From: Hou Tao <houtao1@xxxxxxxxxx>
The initial motivation for qp-trie map is to reduce memory usage for
string keys specially those with large differencies in length. Moreover
as a big-endian lexicographic-ordered map, qp-trie can also be used for
any binary data with fixed or variable length.
The memory efficiency of qp-tries comes partly from the design of qp-trie
which doesn't save key for branch node and uses sparse array to save leaf
nodes, partly comes from the support of bpf_dynptr-typed key: only the
used part in key is saved.
But the memory efficiency and ordered keys come with cost: for strings
(e.g. symbol names in /proc/kallsyms) the lookup performance of qp-trie
is about 30% or more slower compared with hash-table. But the lookup
performance is not always bad than hash-table, for randomly generated
binary data set with big differencies in length, the lookup performance
of qp-trie will be twice as good as hash-table as showed in the
following benchmark.
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
include/linux/bpf_types.h | 1 +
include/uapi/linux/bpf.h | 1 +
kernel/bpf/Makefile | 1 +
kernel/bpf/bpf_qp_trie.c | 1055 ++++++++++++++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 1 +
5 files changed, 1059 insertions(+)
create mode 100644 kernel/bpf/bpf_qp_trie.c
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index 2b9112b80171..a73d47f83d74 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -126,6 +126,7 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_STRUCT_OPS, bpf_struct_ops_map_ops)
#endif
BPF_MAP_TYPE(BPF_MAP_TYPE_RINGBUF, ringbuf_map_ops)
BPF_MAP_TYPE(BPF_MAP_TYPE_BLOOM_FILTER, bloom_filter_map_ops)
+BPF_MAP_TYPE(BPF_MAP_TYPE_QP_TRIE, qp_trie_map_ops)
BPF_LINK_TYPE(BPF_LINK_TYPE_RAW_TRACEPOINT, raw_tracepoint)
BPF_LINK_TYPE(BPF_LINK_TYPE_TRACING, tracing)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 77a2828f8148..e35e70b5cf0d 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -928,6 +928,7 @@ enum bpf_map_type {
BPF_MAP_TYPE_INODE_STORAGE,
BPF_MAP_TYPE_TASK_STORAGE,
BPF_MAP_TYPE_BLOOM_FILTER,
+ BPF_MAP_TYPE_QP_TRIE,
};
/* Note that tracing related programs such as
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index 341c94f208f4..8419f44fea50 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o bpf_i
obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o bloom_filter.o
obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o ringbuf.o
obj-$(CONFIG_BPF_SYSCALL) += bpf_local_storage.o bpf_task_storage.o
+obj-$(CONFIG_BPF_SYSCALL) += bpf_qp_trie.o
obj-${CONFIG_BPF_LSM} += bpf_inode_storage.o
obj-$(CONFIG_BPF_SYSCALL) += disasm.o
obj-$(CONFIG_BPF_JIT) += trampoline.o
diff --git a/kernel/bpf/bpf_qp_trie.c b/kernel/bpf/bpf_qp_trie.c
new file mode 100644
index 000000000000..4f56f69360ce
--- /dev/null
+++ b/kernel/bpf/bpf_qp_trie.c
@@ -0,0 +1,1055 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Derived from qp.c in https://github.com/fanf2/qp.git
+ *
+ * Copyright (C) 2022. Huawei Technologies Co., Ltd
+ */
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/spinlock.h>
+#include <linux/rcupdate.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
+
+/* qp-trie (quadbit popcount trie) is a memory efficient trie. Unlike
+ * normal trie which uses byte as lookup key, qp-trie interprets its keys
+ * as quadbit/nibble array and uses one nibble each time during lookup.
+ * The most significant nibble (upper nibble) of byte N in the key will
+ * be the 2*N element of nibble array, and the least significant nibble
+ * (lower nibble) of byte N will be the 2*N+1 element in nibble array.
+ *
+ * For normal trie, it may have 256 child nodes, and for qp-trie one branch
+ * node may have 17 child nodes. #0 child node is special because it must
+ * be a leaf node and its key is the same as the branch node. #1~#16 child
+ * nodes represent leaf nodes or branch nodes which have different keys
+ * with parent node. The key of branch node is the common prefix for these
+ * child nodes, and the index of child node minus one is the value of first
+ * different nibble between these child nodes.
+ *
+ * qp-trie reduces memory usage through two methods:
+ * (1) Branch node doesn't store the key. It only stores the position of
+ * the first nibble which differentiates child nodes.
+ * (2) Branch node doesn't store all 17 child nodes. It uses a bitmap and
+ * popcount() to implement a sparse array and only allocates memory
+ * for those present children.
+ *
+ * Like normal trie, qp-trie is also ordered and is in big-endian
+ * lexicographic order. If traverse qp-trie in a depth-first way, it will
+ * return a string of ordered keys.
+ *
+ * The following diagrams show the construction of a tiny qp-trie:
+ *
+ * (1) insert abc
+ *
+ * [ leaf node: abc ]
+ *
+ * (2) insert abc_d
+ *
+ * The first different nibble between "abc" and "abc_d" is the upper nibble
+ * of character '_' (0x5), and its position in nibble array is 6
+ * (starts from 0).
+ *
+ * [ branch node ] bitmap: 0x41 diff pos: 6
+ * |
+ * *
+ * children
+ * [0] [6]
+ * | |
+ * [leaf: abc] [leaf: abc_d]
+ *
+ * (3) insert abc_e
+ *
+ * The first different nibble between "abc_d" and "abc_e" is the lower
+ * nibble of character 'd'/'e', and its position in array is 9.
+ *
+ * [ branch node ] bitmap: 0x41 diff pos: 6
+ * |
+ * *
+ * children
+ * [0] [6]
+ * | |
+ * [leaf: abc] |
+ * *
+ * [ branch node ] bitmap: 0x60 diff pos: 9
+ * |
+ * *
+ * children
+ * [5] [6]
+ * | |
+ * [leaf: abc_d] [leaf: abc_e]
+ */
+
+#define QP_TRIE_MANDATORY_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_DYNPTR_KEY)
+#define QP_TRIE_CREATE_FLAG_MASK (QP_TRIE_MANDATORY_FLAG_MASK | BPF_F_NUMA_NODE | \
+ BPF_F_ACCESS_MASK)
+
+/* bit[0] of nodes in qp_trie_branch is used to tell node type:
+ *
+ * bit[0]: 0-branch node
+ * bit[0]: 1-leaf node
+ *
+ * Size of qp_trie_branch is already 2-bytes aligned, so only need to make
+ * allocation of leaf node to be 2-bytes aligned.
+ */
+#define QP_TRIE_LEAF_NODE_MASK 1UL
+#define QP_TRIE_LEAF_ALLOC_ALIGN 2
+
+/* To reduce memory usage, only qp_trie_branch is RCU-freed. To handle
+ * freeing of the last leaf node, an extra qp_trie_branch node is
+ * allocated. The branch node has only one child and its index is 0. It
+ * is set as root node after adding the first leaf node.
+ */
+#define QP_TRIE_ROOT_NODE_INDEX 0
+#define QP_TRIE_NON_ROOT_NODE_MASK 1
+
+#define QP_TRIE_NIBBLE_SHIFT 1
+#define QP_TRIE_BYTE_INDEX_SHIFT 2
+
+#define QP_TRIE_TWIGS_FREE_NONE_IDX 17
+
+struct qp_trie_branch {
+ /* The bottom two bits of index are used as special flags:
+ *
+ * bit[0]: 0-root, 1-not root
+ * bit[1]: 0-upper nibble, 1-lower nibble
+ *
+ * bit[2:31]: byte index for key
+ */
+ unsigned int index;
+ /* 17 bits are used to accommodate arbitrary keys, even when there are
+ * zero-bytes in these keys.
+ *
+ * bit[0]: a leaf node has the same key as the prefix of parent node
+ * bit[N]: a child node with the value of nibble at index as (N - 1)
+ */
+ unsigned int bitmap:17;
+ /* The index of leaf node will be RCU-freed together */
+ unsigned int to_free_idx:5;
+ struct qp_trie_branch __rcu *parent;
+ struct rcu_head rcu;
+ void __rcu *nodes[0];
+};
+
+#define QP_TRIE_NR_SUBTREE 256
+
+struct qp_trie {
+ struct bpf_map map;
+ atomic_t entries;
+ void __rcu *roots[QP_TRIE_NR_SUBTREE];
+ spinlock_t locks[QP_TRIE_NR_SUBTREE];
+};
+
+/* Internally use qp_trie_key instead of bpf_dynptr_kern
+ * to reduce memory usage
+ */
+struct qp_trie_key {
+ /* the length of blob data */
+ unsigned int len;
+ /* blob data */
+ unsigned char data[0];
+};
+
+struct qp_trie_diff {
+ unsigned int index;
+ unsigned int sibling_bm;
+ unsigned int new_bm;
+};
+
+static inline void *to_child_node(const struct qp_trie_key *key)
+{
+ return (void *)((long)key | QP_TRIE_LEAF_NODE_MASK);
+}
+
+static inline struct qp_trie_key *to_leaf_node(void *node)
+{
+ return (void *)((long)node & ~QP_TRIE_LEAF_NODE_MASK);
+}
+
+static inline bool is_branch_node(void *node)
+{
+ return !((long)node & QP_TRIE_LEAF_NODE_MASK);
+}
+
+static inline bool is_same_key(const struct qp_trie_key *k, const unsigned char *data,
+ unsigned int len)
+{
+ return k->len == len && !memcmp(k->data, data, len);
+}
+
+static inline void *qp_trie_leaf_value(const struct qp_trie_key *key)
+{
+ return (void *)key + sizeof(*key) + key->len;
+}
+
+static inline unsigned int calc_twig_index(unsigned int mask, unsigned int bitmap)
+{
+ return hweight32(mask & (bitmap - 1));
+}
+
+static inline unsigned int calc_twig_nr(unsigned int bitmap)
+{
+ return hweight32(bitmap);
+}
+
+static inline unsigned int nibble_to_bitmap(unsigned char nibble)
+{
+ return 1U << (nibble + 1);
+}
+
+static inline unsigned int index_to_byte_index(unsigned int index)
+{
+ return index >> QP_TRIE_BYTE_INDEX_SHIFT;
+}
+
+static inline unsigned int calc_br_bitmap(unsigned int index, const unsigned char *data,
+ unsigned int len)
+{
+ unsigned int byte;
+ unsigned char nibble;
+
+ if (index == QP_TRIE_ROOT_NODE_INDEX)
+ return 1;
+
+ byte = index_to_byte_index(index);
+ if (byte >= len)
+ return 1;
+
+ nibble = data[byte];
+ /* lower nibble */
+ if ((index >> QP_TRIE_NIBBLE_SHIFT) & 1)
+ nibble &= 0xf;
+ else
+ nibble >>= 4;
+ return nibble_to_bitmap(nibble);
+}
+
+static void qp_trie_free_twigs_rcu(struct rcu_head *rcu)
+{
+ struct qp_trie_branch *twigs = container_of(rcu, struct qp_trie_branch, rcu);
+ unsigned int idx = twigs->to_free_idx;
+
+ if (idx != QP_TRIE_TWIGS_FREE_NONE_IDX)
+ kfree(to_leaf_node(rcu_access_pointer(twigs->nodes[idx])));
+ kfree(twigs);
+}
+
+static void qp_trie_branch_free(struct qp_trie_branch *twigs, unsigned int to_free_idx)
+{
+ twigs->to_free_idx = to_free_idx;
+ call_rcu(&twigs->rcu, qp_trie_free_twigs_rcu);
+}
+
+static inline struct qp_trie_branch *
+qp_trie_branch_new(struct bpf_map *map, unsigned int nr)
+{
+ struct qp_trie_branch *a;
+
+ a = bpf_map_kmalloc_node(map, sizeof(*a) + nr * sizeof(*a->nodes),
+ GFP_NOWAIT | __GFP_NOWARN, map->numa_node);
+ return a;
+}
+
+static inline void qp_trie_assign_parent(struct qp_trie_branch *parent, void *node)
+{
+ if (is_branch_node(node))
+ rcu_assign_pointer(((struct qp_trie_branch *)node)->parent, parent);
+}
+
+static void qp_trie_update_parent(struct qp_trie_branch *parent, unsigned int nr)
+{
+ unsigned int i;
+
+ for (i = 0; i < nr; i++)
+ qp_trie_assign_parent(parent, rcu_dereference_protected(parent->nodes[i], 1));
+}
+
+/* new_node can be either a leaf node or a branch node */
+static struct qp_trie_branch *
+qp_trie_branch_replace(struct bpf_map *map, struct qp_trie_branch *old, unsigned int bitmap,
+ void *new_node)
+{
+ unsigned int nr = calc_twig_nr(old->bitmap);
+ unsigned int p = calc_twig_index(old->bitmap, bitmap);
+ struct qp_trie_branch *twigs;
+
+ twigs = qp_trie_branch_new(map, nr);
+ if (!twigs)
+ return NULL;
+
+ if (p)
+ memcpy(twigs->nodes, old->nodes, p * sizeof(*twigs->nodes));
+
+ rcu_assign_pointer(twigs->nodes[p], new_node);
+
+ if (nr - 1 > p)
+ memcpy(&twigs->nodes[p+1], &old->nodes[p+1], (nr - 1 - p) * sizeof(*twigs->nodes));
+
+ twigs->index = old->index;
+ twigs->bitmap = old->bitmap;
+ /* twigs will not be visible to reader until rcu_assign_pointer(), so
+ * use RCU_INIT_POINTER() here.
+ */
+ RCU_INIT_POINTER(twigs->parent, old->parent);
+
+ /* Initialize ->parent of parent node first, then update ->parent for
+ * child nodes after parent node is fully initialized.
+ */
+ qp_trie_update_parent(twigs, nr);
+
+ return twigs;
+}
+
+static struct qp_trie_branch *
+qp_trie_branch_insert(struct bpf_map *map, struct qp_trie_branch *old, unsigned int bitmap,
+ const struct qp_trie_key *new)
+{
+ unsigned int nr = calc_twig_nr(old->bitmap);
+ unsigned int p = calc_twig_index(old->bitmap, bitmap);
+ struct qp_trie_branch *twigs;
+
+ twigs = qp_trie_branch_new(map, nr + 1);
+ if (!twigs)
+ return NULL;
+
+ if (p)
+ memcpy(twigs->nodes, old->nodes, p * sizeof(*twigs->nodes));
+
+ rcu_assign_pointer(twigs->nodes[p], to_child_node(new));
+
+ if (nr > p)
+ memcpy(&twigs->nodes[p+1], &old->nodes[p], (nr - p) * sizeof(*twigs->nodes));
+
+ twigs->bitmap = old->bitmap | bitmap;
+ twigs->index = old->index;
+ RCU_INIT_POINTER(twigs->parent, old->parent);
+
+ qp_trie_update_parent(twigs, nr + 1);
+
+ return twigs;
+}
+
+static struct qp_trie_branch *
+qp_trie_branch_remove(struct bpf_map *map, struct qp_trie_branch *old, unsigned int bitmap)
+{
+ unsigned int nr = calc_twig_nr(old->bitmap);
+ unsigned int p = calc_twig_index(old->bitmap, bitmap);
+ struct qp_trie_branch *twigs;
+
+ twigs = qp_trie_branch_new(map, nr - 1);
+ if (!twigs)
+ return NULL;
+
+ if (p)
+ memcpy(twigs->nodes, old->nodes, p * sizeof(*twigs->nodes));
+ if (nr - 1 > p)
+ memcpy(&twigs->nodes[p], &old->nodes[p+1], (nr - 1 - p) * sizeof(*twigs->nodes));
+
+ twigs->bitmap = old->bitmap & ~bitmap;
+ twigs->index = old->index;
+ RCU_INIT_POINTER(twigs->parent, old->parent);
+
+ qp_trie_update_parent(twigs, nr - 1);
+
+ return twigs;
+}
+
+static struct qp_trie_key *
+qp_trie_init_leaf_node(struct bpf_map *map, const struct bpf_dynptr_kern *k, void *v)
+{
+ unsigned int key_size, total;
+ struct qp_trie_key *new;
+
+ key_size = bpf_dynptr_get_size(k);
+ if (!key_size || key_size > (u32)map->map_extra)
+ return ERR_PTR(-EINVAL);
+
+ total = round_up(sizeof(*new) + key_size + map->value_size, QP_TRIE_LEAF_ALLOC_ALIGN);
+ new = bpf_map_kmalloc_node(map, total, GFP_NOWAIT | __GFP_NOWARN, map->numa_node);
+ if (!new)
+ return ERR_PTR(-ENOMEM);
+
+ new->len = key_size;
+ memcpy(new->data, k->data + k->offset, key_size);
+ memcpy((void *)&new[1] + key_size, v, map->value_size);
+
+ return new;
+}
+
+static bool calc_prefix_len(const struct qp_trie_key *s_key, const struct qp_trie_key *n_key,
+ unsigned int *index)
+{
+ unsigned int i, len = min(s_key->len, n_key->len);
+ unsigned char diff = 0;
+
+ for (i = 0; i < len; i++) {
+ diff = s_key->data[i] ^ n_key->data[i];
+ if (diff)
+ break;
+ }
+
+ *index = (i << QP_TRIE_BYTE_INDEX_SHIFT) | QP_TRIE_NON_ROOT_NODE_MASK;
+ if (!diff)
+ return s_key->len == n_key->len;
+
+ *index += (diff & 0xf0) ? 0 : (1U << QP_TRIE_NIBBLE_SHIFT);
+ return false;
+}
+
+static int qp_trie_new_branch(struct qp_trie *trie, struct qp_trie_branch __rcu **parent,
+ unsigned int bitmap, void *sibling, struct qp_trie_diff *d,
+ const struct qp_trie_key *leaf)
+{
+ struct qp_trie_branch *new_child_twigs, *new_twigs, *old_twigs;
+ struct bpf_map *map;
+ unsigned int iip;
+ int err;
+
+ map = &trie->map;
+ if (atomic_inc_return(&trie->entries) > map->max_entries) {
+ err = -ENOSPC;
+ goto dec_entries;
+ }
+
+ new_child_twigs = qp_trie_branch_new(map, 2);
+ if (!new_child_twigs) {
+ err = -ENOMEM;
+ goto dec_entries;
+ }
+
+ new_child_twigs->index = d->index;
+ new_child_twigs->bitmap = d->sibling_bm | d->new_bm;
+
+ iip = calc_twig_index(new_child_twigs->bitmap, d->sibling_bm);
+ RCU_INIT_POINTER(new_child_twigs->nodes[iip], sibling);
+ rcu_assign_pointer(new_child_twigs->nodes[!iip], to_child_node(leaf));
+ RCU_INIT_POINTER(new_child_twigs->parent, NULL);
+
+ old_twigs = rcu_dereference_protected(*parent, 1);
+ new_twigs = qp_trie_branch_replace(map, old_twigs, bitmap, new_child_twigs);
+ if (!new_twigs) {
+ err = -ENOMEM;
+ goto free_child_twigs;
+ }
+
+ qp_trie_assign_parent(new_child_twigs, sibling);
+ rcu_assign_pointer(*parent, new_twigs);
+ qp_trie_branch_free(old_twigs, QP_TRIE_TWIGS_FREE_NONE_IDX);
+
+ return 0;
+
+free_child_twigs:
+ kfree(new_child_twigs);
+dec_entries:
+ atomic_dec(&trie->entries);
+ return err;
+}
+
+static int qp_trie_ext_branch(struct qp_trie *trie, struct qp_trie_branch __rcu **parent,
+ const struct qp_trie_key *new, unsigned int bitmap)
+{
+ struct qp_trie_branch *old_twigs, *new_twigs;
+ struct bpf_map *map;
+ int err;
+
+ map = &trie->map;
+ if (atomic_inc_return(&trie->entries) > map->max_entries) {
+ err = -ENOSPC;
+ goto dec_entries;
+ }
+
+ old_twigs = rcu_dereference_protected(*parent, 1);
+ new_twigs = qp_trie_branch_insert(map, old_twigs, bitmap, new);
+ if (!new_twigs) {
+ err = -ENOMEM;
+ goto dec_entries;
+ }
+
+ rcu_assign_pointer(*parent, new_twigs);
+ qp_trie_branch_free(old_twigs, QP_TRIE_TWIGS_FREE_NONE_IDX);
+
+ return 0;
+
+dec_entries:
+ atomic_dec(&trie->entries);
+ return err;
+}
+
+static int qp_trie_add_leaf_node(struct qp_trie *trie, struct qp_trie_branch __rcu **parent,
+ const struct qp_trie_key *new)
+{
+ struct bpf_map *map = &trie->map;
+ struct qp_trie_branch *twigs;
+ int err;
+
+ if (atomic_inc_return(&trie->entries) > map->max_entries) {
+ err = -ENOSPC;
+ goto dec_entries;
+ }
+
+ twigs = qp_trie_branch_new(map, 1);
+ if (!twigs) {
+ err = -ENOMEM;
+ goto dec_entries;
+ }
+ twigs->index = QP_TRIE_ROOT_NODE_INDEX;
+ twigs->bitmap = 1;
+ RCU_INIT_POINTER(twigs->parent, NULL);
+ rcu_assign_pointer(twigs->nodes[0], to_child_node(new));
+
+ rcu_assign_pointer(*parent, twigs);
+
+ return 0;
+dec_entries:
+ atomic_dec(&trie->entries);
+ return err;
+}
+
+static int qp_trie_rep_leaf_node(struct qp_trie *trie, struct qp_trie_branch __rcu **parent,
+ const struct qp_trie_key *new, unsigned int bitmap)
+{
+ struct qp_trie_branch *old_twigs, *new_twigs;
+ struct bpf_map *map = &trie->map;
+
+ /* Only branch node is freed by RCU, so replace the old branch node
+ * and free the old leaf node together with the old branch node.
+ */
+ old_twigs = rcu_dereference_protected(*parent, 1);
+ new_twigs = qp_trie_branch_replace(map, old_twigs, bitmap, to_child_node(new));
+ if (!new_twigs)
+ return -ENOMEM;
+
+ rcu_assign_pointer(*parent, new_twigs);
+
+ qp_trie_branch_free(old_twigs, calc_twig_index(old_twigs->bitmap, bitmap));
+
+ return 0;
+}
+
+static int qp_trie_remove_leaf(struct qp_trie *trie, struct qp_trie_branch __rcu **parent,
+ unsigned int bitmap, const struct qp_trie_key *node)
+{
+ struct bpf_map *map = &trie->map;
+ struct qp_trie_branch *new, *old;
+ unsigned int nr;
+
+ old = rcu_dereference_protected(*parent, 1);
+ nr = calc_twig_nr(old->bitmap);
+ if (nr > 2) {
+ new = qp_trie_branch_remove(map, old, bitmap);
+ if (!new)
+ return -ENOMEM;
+ } else {
+ new = NULL;
+ }
+
+ rcu_assign_pointer(*parent, new);
+
+ qp_trie_branch_free(old, calc_twig_index(old->bitmap, bitmap));
+
+ atomic_dec(&trie->entries);
+
+ return 0;
+}
+
+static int qp_trie_merge_node(struct qp_trie *trie, struct qp_trie_branch __rcu **grand_parent,
+ struct qp_trie_branch *parent, unsigned int parent_bitmap,
+ unsigned int bitmap)
+{
+ struct qp_trie_branch *old_twigs, *new_twigs;
+ struct bpf_map *map = &trie->map;
+ void *new_sibling;
+ unsigned int iip;
+
+ iip = calc_twig_index(parent->bitmap, bitmap);
+ new_sibling = rcu_dereference_protected(parent->nodes[!iip], 1);
+
+ old_twigs = rcu_dereference_protected(*grand_parent, 1);
+ new_twigs = qp_trie_branch_replace(map, old_twigs, parent_bitmap, new_sibling);
+ if (!new_twigs)
+ return -ENOMEM;
+
+ rcu_assign_pointer(*grand_parent, new_twigs);
+
+ qp_trie_branch_free(old_twigs, QP_TRIE_TWIGS_FREE_NONE_IDX);
+ qp_trie_branch_free(parent, iip);
+
+ atomic_dec(&trie->entries);
+
+ return 0;
+}
+
+static int qp_trie_alloc_check(union bpf_attr *attr)
+{
+ if (!bpf_capable())
+ return -EPERM;
+
+ if ((attr->map_flags & QP_TRIE_MANDATORY_FLAG_MASK) != QP_TRIE_MANDATORY_FLAG_MASK ||
+ attr->map_flags & ~QP_TRIE_CREATE_FLAG_MASK ||
+ !bpf_map_flags_access_ok(attr->map_flags))
+ return -EINVAL;
+
+ if (!attr->max_entries || !attr->value_size)
+ return -EINVAL;
+
+ /* Key and value are allocated together in qp_trie_init_leaf_node() */
+ if (round_up((u64)sizeof(struct qp_trie_key) + (u32)attr->map_extra + attr->value_size,
+ QP_TRIE_LEAF_ALLOC_ALIGN) >= KMALLOC_MAX_SIZE)
+ return -E2BIG;
+
+ return 0;
+}
+
+static struct bpf_map *qp_trie_alloc(union bpf_attr *attr)
+{
+ struct qp_trie *trie;
+ unsigned int i;
+
+ trie = bpf_map_area_alloc(sizeof(*trie), bpf_map_attr_numa_node(attr));
+ if (!trie)
+ return ERR_PTR(-ENOMEM);
+
+ /* roots are zeroed by bpf_map_area_alloc() */
+ for (i = 0; i < QP_TRIE_NR_SUBTREE; i++)
+ spin_lock_init(&trie->locks[i]);
+
+ atomic_set(&trie->entries, 0);
+ bpf_map_init_from_attr(&trie->map, attr);
+
+ return &trie->map;
+}
+
+static void qp_trie_free_subtree(void *root)
+{
+ struct qp_trie_branch *parent = NULL;
+ struct qp_trie_key *cur = NULL;
+ void *node = root;
+
+ /*
+ * Depth-first deletion
+ *
+ * 1. find left-most key and its parent
+ * 2. get next sibling Y from parent
+ * (a) Y is leaf node: continue
+ * (b) Y is branch node: goto step 1
+ * (c) no more sibling: backtrace upwards if parent is not NULL and
+ * goto step 1
+ */
+ do {
+ while (is_branch_node(node)) {
+ parent = node;
+ node = rcu_dereference_raw(parent->nodes[0]);
+ }
+
+ cur = to_leaf_node(node);
+ while (parent) {
+ unsigned int iip, bitmap, nr;
+ void *ancestor;
+
+ bitmap = calc_br_bitmap(parent->index, cur->data, cur->len);
+ iip = calc_twig_index(parent->bitmap, bitmap) + 1;
+ nr = calc_twig_nr(parent->bitmap);
+
+ for (; iip < nr; iip++) {
+ kfree(cur);
+
+ node = rcu_dereference_raw(parent->nodes[iip]);
+ if (is_branch_node(node))
+ break;
+
+ cur = to_leaf_node(node);
+ }
+ if (iip < nr)
+ break;
+
+ ancestor = rcu_dereference_raw(parent->parent);
+ kfree(parent);
+ parent = ancestor;
+ }
+ } while (parent);
+
+ kfree(cur);
+}
+
+static void qp_trie_free(struct bpf_map *map)
+{
+ struct qp_trie *trie = container_of(map, struct qp_trie, map);
+ unsigned int i;
+
+ /* Wait for the pending qp_trie_free_twigs_rcu() */
+ rcu_barrier();
+
+ for (i = 0; i < ARRAY_SIZE(trie->roots); i++) {
+ void *root = rcu_dereference_raw(trie->roots[i]);
+
+ if (root)
+ qp_trie_free_subtree(root);
+ }
+ bpf_map_area_free(trie);
+}
+
+static inline void qp_trie_copy_leaf(const struct qp_trie_key *leaf, struct bpf_dynptr_kern *key)
+{
+ memcpy(key->data + key->offset, leaf->data, leaf->len);
+ bpf_dynptr_set_size(key, leaf->len);
+}
+
+static void qp_trie_copy_min_key_from(void *root, struct bpf_dynptr_kern *key)
+{
+ void *node;
+
+ node = root;
+ while (is_branch_node(node))
+ node = rcu_dereference(((struct qp_trie_branch *)node)->nodes[0]);
+
+ qp_trie_copy_leaf(to_leaf_node(node), key);
+}
+
+static int qp_trie_lookup_min_key(struct qp_trie *trie, unsigned int from,
+ struct bpf_dynptr_kern *key)
+{
+ unsigned int i;
+
+ for (i = from; i < ARRAY_SIZE(trie->roots); i++) {
+ void *root = rcu_dereference(trie->roots[i]);
+
+ if (root) {
+ qp_trie_copy_min_key_from(root, key);
+ return 0;
+ }
+ }
+
+ return -ENOENT;
+}
+
+static int qp_trie_next_twigs_index(struct qp_trie_branch *twigs, unsigned int bitmap)
+{
+ unsigned int idx, nr, next;
+
+ /* bitmap may not in twigs->bitmap */
+ idx = calc_twig_index(twigs->bitmap, bitmap);
+ nr = calc_twig_nr(twigs->bitmap);
+
+ next = idx;
+ if (twigs->bitmap & bitmap)
+ next += 1;
+
+ if (next >= nr)
+ return -1;
+ return next;
+}
+
+static int qp_trie_lookup_next_node(struct qp_trie *trie, const struct bpf_dynptr_kern *key,
+ struct bpf_dynptr_kern *next_key)
+{
+ const struct qp_trie_key *found;
+ struct qp_trie_branch *parent;
+ const unsigned char *data;
+ unsigned int data_len;
+ void *node, *next;
+
+ /* Non-existent key, so restart from the beginning */
+ data = key->data + key->offset;
+ node = rcu_dereference(trie->roots[*data]);
+ if (!node)
+ return qp_trie_lookup_min_key(trie, 0, next_key);
+
+ parent = NULL;
+ data_len = bpf_dynptr_get_size(key);
+ while (is_branch_node(node)) {
+ struct qp_trie_branch *br = node;
+ unsigned int iip, bitmap;
+
+ bitmap = calc_br_bitmap(br->index, data, data_len);
+ if (bitmap & br->bitmap)
+ iip = calc_twig_index(br->bitmap, bitmap);
+ else
+ iip = 0;
+
+ parent = br;
+ node = rcu_dereference(br->nodes[iip]);
+ }
+ found = to_leaf_node(node);
+ if (!is_same_key(found, data, data_len))
+ return qp_trie_lookup_min_key(trie, 0, next_key);
+
+ /* Pair with store release in rcu_assign_pointer(*parent, twigs) to
+ * ensure reading node->parent will not return the old parent if
+ * the node is found by following the newly-created parent.
+ */
+ smp_rmb();
+
+ next = NULL;
+ while (parent) {
+ unsigned int bitmap;
+ int next_idx;
+
+ bitmap = calc_br_bitmap(parent->index, data, data_len);
+ next_idx = qp_trie_next_twigs_index(parent, bitmap);
+ if (next_idx >= 0) {
+ next = rcu_dereference(parent->nodes[next_idx]);
+ break;
+ }
+ parent = rcu_dereference(parent->parent);
+ }
+
+ /* Goto next sub-tree */
+ if (!next)
+ return qp_trie_lookup_min_key(trie, *data + 1, next_key);
+
+ if (!is_branch_node(next))
+ qp_trie_copy_leaf(to_leaf_node(next), next_key);
+ else
+ qp_trie_copy_min_key_from(next, next_key);
+
+ return 0;
+}
+
+/* Called from syscall */
+static int qp_trie_get_next_key(struct bpf_map *map, void *key, void *next_key)
+{
+ struct qp_trie *trie = container_of(map, struct qp_trie, map);
+ int err;
+
+ if (!key)
+ err = qp_trie_lookup_min_key(trie, 0, next_key);
+ else
+ err = qp_trie_lookup_next_node(trie, key, next_key);
+ return err;
+}
+
+/* Called from syscall or from eBPF program */
+static void *qp_trie_lookup_elem(struct bpf_map *map, void *key)
+{
+ struct qp_trie *trie = container_of(map, struct qp_trie, map);
+ const struct bpf_dynptr_kern *dynptr_key = key;
+ const struct qp_trie_key *found;
+ const unsigned char *data;
+ unsigned int data_len;
+ void *node, *value;
+
+ /* Dynptr with zero length is possible, but is invalid for qp-trie */
+ data_len = bpf_dynptr_get_size(dynptr_key);
+ if (!data_len)
+ return NULL;
+
+ data = dynptr_key->data + dynptr_key->offset;
+ node = rcu_dereference_check(trie->roots[*data], rcu_read_lock_bh_held());
+ if (!node)
+ return NULL;
+
+ value = NULL;
+ while (is_branch_node(node)) {
+ struct qp_trie_branch *br = node;
+ unsigned int bitmap;
+ unsigned int iip;
+
+ /* When byte index equals with key len, the target key
+ * may be in twigs->nodes[0].
+ */
+ if (index_to_byte_index(br->index) > data_len)
+ goto done;
+
+ bitmap = calc_br_bitmap(br->index, data, data_len);
+ if (!(bitmap & br->bitmap))
+ goto done;
+
+ iip = calc_twig_index(br->bitmap, bitmap);
+ node = rcu_dereference_check(br->nodes[iip], rcu_read_lock_bh_held());
+ }
+
+ found = to_leaf_node(node);
+ if (is_same_key(found, data, data_len))
+ value = qp_trie_leaf_value(found);
+done:
+ return value;
+}
+
+/* Called from syscall or from eBPF program */
+static int qp_trie_update_elem(struct bpf_map *map, void *key, void *value, u64 flags)
+{
+ struct qp_trie *trie = container_of(map, struct qp_trie, map);
+ const struct qp_trie_key *leaf_key, *new_key;
+ struct qp_trie_branch __rcu **parent;
+ struct qp_trie_diff d;
+ unsigned int bitmap;
+ void __rcu **node;
+ spinlock_t *lock;
+ unsigned char c;
+ bool equal;
+ int err;
+
+ if (flags > BPF_EXIST)
+ return -EINVAL;
+
+ /* The content of key may change, so copy it firstly */
+ new_key = qp_trie_init_leaf_node(map, key, value);
+ if (IS_ERR(new_key))
+ return PTR_ERR(new_key);
+
+ c = new_key->data[0];
+ lock = &trie->locks[c];
+ spin_lock(lock);
+ parent = (struct qp_trie_branch __rcu **)&trie->roots[c];
+ if (!rcu_dereference_protected(*parent, 1)) {
+ if (flags == BPF_EXIST) {
+ err = -ENOENT;
+ goto unlock;
+ }
+ err = qp_trie_add_leaf_node(trie, parent, new_key);
+ goto unlock;
+ }
+
+ bitmap = 1;
+ node = &rcu_dereference_protected(*parent, 1)->nodes[0];
+ while (is_branch_node(rcu_dereference_protected(*node, 1))) {
+ struct qp_trie_branch *br = rcu_dereference_protected(*node, 1);
+ unsigned int iip;
+
+ bitmap = calc_br_bitmap(br->index, new_key->data, new_key->len);
+ if (bitmap & br->bitmap)
+ iip = calc_twig_index(br->bitmap, bitmap);
+ else
+ iip = 0;
+ parent = (struct qp_trie_branch __rcu **)node;
+ node = &br->nodes[iip];
+ }
+
+ leaf_key = to_leaf_node(rcu_dereference_protected(*node, 1));
+ equal = calc_prefix_len(leaf_key, new_key, &d.index);
+ if (equal) {
+ if (flags == BPF_NOEXIST) {
+ err = -EEXIST;
+ goto unlock;
+ }
+ err = qp_trie_rep_leaf_node(trie, parent, new_key, bitmap);
+ goto unlock;
+ }
+
+ d.sibling_bm = calc_br_bitmap(d.index, leaf_key->data, leaf_key->len);
+ d.new_bm = calc_br_bitmap(d.index, new_key->data, new_key->len);
+
+ bitmap = 1;
+ parent = (struct qp_trie_branch __rcu **)&trie->roots[c];
+ node = &rcu_dereference_protected(*parent, 1)->nodes[0];
+ while (is_branch_node(rcu_dereference_protected(*node, 1))) {
+ struct qp_trie_branch *br = rcu_dereference_protected(*node, 1);
+ unsigned int iip;
+
+ if (d.index < br->index)
+ goto new_branch;
+
+ parent = (struct qp_trie_branch __rcu **)node;
+ if (d.index == br->index) {
+ if (flags == BPF_EXIST) {
+ err = -ENOENT;
+ goto unlock;
+ }
+ err = qp_trie_ext_branch(trie, parent, new_key, d.new_bm);
+ goto unlock;
+ }
+
+ bitmap = calc_br_bitmap(br->index, new_key->data, new_key->len);
+ iip = calc_twig_index(br->bitmap, bitmap);
+ node = &br->nodes[iip];
+ }
+
+new_branch:
+ if (flags == BPF_EXIST) {
+ err = -ENOENT;
+ goto unlock;
+ }
+ err = qp_trie_new_branch(trie, parent, bitmap, rcu_dereference_protected(*node, 1),
+ &d, new_key);
+unlock:
+ spin_unlock(lock);
+ if (err)
+ kfree(new_key);
+ return err;
+}
+
+/* Called from syscall or from eBPF program */
+static int qp_trie_delete_elem(struct bpf_map *map, void *key)
+{
+ struct qp_trie *trie = container_of(map, struct qp_trie, map);
+ unsigned int bitmap, parent_bitmap, data_len, nr;
+ struct qp_trie_branch __rcu **parent, **grand_parent;
+ const struct bpf_dynptr_kern *dynptr_key;
+ const struct qp_trie_key *found;
+ const unsigned char *data;
+ void __rcu **node;
+ spinlock_t *lock;
+ unsigned char c;
+ int err;
+
+ dynptr_key = key;
+ data_len = bpf_dynptr_get_size(dynptr_key);
+ if (!data_len)
+ return -EINVAL;
+
+ err = -ENOENT;
+ data = dynptr_key->data + dynptr_key->offset;
+ c = *data;
+ lock = &trie->locks[c];
+ spin_lock(lock);
+ parent = (struct qp_trie_branch __rcu **)&trie->roots[c];
+ if (!*parent)
+ goto unlock;
+
+ grand_parent = NULL;
+ parent_bitmap = bitmap = 1;
+ node = &rcu_dereference_protected(*parent, 1)->nodes[0];
+ while (is_branch_node(rcu_dereference_protected(*node, 1))) {
+ struct qp_trie_branch *br = rcu_dereference_protected(*node, 1);
+ unsigned int iip;
+
+ if (index_to_byte_index(br->index) > data_len)
+ goto unlock;
+
+ parent_bitmap = bitmap;
+ bitmap = calc_br_bitmap(br->index, data, data_len);
+ if (!(bitmap & br->bitmap))
+ goto unlock;
+
+ grand_parent = parent;
+ parent = (struct qp_trie_branch __rcu **)node;
+ iip = calc_twig_index(br->bitmap, bitmap);
+ node = &br->nodes[iip];
+ }
+
+ found = to_leaf_node(rcu_dereference_protected(*node, 1));
+ if (!is_same_key(found, data, data_len))
+ goto unlock;
+
+ nr = calc_twig_nr(rcu_dereference_protected(*parent, 1)->bitmap);
+ if (nr != 2)
+ err = qp_trie_remove_leaf(trie, parent, bitmap, found);
+ else
+ err = qp_trie_merge_node(trie, grand_parent, rcu_dereference_protected(*parent, 1),
+ parent_bitmap, bitmap);
+unlock:
+ spin_unlock(lock);
+ return err;
+}
+
+static int qp_trie_check_btf(const struct bpf_map *map,
+ const struct btf *btf,
+ const struct btf_type *key_type,
+ const struct btf_type *value_type)
+{
+ return 0;
+}
+
+BTF_ID_LIST_SINGLE(qp_trie_map_btf_ids, struct, qp_trie)
+const struct bpf_map_ops qp_trie_map_ops = {
+ .map_alloc_check = qp_trie_alloc_check,
+ .map_alloc = qp_trie_alloc,
+ .map_free = qp_trie_free,
+ .map_get_next_key = qp_trie_get_next_key,
+ .map_lookup_elem = qp_trie_lookup_elem,
+ .map_update_elem = qp_trie_update_elem,
+ .map_delete_elem = qp_trie_delete_elem,
+ .map_meta_equal = bpf_map_meta_equal,
+ .map_check_btf = qp_trie_check_btf,
+ .map_btf_id = &qp_trie_map_btf_ids[0],
+};
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 600c3fcee37a..1591f0df46f3 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -928,6 +928,7 @@ enum bpf_map_type {
BPF_MAP_TYPE_INODE_STORAGE,
BPF_MAP_TYPE_TASK_STORAGE,
BPF_MAP_TYPE_BLOOM_FILTER,
+ BPF_MAP_TYPE_QP_TRIE,
};
/* Note that tracing related programs such as
--
2.29.2
