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hc
2024-10-09 244b2c5ca8b14627e4a17755e5922221e121c771 
 kernel/lib/random32.c
....@@ -38,6 +38,9 @@
3838 #include <linux/jiffies.h>
3939 #include <linux/random.h>
4040 #include <linux/sched.h>
41
+#include <linux/bitops.h>
42
+#include <linux/slab.h>
43
+#include <linux/notifier.h>
4144 #include <asm/unaligned.h>
4245 
4346 /**
....@@ -336,6 +339,8 @@
336339 };
337340 
338341 static DEFINE_PER_CPU(struct siprand_state, net_rand_state) __latent_entropy;
342
+DEFINE_PER_CPU(unsigned long, net_rand_noise);
343
+EXPORT_PER_CPU_SYMBOL(net_rand_noise);
339344 
340345 /*
341346  * This is the core CPRNG function.  As "pseudorandom", this is not used
....@@ -359,9 +364,12 @@
359364 static inline u32 siprand_u32(struct siprand_state *s)
360365 {
361366 	unsigned long v0 = s->v0, v1 = s->v1, v2 = s->v2, v3 = s->v3;
367
+	unsigned long n = raw_cpu_read(net_rand_noise);
362368 
369
+	v3 ^= n;
363370 	PRND_SIPROUND(v0, v1, v2, v3);
364371 	PRND_SIPROUND(v0, v1, v2, v3);
372
+	v0 ^= n;
365373 	s->v0 = v0;  s->v1 = v1;  s->v2 = v2;  s->v3 = v3;
366374 	return v1 + v3;
367375 }
....@@ -544,10 +552,67 @@
544552  * To avoid worrying about whether it's safe to delay that interrupt
545553  * long enough to seed all CPUs, just schedule an immediate timer event.
546554  */
547
-static void prandom_timer_start(struct random_ready_callback *unused)
555
+static int prandom_timer_start(struct notifier_block *nb,
556
+			       unsigned long action, void *data)
548557 {
549558 	mod_timer(&seed_timer, jiffies);
559
+	return 0;
550560 }
561
+
562
+#ifdef CONFIG_RANDOM32_SELFTEST
563
+/* Principle: True 32-bit random numbers will all have 16 differing bits on
564
+ * average. For each 32-bit number, there are 601M numbers differing by 16
565
+ * bits, and 89% of the numbers differ by at least 12 bits. Note that more
566
+ * than 16 differing bits also implies a correlation with inverted bits. Thus
567
+ * we take 1024 random numbers and compare each of them to the other ones,
568
+ * counting the deviation of correlated bits to 16. Constants report 32,
569
+ * counters 32-log2(TEST_SIZE), and pure randoms, around 6 or lower. With the
570
+ * u32 total, TEST_SIZE may be as large as 4096 samples.
571
+ */
572
+#define TEST_SIZE 1024
573
+static int __init prandom32_state_selftest(void)
574
+{
575
+	unsigned int x, y, bits, samples;
576
+	u32 xor, flip;
577
+	u32 total;
578
+	u32 *data;
579
+
580
+	data = kmalloc(sizeof(*data) * TEST_SIZE, GFP_KERNEL);
581
+	if (!data)
582
+		return 0;
583
+
584
+	for (samples = 0; samples < TEST_SIZE; samples++)
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+		data[samples] = prandom_u32();
586
+
587
+	flip = total = 0;
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+	for (x = 0; x < samples; x++) {
589
+		for (y = 0; y < samples; y++) {
590
+			if (x == y)
591
+				continue;
592
+			xor = data[x] ^ data[y];
593
+			flip |= xor;
594
+			bits = hweight32(xor);
595
+			total += (bits - 16) * (bits - 16);
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+		}
597
+	}
598
+
599
+	/* We'll return the average deviation as 2*sqrt(corr/samples), which
600
+	 * is also sqrt(4*corr/samples) which provides a better resolution.
601
+	 */
602
+	bits = int_sqrt(total / (samples * (samples - 1)) * 4);
603
+	if (bits > 6)
604
+		pr_warn("prandom32: self test failed (at least %u bits"
605
+			" correlated, fixed_mask=%#x fixed_value=%#x\n",
606
+			bits, ~flip, data[0] & ~flip);
607
+	else
608
+		pr_info("prandom32: self test passed (less than %u bits"
609
+			" correlated)\n",
610
+			bits+1);
611
+	kfree(data);
612
+	return 0;
613
+}
614
+core_initcall(prandom32_state_selftest);
615
+#endif /*  CONFIG_RANDOM32_SELFTEST */
551616 
552617 /*
553618  * Start periodic full reseeding as soon as strong
....@@ -555,13 +620,13 @@
555620  */
556621 static int __init prandom_init_late(void)
557622 {
558
-	static struct random_ready_callback random_ready = {
559
-		.func = prandom_timer_start
623
+	static struct notifier_block random_ready = {
624
+		.notifier_call = prandom_timer_start
560625 	};
561
-	int ret = add_random_ready_callback(&random_ready);
626
+	int ret = register_random_ready_notifier(&random_ready);
562627 
563628 	if (ret == -EALREADY) {
564
-		prandom_timer_start(&random_ready);
629
+		prandom_timer_start(&random_ready, 0, NULL);
565630 		ret = 0;
566631 	}
567632 	return ret;