Merge tag 'at91-drivers-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/at91...

[linux-2.6-microblaze.git] / include / linux / prandom.h

diff --git a/include/linux/prandom.h b/include/linux/prandom.h
index aa16e64..bbf4b4a 100644 (file)
--- a/include/linux/prandom.h
+++ b/include/linux/prandom.h
@@ -16,12 +16,62 @@ void prandom_bytes(void *buf, size_t nbytes);
 void prandom_seed(u32 seed);
 void prandom_reseed_late(void);
 
+DECLARE_PER_CPU(unsigned long, net_rand_noise);
+
+#define PRANDOM_ADD_NOISE(a, b, c, d) \
+       prandom_u32_add_noise((unsigned long)(a), (unsigned long)(b), \
+                             (unsigned long)(c), (unsigned long)(d))
+
+#if BITS_PER_LONG == 64
+/*
+ * The core SipHash round function.  Each line can be executed in
+ * parallel given enough CPU resources.
+ */
+#define PRND_SIPROUND(v0, v1, v2, v3) ( \
+       v0 += v1, v1 = rol64(v1, 13),  v2 += v3, v3 = rol64(v3, 16), \
+       v1 ^= v0, v0 = rol64(v0, 32),  v3 ^= v2,                     \
+       v0 += v3, v3 = rol64(v3, 21),  v2 += v1, v1 = rol64(v1, 17), \
+       v3 ^= v0,                      v1 ^= v2, v2 = rol64(v2, 32)  \
+)
+
+#define PRND_K0 (0x736f6d6570736575 ^ 0x6c7967656e657261)
+#define PRND_K1 (0x646f72616e646f6d ^ 0x7465646279746573)
+
+#elif BITS_PER_LONG == 32
+/*
+ * On 32-bit machines, we use HSipHash, a reduced-width version of SipHash.
+ * This is weaker, but 32-bit machines are not used for high-traffic
+ * applications, so there is less output for an attacker to analyze.
+ */
+#define PRND_SIPROUND(v0, v1, v2, v3) ( \
+       v0 += v1, v1 = rol32(v1,  5),  v2 += v3, v3 = rol32(v3,  8), \
+       v1 ^= v0, v0 = rol32(v0, 16),  v3 ^= v2,                     \
+       v0 += v3, v3 = rol32(v3,  7),  v2 += v1, v1 = rol32(v1, 13), \
+       v3 ^= v0,                      v1 ^= v2, v2 = rol32(v2, 16)  \
+)
+#define PRND_K0 0x6c796765
+#define PRND_K1 0x74656462
+
+#else
+#error Unsupported BITS_PER_LONG
+#endif
+
+static inline void prandom_u32_add_noise(unsigned long a, unsigned long b,
+                                        unsigned long c, unsigned long d)
+{
+       /*
+        * This is not used cryptographically; it's just
+        * a convenient 4-word hash function. (3 xor, 2 add, 2 rol)
+        */
+       a ^= raw_cpu_read(net_rand_noise);
+       PRND_SIPROUND(a, b, c, d);
+       raw_cpu_write(net_rand_noise, d);
+}
+
 struct rnd_state {
        __u32 s1, s2, s3, s4;
 };
 
-DECLARE_PER_CPU(struct rnd_state, net_rand_state);
-
 u32 prandom_u32_state(struct rnd_state *state);
 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
 void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
@@ -67,6 +117,7 @@ static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
        state->s2 = __seed(i,   8U);
        state->s3 = __seed(i,  16U);
        state->s4 = __seed(i, 128U);
+       PRANDOM_ADD_NOISE(state, i, 0, 0);
 }
 
 /* Pseudo random number generator from numerical recipes. */