[linux.git] / lib / random32.c

/*
 * 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>

#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);

/**
 *	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(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, int bytes)
{
	unsigned char *p = buf;
	int i;

	for (i = 0; i < round_down(bytes, sizeof(u32)); i += sizeof(u32)) {
		u32 random = prandom_u32_state(state);
		int j;

		for (j = 0; j < sizeof(u32); j++) {
			p[i + j] = random;
			random >>= BITS_PER_BYTE;
		}
	}
	if (i < bytes) {
		u32 random = prandom_u32_state(state);

		for (; i < bytes; i++) {
			p[i] = random;
			random >>= BITS_PER_BYTE;
		}
	}
}
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, int bytes)
{
	struct rnd_state *state = &get_cpu_var(net_rand_state);

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

static void prandom_warmup(struct rnd_state *state)
{
	/* Calling RNG ten times to satify 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)
{
	u32 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(unsigned long dontcare);

static DEFINE_TIMER(seed_timer, __prandom_timer, 0, 0);

static void __prandom_timer(unsigned long dontcare)
{
	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() % 40);
	seed_timer.expires = jiffies + msecs_to_jiffies(expires * MSEC_PER_SEC);

	add_timer(&seed_timer);
}

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

/*
 *	Generate better values after random number generator
 *	is fully initialized.
 */
static void __prandom_reseed(bool late)
{
	int i;
	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;

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