cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ceph_hash.c (2952B)

      1
      2#include <linux/ceph/types.h>
      3#include <linux/module.h>
      4
      5/*
      6 * Robert Jenkin's hash function.
      7 * https://burtleburtle.net/bob/hash/evahash.html
      8 * This is in the public domain.
      9 */
     10#define mix(a, b, c)						\
     11	do {							\
     12		a = a - b;  a = a - c;  a = a ^ (c >> 13);	\
     13		b = b - c;  b = b - a;  b = b ^ (a << 8);	\
     14		c = c - a;  c = c - b;  c = c ^ (b >> 13);	\
     15		a = a - b;  a = a - c;  a = a ^ (c >> 12);	\
     16		b = b - c;  b = b - a;  b = b ^ (a << 16);	\
     17		c = c - a;  c = c - b;  c = c ^ (b >> 5);	\
     18		a = a - b;  a = a - c;  a = a ^ (c >> 3);	\
     19		b = b - c;  b = b - a;  b = b ^ (a << 10);	\
     20		c = c - a;  c = c - b;  c = c ^ (b >> 15);	\
     21	} while (0)
     22
     23unsigned int ceph_str_hash_rjenkins(const char *str, unsigned int length)
     24{
     25	const unsigned char *k = (const unsigned char *)str;
     26	__u32 a, b, c;  /* the internal state */
     27	__u32 len;      /* how many key bytes still need mixing */
     28
     29	/* Set up the internal state */
     30	len = length;
     31	a = 0x9e3779b9;      /* the golden ratio; an arbitrary value */
     32	b = a;
     33	c = 0;               /* variable initialization of internal state */
     34
     35	/* handle most of the key */
     36	while (len >= 12) {
     37		a = a + (k[0] + ((__u32)k[1] << 8) + ((__u32)k[2] << 16) +
     38			 ((__u32)k[3] << 24));
     39		b = b + (k[4] + ((__u32)k[5] << 8) + ((__u32)k[6] << 16) +
     40			 ((__u32)k[7] << 24));
     41		c = c + (k[8] + ((__u32)k[9] << 8) + ((__u32)k[10] << 16) +
     42			 ((__u32)k[11] << 24));
     43		mix(a, b, c);
     44		k = k + 12;
     45		len = len - 12;
     46	}
     47
     48	/* handle the last 11 bytes */
     49	c = c + length;
     50	switch (len) {
     51	case 11:
     52		c = c + ((__u32)k[10] << 24);
     53		fallthrough;
     54	case 10:
     55		c = c + ((__u32)k[9] << 16);
     56		fallthrough;
     57	case 9:
     58		c = c + ((__u32)k[8] << 8);
     59		/* the first byte of c is reserved for the length */
     60		fallthrough;
     61	case 8:
     62		b = b + ((__u32)k[7] << 24);
     63		fallthrough;
     64	case 7:
     65		b = b + ((__u32)k[6] << 16);
     66		fallthrough;
     67	case 6:
     68		b = b + ((__u32)k[5] << 8);
     69		fallthrough;
     70	case 5:
     71		b = b + k[4];
     72		fallthrough;
     73	case 4:
     74		a = a + ((__u32)k[3] << 24);
     75		fallthrough;
     76	case 3:
     77		a = a + ((__u32)k[2] << 16);
     78		fallthrough;
     79	case 2:
     80		a = a + ((__u32)k[1] << 8);
     81		fallthrough;
     82	case 1:
     83		a = a + k[0];
     84		/* case 0: nothing left to add */
     85	}
     86	mix(a, b, c);
     87
     88	return c;
     89}
     90
     91/*
     92 * linux dcache hash
     93 */
     94unsigned int ceph_str_hash_linux(const char *str, unsigned int length)
     95{
     96	unsigned long hash = 0;
     97	unsigned char c;
     98
     99	while (length--) {
    100		c = *str++;
    101		hash = (hash + (c << 4) + (c >> 4)) * 11;
    102	}
    103	return hash;
    104}
    105
    106
    107unsigned int ceph_str_hash(int type, const char *s, unsigned int len)
    108{
    109	switch (type) {
    110	case CEPH_STR_HASH_LINUX:
    111		return ceph_str_hash_linux(s, len);
    112	case CEPH_STR_HASH_RJENKINS:
    113		return ceph_str_hash_rjenkins(s, len);
    114	default:
    115		return -1;
    116	}
    117}
    118EXPORT_SYMBOL(ceph_str_hash);
    119
    120const char *ceph_str_hash_name(int type)
    121{
    122	switch (type) {
    123	case CEPH_STR_HASH_LINUX:
    124		return "linux";
    125	case CEPH_STR_HASH_RJENKINS:
    126		return "rjenkins";
    127	default:
    128		return "unknown";
    129	}
    130}
    131EXPORT_SYMBOL(ceph_str_hash_name);