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1/*2 * Copyright © 2016 Intel Corporation3 *4 * Permission is hereby granted, free of charge, to any person obtaining a5 * copy of this software and associated documentation files (the "Software"),6 * to deal in the Software without restriction, including without limitation7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,8 * and/or sell copies of the Software, and to permit persons to whom the9 * Software is furnished to do so, subject to the following conditions:10 *11 * The above copyright notice and this permission notice (including the next12 * paragraph) shall be included in all copies or substantial portions of the13 * Software.14 *15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS21 * 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 34u64 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 45void 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 70void 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 76unsigned 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 92u64 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