nft_set_pipapo: Prepare for vectorised implementation: helpers

Move most macros and helpers to a header file, so that they can be
conveniently used by related implementations.

No functional changes are intended here.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_set_pipapo.h

+// SPDX-License-Identifier: GPL-2.0-only
+
+#ifndef _NFT_SET_PIPAPO_H
+
+#include <linux/log2.h>
+#include <net/ipv6.h>			/* For the maximum length of a field */
+
+/* Count of concatenated fields depends on count of 32-bit nftables registers */
+#define NFT_PIPAPO_MAX_FIELDS		NFT_REG32_COUNT
+
+/* Largest supported field size */
+#define NFT_PIPAPO_MAX_BYTES		(sizeof(struct in6_addr))
+#define NFT_PIPAPO_MAX_BITS		(NFT_PIPAPO_MAX_BYTES * BITS_PER_BYTE)
+
+/* Bits to be grouped together in table buckets depending on set size */
+#define NFT_PIPAPO_GROUP_BITS_INIT	NFT_PIPAPO_GROUP_BITS_SMALL_SET
+#define NFT_PIPAPO_GROUP_BITS_SMALL_SET	8
+#define NFT_PIPAPO_GROUP_BITS_LARGE_SET	4
+#define NFT_PIPAPO_GROUP_BITS_ARE_8_OR_4				\
+	BUILD_BUG_ON((NFT_PIPAPO_GROUP_BITS_SMALL_SET != 8) ||		\
+		     (NFT_PIPAPO_GROUP_BITS_LARGE_SET != 4))
+#define NFT_PIPAPO_GROUPS_PER_BYTE(f)	(BITS_PER_BYTE / (f)->bb)
+
+/* If a lookup table gets bigger than NFT_PIPAPO_LT_SIZE_HIGH, switch to the
+ * small group width, and switch to the big group width if the table gets
+ * smaller than NFT_PIPAPO_LT_SIZE_LOW.
+ *
+ * Picking 2MiB as threshold (for a single table) avoids as much as possible
+ * crossing page boundaries on most architectures (x86-64 and MIPS huge pages,
+ * ARMv7 supersections, POWER "large" pages, SPARC Level 1 regions, etc.), which
+ * keeps performance nice in case kvmalloc() gives us non-contiguous areas.
+ */
+#define NFT_PIPAPO_LT_SIZE_THRESHOLD	(1 << 21)
+#define NFT_PIPAPO_LT_SIZE_HYSTERESIS	(1 << 16)
+#define NFT_PIPAPO_LT_SIZE_HIGH		NFT_PIPAPO_LT_SIZE_THRESHOLD
+#define NFT_PIPAPO_LT_SIZE_LOW		NFT_PIPAPO_LT_SIZE_THRESHOLD -	\
+					NFT_PIPAPO_LT_SIZE_HYSTERESIS
+
+/* Fields are padded to 32 bits in input registers */
+#define NFT_PIPAPO_GROUPS_PADDED_SIZE(f)				\
+	(round_up((f)->groups / NFT_PIPAPO_GROUPS_PER_BYTE(f), sizeof(u32)))
+#define NFT_PIPAPO_GROUPS_PADDING(f)					\
+	(NFT_PIPAPO_GROUPS_PADDED_SIZE(f) - (f)->groups /		\
+					    NFT_PIPAPO_GROUPS_PER_BYTE(f))
+
+/* Number of buckets given by 2 ^ n, with n bucket bits */
+#define NFT_PIPAPO_BUCKETS(bb)		(1 << (bb))
+
+/* Each n-bit range maps to up to n * 2 rules */
+#define NFT_PIPAPO_MAP_NBITS		(const_ilog2(NFT_PIPAPO_MAX_BITS * 2))
+
+/* Use the rest of mapping table buckets for rule indices, but it makes no sense
+ * to exceed 32 bits
+ */
+#if BITS_PER_LONG == 64
+#define NFT_PIPAPO_MAP_TOBITS		32
+#else
+#define NFT_PIPAPO_MAP_TOBITS		(BITS_PER_LONG - NFT_PIPAPO_MAP_NBITS)
+#endif
+
+/* ...which gives us the highest allowed index for a rule */
+#define NFT_PIPAPO_RULE0_MAX		((1UL << (NFT_PIPAPO_MAP_TOBITS - 1)) \
+					- (1UL << NFT_PIPAPO_MAP_NBITS))
+
+/* Definitions for vectorised implementations */
+#ifdef NFT_PIPAPO_ALIGN
+#define NFT_PIPAPO_ALIGN_HEADROOM					\
+	(NFT_PIPAPO_ALIGN - ARCH_KMALLOC_MINALIGN)
+#define NFT_PIPAPO_LT_ALIGN(lt)		(PTR_ALIGN((lt), NFT_PIPAPO_ALIGN))
+#define NFT_PIPAPO_LT_ASSIGN(field, x)					\
+	do {								\
+		(field)->lt_aligned = NFT_PIPAPO_LT_ALIGN(x);		\
+		(field)->lt = (x);					\
+	} while (0)
+#else
+#define NFT_PIPAPO_ALIGN_HEADROOM	0
+#define NFT_PIPAPO_LT_ALIGN(lt)		(lt)
+#define NFT_PIPAPO_LT_ASSIGN(field, x)	((field)->lt = (x))
+#endif /* NFT_PIPAPO_ALIGN */
+
+#define nft_pipapo_for_each_field(field, index, match)		\
+	for ((field) = (match)->f, (index) = 0;			\
+	     (index) < (match)->field_count;			\
+	     (index)++, (field)++)
+
+/**
+ * union nft_pipapo_map_bucket - Bucket of mapping table
+ * @to:		First rule number (in next field) this rule maps to
+ * @n:		Number of rules (in next field) this rule maps to
+ * @e:		If there's no next field, pointer to element this rule maps to
+ */
+union nft_pipapo_map_bucket {
+	struct {
+#if BITS_PER_LONG == 64
+		static_assert(NFT_PIPAPO_MAP_TOBITS <= 32);
+		u32 to;
+
+		static_assert(NFT_PIPAPO_MAP_NBITS <= 32);
+		u32 n;
+#else
+		unsigned long to:NFT_PIPAPO_MAP_TOBITS;
+		unsigned long  n:NFT_PIPAPO_MAP_NBITS;
+#endif
+	};
+	struct nft_pipapo_elem *e;
+};
+
+/**
+ * struct nft_pipapo_field - Lookup, mapping tables and related data for a field
+ * @groups:	Amount of bit groups
+ * @rules:	Number of inserted rules
+ * @bsize:	Size of each bucket in lookup table, in longs
+ * @bb:		Number of bits grouped together in lookup table buckets
+ * @lt:		Lookup table: 'groups' rows of buckets
+ * @lt_aligned:	Version of @lt aligned to NFT_PIPAPO_ALIGN bytes
+ * @mt:		Mapping table: one bucket per rule
+ */
+struct nft_pipapo_field {
+	int groups;
+	unsigned long rules;
+	size_t bsize;
+	int bb;
+#ifdef NFT_PIPAPO_ALIGN
+	unsigned long *lt_aligned;
+#endif
+	unsigned long *lt;
+	union nft_pipapo_map_bucket *mt;
+};
+
+/**
+ * struct nft_pipapo_match - Data used for lookup and matching
+ * @field_count		Amount of fields in set
+ * @scratch:		Preallocated per-CPU maps for partial matching results
+ * @scratch_aligned:	Version of @scratch aligned to NFT_PIPAPO_ALIGN bytes
+ * @bsize_max:		Maximum lookup table bucket size of all fields, in longs
+ * @rcu			Matching data is swapped on commits
+ * @f:			Fields, with lookup and mapping tables
+ */
+struct nft_pipapo_match {
+	int field_count;
+#ifdef NFT_PIPAPO_ALIGN
+	unsigned long * __percpu *scratch_aligned;
+#endif
+	unsigned long * __percpu *scratch;
+	size_t bsize_max;
+	struct rcu_head rcu;
+	struct nft_pipapo_field f[];
+};
+
+/**
+ * struct nft_pipapo - Representation of a set
+ * @match:	Currently in-use matching data
+ * @clone:	Copy where pending insertions and deletions are kept
+ * @width:	Total bytes to be matched for one packet, including padding
+ * @dirty:	Working copy has pending insertions or deletions
+ * @last_gc:	Timestamp of last garbage collection run, jiffies
+ */
+struct nft_pipapo {
+	struct nft_pipapo_match __rcu *match;
+	struct nft_pipapo_match *clone;
+	int width;
+	bool dirty;
+	unsigned long last_gc;
+};
+
+struct nft_pipapo_elem;
+
+/**
+ * struct nft_pipapo_elem - API-facing representation of single set element
+ * @ext:	nftables API extensions
+ */
+struct nft_pipapo_elem {
+	struct nft_set_ext ext;
+};
+
+int pipapo_refill(unsigned long *map, int len, int rules, unsigned long *dst,
+		  union nft_pipapo_map_bucket *mt, bool match_only);
+
+/**
+ * pipapo_and_field_buckets_4bit() - Intersect 4-bit buckets
+ * @f:		Field including lookup table
+ * @dst:	Area to store result
+ * @data:	Input data selecting table buckets
+ */
+static inline void pipapo_and_field_buckets_4bit(struct nft_pipapo_field *f,
+						 unsigned long *dst,
+						 const u8 *data)
+{
+	unsigned long *lt = NFT_PIPAPO_LT_ALIGN(f->lt);
+	int group;
+
+	for (group = 0; group < f->groups; group += BITS_PER_BYTE / 4, data++) {
+		u8 v;
+
+		v = *data >> 4;
+		__bitmap_and(dst, dst, lt + v * f->bsize,
+			     f->bsize * BITS_PER_LONG);
+		lt += f->bsize * NFT_PIPAPO_BUCKETS(4);
+
+		v = *data & 0x0f;
+		__bitmap_and(dst, dst, lt + v * f->bsize,
+			     f->bsize * BITS_PER_LONG);
+		lt += f->bsize * NFT_PIPAPO_BUCKETS(4);
+	}
+}
+
+/**
+ * pipapo_and_field_buckets_8bit() - Intersect 8-bit buckets
+ * @f:		Field including lookup table
+ * @dst:	Area to store result
+ * @data:	Input data selecting table buckets
+ */
+static inline void pipapo_and_field_buckets_8bit(struct nft_pipapo_field *f,
+						 unsigned long *dst,
+						 const u8 *data)
+{
+	unsigned long *lt = NFT_PIPAPO_LT_ALIGN(f->lt);
+	int group;
+
+	for (group = 0; group < f->groups; group++, data++) {
+		__bitmap_and(dst, dst, lt + *data * f->bsize,
+			     f->bsize * BITS_PER_LONG);
+		lt += f->bsize * NFT_PIPAPO_BUCKETS(8);
+	}
+}
+
+/**
+ * pipapo_estimate_size() - Estimate worst-case for set size
+ * @desc:	Set description, element count and field description used here
+ *
+ * The size for this set type can vary dramatically, as it depends on the number
+ * of rules (composing netmasks) the entries expand to. We compute the worst
+ * case here.
+ *
+ * In general, for a non-ranged entry or a single composing netmask, we need
+ * one bit in each of the sixteen NFT_PIPAPO_BUCKETS, for each 4-bit group (that
+ * is, each input bit needs four bits of matching data), plus a bucket in the
+ * mapping table for each field.
+ *
+ * Return: worst-case set size in bytes, 0 on any overflow
+ */
+static u64 pipapo_estimate_size(const struct nft_set_desc *desc)
+{
+	unsigned long entry_size;
+	u64 size;
+	int i;
+
+	for (i = 0, entry_size = 0; i < desc->field_count; i++) {
+		unsigned long rules;
+
+		if (desc->field_len[i] > NFT_PIPAPO_MAX_BYTES)
+			return 0;
+
+		/* Worst-case ranges for each concatenated field: each n-bit
+		 * field can expand to up to n * 2 rules in each bucket, and
+		 * each rule also needs a mapping bucket.
+		 */
+		rules = ilog2(desc->field_len[i] * BITS_PER_BYTE) * 2;
+		entry_size += rules *
+			      NFT_PIPAPO_BUCKETS(NFT_PIPAPO_GROUP_BITS_INIT) /
+			      BITS_PER_BYTE;
+		entry_size += rules * sizeof(union nft_pipapo_map_bucket);
+	}
+
+	/* Rules in lookup and mapping tables are needed for each entry */
+	size = desc->size * entry_size;
+	if (size && div_u64(size, desc->size) != entry_size)
+		return 0;
+
+	size += sizeof(struct nft_pipapo) + sizeof(struct nft_pipapo_match) * 2;
+
+	size += sizeof(struct nft_pipapo_field) * desc->field_count;
+
+	return size;
+}
+
+#endif /* _NFT_SET_PIPAPO_H */