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. */ 37 typedef struct { 38 pcg32u_random_t states[2]; 39 } pcg64u_random_t; 40 41 static inline void 42 pcg64u_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 48 static inline uint64_t 49 pcg64u_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 55 static inline uint64_t 56 pcg64u_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 67 DPCPU_DEFINE_STATIC(pcg32u_random_t, pcpu_prng32_state); 68 DPCPU_DEFINE_STATIC(pcg64u_random_t, pcpu_prng64_state); 69 70 static void 71 prng_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 } 84 SYSINIT(prng_init, SI_SUB_CPU, SI_ORDER_ANY, prng_init, NULL); 85 86 uint32_t 87 prng32(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 97 uint32_t 98 prng32_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 } 107 108 uint64_t 109 prng64(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 } 118 119 uint64_t 120 prng64_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