_type) <= fp->ctf_typemax)
-	    fp->ctf_ptrtab[ctf_type_to_index (fp, tp->ctt_type)] = id;
-	 /*FALLTHRU*/
+	  if (ctf_type_ischild (fp, suffix->ctt_type) == child
+	      && ctf_type_to_index (fp, suffix->ctt_type) <= fp->ctf_typemax)
+	    fp->ctf_ptrtab[ctf_type_to_index (fp, suffix->ctt_type)] = id;
 
-	case CTF_K_VOLATILE:
-	case CTF_K_CONST:
-	case CTF_K_RESTRICT:
-	  if (!isroot)
 	  break;
 
-	  err = ctf_dynhash_insert_type (fp, fp->ctf_names,
-					 ctf_index_to_type (fp, id), 0);
-	  if (err != 0)
-	    return err * -1;
-	  break;
 	default:
 	  ctf_err_warn (fp, 0, ECTF_CORRUPT,
 			_("init_static_types(): unhandled CTF kind: %x"), kind);
@@ -962,10 +1103,12 @@ init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
 	}
       tp = (ctf_type_t *) ((uintptr_t) tp + increment + vbytes);
     }
-  fp->ctf_typemax--;
-  assert (fp->ctf_typemax == typemax);
+  assert (fp->ctf_typemax == id - 1);
 
-  ctf_dprintf ("%u total types processed\n", fp->ctf_typemax);
+  ctf_dprintf ("%u total types processed\n", id - 1);
+
+  if ((err = init_void (fp) < 0))
+    return err;
 
   /* In the third pass, we traverse the enums we spotted earlier and track all
      the enumeration constants to aid in future detection of duplicates.
@@ -974,6 +1117,9 @@ init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
      enum appears with a constant FOO, then later a type named FOO appears,
      too late to spot the conflict by checking the enum's constants.  */
 
+  ctf_dprintf ("Extracting enumeration constants from %zu enums\n",
+	       ctf_dynset_elements (all_enums));
+
   while ((err = ctf_dynset_next (all_enums, &i, &k)) == 0)
     {
       ctf_id_t enum_id = (uintptr_t) k;
@@ -998,20 +1144,94 @@ init_static_types_names_internal (ctf_dict_t *fp, ctf_header_t *cth,
   if (err != ECTF_NEXT_END)
     return err;
 
+  /* In the final pass, we traverse all datasecs and remember the variables in
+     each, so we can rapidly map from variable back to datasec.  */
+
+  ctf_dprintf ("Getting variable datasec membership\n");
+
+  while ((type = ctf_type_kind_next (fp, &i, CTF_K_DATASEC)) != CTF_ERR)
+    {
+      ctf_next_t *i_sec = NULL;
+      ctf_id_t var_type;
+
+      while ((var_type = ctf_datasec_var_next (fp, type, &i_sec, NULL, NULL))
+	     != CTF_ERR)
+	{
+	  err = ctf_dynhash_insert (fp->ctf_var_datasecs,
+				    (void *) (ptrdiff_t) var_type,
+				    (void *) (ptrdiff_t) type);
+	  if (err != 0)
+	    return err * -1;
+	}
+      if (ctf_errno (fp) != ECTF_NEXT_END)
+	{
+	  ctf_next_destroy (i);
+	  return ctf_errno (fp);
+	}
+    }
+  if (ctf_errno (fp) != ECTF_NEXT_END)
+    return ctf_errno (fp);
+
   ctf_dprintf ("%zu enum names hashed\n",
 	       ctf_dynhash_elements (fp->ctf_enums));
   ctf_dprintf ("%zu conflicting enumerators identified\n",
 	       ctf_dynset_elements (fp->ctf_conflicting_enums));
-  ctf_dprintf ("%zu struct names hashed (%d long)\n",
-	       ctf_dynhash_elements (fp->ctf_structs), nlstructs);
-  ctf_dprintf ("%zu union names hashed (%d long)\n",
-	       ctf_dynhash_elements (fp->ctf_unions), nlunions);
+  ctf_dprintf ("%zu struct names hashed\n",
+	       ctf_dynhash_elements (fp->ctf_structs));
+  ctf_dprintf ("%zu union names hashed\n",
+	       ctf_dynhash_elements (fp->ctf_unions));
   ctf_dprintf ("%zu base type names and identifiers hashed\n",
 	       ctf_dynhash_elements (fp->ctf_names));
 
   return 0;
 }
 
+/* Prepare the void type.  If present, index 0 is pointed at it: otherwise, we
+   make one in the ctf_void_type member and point index 0 at that.  Because this
+   is index 0, it is not written out by serialization (which always starts at
+   index 1): because it is type 0, it is the type expected by BTF consumers:
+   because it is a real, queryable type, CTF consumers will get a proper type
+   back that they can query the properties of.
+
+   As an initialization function, this returns a positive error code, or
+   zero.  */
+
+static int
+init_void (ctf_dict_t *fp)
+{
+  ctf_id_t void_type;
+  ctf_type_t *void_tp;
+
+  void_type = ctf_dynhash_lookup_type (ctf_name_table (fp, CTF_K_INTEGER), "void");
+
+  if (void_type == 0)
+    {
+      uint32_t *vlen;
+
+      if ((void_tp = calloc (1, sizeof (ctf_type_t) + sizeof (uint32_t))) == NULL)
+	return ENOMEM;
+      vlen = (uint32_t *) (void_tp + 1);
+
+      void_tp->ctt_name = ctf_str_add (fp, "void");
+      void_tp->ctt_info = CTF_TYPE_INFO (CTF_K_INTEGER, 0, 0);
+      void_tp->ctt_size = 4;			/* (bytes)  */
+      *vlen = CTF_INT_DATA (CTF_INT_SIGNED, 0, 0);
+
+      fp->ctf_void_type = void_tp;
+    }
+  else
+    {
+      ctf_dict_t *tmp = fp;
+
+      void_tp = (ctf_type_t *) ctf_lookup_by_id (&tmp, void_type, NULL);
+      assert (void_tp != NULL);
+    }
+
+  fp->ctf_txlate[0] = void_tp;
+
+  return 0;
+}
+
 /* Endianness-flipping routines.
 
    We flip everything, mindlessly, even 1-byte entities, so that future
@@ -1371,12 +1591,15 @@ void ctf_set_ctl_hashes (ctf_dict_t *fp)
   fp->ctf_lookups[2].ctl_prefix = "enum";
   fp->ctf_lookups[2].ctl_len = strlen (fp->ctf_lookups[2].ctl_prefix);
   fp->ctf_lookups[2].ctl_hash = fp->ctf_enums;
-  fp->ctf_lookups[3].ctl_prefix = _CTF_NULLSTR;
+  fp->ctf_lookups[3].ctl_prefix = "datasec";
   fp->ctf_lookups[3].ctl_len = strlen (fp->ctf_lookups[3].ctl_prefix);
-  fp->ctf_lookups[3].ctl_hash = fp->ctf_names;
-  fp->ctf_lookups[4].ctl_prefix = NULL;
-  fp->ctf_lookups[4].ctl_len = 0;
-  fp->ctf_lookups[4].ctl_hash = NULL;
+  fp->ctf_lookups[3].ctl_hash = fp->ctf_datasecs;
+  fp->ctf_lookups[4].ctl_prefix = _CTF_NULLSTR;
+  fp->ctf_lookups[4].ctl_len = strlen (fp->ctf_lookups[4].ctl_prefix);
+  fp->ctf_lookups[4].ctl_hash = fp->ctf_names;
+  fp->ctf_lookups[5].ctl_prefix = NULL;
+  fp->ctf_lookups[5].ctl_len = 0;
+  fp->ctf_lookups[5].ctl_hash = NULL;
 }
 
 /* Open a CTF file, mocking up a suitable ctf_sect.  */
@@ -2149,6 +2372,8 @@ ctf_dict_close (ctf_dict_t *fp)
   ctf_dynhash_destroy (fp->ctf_structs);
   ctf_dynhash_destroy (fp->ctf_unions);
   ctf_dynhash_destroy (fp->ctf_enums);
+  ctf_dynhash_destroy (fp->ctf_datasecs);
+  ctf_dynhash_destroy (fp->ctf_tags);
   ctf_dynhash_destroy (fp->ctf_names);
 
   for (dvd = ctf_list_next (&fp->ctf_dvdefs); dvd != NULL; dvd = nvd)
@@ -2157,6 +2382,7 @@ ctf_dict_close (ctf_dict_t *fp)
       ctf_dvd_delete (fp, dvd);
     }
   ctf_dynhash_destroy (fp->ctf_dvhash);
+  ctf_dynhash_destroy (fp->ctf_var_datasecs);
 
   ctf_dynhash_destroy (fp->ctf_symhash_func);
   ctf_dynhash_destroy (fp->ctf_symhash_objt);
@@ -2217,6 +2443,7 @@ ctf_dict_close (ctf_dict_t *fp)
       free (err);
     }
 
+  free (fp->ctf_void_type);
   free (fp->ctf_sxlate);
   free (fp->ctf_txlate);
   free (fp->ctf_ptrtab);
@@ -2439,7 +2666,8 @@ ctf_import_internal (ctf_dict_t *fp, ctf_dict_t *pfp, int unreffed)
   fp->ctf_flags |= LCTF_CHILD;
   fp->ctf_flags &= ~LCTF_NO_STR;
 
-  if (no_strings && (err = init_static_types_names (fp, fp->ctf_header)) < 0)
+  if (no_strings && (err = init_static_types_names (fp, fp->ctf_header,
+						    fp->ctf_opened_btf) < 0))
     {
       /* Undo everything other than cache flushing.  */