cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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i915_random.c (2959B)

      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}