libbpf: Hashmap interface update to allow both long and void* keys/values

An update for libbpf's hashmap interface from void* -> void* to a
polymorphic one, allowing both long and void* keys and values.

This simplifies many use cases in libbpf as hashmaps there are mostly
integer to integer.

Perf copies hashmap implementation from libbpf and has to be
updated as well.

Changes to libbpf, selftests/bpf and perf are packed as a single
commit to avoid compilation issues with any future bisect.

Polymorphic interface is acheived by hiding hashmap interface
functions behind auxiliary macros that take care of necessary
type casts, for example:

#define hashmap_cast_ptr(p) \
({ \
_Static_assert((p) == NULL || sizeof(*(p)) == sizeof(long),\
#p " pointee should be a long-sized integer or a pointer"); \
(long *)(p); \
})

bool hashmap_find(const struct hashmap *map, long key, long *value);

#define hashmap__find(map, key, value) \
hashmap_find((map), (long)(key), hashmap_cast_ptr(value))

- hashmap__find macro casts key and value parameters to long
and long* respectively
- hashmap_cast_ptr ensures that value pointer points to a memory
of appropriate size.

This hack was suggested by Andrii Nakryiko in [1].
This is a follow up for [2].

[1] https://lore.kernel.org/bpf/[e-mail]/
[2] https://lore.kernel.org/bpf/[e-mail]/T/#m65b28f1d6d969fcd318b556db6a3ad499a42607d

Signed-off-by: Eduard Zingerman <[e-mail]>
Signed-off-by: Andrii Nakryiko <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/bpf/bpftool/btf.c

···
 		if (!btf_id)
 			continue;
 
-		err = hashmap__append(tab, u32_as_hash_field(btf_id),
-				      u32_as_hash_field(id));
+		err = hashmap__append(tab, btf_id, id);
 		if (err) {
 			p_err("failed to append entry to hashmap for BTF ID %u, object ID %u: %s",
 			      btf_id, id, strerror(-err));
···
 	printf("size %uB", info->btf_size);
 
 	n = 0;
-	hashmap__for_each_key_entry(btf_prog_table, entry,
-				    u32_as_hash_field(info->id)) {
-		printf("%s%u", n++ == 0 ? "  prog_ids " : ",",
-		       hash_field_as_u32(entry->value));
+	hashmap__for_each_key_entry(btf_prog_table, entry, info->id) {
+		printf("%s%lu", n++ == 0 ? "  prog_ids " : ",", entry->value);
 	}
 
 	n = 0;
-	hashmap__for_each_key_entry(btf_map_table, entry,
-				    u32_as_hash_field(info->id)) {
-		printf("%s%u", n++ == 0 ? "  map_ids " : ",",
-		       hash_field_as_u32(entry->value));
+	hashmap__for_each_key_entry(btf_map_table, entry, info->id) {
+		printf("%s%lu", n++ == 0 ? "  map_ids " : ",", entry->value);
 	}
 
 	emit_obj_refs_plain(refs_table, info->id, "\n\tpids ");
···
 
 	jsonw_name(json_wtr, "prog_ids");
 	jsonw_start_array(json_wtr);	/* prog_ids */
-	hashmap__for_each_key_entry(btf_prog_table, entry,
-				    u32_as_hash_field(info->id)) {
-		jsonw_uint(json_wtr, hash_field_as_u32(entry->value));
+	hashmap__for_each_key_entry(btf_prog_table, entry, info->id) {
+		jsonw_uint(json_wtr, entry->value);
 	}
 	jsonw_end_array(json_wtr);	/* prog_ids */
 
 	jsonw_name(json_wtr, "map_ids");
 	jsonw_start_array(json_wtr);	/* map_ids */
-	hashmap__for_each_key_entry(btf_map_table, entry,
-				    u32_as_hash_field(info->id)) {
-		jsonw_uint(json_wtr, hash_field_as_u32(entry->value));
+	hashmap__for_each_key_entry(btf_map_table, entry, info->id) {
+		jsonw_uint(json_wtr, entry->value);
 	}
 	jsonw_end_array(json_wtr);	/* map_ids */
 

tools/bpf/bpftool/common.c

···
 		goto out_close;
 	}
 
-	err = hashmap__append(build_fn_table, u32_as_hash_field(pinned_info.id), path);
+	err = hashmap__append(build_fn_table, pinned_info.id, path);
 	if (err) {
 		p_err("failed to append entry to hashmap for ID %u, path '%s': %s",
 		      pinned_info.id, path, strerror(errno));
···
 		return;
 
 	hashmap__for_each_entry(map, entry, bkt)
-		free(entry->value);
+		free(entry->pvalue);
 
 	hashmap__free(map);
 }
···
 	return fd;
 }
 
-size_t hash_fn_for_key_as_id(const void *key, void *ctx)
+size_t hash_fn_for_key_as_id(long key, void *ctx)
 {
-	return (size_t)key;
+	return key;
 }
 
-bool equal_fn_for_key_as_id(const void *k1, const void *k2, void *ctx)
+bool equal_fn_for_key_as_id(long k1, long k2, void *ctx)
 {
 	return k1 == k2;
 }

tools/bpf/bpftool/gen.c

···
 	struct btf *marked_btf; /* btf structure used to mark used types */
 };
 
-static size_t btfgen_hash_fn(const void *key, void *ctx)
+static size_t btfgen_hash_fn(long key, void *ctx)
 {
-	return (size_t)key;
+	return key;
 }
 
-static bool btfgen_equal_fn(const void *k1, const void *k2, void *ctx)
+static bool btfgen_equal_fn(long k1, long k2, void *ctx)
 {
 	return k1 == k2;
-}
-
-static void *u32_as_hash_key(__u32 x)
-{
-	return (void *)(uintptr_t)x;
 }
 
 static void btfgen_free_info(struct btfgen_info *info)
···
 			struct bpf_core_spec specs_scratch[3] = {};
 			struct bpf_core_relo_res targ_res = {};
 			struct bpf_core_cand_list *cands = NULL;
-			const void *type_key = u32_as_hash_key(relo->type_id);
 			const char *sec_name = btf__name_by_offset(btf, sec->sec_name_off);
 
 			if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
-			    !hashmap__find(cand_cache, type_key, (void **)&cands)) {
+			    !hashmap__find(cand_cache, relo->type_id, &cands)) {
 				cands = btfgen_find_cands(btf, info->src_btf, relo->type_id);
 				if (!cands) {
 					err = -errno;
 					goto out;
 				}
 
-				err = hashmap__set(cand_cache, type_key, cands, NULL, NULL);
+				err = hashmap__set(cand_cache, relo->type_id, cands,
+						   NULL, NULL);
 				if (err)
 					goto out;
 			}
···
 
 	if (!IS_ERR_OR_NULL(cand_cache)) {
 		hashmap__for_each_entry(cand_cache, entry, i) {
-			bpf_core_free_cands(entry->value);
+			bpf_core_free_cands(entry->pvalue);
 		}
 		hashmap__free(cand_cache);
 	}

tools/bpf/bpftool/link.c

···
 
 		jsonw_name(json_wtr, "pinned");
 		jsonw_start_array(json_wtr);
-		hashmap__for_each_key_entry(link_table, entry,
-					    u32_as_hash_field(info->id))
-			jsonw_string(json_wtr, entry->value);
+		hashmap__for_each_key_entry(link_table, entry, info->id)
+			jsonw_string(json_wtr, entry->pvalue);
 		jsonw_end_array(json_wtr);
 	}
 
···
 	if (!hashmap__empty(link_table)) {
 		struct hashmap_entry *entry;
 
-		hashmap__for_each_key_entry(link_table, entry,
-					    u32_as_hash_field(info->id))
-			printf("\n\tpinned %s", (char *)entry->value);
+		hashmap__for_each_key_entry(link_table, entry, info->id)
+			printf("\n\tpinned %s", (char *)entry->pvalue);
 	}
 	emit_obj_refs_plain(refs_table, info->id, "\n\tpids ");
 

tools/bpf/bpftool/main.h

···
 int print_all_levels(__maybe_unused enum libbpf_print_level level,
 		     const char *format, va_list args);
 
-size_t hash_fn_for_key_as_id(const void *key, void *ctx);
-bool equal_fn_for_key_as_id(const void *k1, const void *k2, void *ctx);
+size_t hash_fn_for_key_as_id(long key, void *ctx);
+bool equal_fn_for_key_as_id(long k1, long k2, void *ctx);
 
 /* bpf_attach_type_input_str - convert the provided attach type value into a
  * textual representation that we accept for input purposes.
···
  * returned for unknown bpf_attach_type values.
  */
 const char *bpf_attach_type_input_str(enum bpf_attach_type t);
-
-static inline void *u32_as_hash_field(__u32 x)
-{
-	return (void *)(uintptr_t)x;
-}
-
-static inline __u32 hash_field_as_u32(const void *x)
-{
-	return (__u32)(uintptr_t)x;
-}
 
 static inline bool hashmap__empty(struct hashmap *map)
 {

tools/bpf/bpftool/map.c

···
 
 		jsonw_name(json_wtr, "pinned");
 		jsonw_start_array(json_wtr);
-		hashmap__for_each_key_entry(map_table, entry,
-					    u32_as_hash_field(info->id))
-			jsonw_string(json_wtr, entry->value);
+		hashmap__for_each_key_entry(map_table, entry, info->id)
+			jsonw_string(json_wtr, entry->pvalue);
 		jsonw_end_array(json_wtr);
 	}
 
···
 	if (!hashmap__empty(map_table)) {
 		struct hashmap_entry *entry;
 
-		hashmap__for_each_key_entry(map_table, entry,
-					    u32_as_hash_field(info->id))
-			printf("\n\tpinned %s", (char *)entry->value);
+		hashmap__for_each_key_entry(map_table, entry, info->id)
+			printf("\n\tpinned %s", (char *)entry->pvalue);
 	}
 
 	if (frozen_str) {

tools/bpf/bpftool/pids.c

···
 	int err, i;
 	void *tmp;
 
-	hashmap__for_each_key_entry(map, entry, u32_as_hash_field(e->id)) {
-		refs = entry->value;
+	hashmap__for_each_key_entry(map, entry, e->id) {
+		refs = entry->pvalue;
 
 		for (i = 0; i < refs->ref_cnt; i++) {
 			if (refs->refs[i].pid == e->pid)
···
 	refs->has_bpf_cookie = e->has_bpf_cookie;
 	refs->bpf_cookie = e->bpf_cookie;
 
-	err = hashmap__append(map, u32_as_hash_field(e->id), refs);
+	err = hashmap__append(map, e->id, refs);
 	if (err)
 		p_err("failed to append entry to hashmap for ID %u: %s",
 		      e->id, strerror(errno));
···
 		return;
 
 	hashmap__for_each_entry(map, entry, bkt) {
-		struct obj_refs *refs = entry->value;
+		struct obj_refs *refs = entry->pvalue;
 
 		free(refs->refs);
 		free(refs);
···
 	if (hashmap__empty(map))
 		return;
 
-	hashmap__for_each_key_entry(map, entry, u32_as_hash_field(id)) {
-		struct obj_refs *refs = entry->value;
+	hashmap__for_each_key_entry(map, entry, id) {
+		struct obj_refs *refs = entry->pvalue;
 		int i;
 
 		if (refs->ref_cnt == 0)
···
 	if (hashmap__empty(map))
 		return;
 
-	hashmap__for_each_key_entry(map, entry, u32_as_hash_field(id)) {
-		struct obj_refs *refs = entry->value;
+	hashmap__for_each_key_entry(map, entry, id) {
+		struct obj_refs *refs = entry->pvalue;
 		int i;
 
 		if (refs->ref_cnt == 0)

tools/bpf/bpftool/prog.c

···
 
 		jsonw_name(json_wtr, "pinned");
 		jsonw_start_array(json_wtr);
-		hashmap__for_each_key_entry(prog_table, entry,
-					    u32_as_hash_field(info->id))
-			jsonw_string(json_wtr, entry->value);
+		hashmap__for_each_key_entry(prog_table, entry, info->id)
+			jsonw_string(json_wtr, entry->pvalue);
 		jsonw_end_array(json_wtr);
 	}
 
···
 	if (!hashmap__empty(prog_table)) {
 		struct hashmap_entry *entry;
 
-		hashmap__for_each_key_entry(prog_table, entry,
-					    u32_as_hash_field(info->id))
-			printf("\n\tpinned %s", (char *)entry->value);
+		hashmap__for_each_key_entry(prog_table, entry, info->id)
+			printf("\n\tpinned %s", (char *)entry->pvalue);
 	}
 
 	if (info->btf_id)

tools/lib/bpf/btf.c

···
 static int btf_rewrite_str(__u32 *str_off, void *ctx)
 {
 	struct btf_pipe *p = ctx;
-	void *mapped_off;
+	long mapped_off;
 	int off, err;
 
 	if (!*str_off) /* nothing to do for empty strings */
 		return 0;
 
 	if (p->str_off_map &&
-	    hashmap__find(p->str_off_map, (void *)(long)*str_off, &mapped_off)) {
-		*str_off = (__u32)(long)mapped_off;
+	    hashmap__find(p->str_off_map, *str_off, &mapped_off)) {
+		*str_off = mapped_off;
 		return 0;
 	}
 
···
 	 * performing expensive string comparisons.
 	 */
 	if (p->str_off_map) {
-		err = hashmap__append(p->str_off_map, (void *)(long)*str_off, (void *)(long)off);
+		err = hashmap__append(p->str_off_map, *str_off, off);
 		if (err)
 			return err;
 	}
···
 	return 0;
 }
 
-static size_t btf_dedup_identity_hash_fn(const void *key, void *ctx);
-static bool btf_dedup_equal_fn(const void *k1, const void *k2, void *ctx);
+static size_t btf_dedup_identity_hash_fn(long key, void *ctx);
+static bool btf_dedup_equal_fn(long k1, long k2, void *ctx);
 
 int btf__add_btf(struct btf *btf, const struct btf *src_btf)
 {
···
 }
 
 #define for_each_dedup_cand(d, node, hash) \
-	hashmap__for_each_key_entry(d->dedup_table, node, (void *)hash)
+	hashmap__for_each_key_entry(d->dedup_table, node, hash)
 
 static int btf_dedup_table_add(struct btf_dedup *d, long hash, __u32 type_id)
 {
-	return hashmap__append(d->dedup_table,
-			       (void *)hash, (void *)(long)type_id);
+	return hashmap__append(d->dedup_table, hash, type_id);
 }
 
 static int btf_dedup_hypot_map_add(struct btf_dedup *d,
···
 	free(d);
 }
 
-static size_t btf_dedup_identity_hash_fn(const void *key, void *ctx)
+static size_t btf_dedup_identity_hash_fn(long key, void *ctx)
 {
-	return (size_t)key;
+	return key;
 }
 
-static size_t btf_dedup_collision_hash_fn(const void *key, void *ctx)
+static size_t btf_dedup_collision_hash_fn(long key, void *ctx)
 {
 	return 0;
 }
 
-static bool btf_dedup_equal_fn(const void *k1, const void *k2, void *ctx)
+static bool btf_dedup_equal_fn(long k1, long k2, void *ctx)
 {
 	return k1 == k2;
 }
···
 	case BTF_KIND_INT:
 		h = btf_hash_int_decl_tag(t);
 		for_each_dedup_cand(d, hash_entry, h) {
-			cand_id = (__u32)(long)hash_entry->value;
+			cand_id = hash_entry->value;
 			cand = btf_type_by_id(d->btf, cand_id);
 			if (btf_equal_int_tag(t, cand)) {
 				new_id = cand_id;
···
 	case BTF_KIND_ENUM64:
 		h = btf_hash_enum(t);
 		for_each_dedup_cand(d, hash_entry, h) {
-			cand_id = (__u32)(long)hash_entry->value;
+			cand_id = hash_entry->value;
 			cand = btf_type_by_id(d->btf, cand_id);
 			if (btf_equal_enum(t, cand)) {
 				new_id = cand_id;
···
 	case BTF_KIND_FLOAT:
 		h = btf_hash_common(t);
 		for_each_dedup_cand(d, hash_entry, h) {
-			cand_id = (__u32)(long)hash_entry->value;
+			cand_id = hash_entry->value;
 			cand = btf_type_by_id(d->btf, cand_id);
 			if (btf_equal_common(t, cand)) {
 				new_id = cand_id;
···
 
 	h = btf_hash_struct(t);
 	for_each_dedup_cand(d, hash_entry, h) {
-		__u32 cand_id = (__u32)(long)hash_entry->value;
+		__u32 cand_id = hash_entry->value;
 		int eq;
 
 		/*
···
 
 		h = btf_hash_common(t);
 		for_each_dedup_cand(d, hash_entry, h) {
-			cand_id = (__u32)(long)hash_entry->value;
+			cand_id = hash_entry->value;
 			cand = btf_type_by_id(d->btf, cand_id);
 			if (btf_equal_common(t, cand)) {
 				new_id = cand_id;
···
 
 		h = btf_hash_int_decl_tag(t);
 		for_each_dedup_cand(d, hash_entry, h) {
-			cand_id = (__u32)(long)hash_entry->value;
+			cand_id = hash_entry->value;
 			cand = btf_type_by_id(d->btf, cand_id);
 			if (btf_equal_int_tag(t, cand)) {
 				new_id = cand_id;
···
 
 		h = btf_hash_array(t);
 		for_each_dedup_cand(d, hash_entry, h) {
-			cand_id = (__u32)(long)hash_entry->value;
+			cand_id = hash_entry->value;
 			cand = btf_type_by_id(d->btf, cand_id);
 			if (btf_equal_array(t, cand)) {
 				new_id = cand_id;
···
 
 		h = btf_hash_fnproto(t);
 		for_each_dedup_cand(d, hash_entry, h) {
-			cand_id = (__u32)(long)hash_entry->value;
+			cand_id = hash_entry->value;
 			cand = btf_type_by_id(d->btf, cand_id);
 			if (btf_equal_fnproto(t, cand)) {
 				new_id = cand_id;

tools/lib/bpf/btf_dump.c

···
 	struct btf_dump_data *typed_dump;
 };
 
-static size_t str_hash_fn(const void *key, void *ctx)
+static size_t str_hash_fn(long key, void *ctx)
 {
-	return str_hash(key);
+	return str_hash((void *)key);
 }
 
-static bool str_equal_fn(const void *a, const void *b, void *ctx)
+static bool str_equal_fn(long a, long b, void *ctx)
 {
-	return strcmp(a, b) == 0;
+	return strcmp((void *)a, (void *)b) == 0;
 }
 
 static const char *btf_name_of(const struct btf_dump *d, __u32 name_off)
···
 	struct hashmap_entry *cur;
 
 	hashmap__for_each_entry(map, cur, bkt)
-		free((void *)cur->key);
+		free((void *)cur->pkey);
 
 	hashmap__free(map);
 }
···
 	if (!new_name)
 		return 1;
 
-	hashmap__find(name_map, orig_name, (void **)&dup_cnt);
+	hashmap__find(name_map, orig_name, &dup_cnt);
 	dup_cnt++;
 
-	err = hashmap__set(name_map, new_name, (void *)dup_cnt,
-			   (const void **)&old_name, NULL);
+	err = hashmap__set(name_map, new_name, dup_cnt, &old_name, NULL);
 	if (err)
 		free(new_name);
 

tools/lib/bpf/hashmap.c

···
 }
 
 static bool hashmap_find_entry(const struct hashmap *map,
-			       const void *key, size_t hash,
+			       const long key, size_t hash,
 			       struct hashmap_entry ***pprev,
 			       struct hashmap_entry **entry)
 {
···
 	return false;
 }
 
-int hashmap__insert(struct hashmap *map, const void *key, void *value,
-		    enum hashmap_insert_strategy strategy,
-		    const void **old_key, void **old_value)
+int hashmap_insert(struct hashmap *map, long key, long value,
+		   enum hashmap_insert_strategy strategy,
+		   long *old_key, long *old_value)
 {
 	struct hashmap_entry *entry;
 	size_t h;
 	int err;
 
 	if (old_key)
-		*old_key = NULL;
+		*old_key = 0;
 	if (old_value)
-		*old_value = NULL;
+		*old_value = 0;
 
 	h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
 	if (strategy != HASHMAP_APPEND &&
···
 	return 0;
 }
 
-bool hashmap__find(const struct hashmap *map, const void *key, void **value)
+bool hashmap_find(const struct hashmap *map, long key, long *value)
 {
 	struct hashmap_entry *entry;
 	size_t h;
···
 	return true;
 }
 
-bool hashmap__delete(struct hashmap *map, const void *key,
-		     const void **old_key, void **old_value)
+bool hashmap_delete(struct hashmap *map, long key,
+		    long *old_key, long *old_value)
 {
 	struct hashmap_entry **pprev, *entry;
 	size_t h;

tools/lib/bpf/hashmap.h

···
 	return h;
 }
 
-typedef size_t (*hashmap_hash_fn)(const void *key, void *ctx);
-typedef bool (*hashmap_equal_fn)(const void *key1, const void *key2, void *ctx);
+typedef size_t (*hashmap_hash_fn)(long key, void *ctx);
+typedef bool (*hashmap_equal_fn)(long key1, long key2, void *ctx);
 
+/*
+ * Hashmap interface is polymorphic, keys and values could be either
+ * long-sized integers or pointers, this is achieved as follows:
+ * - interface functions that operate on keys and values are hidden
+ *   behind auxiliary macros, e.g. hashmap_insert <-> hashmap__insert;
+ * - these auxiliary macros cast the key and value parameters as
+ *   long or long *, so the user does not have to specify the casts explicitly;
+ * - for pointer parameters (e.g. old_key) the size of the pointed
+ *   type is verified by hashmap_cast_ptr using _Static_assert;
+ * - when iterating using hashmap__for_each_* forms
+ *   hasmap_entry->key should be used for integer keys and
+ *   hasmap_entry->pkey should be used for pointer keys,
+ *   same goes for values.
+ */
 struct hashmap_entry {
-	const void *key;
-	void *value;
+	union {
+		long key;
+		const void *pkey;
+	};
+	union {
+		long value;
+		void *pvalue;
+	};
 	struct hashmap_entry *next;
 };
 
···
 	HASHMAP_APPEND,
 };
 
+#define hashmap_cast_ptr(p) ({								\
+	_Static_assert((p) == NULL || sizeof(*(p)) == sizeof(long),			\
+		       #p " pointee should be a long-sized integer or a pointer");	\
+	(long *)(p);									\
+})
+
 /*
  * hashmap__insert() adds key/value entry w/ various semantics, depending on
  * provided strategy value. If a given key/value pair replaced already
···
  * through old_key and old_value to allow calling code do proper memory
  * management.
  */
-int hashmap__insert(struct hashmap *map, const void *key, void *value,
-		    enum hashmap_insert_strategy strategy,
-		    const void **old_key, void **old_value);
+int hashmap_insert(struct hashmap *map, long key, long value,
+		   enum hashmap_insert_strategy strategy,
+		   long *old_key, long *old_value);
 
-static inline int hashmap__add(struct hashmap *map,
-			       const void *key, void *value)
-{
-	return hashmap__insert(map, key, value, HASHMAP_ADD, NULL, NULL);
-}
+#define hashmap__insert(map, key, value, strategy, old_key, old_value) \
+	hashmap_insert((map), (long)(key), (long)(value), (strategy),  \
+		       hashmap_cast_ptr(old_key),		       \
+		       hashmap_cast_ptr(old_value))
 
-static inline int hashmap__set(struct hashmap *map,
-			       const void *key, void *value,
-			       const void **old_key, void **old_value)
-{
-	return hashmap__insert(map, key, value, HASHMAP_SET,
-			       old_key, old_value);
-}
+#define hashmap__add(map, key, value) \
+	hashmap__insert((map), (key), (value), HASHMAP_ADD, NULL, NULL)
 
-static inline int hashmap__update(struct hashmap *map,
-				  const void *key, void *value,
-				  const void **old_key, void **old_value)
-{
-	return hashmap__insert(map, key, value, HASHMAP_UPDATE,
-			       old_key, old_value);
-}
+#define hashmap__set(map, key, value, old_key, old_value) \
+	hashmap__insert((map), (key), (value), HASHMAP_SET, (old_key), (old_value))
 
-static inline int hashmap__append(struct hashmap *map,
-				  const void *key, void *value)
-{
-	return hashmap__insert(map, key, value, HASHMAP_APPEND, NULL, NULL);
-}
+#define hashmap__update(map, key, value, old_key, old_value) \
+	hashmap__insert((map), (key), (value), HASHMAP_UPDATE, (old_key), (old_value))
 
-bool hashmap__delete(struct hashmap *map, const void *key,
-		     const void **old_key, void **old_value);
+#define hashmap__append(map, key, value) \
+	hashmap__insert((map), (key), (value), HASHMAP_APPEND, NULL, NULL)
 
-bool hashmap__find(const struct hashmap *map, const void *key, void **value);
+bool hashmap_delete(struct hashmap *map, long key, long *old_key, long *old_value);
+
+#define hashmap__delete(map, key, old_key, old_value)		       \
+	hashmap_delete((map), (long)(key),			       \
+		       hashmap_cast_ptr(old_key),		       \
+		       hashmap_cast_ptr(old_value))
+
+bool hashmap_find(const struct hashmap *map, long key, long *value);
+
+#define hashmap__find(map, key, value) \
+	hashmap_find((map), (long)(key), hashmap_cast_ptr(value))
 
 /*
  * hashmap__for_each_entry - iterate over all entries in hashmap

tools/lib/bpf/libbpf.c

···
 	return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false, 32);
 }
 
-static size_t bpf_core_hash_fn(const void *key, void *ctx)
+static size_t bpf_core_hash_fn(const long key, void *ctx)
 {
-	return (size_t)key;
+	return key;
 }
 
-static bool bpf_core_equal_fn(const void *k1, const void *k2, void *ctx)
+static bool bpf_core_equal_fn(const long k1, const long k2, void *ctx)
 {
 	return k1 == k2;
-}
-
-static void *u32_as_hash_key(__u32 x)
-{
-	return (void *)(uintptr_t)x;
 }
 
 static int record_relo_core(struct bpf_program *prog,
···
 				 struct bpf_core_relo_res *targ_res)
 {
 	struct bpf_core_spec specs_scratch[3] = {};
-	const void *type_key = u32_as_hash_key(relo->type_id);
 	struct bpf_core_cand_list *cands = NULL;
 	const char *prog_name = prog->name;
 	const struct btf_type *local_type;
···
 		return -EINVAL;
 
 	if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
-	    !hashmap__find(cand_cache, type_key, (void **)&cands)) {
+	    !hashmap__find(cand_cache, local_id, &cands)) {
 		cands = bpf_core_find_cands(prog->obj, local_btf, local_id);
 		if (IS_ERR(cands)) {
 			pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n",
···
 				local_name, PTR_ERR(cands));
 			return PTR_ERR(cands);
 		}
-		err = hashmap__set(cand_cache, type_key, cands, NULL, NULL);
+		err = hashmap__set(cand_cache, local_id, cands, NULL, NULL);
 		if (err) {
 			bpf_core_free_cands(cands);
 			return err;
···
 
 	if (!IS_ERR_OR_NULL(cand_cache)) {
 		hashmap__for_each_entry(cand_cache, entry, i) {
-			bpf_core_free_cands(entry->value);
+			bpf_core_free_cands(entry->pvalue);
 		}
 		hashmap__free(cand_cache);
 	}

tools/lib/bpf/strset.c

···
 	struct hashmap *strs_hash;
 };
 
-static size_t strset_hash_fn(const void *key, void *ctx)
+static size_t strset_hash_fn(long key, void *ctx)
 {
 	const struct strset *s = ctx;
-	const char *str = s->strs_data + (long)key;
+	const char *str = s->strs_data + key;
 
 	return str_hash(str);
 }
 
-static bool strset_equal_fn(const void *key1, const void *key2, void *ctx)
+static bool strset_equal_fn(long key1, long key2, void *ctx)
 {
 	const struct strset *s = ctx;
-	const char *str1 = s->strs_data + (long)key1;
-	const char *str2 = s->strs_data + (long)key2;
+	const char *str1 = s->strs_data + key1;
+	const char *str2 = s->strs_data + key2;
 
 	return strcmp(str1, str2) == 0;
 }
···
 			/* hashmap__add() returns EEXIST if string with the same
 			 * content already is in the hash map
 			 */
-			err = hashmap__add(hash, (void *)off, (void *)off);
+			err = hashmap__add(hash, off, off);
 			if (err == -EEXIST)
 				continue; /* duplicate */
 			if (err)
···
 	new_off = set->strs_data_len;
 	memcpy(p, s, len);
 
-	if (hashmap__find(set->strs_hash, (void *)new_off, (void **)&old_off))
+	if (hashmap__find(set->strs_hash, new_off, &old_off))
 		return old_off;
 
 	return -ENOENT;
···
 	 * contents doesn't exist already (HASHMAP_ADD strategy). If such
 	 * string exists, we'll get its offset in old_off (that's old_key).
 	 */
-	err = hashmap__insert(set->strs_hash, (void *)new_off, (void *)new_off,
-			      HASHMAP_ADD, (const void **)&old_off, NULL);
+	err = hashmap__insert(set->strs_hash, new_off, new_off,
+			      HASHMAP_ADD, &old_off, NULL);
 	if (err == -EEXIST)
 		return old_off; /* duplicated string, return existing offset */
 	if (err)

tools/lib/bpf/usdt.c

···
 	free(usdt_link);
 }
 
-static size_t specs_hash_fn(const void *key, void *ctx)
+static size_t specs_hash_fn(long key, void *ctx)
 {
-	const char *s = key;
-
-	return str_hash(s);
+	return str_hash((char *)key);
 }
 
-static bool specs_equal_fn(const void *key1, const void *key2, void *ctx)
+static bool specs_equal_fn(long key1, long key2, void *ctx)
 {
-	const char *s1 = key1;
-	const char *s2 = key2;
-
-	return strcmp(s1, s2) == 0;
+	return strcmp((char *)key1, (char *)key2) == 0;
 }
 
 static int allocate_spec_id(struct usdt_manager *man, struct hashmap *specs_hash,
 			    struct bpf_link_usdt *link, struct usdt_target *target,
 			    int *spec_id, bool *is_new)
 {
-	void *tmp;
+	long tmp;
+	void *new_ids;
 	int err;
 
 	/* check if we already allocated spec ID for this spec string */
 	if (hashmap__find(specs_hash, target->spec_str, &tmp)) {
-		*spec_id = (long)tmp;
+		*spec_id = tmp;
 		*is_new = false;
 		return 0;
 	}
···
 	/* otherwise it's a new ID that needs to be set up in specs map and
 	 * returned back to usdt_manager when USDT link is detached
 	 */
-	tmp = libbpf_reallocarray(link->spec_ids, link->spec_cnt + 1, sizeof(*link->spec_ids));
-	if (!tmp)
+	new_ids = libbpf_reallocarray(link->spec_ids, link->spec_cnt + 1, sizeof(*link->spec_ids));
+	if (!new_ids)
 		return -ENOMEM;
-	link->spec_ids = tmp;
+	link->spec_ids = new_ids;
 
 	/* get next free spec ID, giving preference to free list, if not empty */
 	if (man->free_spec_cnt) {
 		*spec_id = man->free_spec_ids[man->free_spec_cnt - 1];
 
 		/* cache spec ID for current spec string for future lookups */
-		err = hashmap__add(specs_hash, target->spec_str, (void *)(long)*spec_id);
+		err = hashmap__add(specs_hash, target->spec_str, *spec_id);
 		if (err)
 			 return err;
 
···
 		*spec_id = man->next_free_spec_id;
 
 		/* cache spec ID for current spec string for future lookups */
-		err = hashmap__add(specs_hash, target->spec_str, (void *)(long)*spec_id);
+		err = hashmap__add(specs_hash, target->spec_str, *spec_id);
 		if (err)
 			 return err;
 

tools/perf/tests/expr.c

···
 			expr__find_ids("FOO + BAR + BAZ + BOZO", "FOO",
 					ctx) == 0);
 	TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 3);
-	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "BAR",
-						    (void **)&val_ptr));
-	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "BAZ",
-						    (void **)&val_ptr));
-	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "BOZO",
-						    (void **)&val_ptr));
+	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "BAR", &val_ptr));
+	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "BAZ", &val_ptr));
+	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "BOZO", &val_ptr));
 
 	expr__ctx_clear(ctx);
 	ctx->sctx.runtime = 3;
···
 			expr__find_ids("EVENT1\\,param\\=?@ + EVENT2\\,param\\=?@",
 					NULL, ctx) == 0);
 	TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 2);
-	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT1,param=3@",
-						    (void **)&val_ptr));
-	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT2,param=3@",
-						    (void **)&val_ptr));
+	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT1,param=3@", &val_ptr));
+	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT2,param=3@", &val_ptr));
 
 	expr__ctx_clear(ctx);
 	TEST_ASSERT_VAL("find ids",
 			expr__find_ids("dash\\-event1 - dash\\-event2",
 				       NULL, ctx) == 0);
 	TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 2);
-	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "dash-event1",
-						    (void **)&val_ptr));
-	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "dash-event2",
-						    (void **)&val_ptr));
+	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "dash-event1", &val_ptr));
+	TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "dash-event2", &val_ptr));
 
 	/* Only EVENT1 or EVENT2 need be measured depending on the value of smt_on. */
 	{
···
 		TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 1);
 		TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids,
 							  smton ? "EVENT1" : "EVENT2",
-							  (void **)&val_ptr));
+							  &val_ptr));
 
 		expr__ctx_clear(ctx);
 		TEST_ASSERT_VAL("find ids",
···
 		TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 1);
 		TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids,
 							  corewide ? "EVENT1" : "EVENT2",
-							  (void **)&val_ptr));
+							  &val_ptr));
 
 	}
 	/* The expression is a constant 1.0 without needing to evaluate EVENT1. */
···
 			expr__find_ids("source_count(EVENT1)",
 			NULL, ctx) == 0);
 	TEST_ASSERT_VAL("source count", hashmap__size(ctx->ids) == 1);
-	TEST_ASSERT_VAL("source count", hashmap__find(ctx->ids, "EVENT1",
-							(void **)&val_ptr));
+	TEST_ASSERT_VAL("source count", hashmap__find(ctx->ids, "EVENT1", &val_ptr));
 
 	expr__ctx_free(ctx);
 

tools/perf/tests/pmu-events.c

···
 	 */
 	i = 1;
 	hashmap__for_each_entry(ctx->ids, cur, bkt)
-		expr__add_id_val(ctx, strdup(cur->key), i++);
+		expr__add_id_val(ctx, strdup(cur->pkey), i++);
 
 	hashmap__for_each_entry(ctx->ids, cur, bkt) {
-		if (check_parse_fake(cur->key)) {
+		if (check_parse_fake(cur->pkey)) {
 			pr_err("check_parse_fake failed\n");
 			goto out;
 		}
···
 		 */
 		i = 1024;
 		hashmap__for_each_entry(ctx->ids, cur, bkt)
-			expr__add_id_val(ctx, strdup(cur->key), i--);
+			expr__add_id_val(ctx, strdup(cur->pkey), i--);
 		if (expr__parse(&result, ctx, str)) {
 			pr_err("expr__parse failed\n");
 			ret = -1;

tools/perf/util/bpf-loader.c

···
 		return;
 
 	hashmap__for_each_entry(bpf_program_hash, cur, bkt)
-		clear_prog_priv(cur->key, cur->value);
+		clear_prog_priv(cur->pkey, cur->pvalue);
 
 	hashmap__free(bpf_program_hash);
 	bpf_program_hash = NULL;
···
 	bpf_map_hash_free();
 }
 
-static size_t ptr_hash(const void *__key, void *ctx __maybe_unused)
+static size_t ptr_hash(const long __key, void *ctx __maybe_unused)
 {
-	return (size_t) __key;
+	return __key;
 }
 
-static bool ptr_equal(const void *key1, const void *key2,
-			  void *ctx __maybe_unused)
+static bool ptr_equal(long key1, long key2, void *ctx __maybe_unused)
 {
 	return key1 == key2;
 }
···
 		return;
 
 	hashmap__for_each_entry(bpf_map_hash, cur, bkt)
-		bpf_map_priv__clear(cur->key, cur->value);
+		bpf_map_priv__clear(cur->pkey, cur->pvalue);
 
 	hashmap__free(bpf_map_hash);
 	bpf_map_hash = NULL;

tools/perf/util/evsel.c

···
 
 	if (evsel->per_pkg_mask) {
 		hashmap__for_each_entry(evsel->per_pkg_mask, cur, bkt)
-			free((char *)cur->key);
+			free((void *)cur->pkey);
 
 		hashmap__clear(evsel->per_pkg_mask);
 	}

tools/perf/util/expr.c

···
 	} kind;
 };
 
-static size_t key_hash(const void *key, void *ctx __maybe_unused)
+static size_t key_hash(long key, void *ctx __maybe_unused)
 {
 	const char *str = (const char *)key;
 	size_t hash = 0;
···
 	return hash;
 }
 
-static bool key_equal(const void *key1, const void *key2,
-		    void *ctx __maybe_unused)
+static bool key_equal(long key1, long key2, void *ctx __maybe_unused)
 {
 	return !strcmp((const char *)key1, (const char *)key2);
 }
···
 		return;
 
 	hashmap__for_each_entry(ids, cur, bkt) {
-		free((char *)cur->key);
-		free(cur->value);
+		free((void *)cur->pkey);
+		free((void *)cur->pvalue);
 	}
 
 	hashmap__free(ids);
···
 	char *old_key = NULL;
 	int ret;
 
-	ret = hashmap__set(ids, id, data_ptr,
-			   (const void **)&old_key, (void **)&old_data);
+	ret = hashmap__set(ids, id, data_ptr, &old_key, &old_data);
 	if (ret)
 		free(data_ptr);
 	free(old_key);
···
 		ids2 = tmp;
 	}
 	hashmap__for_each_entry(ids2, cur, bkt) {
-		ret = hashmap__set(ids1, cur->key, cur->value,
-				(const void **)&old_key, (void **)&old_data);
+		ret = hashmap__set(ids1, cur->key, cur->value, &old_key, &old_data);
 		free(old_key);
 		free(old_data);
 
···
 	data_ptr->val.source_count = source_count;
 	data_ptr->kind = EXPR_ID_DATA__VALUE;
 
-	ret = hashmap__set(ctx->ids, id, data_ptr,
-			   (const void **)&old_key, (void **)&old_data);
+	ret = hashmap__set(ctx->ids, id, data_ptr, &old_key, &old_data);
 	if (ret)
 		free(data_ptr);
 	free(old_key);
···
 	data_ptr->ref.metric_expr = ref->metric_expr;
 	data_ptr->kind = EXPR_ID_DATA__REF;
 
-	ret = hashmap__set(ctx->ids, name, data_ptr,
-			   (const void **)&old_key, (void **)&old_data);
+	ret = hashmap__set(ctx->ids, name, data_ptr, &old_key, &old_data);
 	if (ret)
 		free(data_ptr);
 
···
 int expr__get_id(struct expr_parse_ctx *ctx, const char *id,
 		 struct expr_id_data **data)
 {
-	return hashmap__find(ctx->ids, id, (void **)data) ? 0 : -1;
+	return hashmap__find(ctx->ids, id, data) ? 0 : -1;
 }
 
 bool expr__subset_of_ids(struct expr_parse_ctx *haystack,
···
 	struct expr_id_data *data;
 
 	hashmap__for_each_entry(needles->ids, cur, bkt) {
-		if (expr__get_id(haystack, cur->key, &data))
+		if (expr__get_id(haystack, cur->pkey, &data))
 			return false;
 	}
 	return true;
···
 	struct expr_id_data *old_val = NULL;
 	char *old_key = NULL;
 
-	hashmap__delete(ctx->ids, id,
-			(const void **)&old_key, (void **)&old_val);
+	hashmap__delete(ctx->ids, id, &old_key, &old_val);
 	free(old_key);
 	free(old_val);
 }
···
 	size_t bkt;
 
 	hashmap__for_each_entry(ctx->ids, cur, bkt) {
-		free((char *)cur->key);
-		free(cur->value);
+		free((void *)cur->pkey);
+		free(cur->pvalue);
 	}
 	hashmap__clear(ctx->ids);
 }
···
 
 	free(ctx->sctx.user_requested_cpu_list);
 	hashmap__for_each_entry(ctx->ids, cur, bkt) {
-		free((char *)cur->key);
-		free(cur->value);
+		free((void *)cur->pkey);
+		free(cur->pvalue);
 	}
 	hashmap__free(ctx->ids);
 	free(ctx);

tools/perf/util/hashmap.c

···
 }
 
 static bool hashmap_find_entry(const struct hashmap *map,
-			       const void *key, size_t hash,
+			       const long key, size_t hash,
 			       struct hashmap_entry ***pprev,
 			       struct hashmap_entry **entry)
 {
···
 	return false;
 }
 
-int hashmap__insert(struct hashmap *map, const void *key, void *value,
-		    enum hashmap_insert_strategy strategy,
-		    const void **old_key, void **old_value)
+int hashmap_insert(struct hashmap *map, long key, long value,
+		   enum hashmap_insert_strategy strategy,
+		   long *old_key, long *old_value)
 {
 	struct hashmap_entry *entry;
 	size_t h;
 	int err;
 
 	if (old_key)
-		*old_key = NULL;
+		*old_key = 0;
 	if (old_value)
-		*old_value = NULL;
+		*old_value = 0;
 
 	h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
 	if (strategy != HASHMAP_APPEND &&
···
 	return 0;
 }
 
-bool hashmap__find(const struct hashmap *map, const void *key, void **value)
+bool hashmap_find(const struct hashmap *map, long key, long *value)
 {
 	struct hashmap_entry *entry;
 	size_t h;
···
 	return true;
 }
 
-bool hashmap__delete(struct hashmap *map, const void *key,
-		     const void **old_key, void **old_value)
+bool hashmap_delete(struct hashmap *map, long key,
+		    long *old_key, long *old_value)
 {
 	struct hashmap_entry **pprev, *entry;
 	size_t h;

tools/perf/util/hashmap.h

···
 	return h;
 }
 
-typedef size_t (*hashmap_hash_fn)(const void *key, void *ctx);
-typedef bool (*hashmap_equal_fn)(const void *key1, const void *key2, void *ctx);
+typedef size_t (*hashmap_hash_fn)(long key, void *ctx);
+typedef bool (*hashmap_equal_fn)(long key1, long key2, void *ctx);
 
+/*
+ * Hashmap interface is polymorphic, keys and values could be either
+ * long-sized integers or pointers, this is achieved as follows:
+ * - interface functions that operate on keys and values are hidden
+ *   behind auxiliary macros, e.g. hashmap_insert <-> hashmap__insert;
+ * - these auxiliary macros cast the key and value parameters as
+ *   long or long *, so the user does not have to specify the casts explicitly;
+ * - for pointer parameters (e.g. old_key) the size of the pointed
+ *   type is verified by hashmap_cast_ptr using _Static_assert;
+ * - when iterating using hashmap__for_each_* forms
+ *   hasmap_entry->key should be used for integer keys and
+ *   hasmap_entry->pkey should be used for pointer keys,
+ *   same goes for values.
+ */
 struct hashmap_entry {
-	const void *key;
-	void *value;
+	union {
+		long key;
+		const void *pkey;
+	};
+	union {
+		long value;
+		void *pvalue;
+	};
 	struct hashmap_entry *next;
 };
 
···
 	HASHMAP_APPEND,
 };
 
+#define hashmap_cast_ptr(p) ({								\
+	_Static_assert((p) == NULL || sizeof(*(p)) == sizeof(long),			\
+		       #p " pointee should be a long-sized integer or a pointer");	\
+	(long *)(p);									\
+})
+
 /*
  * hashmap__insert() adds key/value entry w/ various semantics, depending on
  * provided strategy value. If a given key/value pair replaced already
···
  * through old_key and old_value to allow calling code do proper memory
  * management.
  */
-int hashmap__insert(struct hashmap *map, const void *key, void *value,
-		    enum hashmap_insert_strategy strategy,
-		    const void **old_key, void **old_value);
+int hashmap_insert(struct hashmap *map, long key, long value,
+		   enum hashmap_insert_strategy strategy,
+		   long *old_key, long *old_value);
 
-static inline int hashmap__add(struct hashmap *map,
-			       const void *key, void *value)
-{
-	return hashmap__insert(map, key, value, HASHMAP_ADD, NULL, NULL);
-}
+#define hashmap__insert(map, key, value, strategy, old_key, old_value) \
+	hashmap_insert((map), (long)(key), (long)(value), (strategy),  \
+		       hashmap_cast_ptr(old_key),		       \
+		       hashmap_cast_ptr(old_value))
 
-static inline int hashmap__set(struct hashmap *map,
-			       const void *key, void *value,
-			       const void **old_key, void **old_value)
-{
-	return hashmap__insert(map, key, value, HASHMAP_SET,
-			       old_key, old_value);
-}
+#define hashmap__add(map, key, value) \
+	hashmap__insert((map), (key), (value), HASHMAP_ADD, NULL, NULL)
 
-static inline int hashmap__update(struct hashmap *map,
-				  const void *key, void *value,
-				  const void **old_key, void **old_value)
-{
-	return hashmap__insert(map, key, value, HASHMAP_UPDATE,
-			       old_key, old_value);
-}
+#define hashmap__set(map, key, value, old_key, old_value) \
+	hashmap__insert((map), (key), (value), HASHMAP_SET, (old_key), (old_value))
 
-static inline int hashmap__append(struct hashmap *map,
-				  const void *key, void *value)
-{
-	return hashmap__insert(map, key, value, HASHMAP_APPEND, NULL, NULL);
-}
+#define hashmap__update(map, key, value, old_key, old_value) \
+	hashmap__insert((map), (key), (value), HASHMAP_UPDATE, (old_key), (old_value))
 
-bool hashmap__delete(struct hashmap *map, const void *key,
-		     const void **old_key, void **old_value);
+#define hashmap__append(map, key, value) \
+	hashmap__insert((map), (key), (value), HASHMAP_APPEND, NULL, NULL)
 
-bool hashmap__find(const struct hashmap *map, const void *key, void **value);
+bool hashmap_delete(struct hashmap *map, long key, long *old_key, long *old_value);
+
+#define hashmap__delete(map, key, old_key, old_value)		       \
+	hashmap_delete((map), (long)(key),			       \
+		       hashmap_cast_ptr(old_key),		       \
+		       hashmap_cast_ptr(old_value))
+
+bool hashmap_find(const struct hashmap *map, long key, long *value);
+
+#define hashmap__find(map, key, value) \
+	hashmap_find((map), (long)(key), hashmap_cast_ptr(value))
 
 /*
  * hashmap__for_each_entry - iterate over all entries in hashmap

tools/perf/util/metricgroup.c

···
 		 * combined or shared groups, this metric may not care
 		 * about this event.
 		 */
-		if (hashmap__find(ids, metric_id, (void **)&val_ptr)) {
+		if (hashmap__find(ids, metric_id, &val_ptr)) {
 			metric_events[matched_events++] = ev;
 
 			if (matched_events >= ids_size)
···
 #define RETURN_IF_NON_ZERO(x) do { if (x) return x; } while (0)
 
 	hashmap__for_each_entry(ctx->ids, cur, bkt) {
-		const char *sep, *rsep, *id = cur->key;
+		const char *sep, *rsep, *id = cur->pkey;
 		enum perf_tool_event ev;
 
 		pr_debug("found event %s\n", id);
···
 	hashmap__for_each_entry(root_metric->pctx->ids, cur, bkt) {
 		struct pmu_event pe;
 
-		if (metricgroup__find_metric(cur->key, table, &pe)) {
+		if (metricgroup__find_metric(cur->pkey, table, &pe)) {
 			pending = realloc(pending,
 					(pending_cnt + 1) * sizeof(struct to_resolve));
 			if (!pending)
 				return -ENOMEM;
 
 			memcpy(&pending[pending_cnt].pe, &pe, sizeof(pe));
-			pending[pending_cnt].key = cur->key;
+			pending[pending_cnt].key = cur->pkey;
 			pending_cnt++;
 		}
 	}
···
 	list_for_each_entry(m, metric_list, nd) {
 		if (m->has_constraint && !m->modifier) {
 			hashmap__for_each_entry(m->pctx->ids, cur, bkt) {
-				dup = strdup(cur->key);
+				dup = strdup(cur->pkey);
 				if (!dup) {
 					ret = -ENOMEM;
 					goto err_out;

tools/perf/util/stat-shadow.c

···
 
 		i = 0;
 		hashmap__for_each_entry(ctx->ids, cur, bkt) {
-			const char *metric_name = (const char *)cur->key;
+			const char *metric_name = cur->pkey;
 
 			found = false;
 			if (leader) {

tools/perf/util/stat.c

···
 	}
 }
 
-static size_t pkg_id_hash(const void *__key, void *ctx __maybe_unused)
+static size_t pkg_id_hash(long __key, void *ctx __maybe_unused)
 {
 	uint64_t *key = (uint64_t *) __key;
 
 	return *key & 0xffffffff;
 }
 
-static bool pkg_id_equal(const void *__key1, const void *__key2,
-			 void *ctx __maybe_unused)
+static bool pkg_id_equal(long __key1, long __key2, void *ctx __maybe_unused)
 {
 	uint64_t *key1 = (uint64_t *) __key1;
 	uint64_t *key2 = (uint64_t *) __key2;
···
 		return -ENOMEM;
 
 	*key = (uint64_t)d << 32 | s;
-	if (hashmap__find(mask, (void *)key, NULL)) {
+	if (hashmap__find(mask, key, NULL)) {
 		*skip = true;
 		free(key);
 	} else
-		ret = hashmap__add(mask, (void *)key, (void *)1);
+		ret = hashmap__add(mask, key, 1);
 
 	return ret;
 }

tools/testing/selftests/bpf/prog_tests/hashmap.c

···
  */
 #include "test_progs.h"
 #include "bpf/hashmap.h"
+#include <stddef.h>
 
 static int duration = 0;
 
-static size_t hash_fn(const void *k, void *ctx)
+static size_t hash_fn(long k, void *ctx)
 {
-	return (long)k;
+	return k;
 }
 
-static bool equal_fn(const void *a, const void *b, void *ctx)
+static bool equal_fn(long a, long b, void *ctx)
 {
-	return (long)a == (long)b;
+	return a == b;
 }
 
 static inline size_t next_pow_2(size_t n)
···
 		return;
 
 	for (i = 0; i < ELEM_CNT; i++) {
-		const void *oldk, *k = (const void *)(long)i;
-		void *oldv, *v = (void *)(long)(1024 + i);
+		long oldk, k = i;
+		long oldv, v = 1024 + i;
 
 		err = hashmap__update(map, k, v, &oldk, &oldv);
 		if (CHECK(err != -ENOENT, "hashmap__update",
···
 			err = hashmap__add(map, k, v);
 		} else {
 			err = hashmap__set(map, k, v, &oldk, &oldv);
-			if (CHECK(oldk != NULL || oldv != NULL, "check_kv",
-				  "unexpected k/v: %p=%p\n", oldk, oldv))
+			if (CHECK(oldk != 0 || oldv != 0, "check_kv",
+				  "unexpected k/v: %ld=%ld\n", oldk, oldv))
 				goto cleanup;
 		}
 
-		if (CHECK(err, "elem_add", "failed to add k/v %ld = %ld: %d\n",
-			       (long)k, (long)v, err))
+		if (CHECK(err, "elem_add", "failed to add k/v %ld = %ld: %d\n", k, v, err))
 			goto cleanup;
 
 		if (CHECK(!hashmap__find(map, k, &oldv), "elem_find",
-			  "failed to find key %ld\n", (long)k))
+			  "failed to find key %ld\n", k))
 			goto cleanup;
-		if (CHECK(oldv != v, "elem_val",
-			  "found value is wrong: %ld\n", (long)oldv))
+		if (CHECK(oldv != v, "elem_val", "found value is wrong: %ld\n", oldv))
 			goto cleanup;
 	}
 
···
 
 	found_msk = 0;
 	hashmap__for_each_entry(map, entry, bkt) {
-		long k = (long)entry->key;
-		long v = (long)entry->value;
+		long k = entry->key;
+		long v = entry->value;
 
 		found_msk |= 1ULL << k;
 		if (CHECK(v - k != 1024, "check_kv",
···
 		goto cleanup;
 
 	for (i = 0; i < ELEM_CNT; i++) {
-		const void *oldk, *k = (const void *)(long)i;
-		void *oldv, *v = (void *)(long)(256 + i);
+		long oldk, k = i;
+		long oldv, v = 256 + i;
 
 		err = hashmap__add(map, k, v);
 		if (CHECK(err != -EEXIST, "hashmap__add",
···
 
 		if (CHECK(err, "elem_upd",
 			  "failed to update k/v %ld = %ld: %d\n",
-			  (long)k, (long)v, err))
+			  k, v, err))
 			goto cleanup;
 		if (CHECK(!hashmap__find(map, k, &oldv), "elem_find",
-			  "failed to find key %ld\n", (long)k))
+			  "failed to find key %ld\n", k))
 			goto cleanup;
 		if (CHECK(oldv != v, "elem_val",
-			  "found value is wrong: %ld\n", (long)oldv))
+			  "found value is wrong: %ld\n", oldv))
 			goto cleanup;
 	}
 
···
 
 	found_msk = 0;
 	hashmap__for_each_entry_safe(map, entry, tmp, bkt) {
-		long k = (long)entry->key;
-		long v = (long)entry->value;
+		long k = entry->key;
+		long v = entry->value;
 
 		found_msk |= 1ULL << k;
 		if (CHECK(v - k != 256, "elem_check",
···
 		goto cleanup;
 
 	found_cnt = 0;
-	hashmap__for_each_key_entry(map, entry, (void *)0) {
+	hashmap__for_each_key_entry(map, entry, 0) {
 		found_cnt++;
 	}
 	if (CHECK(!found_cnt, "found_cnt",
···
 
 	found_msk = 0;
 	found_cnt = 0;
-	hashmap__for_each_key_entry_safe(map, entry, tmp, (void *)0) {
-		const void *oldk, *k;
-		void *oldv, *v;
+	hashmap__for_each_key_entry_safe(map, entry, tmp, 0) {
+		long oldk, k;
+		long oldv, v;
 
 		k = entry->key;
 		v = entry->value;
 
 		found_cnt++;
-		found_msk |= 1ULL << (long)k;
+		found_msk |= 1ULL << k;
 
 		if (CHECK(!hashmap__delete(map, k, &oldk, &oldv), "elem_del",
-			  "failed to delete k/v %ld = %ld\n",
-			  (long)k, (long)v))
+			  "failed to delete k/v %ld = %ld\n", k, v))
 			goto cleanup;
 		if (CHECK(oldk != k || oldv != v, "check_old",
 			  "invalid deleted k/v: expected %ld = %ld, got %ld = %ld\n",
-			  (long)k, (long)v, (long)oldk, (long)oldv))
+			  k, v, oldk, oldv))
 			goto cleanup;
 		if (CHECK(hashmap__delete(map, k, &oldk, &oldv), "elem_del",
-			  "unexpectedly deleted k/v %ld = %ld\n",
-			  (long)oldk, (long)oldv))
+			  "unexpectedly deleted k/v %ld = %ld\n", oldk, oldv))
 			goto cleanup;
 	}
 
···
 		goto cleanup;
 
 	hashmap__for_each_entry_safe(map, entry, tmp, bkt) {
-		const void *oldk, *k;
-		void *oldv, *v;
+		long oldk, k;
+		long oldv, v;
 
 		k = entry->key;
 		v = entry->value;
 
 		found_cnt++;
-		found_msk |= 1ULL << (long)k;
+		found_msk |= 1ULL << k;
 
 		if (CHECK(!hashmap__delete(map, k, &oldk, &oldv), "elem_del",
-			  "failed to delete k/v %ld = %ld\n",
-			  (long)k, (long)v))
+			  "failed to delete k/v %ld = %ld\n", k, v))
 			goto cleanup;
 		if (CHECK(oldk != k || oldv != v, "elem_check",
 			  "invalid old k/v: expect %ld = %ld, got %ld = %ld\n",
-			  (long)k, (long)v, (long)oldk, (long)oldv))
+			  k, v, oldk, oldv))
 			goto cleanup;
 		if (CHECK(hashmap__delete(map, k, &oldk, &oldv), "elem_del",
-			  "unexpectedly deleted k/v %ld = %ld\n",
-			  (long)k, (long)v))
+			  "unexpectedly deleted k/v %ld = %ld\n", k, v))
 			goto cleanup;
 	}
 
···
 	hashmap__for_each_entry(map, entry, bkt) {
 		CHECK(false, "elem_exists",
 		      "unexpected map entries left: %ld = %ld\n",
-		      (long)entry->key, (long)entry->value);
+		      entry->key, entry->value);
 		goto cleanup;
 	}
 
···
 	hashmap__for_each_entry(map, entry, bkt) {
 		CHECK(false, "elem_exists",
 		      "unexpected map entries left: %ld = %ld\n",
-		      (long)entry->key, (long)entry->value);
+		      entry->key, entry->value);
 		goto cleanup;
 	}
 
···
 	hashmap__free(map);
 }
 
-static size_t collision_hash_fn(const void *k, void *ctx)
+static size_t str_hash_fn(long a, void *ctx)
+{
+	return str_hash((char *)a);
+}
+
+static bool str_equal_fn(long a, long b, void *ctx)
+{
+	return strcmp((char *)a, (char *)b) == 0;
+}
+
+/* Verify that hashmap interface works with pointer keys and values */
+static void test_hashmap_ptr_iface(void)
+{
+	const char *key, *value, *old_key, *old_value;
+	struct hashmap_entry *cur;
+	struct hashmap *map;
+	int err, i, bkt;
+
+	map = hashmap__new(str_hash_fn, str_equal_fn, NULL);
+	if (CHECK(!map, "hashmap__new", "can't allocate hashmap\n"))
+		goto cleanup;
+
+#define CHECK_STR(fn, var, expected)					\
+	CHECK(strcmp(var, (expected)), (fn),				\
+	      "wrong value of " #var ": '%s' instead of '%s'\n", var, (expected))
+
+	err = hashmap__insert(map, "a", "apricot", HASHMAP_ADD, NULL, NULL);
+	if (CHECK(err, "hashmap__insert", "unexpected error: %d\n", err))
+		goto cleanup;
+
+	err = hashmap__insert(map, "a", "apple", HASHMAP_SET, &old_key, &old_value);
+	if (CHECK(err, "hashmap__insert", "unexpected error: %d\n", err))
+		goto cleanup;
+	CHECK_STR("hashmap__update", old_key, "a");
+	CHECK_STR("hashmap__update", old_value, "apricot");
+
+	err = hashmap__add(map, "b", "banana");
+	if (CHECK(err, "hashmap__add", "unexpected error: %d\n", err))
+		goto cleanup;
+
+	err = hashmap__set(map, "b", "breadfruit", &old_key, &old_value);
+	if (CHECK(err, "hashmap__set", "unexpected error: %d\n", err))
+		goto cleanup;
+	CHECK_STR("hashmap__set", old_key, "b");
+	CHECK_STR("hashmap__set", old_value, "banana");
+
+	err = hashmap__update(map, "b", "blueberry", &old_key, &old_value);
+	if (CHECK(err, "hashmap__update", "unexpected error: %d\n", err))
+		goto cleanup;
+	CHECK_STR("hashmap__update", old_key, "b");
+	CHECK_STR("hashmap__update", old_value, "breadfruit");
+
+	err = hashmap__append(map, "c", "cherry");
+	if (CHECK(err, "hashmap__append", "unexpected error: %d\n", err))
+		goto cleanup;
+
+	if (CHECK(!hashmap__delete(map, "c", &old_key, &old_value),
+		  "hashmap__delete", "expected to have entry for 'c'\n"))
+		goto cleanup;
+	CHECK_STR("hashmap__delete", old_key, "c");
+	CHECK_STR("hashmap__delete", old_value, "cherry");
+
+	CHECK(!hashmap__find(map, "b", &value), "hashmap__find", "can't find value for 'b'\n");
+	CHECK_STR("hashmap__find", value, "blueberry");
+
+	if (CHECK(!hashmap__delete(map, "b", NULL, NULL),
+		  "hashmap__delete", "expected to have entry for 'b'\n"))
+		goto cleanup;
+
+	i = 0;
+	hashmap__for_each_entry(map, cur, bkt) {
+		if (CHECK(i != 0, "hashmap__for_each_entry", "too many entries"))
+			goto cleanup;
+		key = cur->pkey;
+		value = cur->pvalue;
+		CHECK_STR("entry", key, "a");
+		CHECK_STR("entry", value, "apple");
+		i++;
+	}
+#undef CHECK_STR
+
+cleanup:
+	hashmap__free(map);
+}
+
+static size_t collision_hash_fn(long k, void *ctx)
 {
 	return 0;
 }
 
 static void test_hashmap_multimap(void)
 {
-	void *k1 = (void *)0, *k2 = (void *)1;
+	long k1 = 0, k2 = 1;
 	struct hashmap_entry *entry;
 	struct hashmap *map;
 	long found_msk;
···
 	 * [0] -> 1, 2, 4;
 	 * [1] -> 8, 16, 32;
 	 */
-	err = hashmap__append(map, k1, (void *)1);
+	err = hashmap__append(map, k1, 1);
 	if (CHECK(err, "elem_add", "failed to add k/v: %d\n", err))
 		goto cleanup;
-	err = hashmap__append(map, k1, (void *)2);
+	err = hashmap__append(map, k1, 2);
 	if (CHECK(err, "elem_add", "failed to add k/v: %d\n", err))
 		goto cleanup;
-	err = hashmap__append(map, k1, (void *)4);
+	err = hashmap__append(map, k1, 4);
 	if (CHECK(err, "elem_add", "failed to add k/v: %d\n", err))
 		goto cleanup;
 
-	err = hashmap__append(map, k2, (void *)8);
+	err = hashmap__append(map, k2, 8);
 	if (CHECK(err, "elem_add", "failed to add k/v: %d\n", err))
 		goto cleanup;
-	err = hashmap__append(map, k2, (void *)16);
+	err = hashmap__append(map, k2, 16);
 	if (CHECK(err, "elem_add", "failed to add k/v: %d\n", err))
 		goto cleanup;
-	err = hashmap__append(map, k2, (void *)32);
+	err = hashmap__append(map, k2, 32);
 	if (CHECK(err, "elem_add", "failed to add k/v: %d\n", err))
 		goto cleanup;
 
···
 	/* verify global iteration still works and sees all values */
 	found_msk = 0;
 	hashmap__for_each_entry(map, entry, bkt) {
-		found_msk |= (long)entry->value;
+		found_msk |= entry->value;
 	}
 	if (CHECK(found_msk != (1 << 6) - 1, "found_msk",
 		  "not all keys iterated: %lx\n", found_msk))
···
 	/* iterate values for key 1 */
 	found_msk = 0;
 	hashmap__for_each_key_entry(map, entry, k1) {
-		found_msk |= (long)entry->value;
+		found_msk |= entry->value;
 	}
 	if (CHECK(found_msk != (1 | 2 | 4), "found_msk",
 		  "invalid k1 values: %lx\n", found_msk))
···
 	/* iterate values for key 2 */
 	found_msk = 0;
 	hashmap__for_each_key_entry(map, entry, k2) {
-		found_msk |= (long)entry->value;
+		found_msk |= entry->value;
 	}
 	if (CHECK(found_msk != (8 | 16 | 32), "found_msk",
 		  "invalid k2 values: %lx\n", found_msk))
···
 	struct hashmap_entry *entry;
 	int bkt;
 	struct hashmap *map;
-	void *k = (void *)0;
+	long k = 0;
 
 	/* force collisions */
 	map = hashmap__new(hash_fn, equal_fn, NULL);
···
 		test_hashmap_multimap();
 	if (test__start_subtest("empty"))
 		test_hashmap_empty();
+	if (test__start_subtest("ptr_iface"))
+		test_hashmap_ptr_iface();
 }

tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c

···
 	return (__u64) t.tv_sec * 1000000000 + t.tv_nsec;
 }
 
-static size_t symbol_hash(const void *key, void *ctx __maybe_unused)
+static size_t symbol_hash(long key, void *ctx __maybe_unused)
 {
 	return str_hash((const char *) key);
 }
 
-static bool symbol_equal(const void *key1, const void *key2, void *ctx __maybe_unused)
+static bool symbol_equal(long key1, long key2, void *ctx __maybe_unused)
 {
 	return strcmp((const char *) key1, (const char *) key2) == 0;
 }
···
 			     sizeof("__ftrace_invalid_address__") - 1))
 			continue;
 
-		err = hashmap__add(map, name, NULL);
+		err = hashmap__add(map, name, 0);
 		if (err == -EEXIST)
 			continue;
 		if (err)