summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--include/linux/random.h11
-rw-r--r--lib/random32.c80
2 files changed, 52 insertions, 39 deletions
diff --git a/include/linux/random.h b/include/linux/random.h
index 8ef0b70bd1f9..4002b3df4c85 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -32,10 +32,10 @@ void prandom_seed(u32 seed);
void prandom_reseed_late(void);
struct rnd_state {
- __u32 s1, s2, s3;
+ __u32 s1, s2, s3, s4;
};
-u32 prandom_u32_state(struct rnd_state *);
+u32 prandom_u32_state(struct rnd_state *state);
void prandom_bytes_state(struct rnd_state *state, void *buf, int nbytes);
/*
@@ -55,9 +55,10 @@ static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
{
u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
- state->s1 = __seed(i, 2);
- state->s2 = __seed(i, 8);
- state->s3 = __seed(i, 16);
+ state->s1 = __seed(i, 2U);
+ state->s2 = __seed(i, 8U);
+ state->s3 = __seed(i, 16U);
+ state->s4 = __seed(i, 128U);
}
#ifdef CONFIG_ARCH_RANDOM
diff --git a/lib/random32.c b/lib/random32.c
index 9f2f2fb03dfe..27adb753180f 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -2,19 +2,19 @@
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)
+ lfsr113 version:
- 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))
+ x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
- The period of this generator is about 2^88.
+ s1_{n+1} = (((s1_n & 4294967294) << 18) ^ (((s1_n << 6) ^ s1_n) >> 13))
+ s2_{n+1} = (((s2_n & 4294967288) << 2) ^ (((s2_n << 2) ^ s2_n) >> 27))
+ s3_{n+1} = (((s3_n & 4294967280) << 7) ^ (((s3_n << 13) ^ s3_n) >> 21))
+ s4_{n+1} = (((s4_n & 4294967168) << 13) ^ (((s4_n << 3) ^ s4_n) >> 12))
- 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,
+ The period of this generator is about 2^113 (see erratum paper).
+ From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
+ Generators", Mathematics of Computation, 65, 213 (1996), 203--213:
http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
@@ -29,7 +29,7 @@
that paper.)
This affects the seeding procedure by imposing the requirement
- s1 > 1, s2 > 7, s3 > 15.
+ s1 > 1, s2 > 7, s3 > 15, s4 > 127.
*/
@@ -52,11 +52,12 @@ u32 prandom_u32_state(struct rnd_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);
+ state->s1 = TAUSWORTHE(state->s1, 6U, 13U, 4294967294U, 18U);
+ state->s2 = TAUSWORTHE(state->s2, 2U, 27U, 4294967288U, 2U);
+ state->s3 = TAUSWORTHE(state->s3, 13U, 21U, 4294967280U, 7U);
+ state->s4 = TAUSWORTHE(state->s4, 3U, 12U, 4294967168U, 13U);
- return (state->s1 ^ state->s2 ^ state->s3);
+ return (state->s1 ^ state->s2 ^ state->s3 ^ state->s4);
}
EXPORT_SYMBOL(prandom_u32_state);
@@ -126,6 +127,21 @@ void prandom_bytes(void *buf, int bytes)
}
EXPORT_SYMBOL(prandom_bytes);
+static void prandom_warmup(struct rnd_state *state)
+{
+ /* Calling RNG ten times to satify recurrence condition */
+ prandom_u32_state(state);
+ prandom_u32_state(state);
+ prandom_u32_state(state);
+ prandom_u32_state(state);
+ prandom_u32_state(state);
+ prandom_u32_state(state);
+ prandom_u32_state(state);
+ prandom_u32_state(state);
+ prandom_u32_state(state);
+ prandom_u32_state(state);
+}
+
/**
* prandom_seed - add entropy to pseudo random number generator
* @seed: seed value
@@ -141,8 +157,9 @@ void prandom_seed(u32 entropy)
*/
for_each_possible_cpu (i) {
struct rnd_state *state = &per_cpu(net_rand_state, i);
- state->s1 = __seed(state->s1 ^ entropy, 2);
- prandom_u32_state(state);
+
+ state->s1 = __seed(state->s1 ^ entropy, 2U);
+ prandom_warmup(state);
}
}
EXPORT_SYMBOL(prandom_seed);
@@ -158,18 +175,13 @@ static int __init prandom_init(void)
for_each_possible_cpu(i) {
struct rnd_state *state = &per_cpu(net_rand_state,i);
-#define LCG(x) ((x) * 69069) /* super-duper LCG */
- state->s1 = __seed(LCG(i + jiffies), 2);
- state->s2 = __seed(LCG(state->s1), 8);
- state->s3 = __seed(LCG(state->s2), 16);
-
- /* "warm it up" */
- prandom_u32_state(state);
- prandom_u32_state(state);
- prandom_u32_state(state);
- prandom_u32_state(state);
- prandom_u32_state(state);
- prandom_u32_state(state);
+#define LCG(x) ((x) * 69069U) /* super-duper LCG */
+ state->s1 = __seed(LCG((i + jiffies) ^ random_get_entropy()), 2U);
+ state->s2 = __seed(LCG(state->s1), 8U);
+ state->s3 = __seed(LCG(state->s2), 16U);
+ state->s4 = __seed(LCG(state->s3), 128U);
+
+ prandom_warmup(state);
}
return 0;
}
@@ -215,15 +227,15 @@ static void __prandom_reseed(bool late)
for_each_possible_cpu(i) {
struct rnd_state *state = &per_cpu(net_rand_state,i);
- u32 seeds[3];
+ u32 seeds[4];
get_random_bytes(&seeds, sizeof(seeds));
- state->s1 = __seed(seeds[0], 2);
- state->s2 = __seed(seeds[1], 8);
- state->s3 = __seed(seeds[2], 16);
+ state->s1 = __seed(seeds[0], 2U);
+ state->s2 = __seed(seeds[1], 8U);
+ state->s3 = __seed(seeds[2], 16U);
+ state->s4 = __seed(seeds[3], 128U);
- /* mix it in */
- prandom_u32_state(state);
+ prandom_warmup(state);
}
out:
spin_unlock_irqrestore(&lock, flags);