1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * include/linux/prandom.h 4 * 5 * Include file for the fast pseudo-random 32-bit 6 * generation. 7 */ 8#ifndef _LINUX_PRANDOM_H 9#define _LINUX_PRANDOM_H 10 11#include <linux/types.h> 12#include <linux/once.h> 13#include <linux/random.h> 14 15struct rnd_state { 16 __u32 s1, s2, s3, s4; 17}; 18 19u32 prandom_u32_state(struct rnd_state *state); 20void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes); 21void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state); 22 23#define prandom_init_once(pcpu_state) \ 24 DO_ONCE(prandom_seed_full_state, (pcpu_state)) 25 26/* 27 * Handle minimum values for seeds 28 */ 29static inline u32 __seed(u32 x, u32 m) 30{ 31 return (x < m) ? x + m : x; 32} 33 34/** 35 * prandom_seed_state - set seed for prandom_u32_state(). 36 * @state: pointer to state structure to receive the seed. 37 * @seed: arbitrary 64-bit value to use as a seed. 38 */ 39static inline void prandom_seed_state(struct rnd_state *state, u64 seed) 40{ 41 u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL; 42 43 state->s1 = __seed(i, 2U); 44 state->s2 = __seed(i, 8U); 45 state->s3 = __seed(i, 16U); 46 state->s4 = __seed(i, 128U); 47} 48 49/* Pseudo random number generator from numerical recipes. */ 50static inline u32 next_pseudo_random32(u32 seed) 51{ 52 return seed * 1664525 + 1013904223; 53} 54 55#endif 56