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82 lines
2.1 KiB
82 lines
2.1 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* |
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* include/linux/prandom.h |
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* |
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* Include file for the fast pseudo-random 32-bit |
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* generation. |
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*/ |
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#ifndef _LINUX_PRANDOM_H |
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#define _LINUX_PRANDOM_H |
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#include <linux/types.h> |
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#include <linux/percpu.h> |
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#include <linux/random.h> |
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static inline u32 prandom_u32(void) |
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{ |
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return get_random_u32(); |
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} |
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static inline void prandom_bytes(void *buf, size_t nbytes) |
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{ |
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return get_random_bytes(buf, nbytes); |
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} |
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struct rnd_state { |
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__u32 s1, s2, s3, s4; |
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}; |
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u32 prandom_u32_state(struct rnd_state *state); |
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void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes); |
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void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state); |
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#define prandom_init_once(pcpu_state) \ |
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DO_ONCE(prandom_seed_full_state, (pcpu_state)) |
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/** |
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* prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro) |
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* @ep_ro: right open interval endpoint |
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* |
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* Returns a pseudo-random number that is in interval [0, ep_ro). Note |
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* that the result depends on PRNG being well distributed in [0, ~0U] |
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* u32 space. Here we use maximally equidistributed combined Tausworthe |
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* generator, that is, prandom_u32(). This is useful when requesting a |
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* random index of an array containing ep_ro elements, for example. |
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* |
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* Returns: pseudo-random number in interval [0, ep_ro) |
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*/ |
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static inline u32 prandom_u32_max(u32 ep_ro) |
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{ |
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return (u32)(((u64) prandom_u32() * ep_ro) >> 32); |
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} |
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/* |
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* Handle minimum values for seeds |
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*/ |
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static inline u32 __seed(u32 x, u32 m) |
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{ |
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return (x < m) ? x + m : x; |
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} |
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/** |
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* prandom_seed_state - set seed for prandom_u32_state(). |
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* @state: pointer to state structure to receive the seed. |
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* @seed: arbitrary 64-bit value to use as a seed. |
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*/ |
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static inline void prandom_seed_state(struct rnd_state *state, u64 seed) |
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{ |
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u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL; |
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state->s1 = __seed(i, 2U); |
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state->s2 = __seed(i, 8U); |
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state->s3 = __seed(i, 16U); |
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state->s4 = __seed(i, 128U); |
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} |
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/* Pseudo random number generator from numerical recipes. */ |
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static inline u32 next_pseudo_random32(u32 seed) |
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{ |
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return seed * 1664525 + 1013904223; |
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} |
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#endif
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