1/*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright 2020 Conrad Meyer <cem@FreeBSD.org>. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28#include <sys/param.h> 29#include <sys/kernel.h> 30#include <sys/pcpu.h> 31#include <sys/prng.h> 32#include <sys/smp.h> 33#include <sys/systm.h> 34 35#if !PCG_HAS_128BIT_OPS 36/* On 32-bit platforms, gang together two 32-bit generators. */ 37typedef struct { 38 pcg32u_random_t states[2]; 39} pcg64u_random_t; 40 41static inline void 42pcg64u_srandom_r(pcg64u_random_t *state64, uint64_t seed) 43{ 44 pcg32u_srandom_r(&state64->states[0], seed); 45 pcg32u_srandom_r(&state64->states[1], seed); 46} 47 48static inline uint64_t 49pcg64u_random_r(pcg64u_random_t *state64) 50{ 51 return ((((uint64_t)pcg32u_random_r(&state64->states[0])) << 32) | 52 pcg32u_random_r(&state64->states[1])); 53} 54 55static inline uint64_t 56pcg64u_boundedrand_r(pcg64u_random_t *state64, uint64_t bound) 57{ 58 uint64_t threshold = -bound % bound; 59 for (;;) { 60 uint64_t r = pcg64u_random_r(state64); 61 if (r >= threshold) 62 return (r % bound); 63 } 64} 65#endif 66 67DPCPU_DEFINE_STATIC(pcg32u_random_t, pcpu_prng32_state); 68DPCPU_DEFINE_STATIC(pcg64u_random_t, pcpu_prng64_state); 69 70static void 71prng_init(void *dummy __unused) 72{ 73 pcg32u_random_t *state; 74 pcg64u_random_t *state64; 75 int i; 76 77 CPU_FOREACH(i) { 78 state = DPCPU_ID_PTR(i, pcpu_prng32_state); 79 pcg32u_srandom_r(state, 1); 80 state64 = DPCPU_ID_PTR(i, pcpu_prng64_state); 81 pcg64u_srandom_r(state64, 1); 82 } 83} 84SYSINIT(prng_init, SI_SUB_CPU, SI_ORDER_ANY, prng_init, NULL); 85 86uint32_t 87prng32(void) 88{ 89 uint32_t r; 90 91 critical_enter(); 92 r = pcg32u_random_r(DPCPU_PTR(pcpu_prng32_state)); 93 critical_exit(); 94 return (r); 95} 96 97uint32_t 98prng32_bounded(uint32_t bound) 99{ 100 uint32_t r; 101 102 critical_enter(); 103 r = pcg32u_boundedrand_r(DPCPU_PTR(pcpu_prng32_state), bound); 104 critical_exit(); 105 return (r); 106} 107 108uint64_t 109prng64(void) 110{ 111 uint64_t r; 112 113 critical_enter(); 114 r = pcg64u_random_r(DPCPU_PTR(pcpu_prng64_state)); 115 critical_exit(); 116 return (r); 117} 118 119uint64_t 120prng64_bounded(uint64_t bound) 121{ 122 uint64_t r; 123 124 critical_enter(); 125 r = pcg64u_boundedrand_r(DPCPU_PTR(pcpu_prng64_state), bound); 126 critical_exit(); 127 return (r); 128} 129