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/percpu.h> 14 #include <linux/random.h> 15 16 struct rnd_state { 17 __u32 s1, s2, s3, s4; 18 }; 19 20 u32 prandom_u32_state(struct rnd_state *state); 21 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes); 22 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state); 23 24 #define prandom_init_once(pcpu_state) \ 25 DO_ONCE(prandom_seed_full_state, (pcpu_state)) 26 27 /* Deprecated: use get_random_u32_below() instead. */ 28 static inline u32 prandom_u32_max(u32 ep_ro) 29 { 30 return get_random_u32_below(ep_ro); 31 } 32 33 /* 34 * Handle minimum values for seeds 35 */ 36 static inline u32 __seed(u32 x, u32 m) 37 { 38 return (x < m) ? x + m : x; 39 } 40 41 /** 42 * prandom_seed_state - set seed for prandom_u32_state(). 43 * @state: pointer to state structure to receive the seed. 44 * @seed: arbitrary 64-bit value to use as a seed. 45 */ 46 static inline void prandom_seed_state(struct rnd_state *state, u64 seed) 47 { 48 u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL; 49 50 state->s1 = __seed(i, 2U); 51 state->s2 = __seed(i, 8U); 52 state->s3 = __seed(i, 16U); 53 state->s4 = __seed(i, 128U); 54 } 55 56 /* Pseudo random number generator from numerical recipes. */ 57 static inline u32 next_pseudo_random32(u32 seed) 58 { 59 return seed * 1664525 + 1013904223; 60 } 61 62 #endif 63