powercap: Adjust printing the constraint name with new line

[linux-2.6-microblaze.git] / lib / random32.c

diff --git a/lib/random32.c b/lib/random32.c
index be9f242..4d0e05e 100644 (file)
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -38,6 +38,7 @@
 #include <linux/jiffies.h>
 #include <linux/random.h>
 #include <linux/sched.h>
+#include <linux/bitops.h>
 #include <asm/unaligned.h>
 #include <trace/events/random.h>
 
@@ -337,6 +338,8 @@ struct siprand_state {
 };
 
 static DEFINE_PER_CPU(struct siprand_state, net_rand_state) __latent_entropy;
+DEFINE_PER_CPU(unsigned long, net_rand_noise);
+EXPORT_PER_CPU_SYMBOL(net_rand_noise);
 
 /*
  * This is the core CPRNG function.  As "pseudorandom", this is not used
@@ -360,9 +363,12 @@ static DEFINE_PER_CPU(struct siprand_state, net_rand_state) __latent_entropy;
 static inline u32 siprand_u32(struct siprand_state *s)
 {
        unsigned long v0 = s->v0, v1 = s->v1, v2 = s->v2, v3 = s->v3;
+       unsigned long n = raw_cpu_read(net_rand_noise);
 
+       v3 ^= n;
        PRND_SIPROUND(v0, v1, v2, v3);
        PRND_SIPROUND(v0, v1, v2, v3);
+       v0 ^= n;
        s->v0 = v0;  s->v1 = v1;  s->v2 = v2;  s->v3 = v3;
        return v1 + v3;
 }
@@ -551,6 +557,61 @@ static void prandom_timer_start(struct random_ready_callback *unused)
        mod_timer(&seed_timer, jiffies);
 }
 
+#ifdef CONFIG_RANDOM32_SELFTEST
+/* Principle: True 32-bit random numbers will all have 16 differing bits on
+ * average. For each 32-bit number, there are 601M numbers differing by 16
+ * bits, and 89% of the numbers differ by at least 12 bits. Note that more
+ * than 16 differing bits also implies a correlation with inverted bits. Thus
+ * we take 1024 random numbers and compare each of them to the other ones,
+ * counting the deviation of correlated bits to 16. Constants report 32,
+ * counters 32-log2(TEST_SIZE), and pure randoms, around 6 or lower. With the
+ * u32 total, TEST_SIZE may be as large as 4096 samples.
+ */
+#define TEST_SIZE 1024
+static int __init prandom32_state_selftest(void)
+{
+       unsigned int x, y, bits, samples;
+       u32 xor, flip;
+       u32 total;
+       u32 *data;
+
+       data = kmalloc(sizeof(*data) * TEST_SIZE, GFP_KERNEL);
+       if (!data)
+               return 0;
+
+       for (samples = 0; samples < TEST_SIZE; samples++)
+               data[samples] = prandom_u32();
+
+       flip = total = 0;
+       for (x = 0; x < samples; x++) {
+               for (y = 0; y < samples; y++) {
+                       if (x == y)
+                               continue;
+                       xor = data[x] ^ data[y];
+                       flip |= xor;
+                       bits = hweight32(xor);
+                       total += (bits - 16) * (bits - 16);
+               }
+       }
+
+       /* We'll return the average deviation as 2*sqrt(corr/samples), which
+        * is also sqrt(4*corr/samples) which provides a better resolution.
+        */
+       bits = int_sqrt(total / (samples * (samples - 1)) * 4);
+       if (bits > 6)
+               pr_warn("prandom32: self test failed (at least %u bits"
+                       " correlated, fixed_mask=%#x fixed_value=%#x\n",
+                       bits, ~flip, data[0] & ~flip);
+       else
+               pr_info("prandom32: self test passed (less than %u bits"
+                       " correlated)\n",
+                       bits+1);
+       kfree(data);
+       return 0;
+}
+core_initcall(prandom32_state_selftest);
+#endif /*  CONFIG_RANDOM32_SELFTEST */
+
 /*
  * Start periodic full reseeding as soon as strong
  * random numbers are available.