| 1 |
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| 2 | |
| 3 | * include/linux/prandom.h
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| 4 | *
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| 5 | * Include file for the fast pseudo-random 32-bit
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| 6 | * generation.
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| 7 |
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| 8 | #ifndef _LINUX_PRANDOM_H
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| 9 | #define _LINUX_PRANDOM_H
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| 10 |
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| 11 | #include <linux/types.h>
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| 12 | #include <linux/once.h>
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| 13 | #include <linux/percpu.h>
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| 14 | #include <linux/random.h>
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| 15 |
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| 16 | struct rnd_state {
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| 17 | __u32 s1, s2, s3, s4;
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| 18 | };
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| 19 |
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| 20 | u32 prandom_u32_state(struct rnd_state *state);
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| 21 | void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
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| 22 | void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
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| 23 |
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| 24 | #define prandom_init_once(pcpu_state) \
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| 25 | DO_ONCE(prandom_seed_full_state, (pcpu_state))
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| 26 |
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| 27 | |
| 28 | * Handle minimum values for seeds
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| 29 |
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| 30 | static inline u32 __seed(u32 x, u32 m)
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| 31 | {
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| 32 | return (x < m) ? x + m : x;
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| 33 | }
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| 34 |
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| 35 | |
| 36 | * prandom_seed_state - set seed for prandom_u32_state().
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| 37 | * @state: pointer to state structure to receive the seed.
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| 38 | * @seed: arbitrary 64-bit value to use as a seed.
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| 39 |
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| 40 | static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
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| 41 | {
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| 42 | u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL;
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| 43 |
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| 44 | state->s1 = __seed(i, 2U);
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| 45 | state->s2 = __seed(i, 8U);
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| 46 | state->s3 = __seed(i, 16U);
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| 47 | state->s4 = __seed(i, 128U);
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| 48 | }
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| 49 |
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| 50 |
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| 51 | static inline u32 next_pseudo_random32(u32 seed)
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| 52 | {
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| 53 | return seed * 1664525 + 1013904223;
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| 54 | }
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| 55 |
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| 56 | #endif
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