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authorChristian Poessinger <christian@poessinger.com>2020-12-18 17:13:13 +0100
committerChristian Poessinger <christian@poessinger.com>2020-12-19 21:56:19 +0100
commitb5c80d310527223b93e4133ac2f4c8c063c70a98 (patch)
tree48ae9e2752b4b94c07f767a019c99a8c2460c014 /src/xdp/include/jhash.h
parent22308b05dfbcd8da0230bbd8ba3bbc2a55da7786 (diff)
downloadvyos-1x-b5c80d310527223b93e4133ac2f4c8c063c70a98.tar.gz
vyos-1x-b5c80d310527223b93e4133ac2f4c8c063c70a98.zip
xdp: T2666: switch to example code provided by xdp-tutorial
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+#ifndef _LINUX_JHASH_H
+#define _LINUX_JHASH_H
+
+/* Copied from $(LINUX)/include/linux/jhash.h (kernel 4.18) */
+
+/* jhash.h: Jenkins hash support.
+ *
+ * Copyright (C) 2006. Bob Jenkins (bob_jenkins@burtleburtle.net)
+ *
+ * http://burtleburtle.net/bob/hash/
+ *
+ * These are the credits from Bob's sources:
+ *
+ * lookup3.c, by Bob Jenkins, May 2006, Public Domain.
+ *
+ * These are functions for producing 32-bit hashes for hash table lookup.
+ * hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final()
+ * are externally useful functions. Routines to test the hash are included
+ * if SELF_TEST is defined. You can use this free for any purpose. It's in
+ * the public domain. It has no warranty.
+ *
+ * Copyright (C) 2009-2010 Jozsef Kadlecsik (kadlec@blackhole.kfki.hu)
+ */
+
+static inline __u32 rol32(__u32 word, unsigned int shift)
+{
+ return (word << shift) | (word >> ((-shift) & 31));
+}
+
+/* copy paste of jhash from kernel sources (include/linux/jhash.h) to make sure
+ * LLVM can compile it into valid sequence of BPF instructions
+ */
+#define __jhash_mix(a, b, c) \
+{ \
+ a -= c; a ^= rol32(c, 4); c += b; \
+ b -= a; b ^= rol32(a, 6); a += c; \
+ c -= b; c ^= rol32(b, 8); b += a; \
+ a -= c; a ^= rol32(c, 16); c += b; \
+ b -= a; b ^= rol32(a, 19); a += c; \
+ c -= b; c ^= rol32(b, 4); b += a; \
+}
+
+#define __jhash_final(a, b, c) \
+{ \
+ c ^= b; c -= rol32(b, 14); \
+ a ^= c; a -= rol32(c, 11); \
+ b ^= a; b -= rol32(a, 25); \
+ c ^= b; c -= rol32(b, 16); \
+ a ^= c; a -= rol32(c, 4); \
+ b ^= a; b -= rol32(a, 14); \
+ c ^= b; c -= rol32(b, 24); \
+}
+
+#define JHASH_INITVAL 0xdeadbeef
+
+typedef unsigned int u32;
+
+/* jhash - hash an arbitrary key
+ * @k: sequence of bytes as key
+ * @length: the length of the key
+ * @initval: the previous hash, or an arbitray value
+ *
+ * The generic version, hashes an arbitrary sequence of bytes.
+ * No alignment or length assumptions are made about the input key.
+ *
+ * Returns the hash value of the key. The result depends on endianness.
+ */
+static inline u32 jhash(const void *key, u32 length, u32 initval)
+{
+ u32 a, b, c;
+ const unsigned char *k = key;
+
+ /* Set up the internal state */
+ a = b = c = JHASH_INITVAL + length + initval;
+
+ /* All but the last block: affect some 32 bits of (a,b,c) */
+ while (length > 12) {
+ a += *(u32 *)(k);
+ b += *(u32 *)(k + 4);
+ c += *(u32 *)(k + 8);
+ __jhash_mix(a, b, c);
+ length -= 12;
+ k += 12;
+ }
+ /* Last block: affect all 32 bits of (c) */
+ switch (length) {
+ case 12: c += (u32)k[11]<<24; /* fall through */
+ case 11: c += (u32)k[10]<<16; /* fall through */
+ case 10: c += (u32)k[9]<<8; /* fall through */
+ case 9: c += k[8]; /* fall through */
+ case 8: b += (u32)k[7]<<24; /* fall through */
+ case 7: b += (u32)k[6]<<16; /* fall through */
+ case 6: b += (u32)k[5]<<8; /* fall through */
+ case 5: b += k[4]; /* fall through */
+ case 4: a += (u32)k[3]<<24; /* fall through */
+ case 3: a += (u32)k[2]<<16; /* fall through */
+ case 2: a += (u32)k[1]<<8; /* fall through */
+ case 1: a += k[0];
+ __jhash_final(a, b, c);
+ case 0: /* Nothing left to add */
+ break;
+ }
+
+ return c;
+}
+
+/* jhash2 - hash an array of u32's
+ * @k: the key which must be an array of u32's
+ * @length: the number of u32's in the key
+ * @initval: the previous hash, or an arbitray value
+ *
+ * Returns the hash value of the key.
+ */
+static inline u32 jhash2(const u32 *k, u32 length, u32 initval)
+{
+ u32 a, b, c;
+
+ /* Set up the internal state */
+ a = b = c = JHASH_INITVAL + (length<<2) + initval;
+
+ /* Handle most of the key */
+ while (length > 3) {
+ a += k[0];
+ b += k[1];
+ c += k[2];
+ __jhash_mix(a, b, c);
+ length -= 3;
+ k += 3;
+ }
+
+ /* Handle the last 3 u32's */
+ switch (length) {
+ case 3: c += k[2]; /* fall through */
+ case 2: b += k[1]; /* fall through */
+ case 1: a += k[0];
+ __jhash_final(a, b, c);
+ case 0: /* Nothing left to add */
+ break;
+ }
+
+ return c;
+}
+
+
+/* __jhash_nwords - hash exactly 3, 2 or 1 word(s) */
+static inline u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
+{
+ a += initval;
+ b += initval;
+ c += initval;
+
+ __jhash_final(a, b, c);
+
+ return c;
+}
+
+static inline u32 jhash_3words(u32 a, u32 b, u32 c, u32 initval)
+{
+ return __jhash_nwords(a, b, c, initval + JHASH_INITVAL + (3 << 2));
+}
+
+static inline u32 jhash_2words(u32 a, u32 b, u32 initval)
+{
+ return __jhash_nwords(a, b, 0, initval + JHASH_INITVAL + (2 << 2));
+}
+
+static inline u32 jhash_1word(u32 a, u32 initval)
+{
+ return __jhash_nwords(a, 0, 0, initval + JHASH_INITVAL + (1 << 2));
+}
+
+#endif /* _LINUX_JHASH_H */