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Diffstat (limited to 'net/core/utils.c')
| -rw-r--r-- | net/core/utils.c | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/net/core/utils.c b/net/core/utils.c new file mode 100644 index 00000000000..e11a8654f36 --- /dev/null +++ b/net/core/utils.c @@ -0,0 +1,155 @@ +/* + * Generic address resultion entity + * + * Authors: + * net_random Alan Cox + * net_ratelimit Andy Kleen + * + * Created by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/module.h> +#include <linux/jiffies.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/string.h> +#include <linux/types.h> +#include <linux/random.h> +#include <linux/percpu.h> +#include <linux/init.h> + +#include <asm/system.h> +#include <asm/uaccess.h> + + +/* + This is a maximally equidistributed combined Tausworthe generator + based on code from GNU Scientific Library 1.5 (30 Jun 2004) + + x_n = (s1_n ^ s2_n ^ s3_n) + + s1_{n+1} = (((s1_n & 4294967294) <<12) ^ (((s1_n <<13) ^ s1_n) >>19)) + s2_{n+1} = (((s2_n & 4294967288) << 4) ^ (((s2_n << 2) ^ s2_n) >>25)) + s3_{n+1} = (((s3_n & 4294967280) <<17) ^ (((s3_n << 3) ^ s3_n) >>11)) + + The period of this generator is about 2^88. + + From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe + Generators", Mathematics of Computation, 65, 213 (1996), 203--213. + + This is available on the net from L'Ecuyer's home page, + + http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps + ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps + + There is an erratum in the paper "Tables of Maximally + Equidistributed Combined LFSR Generators", Mathematics of + Computation, 68, 225 (1999), 261--269: + http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps + + ... the k_j most significant bits of z_j must be non- + zero, for each j. (Note: this restriction also applies to the + computer code given in [4], but was mistakenly not mentioned in + that paper.) + + This affects the seeding procedure by imposing the requirement + s1 > 1, s2 > 7, s3 > 15. + +*/ +struct nrnd_state { + u32 s1, s2, s3; +}; + +static DEFINE_PER_CPU(struct nrnd_state, net_rand_state); + +static u32 __net_random(struct nrnd_state *state) +{ +#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b) + + state->s1 = TAUSWORTHE(state->s1, 13, 19, 4294967294UL, 12); + state->s2 = TAUSWORTHE(state->s2, 2, 25, 4294967288UL, 4); + state->s3 = TAUSWORTHE(state->s3, 3, 11, 4294967280UL, 17); + + return (state->s1 ^ state->s2 ^ state->s3); +} + +static void __net_srandom(struct nrnd_state *state, unsigned long s) +{ + if (s == 0) + s = 1; /* default seed is 1 */ + +#define LCG(n) (69069 * n) + state->s1 = LCG(s); + state->s2 = LCG(state->s1); + state->s3 = LCG(state->s2); + + /* "warm it up" */ + __net_random(state); + __net_random(state); + __net_random(state); + __net_random(state); + __net_random(state); + __net_random(state); +} + + +unsigned long net_random(void) +{ + unsigned long r; + struct nrnd_state *state = &get_cpu_var(net_rand_state); + r = __net_random(state); + put_cpu_var(state); + return r; +} + + +void net_srandom(unsigned long entropy) +{ + struct nrnd_state *state = &get_cpu_var(net_rand_state); + __net_srandom(state, state->s1^entropy); + put_cpu_var(state); +} + +void __init net_random_init(void) +{ + int i; + + for (i = 0; i < NR_CPUS; i++) { + struct nrnd_state *state = &per_cpu(net_rand_state,i); + __net_srandom(state, i+jiffies); + } +} + +static int net_random_reseed(void) +{ + int i; + unsigned long seed[NR_CPUS]; + + get_random_bytes(seed, sizeof(seed)); + for (i = 0; i < NR_CPUS; i++) { + struct nrnd_state *state = &per_cpu(net_rand_state,i); + __net_srandom(state, seed[i]); + } + return 0; +} +late_initcall(net_random_reseed); + +int net_msg_cost = 5*HZ; +int net_msg_burst = 10; + +/* + * All net warning printk()s should be guarded by this function. + */ +int net_ratelimit(void) +{ + return __printk_ratelimit(net_msg_cost, net_msg_burst); +} + +EXPORT_SYMBOL(net_random); +EXPORT_SYMBOL(net_ratelimit); +EXPORT_SYMBOL(net_srandom); |