// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
/*
* Copyright (C) 2017-2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
* Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005
* Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All rights reserved.
*
* This driver produces cryptographically secure pseudorandom data. It is divided
* into roughly six sections, each with a section header:
*
* - Initialization and readiness waiting.
* - Fast key erasure RNG, the "crng".
* - Entropy accumulation and extraction routines.
* - Entropy collection routines.
* - Userspace reader/writer interfaces.
* - Sysctl interface.
*
* The high level overview is that there is one input pool, into which
* various pieces of data are hashed. Prior to initialization, some of that
* data is then "credited" as having a certain number of bits of entropy.
* When enough bits of entropy are available, the hash is finalized and
* handed as a key to a stream cipher that expands it indefinitely for
* various consumers. This key is periodically refreshed as the various
* entropy collectors, described below, add data to the input pool.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/utsname.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/nodemask.h>
#include <
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