| 1 | // SPDX-License-Identifier: GPL-2.0 |
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| 2 | #include <linux/bitops.h> |
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| 3 | #include <linux/kernel.h> |
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| 4 | #include <linux/random.h> |
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| 5 | #include <linux/slab.h> |
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| 6 | #include <linux/types.h> |
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| 7 | |
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| 8 | #include "drm_random.h" |
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| 9 | |
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| 10 | u32 drm_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state) |
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| 11 | { |
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| 12 | return upper_32_bits((u64)prandom_u32_state(state) * ep_ro); |
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| 13 | } |
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| 14 | EXPORT_SYMBOL(drm_prandom_u32_max_state); |
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| 15 | |
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| 16 | void drm_random_reorder(unsigned int *order, unsigned int count, |
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| 17 | struct rnd_state *state) |
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| 18 | { |
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| 19 | unsigned int i, j; |
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| 20 | |
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| 21 | for (i = 0; i < count; ++i) { |
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| 22 | BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32)); |
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| 23 | j = drm_prandom_u32_max_state(count, state); |
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| 24 | swap(order[i], order[j]); |
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| 25 | } |
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| 26 | } |
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| 27 | EXPORT_SYMBOL(drm_random_reorder); |
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| 28 | |
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| 29 | unsigned int *drm_random_order(unsigned int count, struct rnd_state *state) |
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| 30 | { |
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| 31 | unsigned int *order, i; |
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| 32 | |
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| 33 | order = kmalloc_array(n: count, size: sizeof(*order), GFP_KERNEL); |
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| 34 | if (!order) |
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| 35 | return order; |
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| 36 | |
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| 37 | for (i = 0; i < count; i++) |
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| 38 | order[i] = i; |
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| 39 | |
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| 40 | drm_random_reorder(order, count, state); |
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| 41 | return order; |
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| 42 | } |
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| 43 | EXPORT_SYMBOL(drm_random_order); |
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| 44 | |
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