include/linux/random.h

   1 /*
   2  * include/linux/random.h
   3  *
   4  * Include file for the random number generator.
   5  */
   6 #ifndef _LINUX_RANDOM_H
   7 #define _LINUX_RANDOM_H
   8
   9 #include <linux/list.h>
  10 #include <linux/once.h>
  11
  12 #include <uapi/linux/random.h>
  13
  14 struct random_ready_callback {
  15         struct list_head list;
  16         void (*func)(struct random_ready_callback *rdy);
  17         struct module *owner;
  18 };
  19
  20 extern void add_device_randomness(const void *, unsigned int);
  21
  22 #if defined(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) && !defined(__CHECKER__)
  23 static inline void add_latent_entropy(void)
  24 {
  25         add_device_randomness((const void *)&latent_entropy,
  26                               sizeof(latent_entropy));
  27 }
  28 #else
  29 static inline void add_latent_entropy(void) {}
  30 #endif
  31
  32 extern void add_input_randomness(unsigned int type, unsigned int code,
  33                                  unsigned int value) __latent_entropy;
  34 extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
  35
  36 extern void get_random_bytes(void *buf, int nbytes);
  37 extern int add_random_ready_callback(struct random_ready_callback *rdy);
  38 extern void del_random_ready_callback(struct random_ready_callback *rdy);
  39 extern void get_random_bytes_arch(void *buf, int nbytes);
  40
  41 #ifndef MODULE
  42 extern const struct file_operations random_fops, urandom_fops;
  43 #endif
  44
  45 unsigned int get_random_int(void);
  46 unsigned long get_random_long(void);
  47 unsigned long randomize_page(unsigned long start, unsigned long range);
  48
  49 u32 prandom_u32(void);
  50 void prandom_bytes(void *buf, size_t nbytes);
  51 void prandom_seed(u32 seed);
  52 void prandom_reseed_late(void);
  53
  54 struct rnd_state {
  55         __u32 s1, s2, s3, s4;
  56 };
  57
  58 u32 prandom_u32_state(struct rnd_state *state);
  59 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
  60 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
  61
  62 #define prandom_init_once(pcpu_state)                   \
  63         DO_ONCE(prandom_seed_full_state, (pcpu_state))
  64
  65 /**
  66  * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
  67  * @ep_ro: right open interval endpoint
  68  *
  69  * Returns a pseudo-random number that is in interval [0, ep_ro). Note
  70  * that the result depends on PRNG being well distributed in [0, ~0U]
  71  * u32 space. Here we use maximally equidistributed combined Tausworthe
  72  * generator, that is, prandom_u32(). This is useful when requesting a
  73  * random index of an array containing ep_ro elements, for example.
  74  *
  75  * Returns: pseudo-random number in interval [0, ep_ro)
  76  */
  77 static inline u32 prandom_u32_max(u32 ep_ro)
  78 {
  79         return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
  80 }
  81
  82 /*
  83  * Handle minimum values for seeds
  84  */
  85 static inline u32 __seed(u32 x, u32 m)
  86 {
  87         return (x < m) ? x + m : x;
  88 }
  89
  90 /**
  91  * prandom_seed_state - set seed for prandom_u32_state().
  92  * @state: pointer to state structure to receive the seed.
  93  * @seed: arbitrary 64-bit value to use as a seed.
  94  */
  95 static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
  96 {
  97         u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
  98
  99         state->s1 = __seed(i,   2U);
 100         state->s2 = __seed(i,   8U);
 101         state->s3 = __seed(i,  16U);
 102         state->s4 = __seed(i, 128U);
 103 }
 104
 105 #ifdef CONFIG_ARCH_RANDOM
 106 # include <asm/archrandom.h>
 107 #else
 108 static inline bool arch_get_random_long(unsigned long *v)
 109 {
 110         return 0;
 111 }
 112 static inline bool arch_get_random_int(unsigned int *v)
 113 {
 114         return 0;
 115 }
 116 static inline bool arch_has_random(void)
 117 {
 118         return 0;
 119 }
 120 static inline bool arch_get_random_seed_long(unsigned long *v)
 121 {
 122         return 0;
 123 }
 124 static inline bool arch_get_random_seed_int(unsigned int *v)
 125 {
 126         return 0;
 127 }
 128 static inline bool arch_has_random_seed(void)
 129 {
 130         return 0;
 131 }
 132 #endif
 133
 134 /* Pseudo random number generator from numerical recipes. */
 135 static inline u32 next_pseudo_random32(u32 seed)
 136 {
 137         return seed * 1664525 + 1013904223;
 138 }
 139
 140 #endif /* _LINUX_RANDOM_H */