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/* * 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_SELFTESTstatic void __init prandom_state_selftest(void);#elsestatic 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(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_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_SELFTESTstatic 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