LXR linux/drivers/gpu/drm/i915/selftests/i915

   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
  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