summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--include/linux/random.h28
-rw-r--r--lib/random32.c38
2 files changed, 45 insertions, 21 deletions
diff --git a/include/linux/random.h b/include/linux/random.h
index 25d02fe5c9b5..fb7ab9de5f36 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -40,6 +40,10 @@ struct rand_pool_info {
__u32 buf[0];
};
+struct rnd_state {
+ __u32 s1, s2, s3;
+};
+
/* Exported functions */
#ifdef __KERNEL__
@@ -74,6 +78,30 @@ unsigned long randomize_range(unsigned long start, unsigned long end, unsigned l
u32 random32(void);
void srandom32(u32 seed);
+u32 prandom32(struct rnd_state *);
+
+/*
+ * Handle minimum values for seeds
+ */
+static inline u32 __seed(u32 x, u32 m)
+{
+ return (x < m) ? x + m : x;
+}
+
+/**
+ * prandom32_seed - set seed for prandom32().
+ * @state: pointer to state structure to receive the seed.
+ * @seed: arbitrary 64-bit value to use as a seed.
+ */
+static inline void prandom32_seed(struct rnd_state *state, u64 seed)
+{
+ u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
+
+ state->s1 = __seed(i, 1);
+ state->s2 = __seed(i, 7);
+ state->s3 = __seed(i, 15);
+}
+
#endif /* __KERNEL___ */
#endif /* _LINUX_RANDOM_H */
diff --git a/lib/random32.c b/lib/random32.c
index 217d5c4b666d..870dc3fc0f0f 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -39,13 +39,16 @@
#include <linux/jiffies.h>
#include <linux/random.h>
-struct rnd_state {
- u32 s1, s2, s3;
-};
-
static DEFINE_PER_CPU(struct rnd_state, net_rand_state);
-static u32 __random32(struct rnd_state *state)
+/**
+ * prandom32 - seeded pseudo-random number generator.
+ * @state: pointer to state structure holding seeded state.
+ *
+ * This is used for pseudo-randomness with no outside seeding.
+ * For more random results, use random32().
+ */
+u32 prandom32(struct rnd_state *state)
{
#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b)
@@ -55,14 +58,7 @@ static u32 __random32(struct rnd_state *state)
return (state->s1 ^ state->s2 ^ state->s3);
}
-
-/*
- * Handle minimum values for seeds
- */
-static inline u32 __seed(u32 x, u32 m)
-{
- return (x < m) ? x + m : x;
-}
+EXPORT_SYMBOL(prandom32);
/**
* random32 - pseudo random number generator
@@ -75,7 +71,7 @@ u32 random32(void)
{
unsigned long r;
struct rnd_state *state = &get_cpu_var(net_rand_state);
- r = __random32(state);
+ r = prandom32(state);
put_cpu_var(state);
return r;
}
@@ -118,12 +114,12 @@ static int __init random32_init(void)
state->s3 = __seed(LCG(state->s2), 15);
/* "warm it up" */
- __random32(state);
- __random32(state);
- __random32(state);
- __random32(state);
- __random32(state);
- __random32(state);
+ prandom32(state);
+ prandom32(state);
+ prandom32(state);
+ prandom32(state);
+ prandom32(state);
+ prandom32(state);
}
return 0;
}
@@ -147,7 +143,7 @@ static int __init random32_reseed(void)
state->s3 = __seed(seeds[2], 15);
/* mix it in */
- __random32(state);
+ prandom32(state);
}
return 0;
}