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/CAEf4BzZ8KFneEJxFAaNCCFPGqp20hSpS2aCj76uRk3-qZUH5xg@mail.gmail.com/
[2] https://lore.kernel.org/bpf/af1facf9-7bc8-8a3d-0db4-7b3f333589a2@meta.com/T/#m65b28f1d6d969fcd318b556db6a3ad499a42607dSigned-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221109142611.879983-2-eddyz87@gmail.com

tools/bpf/bpftool/btf.c

@@ -815,8 +815,7 @@ build_btf_type_table(struct hashmap *tab, enum bpf_obj_type type,
 		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));
@@ -875,17 +874,13 @@ show_btf_plain(struct bpf_btf_info *info, int fd,
 	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 ");
@@ -907,17 +902,15 @@ show_btf_json(struct bpf_btf_info *info, int fd,
 
 	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

@@ -494,7 +494,7 @@ static int do_build_table_cb(const char *fpath, const struct stat *sb,
 		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));
@@ -545,7 +545,7 @@ void delete_pinned_obj_table(struct hashmap *map)
 		return;
 
 	hashmap__for_each_entry(map, entry, bkt)
-		free(entry->value);
+		free(entry->pvalue);
 
 	hashmap__free(map);
 }
@@ -1041,12 +1041,12 @@ int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 *info_len)
 	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

@@ -1660,21 +1660,16 @@ struct btfgen_info {
 	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)
 {
 	if (!info)
@@ -2086,18 +2081,18 @@ static int btfgen_record_obj(struct btfgen_info *info, const char *obj_path)
 			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;
 			}
@@ -2120,7 +2115,7 @@ static int btfgen_record_obj(struct btfgen_info *info, const char *obj_path)
 
 	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

@@ -204,9 +204,8 @@ static int show_link_close_json(int fd, struct bpf_link_info *info)
 
 		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);
 	}
 
@@ -309,9 +308,8 @@ static int show_link_close_plain(int fd, struct bpf_link_info *info)
 	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

@@ -240,8 +240,8 @@ int do_filter_dump(struct tcmsg *ifinfo, struct nlattr **tb, const char *kind,
 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.
@@ -257,16 +257,6 @@ bool equal_fn_for_key_as_id(const void *k1, const void *k2, void *ctx);
  */
 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)
 {
 	return map ? hashmap__size(map) == 0 : true;

tools/bpf/bpftool/map.c

@@ -518,9 +518,8 @@ static int show_map_close_json(int fd, struct bpf_map_info *info)
 
 		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);
 	}
 
@@ -595,9 +594,8 @@ static int show_map_close_plain(int fd, struct bpf_map_info *info)
 	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

@@ -36,8 +36,8 @@ static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
 	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)
@@ -81,7 +81,7 @@ static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
 	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));
@@ -183,7 +183,7 @@ void delete_obj_refs_table(struct hashmap *map)
 		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);
@@ -200,8 +200,8 @@ void emit_obj_refs_json(struct hashmap *map, __u32 id,
 	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)
@@ -232,8 +232,8 @@ void emit_obj_refs_plain(struct hashmap *map, __u32 id, const char *prefix)
 	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

@@ -486,9 +486,8 @@ static void print_prog_json(struct bpf_prog_info *info, int fd)
 
 		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);
 	}
 
@@ -561,9 +560,8 @@ static void print_prog_plain(struct bpf_prog_info *info, int fd)
 	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

@@ -1559,15 +1559,15 @@ struct btf_pipe {
 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;
 	}
 
@@ -1579,7 +1579,7 @@ static int btf_rewrite_str(__u32 *str_off, void *ctx)
 	 * 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;
 	}
@@ -1630,8 +1630,8 @@ static int btf_rewrite_type_ids(__u32 *type_id, void *ctx)
 	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)
 {
@@ -3126,12 +3126,11 @@ static long hash_combine(long h, long value)
 }
 
 #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,
@@ -3178,17 +3177,17 @@ static void btf_dedup_free(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;
 }
@@ -3750,7 +3749,7 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
 	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;
@@ -3763,7 +3762,7 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_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;
@@ -3785,7 +3784,7 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_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;
@@ -4288,7 +4287,7 @@ static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_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;
 
 		/*
@@ -4393,7 +4392,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
 
 		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;
@@ -4410,7 +4409,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_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;
@@ -4434,7 +4433,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_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;
@@ -4466,7 +4465,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_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

@@ -117,14 +117,14 @@ struct btf_dump {
 	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)
@@ -225,7 +225,7 @@ static void btf_dump_free_names(struct hashmap *map)
 	struct hashmap_entry *cur;
 
 	hashmap__for_each_entry(map, cur, bkt)
-		free((void *)cur->key);
+		free((void *)cur->pkey);
 
 	hashmap__free(map);
 }
@@ -1543,11 +1543,10 @@ static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_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

@@ -128,7 +128,7 @@ static int hashmap_grow(struct hashmap *map)
 }
 
 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)
 {
@@ -151,18 +151,18 @@ static bool hashmap_find_entry(const struct hashmap *map,
 	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 &&
@@ -203,7 +203,7 @@ int hashmap__insert(struct hashmap *map, const void *key, void *value,
 	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;
@@ -217,8 +217,8 @@ bool hashmap__find(const struct hashmap *map, const void *key, void **value)
 	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

@@ -40,12 +40,32 @@ static inline size_t str_hash(const char *s)
 	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;
 };
 
@@ -102,6 +122,12 @@ enum hashmap_insert_strategy {
 	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
@@ -109,42 +135,38 @@ enum hashmap_insert_strategy {
  * 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))
+
+#define hashmap__append(map, key, value) \
+	hashmap__insert((map), (key), (value), HASHMAP_APPEND, NULL, NULL)
+
+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__delete(struct hashmap *map, const void *key,
-		     const void **old_key, void **old_value);
+bool hashmap_find(const struct hashmap *map, long key, long *value);
 
-bool hashmap__find(const struct hashmap *map, const void *key, void **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

@@ -5601,21 +5601,16 @@ int bpf_core_types_match(const struct btf *local_btf, __u32 local_id,
 	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,
 			    const struct bpf_core_relo *core_relo, int insn_idx)
 {
@@ -5658,7 +5653,6 @@ static int bpf_core_resolve_relo(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;
@@ -5675,7 +5669,7 @@ static int bpf_core_resolve_relo(struct bpf_program *prog,
 		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",
@@ -5683,7 +5677,7 @@ static int bpf_core_resolve_relo(struct bpf_program *prog,
 				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;
@@ -5806,7 +5800,7 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
 
 	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

@@ -19,19 +19,19 @@ struct strset {
 	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;
 }
@@ -67,7 +67,7 @@ struct strset *strset__new(size_t max_data_sz, const char *init_data, size_t ini
 			/* 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)
@@ -127,7 +127,7 @@ int strset__find_str(struct strset *set, const char *s)
 	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;
@@ -165,8 +165,8 @@ int strset__add_str(struct strset *set, const char *s)
 	 * 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

@@ -873,31 +873,27 @@ static void bpf_link_usdt_dealloc(struct bpf_link *link)
 	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;
 	}
@@ -905,17 +901,17 @@ static int allocate_spec_id(struct usdt_manager *man, struct hashmap *specs_hash
 	/* 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;
 
@@ -928,7 +924,7 @@ static int allocate_spec_id(struct usdt_manager *man, struct hashmap *specs_hash
 		*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

@@ -130,12 +130,9 @@ static int test__expr(struct test_suite *t __maybe_unused, int subtest __maybe_u
 			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;
@@ -143,20 +140,16 @@ static int test__expr(struct test_suite *t __maybe_unused, int subtest __maybe_u
 			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. */
 	{
@@ -174,7 +167,7 @@ static int test__expr(struct test_suite *t __maybe_unused, int subtest __maybe_u
 		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",
@@ -183,7 +176,7 @@ static int test__expr(struct test_suite *t __maybe_unused, int subtest __maybe_u
 		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. */
@@ -220,8 +213,7 @@ static int test__expr(struct test_suite *t __maybe_unused, int subtest __maybe_u
 			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

@@ -986,10 +986,10 @@ static int metric_parse_fake(const char *str)
 	 */
 	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;
 		}
@@ -1003,7 +1003,7 @@ static int metric_parse_fake(const char *str)
 		 */
 		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

@@ -318,7 +318,7 @@ static void bpf_program_hash_free(void)
 		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;
@@ -339,13 +339,12 @@ void bpf__clear(void)
 	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;
 }
@@ -1185,7 +1184,7 @@ static void bpf_map_hash_free(void)
 		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

@@ -3123,7 +3123,7 @@ void evsel__zero_per_pkg(struct evsel *evsel)
 
 	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

@@ -46,7 +46,7 @@ struct expr_id_data {
 	} 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;
@@ -59,8 +59,7 @@ static size_t key_hash(const void *key, void *ctx __maybe_unused)
 	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);
 }
@@ -84,8 +83,8 @@ void ids__free(struct hashmap *ids)
 		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);
@@ -97,8 +96,7 @@ int ids__insert(struct hashmap *ids, const char *id)
 	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);
@@ -127,8 +125,7 @@ struct hashmap *ids__union(struct hashmap *ids1, struct hashmap *ids2)
 		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);
 
@@ -169,8 +166,7 @@ int expr__add_id_val_source_count(struct expr_parse_ctx *ctx, const char *id,
 	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);
@@ -205,8 +201,7 @@ int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref)
 	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);
 
@@ -221,7 +216,7 @@ int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref)
 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,
@@ -232,7 +227,7 @@ 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;
@@ -282,8 +277,7 @@ void expr__del_id(struct expr_parse_ctx *ctx, const char *id)
 	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);
 }
@@ -314,8 +308,8 @@ void expr__ctx_clear(struct expr_parse_ctx *ctx)
 	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);
 }
@@ -330,8 +324,8 @@ void expr__ctx_free(struct expr_parse_ctx *ctx)
 
 	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

@@ -128,7 +128,7 @@ static int hashmap_grow(struct hashmap *map)
 }
 
 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)
 {
@@ -151,18 +151,18 @@ static bool hashmap_find_entry(const struct hashmap *map,
 	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 &&
@@ -203,7 +203,7 @@ int hashmap__insert(struct hashmap *map, const void *key, void *value,
 	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;
@@ -217,8 +217,8 @@ bool hashmap__find(const struct hashmap *map, const void *key, void **value)
 	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

@@ -40,12 +40,32 @@ static inline size_t str_hash(const char *s)
 	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;
 };
 
@@ -102,6 +122,12 @@ enum hashmap_insert_strategy {
 	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
@@ -109,42 +135,38 @@ enum hashmap_insert_strategy {
  * 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))
+
+#define hashmap__append(map, key, value) \
+	hashmap__insert((map), (key), (value), HASHMAP_APPEND, NULL, NULL)
+
+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__delete(struct hashmap *map, const void *key,
-		     const void **old_key, void **old_value);
+bool hashmap_find(const struct hashmap *map, long key, long *value);
 
-bool hashmap__find(const struct hashmap *map, const void *key, void **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

@@ -288,7 +288,7 @@ static int setup_metric_events(struct hashmap *ids,
 		 * 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)
@@ -764,7 +764,7 @@ static int metricgroup__build_event_string(struct strbuf *events,
 #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);
@@ -945,14 +945,14 @@ static int resolve_metric(struct list_head *metric_list,
 	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++;
 		}
 	}
@@ -1433,7 +1433,7 @@ static int build_combined_expr_ctx(const struct list_head *metric_list,
 	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

@@ -398,7 +398,7 @@ void perf_stat__collect_metric_expr(struct evlist *evsel_list)
 
 		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

@@ -278,15 +278,14 @@ void evlist__save_aggr_prev_raw_counts(struct evlist *evlist)
 	}
 }
 
-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;
@@ -347,11 +346,11 @@ static int check_per_pkg(struct evsel *counter, struct perf_counts_values *vals,
 		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/kprobe_multi_test.c

@@ -312,12 +312,12 @@ static inline __u64 get_time_ns(void)
 	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;
 }
@@ -372,7 +372,7 @@ static int get_syms(char ***symsp, size_t *cntp)
 			     sizeof("__ftrace_invalid_address__") - 1))
 			continue;
 
-		err = hashmap__add(map, name, NULL);
+		err = hashmap__add(map, name, 0);
 		if (err == -EEXIST)
 			continue;
 		if (err)