1 /* 2 * Copyright © 2016 Intel Corporation 3 * 4 * Permission is hereby granted, free of charge, to any person obtaining a 5 * copy of this software and associated documentation files (the "Software"), 6 * to deal in the Software without restriction, including without limitation 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 8 * and/or sell copies of the Software, and to permit persons to whom the 9 * Software is furnished to do so, subject to the following conditions: 10 * 11 * The above copyright notice and this permission notice (including the next 12 * paragraph) shall be included in all copies or substantial portions of the 13 * Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 21 * IN THE SOFTWARE. 22 * 23 */ 24 25 #include <linux/bitops.h> 26 #include <linux/kernel.h> 27 #include <linux/random.h> 28 #include <linux/slab.h> 29 #include <linux/types.h> 30 31 #include "i915_random.h" 32 #include "i915_utils.h" 33 34 u64 i915_prandom_u64_state(struct rnd_state *rnd) 35 { 36 u64 x; 37 38 x = prandom_u32_state(rnd); 39 x <<= 32; 40 x |= prandom_u32_state(rnd); 41 42 return x; 43 } 44 45 void i915_prandom_shuffle(void *arr, size_t elsz, size_t count, 46 struct rnd_state *state) 47 { 48 char stack[128]; 49 50 if (WARN_ON(elsz > sizeof(stack) || count > U32_MAX)) 51 return; 52 53 if (!elsz || !count) 54 return; 55 56 /* Fisher-Yates shuffle courtesy of Knuth */ 57 while (--count) { 58 size_t swp; 59 60 swp = i915_prandom_u32_max_state(count + 1, state); 61 if (swp == count) 62 continue; 63 64 memcpy(stack, arr + count * elsz, elsz); 65 memcpy(arr + count * elsz, arr + swp * elsz, elsz); 66 memcpy(arr + swp * elsz, stack, elsz); 67 } 68 } 69 70 void i915_random_reorder(unsigned int *order, unsigned int count, 71 struct rnd_state *state) 72 { 73 i915_prandom_shuffle(order, sizeof(*order), count, state); 74 } 75 76 unsigned int *i915_random_order(unsigned int count, struct rnd_state *state) 77 { 78 unsigned int *order, i; 79 80 order = kmalloc_array(count, sizeof(*order), 81 GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN); 82 if (!order) 83 return order; 84 85 for (i = 0; i < count; i++) 86 order[i] = i; 87 88 i915_random_reorder(order, count, state); 89 return order; 90 } 91 92 u64 igt_random_offset(struct rnd_state *state, 93 u64 start, u64 end, 94 u64 len, u64 align) 95 { 96 u64 range, addr; 97 98 BUG_ON(range_overflows(start, len, end)); 99 BUG_ON(round_up(start, align) > round_down(end - len, align)); 100 101 range = round_down(end - len, align) - round_up(start, align); 102 if (range) { 103 addr = i915_prandom_u64_state(state); 104 div64_u64_rem(addr, range, &addr); 105 start += addr; 106 } 107 108 return round_up(start, align); 109 } 110