[PATCH 5/8] tools lib/api: Copy libbpf hashmap to libapi

Ian Rogers
2020-05-15T06:56:47Z

Allow use of hashmap in more than just libbpf, where it isn't an
exported symbol. Place in libapi as that is a required part of
tools/perf whereas libbpf is currently optional.
Modify perf's check-headers.sh script to check that the files are kept
in sync, in the same way kernel headers are checked. This will warn if
they are out of sync at the start of a perf build.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/lib/api/Build | 1 +
tools/lib/api/hashmap.c | 238 ++++++++++++++++++++++++++++++++++++
tools/lib/api/hashmap.h | 177 +++++++++++++++++++++++++++
tools/perf/check-headers.sh | 4 +
4 files changed, 420 insertions(+)
create mode 100644 tools/lib/api/hashmap.c
create mode 100644 tools/lib/api/hashmap.h

diff --git a/tools/lib/api/Build b/tools/lib/api/Build
index 6e2373db5598..2c8787a88080 100644
--- a/tools/lib/api/Build
+++ b/tools/lib/api/Build
@@ -2,6 +2,7 @@ libapi-y += fd/
libapi-y += fs/
libapi-y += cpu.o
libapi-y += debug.o
+libapi-y += hashmap.o
libapi-y += str_error_r.o

$(OUTPUT)str_error_r.o: ../str_error_r.c FORCE
diff --git a/tools/lib/api/hashmap.c b/tools/lib/api/hashmap.c
new file mode 100644
index 000000000000..a405dad068f5
--- /dev/null
+++ b/tools/lib/api/hashmap.c
@@ -0,0 +1,238 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * Generic non-thread safe hash map implementation.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <linux/err.h>
+#include "hashmap.h"
+
+/* make sure libbpf doesn't use kernel-only integer typedefs */
+#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
+
+/* start with 4 buckets */
+#define HASHMAP_MIN_CAP_BITS 2
+
+static void hashmap_add_entry(struct hashmap_entry **pprev,
+ struct hashmap_entry *entry)
+{
+ entry->next = *pprev;
+ *pprev = entry;
+}
+
+static void hashmap_del_entry(struct hashmap_entry **pprev,
+ struct hashmap_entry *entry)
+{
+ *pprev = entry->next;
+ entry->next = NULL;
+}
+
+void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
+ hashmap_equal_fn equal_fn, void *ctx)
+{
+ map->hash_fn = hash_fn;
+ map->equal_fn = equal_fn;
+ map->ctx = ctx;
+
+ map->buckets = NULL;
+ map->cap = 0;
+ map->cap_bits = 0;
+ map->sz = 0;
+}
+
+struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
+ hashmap_equal_fn equal_fn,
+ void *ctx)
+{
+ struct hashmap *map = malloc(sizeof(struct hashmap));
+
+ if (!map)
+ return ERR_PTR(-ENOMEM);
+ hashmap__init(map, hash_fn, equal_fn, ctx);
+ return map;
+}
+
+void hashmap__clear(struct hashmap *map)
+{
+ struct hashmap_entry *cur, *tmp;
+ size_t bkt;
+
+ hashmap__for_each_entry_safe(map, cur, tmp, bkt) {
+ free(cur);
+ }
+ free(map->buckets);
+ map->buckets = NULL;
+ map->cap = map->cap_bits = map->sz = 0;
+}
+
+void hashmap__free(struct hashmap *map)
+{
+ if (!map)
+ return;
+
+ hashmap__clear(map);
+ free(map);
+}
+
+size_t hashmap__size(const struct hashmap *map)
+{
+ return map->sz;
+}
+
+size_t hashmap__capacity(const struct hashmap *map)
+{
+ return map->cap;
+}
+
+static bool hashmap_needs_to_grow(struct hashmap *map)
+{
+ /* grow if empty or more than 75% filled */
+ return (map->cap == 0) || ((map->sz + 1) * 4 / 3 > map->cap);
+}
+
+static int hashmap_grow(struct hashmap *map)
+{
+ struct hashmap_entry **new_buckets;
+ struct hashmap_entry *cur, *tmp;
+ size_t new_cap_bits, new_cap;
+ size_t h, bkt;
+
+ new_cap_bits = map->cap_bits + 1;
+ if (new_cap_bits < HASHMAP_MIN_CAP_BITS)
+ new_cap_bits = HASHMAP_MIN_CAP_BITS;
+
+ new_cap = 1UL << new_cap_bits;
+ new_buckets = calloc(new_cap, sizeof(new_buckets[0]));
+ if (!new_buckets)
+ return -ENOMEM;
+
+ hashmap__for_each_entry_safe(map, cur, tmp, bkt) {
+ h = hash_bits(map->hash_fn(cur->key, map->ctx), new_cap_bits);
+ hashmap_add_entry(&new_buckets[h], cur);
+ }
+
+ map->cap = new_cap;
+ map->cap_bits = new_cap_bits;
+ free(map->buckets);
+ map->buckets = new_buckets;
+
+ return 0;
+}
+
+static bool hashmap_find_entry(const struct hashmap *map,
+ const void *key, size_t hash,
+ struct hashmap_entry ***pprev,
+ struct hashmap_entry **entry)
+{
+ struct hashmap_entry *cur, **prev_ptr;
+
+ if (!map->buckets)
+ return false;
+
+ for (prev_ptr = &map->buckets[hash], cur = *prev_ptr;
+ cur;
+ prev_ptr = &cur->next, cur = cur->next) {
+ if (map->equal_fn(cur->key, key, map->ctx)) {
+ if (pprev)
+ *pprev = prev_ptr;
+ *entry = cur;
+ return true;
+ }
+ }
+
+ 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)
+{
+ struct hashmap_entry *entry;
+ size_t h;
+ int err;
+
+ if (old_key)
+ *old_key = NULL;
+ if (old_value)
+ *old_value = NULL;
+
+ h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+ if (strategy != HASHMAP_APPEND &&
+ hashmap_find_entry(map, key, h, NULL, &entry)) {
+ if (old_key)
+ *old_key = entry->key;
+ if (old_value)
+ *old_value = entry->value;
+
+ if (strategy == HASHMAP_SET || strategy == HASHMAP_UPDATE) {
+ entry->key = key;
+ entry->value = value;
+ return 0;
+ } else if (strategy == HASHMAP_ADD) {
+ return -EEXIST;
+ }
+ }
+
+ if (strategy == HASHMAP_UPDATE)
+ return -ENOENT;
+
+ if (hashmap_needs_to_grow(map)) {
+ err = hashmap_grow(map);
+ if (err)
+ return err;
+ h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+ }
+
+ entry = malloc(sizeof(struct hashmap_entry));
+ if (!entry)
+ return -ENOMEM;
+
+ entry->key = key;
+ entry->value = value;
+ hashmap_add_entry(&map->buckets[h], entry);
+ map->sz++;
+
+ return 0;
+}
+
+bool hashmap__find(const struct hashmap *map, const void *key, void **value)
+{
+ struct hashmap_entry *entry;
+ size_t h;
+
+ h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+ if (!hashmap_find_entry(map, key, h, NULL, &entry))
+ return false;
+
+ if (value)
+ *value = entry->value;
+ return true;
+}
+
+bool hashmap__delete(struct hashmap *map, const void *key,
+ const void **old_key, void **old_value)
+{
+ struct hashmap_entry **pprev, *entry;
+ size_t h;
+
+ h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+ if (!hashmap_find_entry(map, key, h, &pprev, &entry))
+ return false;
+
+ if (old_key)
+ *old_key = entry->key;
+ if (old_value)
+ *old_value = entry->value;
+
+ hashmap_del_entry(pprev, entry);
+ free(entry);
+ map->sz--;
+
+ return true;
+}
+
diff --git a/tools/lib/api/hashmap.h b/tools/lib/api/hashmap.h
new file mode 100644
index 000000000000..e823b35e7371
--- /dev/null
+++ b/tools/lib/api/hashmap.h
@@ -0,0 +1,177 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Generic non-thread safe hash map implementation.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+#ifndef __LIBBPF_HASHMAP_H
+#define __LIBBPF_HASHMAP_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#ifdef __GLIBC__
+#include <bits/wordsize.h>
+#else
+#include <bits/reg.h>
+#endif
+
+static inline size_t hash_bits(size_t h, int bits)
+{
+ /* shuffle bits and return requested number of upper bits */
+ return (h * 11400714819323198485llu) >> (__WORDSIZE - bits);
+}
+
+typedef size_t (*hashmap_hash_fn)(const void *key, void *ctx);
+typedef bool (*hashmap_equal_fn)(const void *key1, const void *key2, void *ctx);
+
+struct hashmap_entry {
+ const void *key;
+ void *value;
+ struct hashmap_entry *next;
+};
+
+struct hashmap {
+ hashmap_hash_fn hash_fn;
+ hashmap_equal_fn equal_fn;
+ void *ctx;
+
+ struct hashmap_entry **buckets;
+ size_t cap;
+ size_t cap_bits;
+ size_t sz;
+};
+
+#define HASHMAP_INIT(hash_fn, equal_fn, ctx) { \
+ .hash_fn = (hash_fn), \
+ .equal_fn = (equal_fn), \
+ .ctx = (ctx), \
+ .buckets = NULL, \
+ .cap = 0, \
+ .cap_bits = 0, \
+ .sz = 0, \
+}
+
+void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
+ hashmap_equal_fn equal_fn, void *ctx);
+struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
+ hashmap_equal_fn equal_fn,
+ void *ctx);
+void hashmap__clear(struct hashmap *map);
+void hashmap__free(struct hashmap *map);
+
+size_t hashmap__size(const struct hashmap *map);
+size_t hashmap__capacity(const struct hashmap *map);
+
+/*
+ * Hashmap insertion strategy:
+ * - HASHMAP_ADD - only add key/value if key doesn't exist yet;
+ * - HASHMAP_SET - add key/value pair if key doesn't exist yet; otherwise,
+ * update value;
+ * - HASHMAP_UPDATE - update value, if key already exists; otherwise, do
+ * nothing and return -ENOENT;
+ * - HASHMAP_APPEND - always add key/value pair, even if key already exists.
+ * This turns hashmap into a multimap by allowing multiple values to be
+ * associated with the same key. Most useful read API for such hashmap is
+ * hashmap__for_each_key_entry() iteration. If hashmap__find() is still
+ * used, it will return last inserted key/value entry (first in a bucket
+ * chain).
+ */
+enum hashmap_insert_strategy {
+ HASHMAP_ADD,
+ HASHMAP_SET,
+ HASHMAP_UPDATE,
+ HASHMAP_APPEND,
+};
+
+/*
+ * hashmap__insert() adds key/value entry w/ various semantics, depending on
+ * provided strategy value. If a given key/value pair replaced already
+ * existing key/value pair, both old key and old value will be returned
+ * 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);
+
+static inline int hashmap__add(struct hashmap *map,
+ const void *key, void *value)
+{
+ return hashmap__insert(map, key, value, HASHMAP_ADD, NULL, NULL);
+}
+
+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);
+}
+
+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);
+}
+
+static inline int hashmap__append(struct hashmap *map,
+ const void *key, void *value)
+{
+ return hashmap__insert(map, key, value, HASHMAP_APPEND, NULL, NULL);
+}
+
+bool hashmap__delete(struct hashmap *map, const void *key,
+ const void **old_key, void **old_value);
+
+bool hashmap__find(const struct hashmap *map, const void *key, void **value);
+
+/*
+ * hashmap__for_each_entry - iterate over all entries in hashmap
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @bkt: integer used as a bucket loop cursor
+ */
+#define hashmap__for_each_entry(map, cur, bkt) \
+ for (bkt = 0; bkt < map->cap; bkt++) \
+ for (cur = map->buckets[bkt]; cur; cur = cur->next)
+
+/*
+ * hashmap__for_each_entry_safe - iterate over all entries in hashmap, safe
+ * against removals
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @tmp: struct hashmap_entry * used as a temporary next cursor storage
+ * @bkt: integer used as a bucket loop cursor
+ */
+#define hashmap__for_each_entry_safe(map, cur, tmp, bkt) \
+ for (bkt = 0; bkt < map->cap; bkt++) \
+ for (cur = map->buckets[bkt]; \
+ cur && ({tmp = cur->next; true; }); \
+ cur = tmp)
+
+/*
+ * hashmap__for_each_key_entry - iterate over entries associated with given key
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @key: key to iterate entries for
+ */
+#define hashmap__for_each_key_entry(map, cur, _key) \
+ for (cur = ({ size_t bkt = hash_bits(map->hash_fn((_key), map->ctx),\
+ map->cap_bits); \
+ map->buckets ? map->buckets[bkt] : NULL; }); \
+ cur; \
+ cur = cur->next) \
+ if (map->equal_fn(cur->key, (_key), map->ctx))
+
+#define hashmap__for_each_key_entry_safe(map, cur, tmp, _key) \
+ for (cur = ({ size_t bkt = hash_bits(map->hash_fn((_key), map->ctx),\
+ map->cap_bits); \
+ cur = map->buckets ? map->buckets[bkt] : NULL; }); \
+ cur && ({ tmp = cur->next; true; }); \
+ cur = tmp) \
+ if (map->equal_fn(cur->key, (_key), map->ctx))
+
+#endif /* __LIBBPF_HASHMAP_H */
diff --git a/tools/perf/check-headers.sh b/tools/perf/check-headers.sh
index cf147db4e5ca..87fcffa33a4d 100755
--- a/tools/perf/check-headers.sh
+++ b/tools/perf/check-headers.sh
@@ -128,4 +128,8 @@ check arch/x86/lib/insn.c '-I "^#include [\"<]\(../include/\)*asm/in
# diff non-symmetric files
check_2 tools/perf/arch/x86/entry/syscalls/syscall_64.tbl arch/x86/entry/syscalls/syscall_64.tbl

+# check duplicated library files
+check_2 tools/lib/api/hashmap.h tools/lib/bpf/hashmap.h
+check_2 tools/lib/api/hashmap.c tools/lib/bpf/hashmap.c
+
cd tools/perf
--
2.26.2.761.g0e0b3e54be-goog