cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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prandom.h (2122B)

      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/percpu.h>
     13#include <linux/random.h>
     14
     15static inline u32 prandom_u32(void)
     16{
     17	return get_random_u32();
     18}
     19
     20static inline void prandom_bytes(void *buf, size_t nbytes)
     21{
     22	return get_random_bytes(buf, nbytes);
     23}
     24
     25struct rnd_state {
     26	__u32 s1, s2, s3, s4;
     27};
     28
     29u32 prandom_u32_state(struct rnd_state *state);
     30void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
     31void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
     32
     33#define prandom_init_once(pcpu_state)			\
     34	DO_ONCE(prandom_seed_full_state, (pcpu_state))
     35
     36/**
     37 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
     38 * @ep_ro: right open interval endpoint
     39 *
     40 * Returns a pseudo-random number that is in interval [0, ep_ro). Note
     41 * that the result depends on PRNG being well distributed in [0, ~0U]
     42 * u32 space. Here we use maximally equidistributed combined Tausworthe
     43 * generator, that is, prandom_u32(). This is useful when requesting a
     44 * random index of an array containing ep_ro elements, for example.
     45 *
     46 * Returns: pseudo-random number in interval [0, ep_ro)
     47 */
     48static inline u32 prandom_u32_max(u32 ep_ro)
     49{
     50	return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
     51}
     52
     53/*
     54 * Handle minimum values for seeds
     55 */
     56static inline u32 __seed(u32 x, u32 m)
     57{
     58	return (x < m) ? x + m : x;
     59}
     60
     61/**
     62 * prandom_seed_state - set seed for prandom_u32_state().
     63 * @state: pointer to state structure to receive the seed.
     64 * @seed: arbitrary 64-bit value to use as a seed.
     65 */
     66static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
     67{
     68	u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL;
     69
     70	state->s1 = __seed(i,   2U);
     71	state->s2 = __seed(i,   8U);
     72	state->s3 = __seed(i,  16U);
     73	state->s4 = __seed(i, 128U);
     74}
     75
     76/* Pseudo random number generator from numerical recipes. */
     77static inline u32 next_pseudo_random32(u32 seed)
     78{
     79	return seed * 1664525 + 1013904223;
     80}
     81
     82#endif