110 lines
2.9 KiB
C
110 lines
2.9 KiB
C
/*
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* Copyright © 2016 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*
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*/
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#include <linux/bitops.h>
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#include <linux/kernel.h>
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#include <linux/random.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include "i915_random.h"
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#include "i915_utils.h"
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u64 i915_prandom_u64_state(struct rnd_state *rnd)
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{
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u64 x;
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x = prandom_u32_state(rnd);
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x <<= 32;
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x |= prandom_u32_state(rnd);
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return x;
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}
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void i915_prandom_shuffle(void *arr, size_t elsz, size_t count,
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struct rnd_state *state)
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{
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char stack[128];
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if (WARN_ON(elsz > sizeof(stack) || count > U32_MAX))
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return;
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if (!elsz || !count)
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return;
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/* Fisher-Yates shuffle courtesy of Knuth */
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while (--count) {
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size_t swp;
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swp = i915_prandom_u32_max_state(count + 1, state);
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if (swp == count)
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continue;
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memcpy(stack, arr + count * elsz, elsz);
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memcpy(arr + count * elsz, arr + swp * elsz, elsz);
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memcpy(arr + swp * elsz, stack, elsz);
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}
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}
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void i915_random_reorder(unsigned int *order, unsigned int count,
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struct rnd_state *state)
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{
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i915_prandom_shuffle(order, sizeof(*order), count, state);
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}
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unsigned int *i915_random_order(unsigned int count, struct rnd_state *state)
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{
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unsigned int *order, i;
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order = kmalloc_array(count, sizeof(*order),
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GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
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if (!order)
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return order;
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for (i = 0; i < count; i++)
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order[i] = i;
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i915_random_reorder(order, count, state);
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return order;
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}
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u64 igt_random_offset(struct rnd_state *state,
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u64 start, u64 end,
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u64 len, u64 align)
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{
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u64 range, addr;
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BUG_ON(range_overflows(start, len, end));
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BUG_ON(round_up(start, align) > round_down(end - len, align));
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range = round_down(end - len, align) - round_up(start, align);
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if (range) {
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addr = i915_prandom_u64_state(state);
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div64_u64_rem(addr, range, &addr);
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start += addr;
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}
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return round_up(start, align);
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}
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