[mirror_ubuntu-bionic-kernel.git] / lib / random32.c

// SPDX-License-Identifier: GPL-2.0
/*
 * This is a maximally equidistributed combined Tausworthe generator
 * based on code from GNU Scientific Library 1.5 (30 Jun 2004)
 *
 * lfsr113 version:
 *
 * x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
 *
 * s1_{n+1} = (((s1_n & 4294967294) << 18) ^ (((s1_n <<  6) ^ s1_n) >> 13))
 * s2_{n+1} = (((s2_n & 4294967288) <<  2) ^ (((s2_n <<  2) ^ s2_n) >> 27))
 * s3_{n+1} = (((s3_n & 4294967280) <<  7) ^ (((s3_n << 13) ^ s3_n) >> 21))
 * s4_{n+1} = (((s4_n & 4294967168) << 13) ^ (((s4_n <<  3) ^ s4_n) >> 12))
 *
 * The period of this generator is about 2^113 (see erratum paper).
 *
 * From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
 * Generators", Mathematics of Computation, 65, 213 (1996), 203--213:
 * http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
 * ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
 *
 * There is an erratum in the paper "Tables of Maximally Equidistributed
 * Combined LFSR Generators", Mathematics of Computation, 68, 225 (1999),
 * 261--269: http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
 *
 *      ... the k_j most significant bits of z_j must be non-zero,
 *      for each j. (Note: this restriction also applies to the
 *      computer code given in [4], but was mistakenly not mentioned
 *      in that paper.)
 *
 * This affects the seeding procedure by imposing the requirement
 * s1 > 1, s2 > 7, s3 > 15, s4 > 127.
 */

#include <linux/types.h>
#include <linux/percpu.h>
#include <linux/export.h>
#include <linux/jiffies.h>
#include <linux/random.h>
#include <linux/sched.h>
#include <asm/unaligned.h>

#ifdef CONFIG_RANDOM32_SELFTEST
static void __init prandom_state_selftest(void);
#else
static inline void prandom_state_selftest(void)
{
}
#endif

static DEFINE_PER_CPU(struct rnd_state, net_rand_state) __latent_entropy;

/**
 *	prandom_u32_state - seeded pseudo-random number generator.
 *	@state: pointer to state structure holding seeded state.
 *
 *	This is used for pseudo-randomness with no outside seeding.
 *	For more random results, use prandom_u32().
 */
u32 prandom_u32_state(struct rnd_state *state)
{
#define TAUSWORTHE(s, a, b, c, d) ((s & c) << d) ^ (((s << a) ^ s) >> b)
	state->s1 = TAUSWORTHE(state->s1,  6U, 13U, 4294967294U, 18U);
	state->s2 = TAUSWORTHE(state->s2,  2U, 27U, 4294967288U,  2U);
	state->s3 = TAUSWORTHE(state->s3, 13U, 21U, 4294967280U,  7U);
	state->s4 = TAUSWORTHE(state->s4,  3U, 12U, 4294967168U, 13U);

	return (state->s1 ^ state->s2 ^ state->s3 ^ state->s4);
}
EXPORT_SYMBOL(prandom_u32_state);

/**
 *	prandom_u32 - pseudo random number generator
 *
 *	A 32 bit pseudo-random number is generated using a fast
 *	algorithm suitable for simulation. This algorithm is NOT
 *	considered safe for cryptographic use.
 */
u32 prandom_u32(void)
{
	struct rnd_state *state = &get_cpu_var(net_rand_state);
	u32 res;

	res = prandom_u32_state(state);
	put_cpu_var(net_rand_state);

	return res;
}
EXPORT_SYMBOL(prandom_u32);

/**
 *	prandom_bytes_state - get the requested number of pseudo-random bytes
 *
 *	@state: pointer to state structure holding seeded state.
 *	@buf: where to copy the pseudo-random bytes to
 *	@bytes: the requested number of bytes
 *
 *	This is used for pseudo-randomness with no outside seeding.
 *	For more random results, use prandom_bytes().
 */
void prandom_bytes_state(struct rnd_state *state, void *buf, size_t bytes)
{
	u8 *ptr = buf;

	while (bytes >= sizeof(u32)) {
		put_unaligned(prandom_u32_state(state), (u32 *) ptr);
		ptr += sizeof(u32);
		bytes -= sizeof(u32);
	}

	if (bytes > 0) {
		u32 rem = prandom_u32_state(state);
		do {
			*ptr++ = (u8) rem;
			bytes--;
			rem >>= BITS_PER_BYTE;
		} while (bytes > 0);
	}
}
EXPORT_SYMBOL(prandom_bytes_state);

/**
 *	prandom_bytes - get the requested number of pseudo-random bytes
 *	@buf: where to copy the pseudo-random bytes to
 *	@bytes: the requested number of bytes
 */
void prandom_bytes(void *buf, size_t bytes)
{
	struct rnd_state *state = &get_cpu_var(net_rand_state);

	prandom_bytes_state(state, buf, bytes);
	put_cpu_var(net_rand_state);
}
EXPORT_SYMBOL(prandom_bytes);

static void prandom_warmup(struct rnd_state *state)
{
	/* Calling RNG ten times to satisfy recurrence condition */
	prandom_u32_state(state);
	prandom_u32_state(state);
	prandom_u32_state(state);
	prandom_u32_state(state);
	prandom_u32_state(state);
	prandom_u32_state(state);
	prandom_u32_state(state);
	prandom_u32_state(state);
	prandom_u32_state(state);
	prandom_u32_state(state);
}

static u32 __extract_hwseed(void)
{
	unsigned int val = 0;

	(void)(arch_get_random_seed_int(&val) ||
	       arch_get_random_int(&val));

	return val;
}

static void prandom_seed_early(struct rnd_state *state, u32 seed,
			       bool mix_with_hwseed)
{
#define LCG(x)	 ((x) * 69069U)	/* super-duper LCG */
#define HWSEED() (mix_with_hwseed ? __extract_hwseed() : 0)
	state->s1 = __seed(HWSEED() ^ LCG(seed),        2U);
	state->s2 = __seed(HWSEED() ^ LCG(state->s1),   8U);
	state->s3 = __seed(HWSEED() ^ LCG(state->s2),  16U);
	state->s4 = __seed(HWSEED() ^ LCG(state->s3), 128U);
}

/**
 *	prandom_seed - add entropy to pseudo random number generator
 *	@seed: seed value
 *
 *	Add some additional seeding to the prandom pool.
 */
void prandom_seed(u32 entropy)
{
	int i;
	/*
	 * No locking on the CPUs, but then somewhat random results are, well,
	 * expected.
	 */
	for_each_possible_cpu(i) {
		struct rnd_state *state = &per_cpu(net_rand_state, i);

		state->s1 = __seed(state->s1 ^ entropy, 2U);
		prandom_warmup(state);
	}
}
EXPORT_SYMBOL(prandom_seed);

/*
 *	Generate some initially weak seeding values to allow
 *	to start the prandom_u32() engine.
 */
static int __init prandom_init(void)
{
	int i;

	prandom_state_selftest();

	for_each_possible_cpu(i) {
		struct rnd_state *state = &per_cpu(net_rand_state, i);
		u32 weak_seed = (i + jiffies) ^ random_get_entropy();

		prandom_seed_early(state, weak_seed, true);
		prandom_warmup(state);
	}

	return 0;
}
core_initcall(prandom_init);

static void __prandom_timer(struct timer_list *unused);

static DEFINE_TIMER(seed_timer, __prandom_timer);

static void __prandom_timer(struct timer_list *unused)
{
	u32 entropy;
	unsigned long expires;

	get_random_bytes(&entropy, sizeof(entropy));
	prandom_seed(entropy);

	/* reseed every ~60 seconds, in [40 .. 80) interval with slack */
	expires = 40 + prandom_u32_max(40);
	seed_timer.expires = jiffies + msecs_to_jiffies(expires * MSEC_PER_SEC);

	add_timer(&seed_timer);
}

static void __init __prandom_start_seed_timer(void)
{
	seed_timer.expires = jiffies + msecs_to_jiffies(40 * MSEC_PER_SEC);
	add_timer(&seed_timer);
}

void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state)
{
	int i;

	for_each_possible_cpu(i) {
		struct rnd_state *state = per_cpu_ptr(pcpu_state, i);
		u32 seeds[4];

		get_random_bytes(&seeds, sizeof(seeds));
		state->s1 = __seed(seeds[0],   2U);
		state->s2 = __seed(seeds[1],   8U);
		state->s3 = __seed(seeds[2],  16U);
		state->s4 = __seed(seeds[3], 128U);

		prandom_warmup(state);
	}
}
EXPORT_SYMBOL(prandom_seed_full_state);

/*
 *	Generate better values after random number generator
 *	is fully initialized.
 */
static void __prandom_reseed(bool late)
{
	unsigned long flags;
	static bool latch = false;
	static DEFINE_SPINLOCK(lock);

	/* Asking for random bytes might result in bytes getting
	 * moved into the nonblocking pool and thus marking it
	 * as initialized. In this case we would double back into
	 * this function and attempt to do a late reseed.
	 * Ignore the pointless attempt to reseed again if we're
	 * already waiting for bytes when the nonblocking pool
	 * got initialized.
	 */

	/* only allow initial seeding (late == false) once */
	if (!spin_trylock_irqsave(&lock, flags))
		return;

	if (latch && !late)
		goto out;

	latch = true;
	prandom_seed_full_state(&net_rand_state);
out:
	spin_unlock_irqrestore(&lock, flags);
}

void prandom_reseed_late(void)
{
	__prandom_reseed(true);
}

static int __init prandom_reseed(void)
{
	__prandom_reseed(false);
	__prandom_start_seed_timer();
	return 0;
}
late_initcall(prandom_reseed);

#ifdef CONFIG_RANDOM32_SELFTEST
static struct prandom_test1 {
	u32 seed;
	u32 result;
} test1[] = {
	{ 1U, 3484351685U },
	{ 2U, 2623130059U },
	{ 3U, 3125133893U },
	{ 4U,  984847254U },
};

static struct prandom_test2 {
	u32 seed;
	u32 iteration;
	u32 result;
} test2[] = {
	/* Test cases against taus113 from GSL library. */
	{  931557656U, 959U, 2975593782U },
	{ 1339693295U, 876U, 3887776532U },
	{ 1545556285U, 961U, 1615538833U },
	{  601730776U, 723U, 1776162651U },
	{ 1027516047U, 687U,  511983079U },
	{  416526298U, 700U,  916156552U },
	{ 1395522032U, 652U, 2222063676U },
	{  366221443U, 617U, 2992857763U },
	{ 1539836965U, 714U, 3783265725U },
	{  556206671U, 994U,  799626459U },
	{  684907218U, 799U,  367789491U },
	{ 2121230701U, 931U, 2115467001U },
	{ 1668516451U, 644U, 3620590685U },
	{  768046066U, 883U, 2034077390U },
	{ 1989159136U, 833U, 1195767305U },
	{  536585145U, 996U, 3577259204U },
	{ 1008129373U, 642U, 1478080776U },
	{ 1740775604U, 939U, 1264980372U },
	{ 1967883163U, 508U,   10734624U },
	{ 1923019697U, 730U, 3821419629U },
	{  442079932U, 560U, 3440032343U },
	{ 1961302714U, 845U,  841962572U },
	{ 2030205964U, 962U, 1325144227U },
	{ 1160407529U, 507U,  240940858U },
	{  635482502U, 779U, 4200489746U },
	{ 1252788931U, 699U,  867195434U },
	{ 1961817131U, 719U,  668237657U },
	{ 1071468216U, 983U,  917876630U },
	{ 1281848367U, 932U, 1003100039U },
	{  582537119U, 780U, 1127273778U },
	{ 1973672777U, 853U, 1071368872U },
	{ 1896756996U, 762U, 1127851055U },
	{  847917054U, 500U, 1717499075U },
	{ 1240520510U, 951U, 2849576657U },
	{ 1685071682U, 567U, 1961810396U },
	{ 1516232129U, 557U,    3173877U },
	{ 1208118903U, 612U, 1613145022U },
	{ 1817269927U, 693U, 4279122573U },
	{ 1510091701U, 717U,  638191229U },
	{  365916850U, 807U,  600424314U },
	{  399324359U, 702U, 1803598116U },
	{ 1318480274U, 779U, 2074237022U },
	{  697758115U, 840U, 1483639402U },
	{ 1696507773U, 840U,  577415447U },
	{ 2081979121U, 981U, 3041486449U },
	{  955646687U, 742U, 3846494357U },
	{ 1250683506U, 749U,  836419859U },
	{  595003102U, 534U,  366794109U },
	{   47485338U, 558U, 3521120834U },
	{  619433479U, 610U, 3991783875U },
	{  704096520U, 518U, 4139493852U },
	{ 1712224984U, 606U, 2393312003U },
	{ 1318233152U, 922U, 3880361134U },
	{  855572992U, 761U, 1472974787U },
	{   64721421U, 703U,  683860550U },
	{  678931758U, 840U,  380616043U },
	{  692711973U, 778U, 1382361947U },
	{  677703619U, 530U, 2826914161U },
	{   92393223U, 586U, 1522128471U },
	{ 1222592920U, 743U, 3466726667U },
	{  358288986U, 695U, 1091956998U },
	{ 1935056945U, 958U,  514864477U },
	{  735675993U, 990U, 1294239989U },
	{ 1560089402U, 897U, 2238551287U },
	{   70616361U, 829U,   22483098U },
	{  368234700U, 731U, 2913875084U },
	{   20221190U, 879U, 1564152970U },
	{  539444654U, 682U, 1835141259U },
	{ 1314987297U, 840U, 1801114136U },
	{ 2019295544U, 645U, 3286438930U },
	{  469023838U, 716U, 1637918202U },
	{ 1843754496U, 653U, 2562092152U },
	{  400672036U, 809U, 4264212785U },
	{  404722249U, 965U, 2704116999U },
	{  600702209U, 758U,  584979986U },
	{  519953954U, 667U, 2574436237U },
	{ 1658071126U, 694U, 2214569490U },
	{  420480037U, 749U, 3430010866U },
	{  690103647U, 969U, 3700758083U },
	{ 1029424799U, 937U, 3787746841U },
	{ 2012608669U, 506U, 3362628973U },
	{ 1535432887U, 998U,   42610943U },
	{ 1330635533U, 857U, 3040806504U },
	{ 1223800550U, 539U, 3954229517U },
	{ 1322411537U, 680U, 3223250324U },
	{ 1877847898U, 945U, 2915147143U },
	{ 1646356099U, 874U,  965988280U },
	{  805687536U, 744U, 4032277920U },
	{ 1948093210U, 633U, 1346597684U },
	{  392609744U, 783U, 1636083295U },
	{  690241304U, 770U, 1201031298U },
	{ 1360302965U, 696U, 1665394461U },
	{ 1220090946U, 780U, 1316922812U },
	{  447092251U, 500U, 3438743375U },
	{ 1613868791U, 592U,  828546883U },
	{  523430951U, 548U, 2552392304U },
	{  726692899U, 810U, 1656872867U },
	{ 1364340021U, 836U, 3710513486U },
	{ 1986257729U, 931U,  935013962U },
	{  407983964U, 921U,  728767059U },
};

static void __init prandom_state_selftest(void)
{
	int i, j, errors = 0, runs = 0;
	bool error = false;

	for (i = 0; i < ARRAY_SIZE(test1); i++) {
		struct rnd_state state;

		prandom_seed_early(&state, test1[i].seed, false);
		prandom_warmup(&state);

		if (test1[i].result != prandom_u32_state(&state))
			error = true;
	}

	if (error)
		pr_warn("prandom: seed boundary self test failed\n");
	else
		pr_info("prandom: seed boundary self test passed\n");

	for (i = 0; i < ARRAY_SIZE(test2); i++) {
		struct rnd_state state;

		prandom_seed_early(&state, test2[i].seed, false);
		prandom_warmup(&state);

		for (j = 0; j < test2[i].iteration - 1; j++)
			prandom_u32_state(&state);

		if (test2[i].result != prandom_u32_state(&state))
			errors++;

		runs++;
		cond_resched();
	}

	if (errors)
		pr_warn("prandom: %d/%d self tests failed\n", errors, runs);
	else
		pr_info("prandom: %d self tests passed\n", runs);
}
#endif
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
aaa248f6	2	/*
d3d47eb2 DB	3	* This is a maximally equidistributed combined Tausworthe generator
	4	* based on code from GNU Scientific Library 1.5 (30 Jun 2004)
	5	*
	6	* lfsr113 version:
	7	*
	8	* x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
	9	*
	10	* s1_{n+1} = (((s1_n & 4294967294) << 18) ^ (((s1_n << 6) ^ s1_n) >> 13))
	11	* s2_{n+1} = (((s2_n & 4294967288) << 2) ^ (((s2_n << 2) ^ s2_n) >> 27))
	12	* s3_{n+1} = (((s3_n & 4294967280) << 7) ^ (((s3_n << 13) ^ s3_n) >> 21))
	13	* s4_{n+1} = (((s4_n & 4294967168) << 13) ^ (((s4_n << 3) ^ s4_n) >> 12))
	14	*
	15	* The period of this generator is about 2^113 (see erratum paper).
	16	*
	17	* From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
	18	* Generators", Mathematics of Computation, 65, 213 (1996), 203--213:
	19	* http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
	20	* ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
	21	*
	22	* There is an erratum in the paper "Tables of Maximally Equidistributed
	23	* Combined LFSR Generators", Mathematics of Computation, 68, 225 (1999),
	24	* 261--269: http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
	25	*
	26	* ... the k_j most significant bits of z_j must be non-zero,
	27	* for each j. (Note: this restriction also applies to the
	28	* computer code given in [4], but was mistakenly not mentioned
	29	* in that paper.)
	30	*
	31	* This affects the seeding procedure by imposing the requirement
	32	* s1 > 1, s2 > 7, s3 > 15, s4 > 127.
	33	*/
aaa248f6 SH	34
	35	#include <linux/types.h>
	36	#include <linux/percpu.h>
8bc3bcc9	37	#include <linux/export.h>
f6a57033	38	#include <linux/jiffies.h>
aaa248f6	39	#include <linux/random.h>
a6a9c0f1	40	#include <linux/sched.h>
a98406e2	41	#include <asm/unaligned.h>
a6a9c0f1 DB	42
	43	#ifdef CONFIG_RANDOM32_SELFTEST
	44	static void __init prandom_state_selftest(void);
4ada97ab HFS	45	#else
	46	static inline void prandom_state_selftest(void)
	47	{
	48	}
a6a9c0f1	49	#endif
aaa248f6	50
0766f788	51	static DEFINE_PER_CPU(struct rnd_state, net_rand_state) __latent_entropy;
aaa248f6	52
5960164f	53	/**
496f2f93	54	* prandom_u32_state - seeded pseudo-random number generator.
5960164f JE	55	* @state: pointer to state structure holding seeded state.
	56	*
	57	* This is used for pseudo-randomness with no outside seeding.
496f2f93	58	* For more random results, use prandom_u32().
5960164f	59	*/
496f2f93	60	u32 prandom_u32_state(struct rnd_state *state)
aaa248f6	61	{
4ada97ab	62	#define TAUSWORTHE(s, a, b, c, d) ((s & c) << d) ^ (((s << a) ^ s) >> b)
a98814ce DB	63	state->s1 = TAUSWORTHE(state->s1, 6U, 13U, 4294967294U, 18U);
	64	state->s2 = TAUSWORTHE(state->s2, 2U, 27U, 4294967288U, 2U);
	65	state->s3 = TAUSWORTHE(state->s3, 13U, 21U, 4294967280U, 7U);
	66	state->s4 = TAUSWORTHE(state->s4, 3U, 12U, 4294967168U, 13U);
aaa248f6	67
a98814ce	68	return (state->s1 ^ state->s2 ^ state->s3 ^ state->s4);
aaa248f6	69	}
496f2f93	70	EXPORT_SYMBOL(prandom_u32_state);
aaa248f6 SH	71
aaa248f6 SH	72	/**
496f2f93	73	* prandom_u32 - pseudo random number generator
aaa248f6 SH	74	*
	75	* A 32 bit pseudo-random number is generated using a fast
	76	* algorithm suitable for simulation. This algorithm is NOT
	77	* considered safe for cryptographic use.
	78	*/
496f2f93	79	u32 prandom_u32(void)
aaa248f6	80	{
aaa248f6	81	struct rnd_state *state = &get_cpu_var(net_rand_state);
d3d47eb2 DB	82	u32 res;
	83
	84	res = prandom_u32_state(state);
3796c3cb	85	put_cpu_var(net_rand_state);
d3d47eb2 DB	86
d3d47eb2 DB	87	return res;
aaa248f6	88	}
496f2f93	89	EXPORT_SYMBOL(prandom_u32);
aaa248f6	90
d3d47eb2	91	/**
6582c665 AM	92	* prandom_bytes_state - get the requested number of pseudo-random bytes
	93	*
	94	* @state: pointer to state structure holding seeded state.
	95	* @buf: where to copy the pseudo-random bytes to
	96	* @bytes: the requested number of bytes
	97	*
	98	* This is used for pseudo-randomness with no outside seeding.
	99	* For more random results, use prandom_bytes().
	100	*/
a98406e2	101	void prandom_bytes_state(struct rnd_state state, void buf, size_t bytes)
6582c665	102	{
a98406e2	103	u8 *ptr = buf;
6582c665	104
a98406e2 DB	105	while (bytes >= sizeof(u32)) {
	106	put_unaligned(prandom_u32_state(state), (u32 *) ptr);
	107	ptr += sizeof(u32);
	108	bytes -= sizeof(u32);
6582c665	109	}
6582c665	110
a98406e2 DB	111	if (bytes > 0) {
	112	u32 rem = prandom_u32_state(state);
	113	do {
	114	*ptr++ = (u8) rem;
	115	bytes--;
	116	rem >>= BITS_PER_BYTE;
	117	} while (bytes > 0);
6582c665 AM	118	}
	119	}
	120	EXPORT_SYMBOL(prandom_bytes_state);
	121
	122	/**
	123	* prandom_bytes - get the requested number of pseudo-random bytes
	124	* @buf: where to copy the pseudo-random bytes to
	125	* @bytes: the requested number of bytes
	126	*/
a98406e2	127	void prandom_bytes(void *buf, size_t bytes)
6582c665 AM	128	{
	129	struct rnd_state *state = &get_cpu_var(net_rand_state);
	130
	131	prandom_bytes_state(state, buf, bytes);
3796c3cb	132	put_cpu_var(net_rand_state);
6582c665 AM	133	}
	134	EXPORT_SYMBOL(prandom_bytes);
	135
a98814ce DB	136	static void prandom_warmup(struct rnd_state *state)
a98814ce DB	137	{
a98406e2	138	/* Calling RNG ten times to satisfy recurrence condition */
a98814ce DB	139	prandom_u32_state(state);
	140	prandom_u32_state(state);
	141	prandom_u32_state(state);
	142	prandom_u32_state(state);
	143	prandom_u32_state(state);
	144	prandom_u32_state(state);
	145	prandom_u32_state(state);
	146	prandom_u32_state(state);
	147	prandom_u32_state(state);
	148	prandom_u32_state(state);
	149	}
	150
4ada97ab	151	static u32 __extract_hwseed(void)
a6a9c0f1	152	{
a98406e2	153	unsigned int val = 0;
4ada97ab HFS	154
	155	(void)(arch_get_random_seed_int(&val) \|\|
	156	arch_get_random_int(&val));
	157
	158	return val;
	159	}
	160
	161	static void prandom_seed_early(struct rnd_state *state, u32 seed,
	162	bool mix_with_hwseed)
	163	{
	164	#define LCG(x) ((x) * 69069U) /* super-duper LCG */
	165	#define HWSEED() (mix_with_hwseed ? __extract_hwseed() : 0)
	166	state->s1 = __seed(HWSEED() ^ LCG(seed), 2U);
	167	state->s2 = __seed(HWSEED() ^ LCG(state->s1), 8U);
	168	state->s3 = __seed(HWSEED() ^ LCG(state->s2), 16U);
	169	state->s4 = __seed(HWSEED() ^ LCG(state->s3), 128U);
a6a9c0f1 DB	170	}
a6a9c0f1 DB	171
aaa248f6	172	/**
496f2f93	173	* prandom_seed - add entropy to pseudo random number generator
aaa248f6 SH	174	* @seed: seed value
aaa248f6 SH	175	*
496f2f93	176	* Add some additional seeding to the prandom pool.
aaa248f6	177	*/
496f2f93	178	void prandom_seed(u32 entropy)
aaa248f6	179	{
61407f80 AK	180	int i;
	181	/*
	182	* No locking on the CPUs, but then somewhat random results are, well,
	183	* expected.
	184	*/
0dd50d1b	185	for_each_possible_cpu(i) {
61407f80	186	struct rnd_state *state = &per_cpu(net_rand_state, i);
a98814ce DB	187
	188	state->s1 = __seed(state->s1 ^ entropy, 2U);
	189	prandom_warmup(state);
61407f80	190	}
aaa248f6	191	}
496f2f93	192	EXPORT_SYMBOL(prandom_seed);
aaa248f6 SH	193
	194	/*
	195	* Generate some initially weak seeding values to allow
496f2f93	196	* to start the prandom_u32() engine.
aaa248f6	197	*/
496f2f93	198	static int __init prandom_init(void)
aaa248f6 SH	199	{
	200	int i;
	201
a6a9c0f1	202	prandom_state_selftest();
a6a9c0f1	203
aaa248f6	204	for_each_possible_cpu(i) {
0dd50d1b	205	struct rnd_state *state = &per_cpu(net_rand_state, i);
4ada97ab	206	u32 weak_seed = (i + jiffies) ^ random_get_entropy();
697f8d03	207
4ada97ab	208	prandom_seed_early(state, weak_seed, true);
a98814ce	209	prandom_warmup(state);
aaa248f6	210	}
d3d47eb2	211
aaa248f6 SH	212	return 0;
aaa248f6 SH	213	}
496f2f93	214	core_initcall(prandom_init);
aaa248f6	215
24ed960a	216	static void __prandom_timer(struct timer_list *unused);
4ada97ab	217
1d27e3e2	218	static DEFINE_TIMER(seed_timer, __prandom_timer);
6d319202	219
24ed960a	220	static void __prandom_timer(struct timer_list *unused)
6d319202 HFS	221	{
6d319202 HFS	222	u32 entropy;
0125737a	223	unsigned long expires;
6d319202 HFS	224
	225	get_random_bytes(&entropy, sizeof(entropy));
	226	prandom_seed(entropy);
0125737a	227
6d319202	228	/* reseed every ~60 seconds, in [40 .. 80) interval with slack */
a98406e2	229	expires = 40 + prandom_u32_max(40);
0125737a DB	230	seed_timer.expires = jiffies + msecs_to_jiffies(expires * MSEC_PER_SEC);
0125737a DB	231
6d319202 HFS	232	add_timer(&seed_timer);
	233	}
	234
66b25142	235	static void __init __prandom_start_seed_timer(void)
6d319202	236	{
0125737a	237	seed_timer.expires = jiffies + msecs_to_jiffies(40 * MSEC_PER_SEC);
6d319202 HFS	238	add_timer(&seed_timer);
	239	}
	240
897ece56	241	void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state)
0dd50d1b DB	242	{
	243	int i;
	244
	245	for_each_possible_cpu(i) {
	246	struct rnd_state *state = per_cpu_ptr(pcpu_state, i);
	247	u32 seeds[4];
	248
	249	get_random_bytes(&seeds, sizeof(seeds));
	250	state->s1 = __seed(seeds[0], 2U);
	251	state->s2 = __seed(seeds[1], 8U);
	252	state->s3 = __seed(seeds[2], 16U);
	253	state->s4 = __seed(seeds[3], 128U);
	254
	255	prandom_warmup(state);
	256	}
	257	}
b07edbe1	258	EXPORT_SYMBOL(prandom_seed_full_state);
0dd50d1b	259
aaa248f6 SH	260	/*
aaa248f6 SH	261	* Generate better values after random number generator
421f91d2	262	* is fully initialized.
aaa248f6	263	*/
4af712e8	264	static void __prandom_reseed(bool late)
aaa248f6	265	{
4af712e8 HFS	266	unsigned long flags;
	267	static bool latch = false;
	268	static DEFINE_SPINLOCK(lock);
	269
05efa8c9 SL	270	/* Asking for random bytes might result in bytes getting
	271	* moved into the nonblocking pool and thus marking it
	272	* as initialized. In this case we would double back into
	273	* this function and attempt to do a late reseed.
	274	* Ignore the pointless attempt to reseed again if we're
	275	* already waiting for bytes when the nonblocking pool
	276	* got initialized.
	277	*/
	278
4af712e8	279	/* only allow initial seeding (late == false) once */
05efa8c9 SL	280	if (!spin_trylock_irqsave(&lock, flags))
	281	return;
	282
4af712e8 HFS	283	if (latch && !late)
4af712e8 HFS	284	goto out;
d3d47eb2	285
4af712e8	286	latch = true;
0dd50d1b	287	prandom_seed_full_state(&net_rand_state);
4af712e8 HFS	288	out:
	289	spin_unlock_irqrestore(&lock, flags);
	290	}
	291
	292	void prandom_reseed_late(void)
	293	{
	294	__prandom_reseed(true);
	295	}
	296
	297	static int __init prandom_reseed(void)
	298	{
	299	__prandom_reseed(false);
66b25142	300	__prandom_start_seed_timer();
aaa248f6 SH	301	return 0;
aaa248f6 SH	302	}
496f2f93	303	late_initcall(prandom_reseed);
a6a9c0f1 DB	304
	305	#ifdef CONFIG_RANDOM32_SELFTEST
	306	static struct prandom_test1 {
	307	u32 seed;
	308	u32 result;
	309	} test1[] = {
	310	{ 1U, 3484351685U },
	311	{ 2U, 2623130059U },
	312	{ 3U, 3125133893U },
	313	{ 4U, 984847254U },
	314	};
	315
	316	static struct prandom_test2 {
	317	u32 seed;
	318	u32 iteration;
	319	u32 result;
	320	} test2[] = {
	321	/* Test cases against taus113 from GSL library. */
	322	{ 931557656U, 959U, 2975593782U },
	323	{ 1339693295U, 876U, 3887776532U },
	324	{ 1545556285U, 961U, 1615538833U },
	325	{ 601730776U, 723U, 1776162651U },
	326	{ 1027516047U, 687U, 511983079U },
	327	{ 416526298U, 700U, 916156552U },
	328	{ 1395522032U, 652U, 2222063676U },
	329	{ 366221443U, 617U, 2992857763U },
	330	{ 1539836965U, 714U, 3783265725U },
	331	{ 556206671U, 994U, 799626459U },
	332	{ 684907218U, 799U, 367789491U },
	333	{ 2121230701U, 931U, 2115467001U },
	334	{ 1668516451U, 644U, 3620590685U },
	335	{ 768046066U, 883U, 2034077390U },
	336	{ 1989159136U, 833U, 1195767305U },
	337	{ 536585145U, 996U, 3577259204U },
	338	{ 1008129373U, 642U, 1478080776U },
	339	{ 1740775604U, 939U, 1264980372U },
	340	{ 1967883163U, 508U, 10734624U },
	341	{ 1923019697U, 730U, 3821419629U },
	342	{ 442079932U, 560U, 3440032343U },
	343	{ 1961302714U, 845U, 841962572U },
	344	{ 2030205964U, 962U, 1325144227U },
	345	{ 1160407529U, 507U, 240940858U },
	346	{ 635482502U, 779U, 4200489746U },
	347	{ 1252788931U, 699U, 867195434U },
	348	{ 1961817131U, 719U, 668237657U },
	349	{ 1071468216U, 983U, 917876630U },
	350	{ 1281848367U, 932U, 1003100039U },
	351	{ 582537119U, 780U, 1127273778U },
	352	{ 1973672777U, 853U, 1071368872U },
	353	{ 1896756996U, 762U, 1127851055U },
	354	{ 847917054U, 500U, 1717499075U },
	355	{ 1240520510U, 951U, 2849576657U },
	356	{ 1685071682U, 567U, 1961810396U },
	357	{ 1516232129U, 557U, 3173877U },
	358	{ 1208118903U, 612U, 1613145022U },
	359	{ 1817269927U, 693U, 4279122573U },
	360	{ 1510091701U, 717U, 638191229U },
	361	{ 365916850U, 807U, 600424314U },
	362	{ 399324359U, 702U, 1803598116U },
	363	{ 1318480274U, 779U, 2074237022U },
	364	{ 697758115U, 840U, 1483639402U },
	365	{ 1696507773U, 840U, 577415447U },
	366	{ 2081979121U, 981U, 3041486449U },
	367	{ 955646687U, 742U, 3846494357U },
368	{ 1250683506U, 749U, 836419859U },
369	{ 595003102U, 534U, 366794109U },
370	{ 47485338U, 558U, 3521120834U },
371	{ 619433479U, 610U, 3991783875U },
372	{ 704096520U, 518U, 4139493852U },
373	{ 1712224984U, 606U, 2393312003U },
374	{ 1318233152U, 922U, 3880361134U },
375	{ 855572992U, 761U, 1472974787U },
376	{ 64721421U, 703U, 683860550U },
377	{ 678931758U, 840U, 380616043U },
378	{ 692711973U, 778U, 1382361947U },
379	{ 677703619U, 530U, 2826914161U },
380	{ 92393223U, 586U, 1522128471U },
381	{ 1222592920U, 743U, 3466726667U },
382	{ 358288986U, 695U, 1091956998U },
383	{ 1935056945U, 958U, 514864477U },
384	{ 735675993U, 990U, 1294239989U },
385	{ 1560089402U, 897U, 2238551287U },
386	{ 70616361U, 829U, 22483098U },
387	{ 368234700U, 731U, 2913875084U },
388	{ 20221190U, 879U, 1564152970U },
389	{ 539444654U, 682U, 1835141259U },
390	{ 1314987297U, 840U, 1801114136U },
391	{ 2019295544U, 645U, 3286438930U },
392	{ 469023838U, 716U, 1637918202U },
393	{ 1843754496U, 653U, 2562092152U },
394	{ 400672036U, 809U, 4264212785U },
395	{ 404722249U, 965U, 2704116999U },
396	{ 600702209U, 758U, 584979986U },
397	{ 519953954U, 667U, 2574436237U },
398	{ 1658071126U, 694U, 2214569490U },
399	{ 420480037U, 749U, 3430010866U },
400	{ 690103647U, 969U, 3700758083U },
401	{ 1029424799U, 937U, 3787746841U },
402	{ 2012608669U, 506U, 3362628973U },
403	{ 1535432887U, 998U, 42610943U },
404	{ 1330635533U, 857U, 3040806504U },
405	{ 1223800550U, 539U, 3954229517U },
406	{ 1322411537U, 680U, 3223250324U },
407	{ 1877847898U, 945U, 2915147143U },
408	{ 1646356099U, 874U, 965988280U },
409	{ 805687536U, 744U, 4032277920U },
410	{ 1948093210U, 633U, 1346597684U },
411	{ 392609744U, 783U, 1636083295U },
412	{ 690241304U, 770U, 1201031298U },
413	{ 1360302965U, 696U, 1665394461U },
414	{ 1220090946U, 780U, 1316922812U },
415	{ 447092251U, 500U, 3438743375U },
416	{ 1613868791U, 592U, 828546883U },
417	{ 523430951U, 548U, 2552392304U },
418	{ 726692899U, 810U, 1656872867U },
419	{ 1364340021U, 836U, 3710513486U },
420	{ 1986257729U, 931U, 935013962U },
421	{ 407983964U, 921U, 728767059U },
422	};
423
424	static void __init prandom_state_selftest(void)
425	{
426	int i, j, errors = 0, runs = 0;
427	bool error = false;
428
429	for (i = 0; i < ARRAY_SIZE(test1); i++) {
430	struct rnd_state state;
431
4ada97ab	432	prandom_seed_early(&state, test1[i].seed, false);
a6a9c0f1 DB	433	prandom_warmup(&state);
	434
	435	if (test1[i].result != prandom_u32_state(&state))
	436	error = true;
	437	}
	438
	439	if (error)
	440	pr_warn("prandom: seed boundary self test failed\n");
	441	else
	442	pr_info("prandom: seed boundary self test passed\n");
	443
	444	for (i = 0; i < ARRAY_SIZE(test2); i++) {
	445	struct rnd_state state;
	446
4ada97ab	447	prandom_seed_early(&state, test2[i].seed, false);
a6a9c0f1 DB	448	prandom_warmup(&state);
	449
	450	for (j = 0; j < test2[i].iteration - 1; j++)
	451	prandom_u32_state(&state);
	452
	453	if (test2[i].result != prandom_u32_state(&state))
	454	errors++;
	455
	456	runs++;
	457	cond_resched();
	458	}
	459
	460	if (errors)
	461	pr_warn("prandom: %d/%d self tests failed\n", errors, runs);
	462	else
	463	pr_info("prandom: %d self tests passed\n", runs);
	464	}
	465	#endif