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a98406e22c
This patch addresses a couple of minor items, mostly addesssing
prandom_bytes(): 1) prandom_bytes{,_state}() should use size_t
for length arguments, 2) We can use put_unaligned() when filling
the array instead of open coding it [ perhaps some archs will
further benefit from their own arch specific implementation when
GCC cannot make up for it ], 3) Fix a typo, 4) Better use unsigned
int as type for getting the arch seed, 5) Make use of
prandom_u32_max() for timer slack.
Regarding the change to put_unaligned(), callers of prandom_bytes()
which internally invoke prandom_bytes_state(), don't bother as
they expect the array to be filled randomly and don't have any
control of the internal state what-so-ever (that's also why we
have periodic reseeding there, etc), so they really don't care.
Now for the direct callers of prandom_bytes_state(), which
are solely located in test cases for MTD devices, that is,
drivers/mtd/tests/{oobtest.c,pagetest.c,subpagetest.c}:
These tests basically fill a test write-vector through
prandom_bytes_state() with an a-priori defined seed each time
and write that to a MTD device. Later on, they set up a read-vector
and read back that blocks from the device. So in the verification
phase, the write-vector is being re-setup [ so same seed and
prandom_bytes_state() called ], and then memcmp()'ed against the
read-vector to check if the data is the same.
Akinobu, Lothar and I also tested this patch and it runs through
the 3 relevant MTD test cases w/o any errors on the nandsim device
(simulator for MTD devs) for x86_64, ppc64, ARM (i.MX28, i.MX53
and i.MX6):
# modprobe nandsim first_id_byte=0x20 second_id_byte=0xac \
third_id_byte=0x00 fourth_id_byte=0x15
# modprobe mtd_oobtest dev=0
# modprobe mtd_pagetest dev=0
# modprobe mtd_subpagetest dev=0
We also don't have any users depending directly on a particular
result of the PRNG (except the PRNG self-test itself), and that's
just fine as it e.g. allowed us easily to do things like upgrading
from taus88 to taus113.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Tested-by: Akinobu Mita <akinobu.mita@gmail.com>
Tested-by: Lothar Waßmann <LW@KARO-electronics.de>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
460 lines
13 KiB
C
460 lines
13 KiB
C
/*
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* This is a maximally equidistributed combined Tausworthe generator
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* based on code from GNU Scientific Library 1.5 (30 Jun 2004)
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*
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* lfsr113 version:
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*
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* x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
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*
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* s1_{n+1} = (((s1_n & 4294967294) << 18) ^ (((s1_n << 6) ^ s1_n) >> 13))
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* s2_{n+1} = (((s2_n & 4294967288) << 2) ^ (((s2_n << 2) ^ s2_n) >> 27))
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* s3_{n+1} = (((s3_n & 4294967280) << 7) ^ (((s3_n << 13) ^ s3_n) >> 21))
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* s4_{n+1} = (((s4_n & 4294967168) << 13) ^ (((s4_n << 3) ^ s4_n) >> 12))
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*
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* The period of this generator is about 2^113 (see erratum paper).
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*
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* From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
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* Generators", Mathematics of Computation, 65, 213 (1996), 203--213:
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* http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
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* ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
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*
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* There is an erratum in the paper "Tables of Maximally Equidistributed
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* Combined LFSR Generators", Mathematics of Computation, 68, 225 (1999),
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* 261--269: http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
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*
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* ... the k_j most significant bits of z_j must be non-zero,
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* for each j. (Note: this restriction also applies to the
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* computer code given in [4], but was mistakenly not mentioned
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* in that paper.)
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*
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* This affects the seeding procedure by imposing the requirement
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* s1 > 1, s2 > 7, s3 > 15, s4 > 127.
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*/
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#include <linux/types.h>
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#include <linux/percpu.h>
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#include <linux/export.h>
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#include <linux/jiffies.h>
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#include <linux/random.h>
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#include <linux/sched.h>
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#include <asm/unaligned.h>
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#ifdef CONFIG_RANDOM32_SELFTEST
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static void __init prandom_state_selftest(void);
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#else
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static inline void prandom_state_selftest(void)
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{
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}
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#endif
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static DEFINE_PER_CPU(struct rnd_state, net_rand_state);
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/**
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* prandom_u32_state - seeded pseudo-random number generator.
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* @state: pointer to state structure holding seeded state.
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*
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* This is used for pseudo-randomness with no outside seeding.
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* For more random results, use prandom_u32().
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*/
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u32 prandom_u32_state(struct rnd_state *state)
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{
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#define TAUSWORTHE(s, a, b, c, d) ((s & c) << d) ^ (((s << a) ^ s) >> b)
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state->s1 = TAUSWORTHE(state->s1, 6U, 13U, 4294967294U, 18U);
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state->s2 = TAUSWORTHE(state->s2, 2U, 27U, 4294967288U, 2U);
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state->s3 = TAUSWORTHE(state->s3, 13U, 21U, 4294967280U, 7U);
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state->s4 = TAUSWORTHE(state->s4, 3U, 12U, 4294967168U, 13U);
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return (state->s1 ^ state->s2 ^ state->s3 ^ state->s4);
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}
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EXPORT_SYMBOL(prandom_u32_state);
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/**
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* prandom_u32 - pseudo random number generator
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*
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* A 32 bit pseudo-random number is generated using a fast
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* algorithm suitable for simulation. This algorithm is NOT
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* considered safe for cryptographic use.
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*/
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u32 prandom_u32(void)
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{
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struct rnd_state *state = &get_cpu_var(net_rand_state);
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u32 res;
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res = prandom_u32_state(state);
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put_cpu_var(state);
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return res;
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}
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EXPORT_SYMBOL(prandom_u32);
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/**
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* prandom_bytes_state - get the requested number of pseudo-random bytes
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*
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* @state: pointer to state structure holding seeded state.
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* @buf: where to copy the pseudo-random bytes to
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* @bytes: the requested number of bytes
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*
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* This is used for pseudo-randomness with no outside seeding.
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* For more random results, use prandom_bytes().
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*/
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void prandom_bytes_state(struct rnd_state *state, void *buf, size_t bytes)
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{
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u8 *ptr = buf;
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while (bytes >= sizeof(u32)) {
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put_unaligned(prandom_u32_state(state), (u32 *) ptr);
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ptr += sizeof(u32);
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bytes -= sizeof(u32);
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}
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if (bytes > 0) {
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u32 rem = prandom_u32_state(state);
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do {
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*ptr++ = (u8) rem;
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bytes--;
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rem >>= BITS_PER_BYTE;
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} while (bytes > 0);
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}
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}
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EXPORT_SYMBOL(prandom_bytes_state);
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/**
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* prandom_bytes - get the requested number of pseudo-random bytes
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* @buf: where to copy the pseudo-random bytes to
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* @bytes: the requested number of bytes
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*/
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void prandom_bytes(void *buf, size_t bytes)
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{
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struct rnd_state *state = &get_cpu_var(net_rand_state);
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prandom_bytes_state(state, buf, bytes);
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put_cpu_var(state);
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}
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EXPORT_SYMBOL(prandom_bytes);
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static void prandom_warmup(struct rnd_state *state)
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{
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/* Calling RNG ten times to satisfy recurrence condition */
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prandom_u32_state(state);
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prandom_u32_state(state);
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prandom_u32_state(state);
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prandom_u32_state(state);
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prandom_u32_state(state);
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prandom_u32_state(state);
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prandom_u32_state(state);
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prandom_u32_state(state);
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prandom_u32_state(state);
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prandom_u32_state(state);
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}
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static u32 __extract_hwseed(void)
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{
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unsigned int val = 0;
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(void)(arch_get_random_seed_int(&val) ||
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arch_get_random_int(&val));
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return val;
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}
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static void prandom_seed_early(struct rnd_state *state, u32 seed,
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bool mix_with_hwseed)
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{
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#define LCG(x) ((x) * 69069U) /* super-duper LCG */
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#define HWSEED() (mix_with_hwseed ? __extract_hwseed() : 0)
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state->s1 = __seed(HWSEED() ^ LCG(seed), 2U);
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state->s2 = __seed(HWSEED() ^ LCG(state->s1), 8U);
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state->s3 = __seed(HWSEED() ^ LCG(state->s2), 16U);
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state->s4 = __seed(HWSEED() ^ LCG(state->s3), 128U);
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}
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/**
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* prandom_seed - add entropy to pseudo random number generator
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* @seed: seed value
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*
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* Add some additional seeding to the prandom pool.
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*/
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void prandom_seed(u32 entropy)
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{
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int i;
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/*
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* No locking on the CPUs, but then somewhat random results are, well,
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* expected.
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*/
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for_each_possible_cpu (i) {
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struct rnd_state *state = &per_cpu(net_rand_state, i);
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state->s1 = __seed(state->s1 ^ entropy, 2U);
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prandom_warmup(state);
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}
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}
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EXPORT_SYMBOL(prandom_seed);
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/*
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* Generate some initially weak seeding values to allow
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* to start the prandom_u32() engine.
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*/
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static int __init prandom_init(void)
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{
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int i;
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prandom_state_selftest();
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for_each_possible_cpu(i) {
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struct rnd_state *state = &per_cpu(net_rand_state,i);
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u32 weak_seed = (i + jiffies) ^ random_get_entropy();
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prandom_seed_early(state, weak_seed, true);
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prandom_warmup(state);
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}
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return 0;
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}
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core_initcall(prandom_init);
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static void __prandom_timer(unsigned long dontcare);
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static DEFINE_TIMER(seed_timer, __prandom_timer, 0, 0);
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static void __prandom_timer(unsigned long dontcare)
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{
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u32 entropy;
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unsigned long expires;
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get_random_bytes(&entropy, sizeof(entropy));
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prandom_seed(entropy);
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/* reseed every ~60 seconds, in [40 .. 80) interval with slack */
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expires = 40 + prandom_u32_max(40);
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seed_timer.expires = jiffies + msecs_to_jiffies(expires * MSEC_PER_SEC);
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add_timer(&seed_timer);
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}
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static void __init __prandom_start_seed_timer(void)
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{
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set_timer_slack(&seed_timer, HZ);
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seed_timer.expires = jiffies + msecs_to_jiffies(40 * MSEC_PER_SEC);
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add_timer(&seed_timer);
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}
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/*
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* Generate better values after random number generator
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* is fully initialized.
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*/
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static void __prandom_reseed(bool late)
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{
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int i;
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unsigned long flags;
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static bool latch = false;
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static DEFINE_SPINLOCK(lock);
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/* Asking for random bytes might result in bytes getting
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* moved into the nonblocking pool and thus marking it
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* as initialized. In this case we would double back into
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* this function and attempt to do a late reseed.
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* Ignore the pointless attempt to reseed again if we're
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* already waiting for bytes when the nonblocking pool
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* got initialized.
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*/
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/* only allow initial seeding (late == false) once */
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if (!spin_trylock_irqsave(&lock, flags))
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return;
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if (latch && !late)
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goto out;
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latch = true;
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for_each_possible_cpu(i) {
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struct rnd_state *state = &per_cpu(net_rand_state,i);
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u32 seeds[4];
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get_random_bytes(&seeds, sizeof(seeds));
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state->s1 = __seed(seeds[0], 2U);
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state->s2 = __seed(seeds[1], 8U);
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state->s3 = __seed(seeds[2], 16U);
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state->s4 = __seed(seeds[3], 128U);
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prandom_warmup(state);
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}
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out:
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spin_unlock_irqrestore(&lock, flags);
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}
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void prandom_reseed_late(void)
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{
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__prandom_reseed(true);
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}
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static int __init prandom_reseed(void)
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{
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__prandom_reseed(false);
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__prandom_start_seed_timer();
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return 0;
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}
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late_initcall(prandom_reseed);
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#ifdef CONFIG_RANDOM32_SELFTEST
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static struct prandom_test1 {
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u32 seed;
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u32 result;
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} test1[] = {
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{ 1U, 3484351685U },
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{ 2U, 2623130059U },
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{ 3U, 3125133893U },
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{ 4U, 984847254U },
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};
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static struct prandom_test2 {
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u32 seed;
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u32 iteration;
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u32 result;
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} test2[] = {
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/* Test cases against taus113 from GSL library. */
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{ 931557656U, 959U, 2975593782U },
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{ 1339693295U, 876U, 3887776532U },
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{ 1545556285U, 961U, 1615538833U },
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{ 601730776U, 723U, 1776162651U },
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{ 1027516047U, 687U, 511983079U },
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{ 416526298U, 700U, 916156552U },
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{ 1395522032U, 652U, 2222063676U },
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{ 366221443U, 617U, 2992857763U },
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{ 1539836965U, 714U, 3783265725U },
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{ 556206671U, 994U, 799626459U },
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{ 684907218U, 799U, 367789491U },
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{ 2121230701U, 931U, 2115467001U },
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{ 1668516451U, 644U, 3620590685U },
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{ 768046066U, 883U, 2034077390U },
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{ 1989159136U, 833U, 1195767305U },
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{ 536585145U, 996U, 3577259204U },
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{ 1008129373U, 642U, 1478080776U },
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{ 1740775604U, 939U, 1264980372U },
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{ 1967883163U, 508U, 10734624U },
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{ 1923019697U, 730U, 3821419629U },
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{ 442079932U, 560U, 3440032343U },
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{ 1961302714U, 845U, 841962572U },
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{ 2030205964U, 962U, 1325144227U },
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{ 1160407529U, 507U, 240940858U },
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{ 635482502U, 779U, 4200489746U },
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{ 1252788931U, 699U, 867195434U },
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{ 1961817131U, 719U, 668237657U },
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{ 1071468216U, 983U, 917876630U },
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{ 1281848367U, 932U, 1003100039U },
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{ 582537119U, 780U, 1127273778U },
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{ 1973672777U, 853U, 1071368872U },
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{ 1896756996U, 762U, 1127851055U },
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{ 847917054U, 500U, 1717499075U },
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{ 1240520510U, 951U, 2849576657U },
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{ 1685071682U, 567U, 1961810396U },
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{ 1516232129U, 557U, 3173877U },
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{ 1208118903U, 612U, 1613145022U },
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{ 1817269927U, 693U, 4279122573U },
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{ 1510091701U, 717U, 638191229U },
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{ 365916850U, 807U, 600424314U },
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{ 399324359U, 702U, 1803598116U },
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{ 1318480274U, 779U, 2074237022U },
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{ 697758115U, 840U, 1483639402U },
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{ 1696507773U, 840U, 577415447U },
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{ 2081979121U, 981U, 3041486449U },
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{ 955646687U, 742U, 3846494357U },
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{ 1250683506U, 749U, 836419859U },
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{ 595003102U, 534U, 366794109U },
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{ 47485338U, 558U, 3521120834U },
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{ 619433479U, 610U, 3991783875U },
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{ 704096520U, 518U, 4139493852U },
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{ 1712224984U, 606U, 2393312003U },
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{ 1318233152U, 922U, 3880361134U },
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{ 855572992U, 761U, 1472974787U },
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{ 64721421U, 703U, 683860550U },
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{ 678931758U, 840U, 380616043U },
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{ 692711973U, 778U, 1382361947U },
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{ 677703619U, 530U, 2826914161U },
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{ 92393223U, 586U, 1522128471U },
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{ 1222592920U, 743U, 3466726667U },
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{ 358288986U, 695U, 1091956998U },
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{ 1935056945U, 958U, 514864477U },
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{ 735675993U, 990U, 1294239989U },
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{ 1560089402U, 897U, 2238551287U },
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{ 70616361U, 829U, 22483098U },
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{ 368234700U, 731U, 2913875084U },
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{ 20221190U, 879U, 1564152970U },
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{ 539444654U, 682U, 1835141259U },
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{ 1314987297U, 840U, 1801114136U },
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{ 2019295544U, 645U, 3286438930U },
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{ 469023838U, 716U, 1637918202U },
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{ 1843754496U, 653U, 2562092152U },
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{ 400672036U, 809U, 4264212785U },
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{ 404722249U, 965U, 2704116999U },
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{ 600702209U, 758U, 584979986U },
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{ 519953954U, 667U, 2574436237U },
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{ 1658071126U, 694U, 2214569490U },
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{ 420480037U, 749U, 3430010866U },
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{ 690103647U, 969U, 3700758083U },
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{ 1029424799U, 937U, 3787746841U },
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{ 2012608669U, 506U, 3362628973U },
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{ 1535432887U, 998U, 42610943U },
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{ 1330635533U, 857U, 3040806504U },
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{ 1223800550U, 539U, 3954229517U },
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{ 1322411537U, 680U, 3223250324U },
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{ 1877847898U, 945U, 2915147143U },
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{ 1646356099U, 874U, 965988280U },
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{ 805687536U, 744U, 4032277920U },
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{ 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
|