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/cdefs.h> 29 #include <sys/param.h> 30 #include <sys/kernel.h> 31 #include <sys/pcpu.h> 32 #include <sys/prng.h> 33 #include <sys/smp.h> 34 #include <sys/systm.h> 35 36 #if !PCG_HAS_128BIT_OPS 37 /* On 32-bit platforms, gang together two 32-bit generators. */ 38 typedef struct { 39 pcg32u_random_t states[2]; 40 } pcg64u_random_t; 41 42 static inline void 43 pcg64u_srandom_r(pcg64u_random_t *state64, uint64_t seed) 44 { 45 pcg32u_srandom_r(&state64->states[0], seed); 46 pcg32u_srandom_r(&state64->states[1], seed); 47 } 48 49 static inline uint64_t 50 pcg64u_random_r(pcg64u_random_t *state64) 51 { 52 return ((((uint64_t)pcg32u_random_r(&state64->states[0])) << 32) | 53 pcg32u_random_r(&state64->states[1])); 54 } 55 56 static inline uint64_t 57 pcg64u_boundedrand_r(pcg64u_random_t *state64, uint64_t bound) 58 { 59 uint64_t threshold = -bound % bound; 60 for (;;) { 61 uint64_t r = pcg64u_random_r(state64); 62 if (r >= threshold) 63 return (r % bound); 64 } 65 } 66 #endif 67 68 DPCPU_DEFINE_STATIC(pcg32u_random_t, pcpu_prng32_state); 69 DPCPU_DEFINE_STATIC(pcg64u_random_t, pcpu_prng64_state); 70 71 static void 72 prng_init(void *dummy __unused) 73 { 74 pcg32u_random_t *state; 75 pcg64u_random_t *state64; 76 int i; 77 78 CPU_FOREACH(i) { 79 state = DPCPU_ID_PTR(i, pcpu_prng32_state); 80 pcg32u_srandom_r(state, 1); 81 state64 = DPCPU_ID_PTR(i, pcpu_prng64_state); 82 pcg64u_srandom_r(state64, 1); 83 } 84 } 85 SYSINIT(prng_init, SI_SUB_CPU, SI_ORDER_ANY, prng_init, NULL); 86 87 uint32_t 88 prng32(void) 89 { 90 uint32_t r; 91 92 critical_enter(); 93 r = pcg32u_random_r(DPCPU_PTR(pcpu_prng32_state)); 94 critical_exit(); 95 return (r); 96 } 97 98 uint32_t 99 prng32_bounded(uint32_t bound) 100 { 101 uint32_t r; 102 103 critical_enter(); 104 r = pcg32u_boundedrand_r(DPCPU_PTR(pcpu_prng32_state), bound); 105 critical_exit(); 106 return (r); 107 } 108 109 uint64_t 110 prng64(void) 111 { 112 uint64_t r; 113 114 critical_enter(); 115 r = pcg64u_random_r(DPCPU_PTR(pcpu_prng64_state)); 116 critical_exit(); 117 return (r); 118 } 119 120 uint64_t 121 prng64_bounded(uint64_t bound) 122 { 123 uint64_t r; 124 125 critical_enter(); 126 r = pcg64u_boundedrand_r(DPCPU_PTR(pcpu_prng64_state), bound); 127 critical_exit(); 128 return (r); 129 } 130