Merge tag 'random-5.19-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull random number generator updates from Jason Donenfeld:
 "These updates continue to refine the work began in 5.17 and 5.18 of
  modernizing the RNG's crypto and streamlining and documenting its
  code.

  New for 5.19, the updates aim to improve entropy collection methods
  and make some initial decisions regarding the "premature next" problem
  and our threat model. The cloc utility now reports that random.c is
  931 lines of code and 466 lines of comments, not that basic metrics
  like that mean all that much, but at the very least it tells you that
  this is very much a manageable driver now.

  Here's a summary of the various updates:

   - The random_get_entropy() function now always returns something at
     least minimally useful. This is the primary entropy source in most
     collectors, which in the best case expands to something like RDTSC,
     but prior to this change, in the worst case it would just return 0,
     contributing nothing. For 5.19, additional architectures are wired
     up, and architectures that are entirely missing a cycle counter now
     have a generic fallback path, which uses the highest resolution
     clock available from the timekeeping subsystem.

     Some of those clocks can actually be quite good, despite the CPU
     not having a cycle counter of its own, and going off-core for a
     stamp is generally thought to increase jitter, something positive
     from the perspective of entropy gathering. Done very early on in
     the development cycle, this has been sitting in next getting some
     testing for a while now and has relevant acks from the archs, so it
     should be pretty well tested and fine, but is nonetheless the thing
     I'll be keeping my eye on most closely.

   - Of particular note with the random_get_entropy() improvements is
     MIPS, which, on CPUs that lack the c0 count register, will now
     combine the high-speed but short-cycle c0 random register with the
     lower-speed but long-cycle generic fallback path.

   - With random_get_entropy() now always returning something useful,
     the interrupt handler now collects entropy in a consistent
     construction.

   - Rather than comparing two samples of random_get_entropy() for the
     jitter dance, the algorithm now tests many samples, and uses the
     amount of differing ones to determine whether or not jitter entropy
     is usable and how laborious it must be. The problem with comparing
     only two samples was that if the cycle counter was extremely slow,
     but just so happened to be on the cusp of a change, the slowness
     wouldn't be detected. Taking many samples fixes that to some
     degree.

     This, combined with the other improvements to random_get_entropy(),
     should make future unification of /dev/random and /dev/urandom
     maybe more possible. At the very least, were we to attempt it again
     today (we're not), it wouldn't break any of Guenter's test rigs
     that broke when we tried it with 5.18. So, not today, but perhaps
     down the road, that's something we can revisit.

   - We attempt to reseed the RNG immediately upon waking up from system
     suspend or hibernation, making use of the various timestamps about
     suspend time and such available, as well as the usual inputs such
     as RDRAND when available.

   - Batched randomness now falls back to ordinary randomness before the
     RNG is initialized. This provides more consistent guarantees to the
     types of random numbers being returned by the various accessors.

   - The "pre-init injection" code is now gone for good. I suspect you
     in particular will be happy to read that, as I recall you
     expressing your distaste for it a few months ago. Instead, to avoid
     a "premature first" issue, while still allowing for maximal amount
     of entropy availability during system boot, the first 128 bits of
     estimated entropy are used immediately as it arrives, with the next
     128 bits being buffered. And, as before, after the RNG has been
     fully initialized, it winds up reseeding anyway a few seconds later
     in most cases. This resulted in a pretty big simplification of the
     initialization code and let us remove various ad-hoc mechanisms
     like the ugly crng_pre_init_inject().

   - The RNG no longer pretends to handle the "premature next" security
     model, something that various academics and other RNG designs have
     tried to care about in the past. After an interesting mailing list
     thread, these issues are thought to be a) mainly academic and not
     practical at all, and b) actively harming the real security of the
     RNG by delaying new entropy additions after a potential compromise,
     making a potentially bad situation even worse. As well, in the
     first place, our RNG never even properly handled the premature next
     issue, so removing an incomplete solution to a fake problem was
     particularly nice.

     This allowed for numerous other simplifications in the code, which
     is a lot cleaner as a consequence. If you didn't see it before,
     https://lore.kernel.org/lkml/YmlMGx6+uigkGiZ0@zx2c4.com/ may be a
     thread worth skimming through.

   - While the interrupt handler received a separate code path years ago
     that avoids locks by using per-cpu data structures and a faster
     mixing algorithm, in order to reduce interrupt latency, input and
     disk events that are triggered in hardirq handlers were still
     hitting locks and more expensive algorithms. Those are now
     redirected to use the faster per-cpu data structures.

   - Rather than having the fake-crypto almost-siphash-based random32
     implementation be used right and left, and in many places where
     cryptographically secure randomness is desirable, the batched
     entropy code is now fast enough to replace that.

   - As usual, numerous code quality and documentation cleanups. For
     example, the initialization state machine now uses enum symbolic
     constants instead of just hard coding numbers everywhere.

   - Since the RNG initializes once, and then is always initialized
     thereafter, a pretty heavy amount of code used during that
     initialization is never used again. It is now completely cordoned
     off using static branches and it winds up in the .text.unlikely
     section so that it doesn't reduce cache compactness after the RNG
     is ready.

   - A variety of functions meant for waiting on the RNG to be
     initialized were only used by vsprintf, and in not a particularly
     optimal way. Replacing that usage with a more ordinary setup made
     it possible to remove those functions.

   - A cleanup of how we warn userspace about the use of uninitialized
     /dev/urandom and uninitialized get_random_bytes() usage.
     Interestingly, with the change you merged for 5.18 that attempts to
     use jitter (but does not block if it can't), the majority of users
     should never see those warnings for /dev/urandom at all now, and
     the one for in-kernel usage is mainly a debug thing.

   - The file_operations struct for /dev/[u]random now implements
     .read_iter and .write_iter instead of .read and .write, allowing it
     to also implement .splice_read and .splice_write, which makes
     splice(2) work again after it was broken here (and in many other
     places in the tree) during the set_fs() removal. This was a bit of
     a last minute arrival from Jens that hasn't had as much time to
     bake, so I'll be keeping my eye on this as well, but it seems
     fairly ordinary. Unfortunately, read_iter() is around 3% slower
     than read() in my tests, which I'm not thrilled about. But Jens and
     Al, spurred by this observation, seem to be making progress in
     removing the bottlenecks on the iter paths in the VFS layer in
     general, which should remove the performance gap for all drivers.

   - Assorted other bug fixes, cleanups, and optimizations.

   - A small SipHash cleanup"

* tag 'random-5.19-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (49 commits)
  random: check for signals after page of pool writes
  random: wire up fops->splice_{read,write}_iter()
  random: convert to using fops->write_iter()
  random: convert to using fops->read_iter()
  random: unify batched entropy implementations
  random: move randomize_page() into mm where it belongs
  random: remove mostly unused async readiness notifier
  random: remove get_random_bytes_arch() and add rng_has_arch_random()
  random: move initialization functions out of hot pages
  random: make consistent use of buf and len
  random: use proper return types on get_random_{int,long}_wait()
  random: remove extern from functions in header
  random: use static branch for crng_ready()
  random: credit architectural init the exact amount
  random: handle latent entropy and command line from random_init()
  random: use proper jiffies comparison macro
  random: remove ratelimiting for in-kernel unseeded randomness
  random: move initialization out of reseeding hot path
  random: avoid initializing twice in credit race
  random: use symbolic constants for crng_init states
  ...

1 files changed, 561 insertions, 785 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 4c9adb4f3d5d..b691b9d59503 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -15,14 +15,12 @@
  *   - Sysctl interface.
  *
  * The high level overview is that there is one input pool, into which
- * various pieces of data are hashed. Some of that data is then "credited" as
- * having a certain number of bits of entropy. When enough bits of entropy are
- * available, the hash is finalized and handed as a key to a stream cipher that
- * expands it indefinitely for various consumers. This key is periodically
- * refreshed as the various entropy collectors, described below, add data to the
- * input pool and credit it. There is currently no Fortuna-like scheduler
- * involved, which can lead to malicious entropy sources causing a premature
- * reseed, and the entropy estimates are, at best, conservative guesses.
+ * various pieces of data are hashed. Prior to initialization, some of that
+ * data is then "credited" as having a certain number of bits of entropy.
+ * When enough bits of entropy are available, the hash is finalized and
+ * handed as a key to a stream cipher that expands it indefinitely for
+ * various consumers. This key is periodically refreshed as the various
+ * entropy collectors, described below, add data to the input pool.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -53,6 +51,8 @@
 #include <linux/completion.h>
 #include <linux/uuid.h>
 #include <linux/uaccess.h>
+#include <linux/suspend.h>
+#include <linux/siphash.h>
 #include <crypto/chacha.h>
 #include <crypto/blake2s.h>
 #include <asm/processor.h>
@@ -71,27 +71,25 @@
  *********************************************************************/
 
 /*
- * crng_init =  0 --> Uninitialized
- *		1 --> Initialized
- *		2 --> Initialized from input_pool
- *
  * crng_init is protected by base_crng->lock, and only increases
- * its value (from 0->1->2).
+ * its value (from empty->early->ready).
  */
-static int crng_init = 0;
-#define crng_ready() (likely(crng_init > 1))
-/* Various types of waiters for crng_init->2 transition. */
+static enum {
+	CRNG_EMPTY = 0, /* Little to no entropy collected */
+	CRNG_EARLY = 1, /* At least POOL_EARLY_BITS collected */
+	CRNG_READY = 2  /* Fully initialized with POOL_READY_BITS collected */
+} crng_init __read_mostly = CRNG_EMPTY;
+static DEFINE_STATIC_KEY_FALSE(crng_is_ready);
+#define crng_ready() (static_branch_likely(&crng_is_ready) || crng_init >= CRNG_READY)
+/* Various types of waiters for crng_init->CRNG_READY transition. */
 static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
 static struct fasync_struct *fasync;
-static DEFINE_SPINLOCK(random_ready_chain_lock);
-static RAW_NOTIFIER_HEAD(random_ready_chain);
 
 /* Control how we warn userspace. */
-static struct ratelimit_state unseeded_warning =
-	RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3);
 static struct ratelimit_state urandom_warning =
 	RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3);
-static int ratelimit_disable __read_mostly;
+static int ratelimit_disable __read_mostly =
+	IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM);
 module_param_named(ratelimit_disable, ratelimit_disable, int, 0644);
 MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
 
@@ -110,6 +108,11 @@ bool rng_is_initialized(void)
 }
 EXPORT_SYMBOL(rng_is_initialized);
 
+static void __cold crng_set_ready(struct work_struct *work)
+{
+	static_branch_enable(&crng_is_ready);
+}
+
 /* Used by wait_for_random_bytes(), and considered an entropy collector, below. */
 static void try_to_generate_entropy(void);
 
@@ -137,73 +140,10 @@ int wait_for_random_bytes(void)
 }
 EXPORT_SYMBOL(wait_for_random_bytes);
 
-/*
- * Add a callback function that will be invoked when the input
- * pool is initialised.
- *
- * returns: 0 if callback is successfully added
- *	    -EALREADY if pool is already initialised (callback not called)
- */
-int register_random_ready_notifier(struct notifier_block *nb)
-{
-	unsigned long flags;
-	int ret = -EALREADY;
-
-	if (crng_ready())
-		return ret;
-
-	spin_lock_irqsave(&random_ready_chain_lock, flags);
-	if (!crng_ready())
-		ret = raw_notifier_chain_register(&random_ready_chain, nb);
-	spin_unlock_irqrestore(&random_ready_chain_lock, flags);
-	return ret;
-}
-
-/*
- * Delete a previously registered readiness callback function.
- */
-int unregister_random_ready_notifier(struct notifier_block *nb)
-{
-	unsigned long flags;
-	int ret;
-
-	spin_lock_irqsave(&random_ready_chain_lock, flags);
-	ret = raw_notifier_chain_unregister(&random_ready_chain, nb);
-	spin_unlock_irqrestore(&random_ready_chain_lock, flags);
-	return ret;
-}
-
-static void process_random_ready_list(void)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&random_ready_chain_lock, flags);
-	raw_notifier_call_chain(&random_ready_chain, 0, NULL);
-	spin_unlock_irqrestore(&random_ready_chain_lock, flags);
-}
-
-#define warn_unseeded_randomness(previous) \
-	_warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous))
-
-static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous)
-{
-#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
-	const bool print_once = false;
-#else
-	static bool print_once __read_mostly;
-#endif
-
-	if (print_once || crng_ready() ||
-	    (previous && (caller == READ_ONCE(*previous))))
-		return;
-	WRITE_ONCE(*previous, caller);
-#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
-	print_once = true;
-#endif
-	if (__ratelimit(&unseeded_warning))
-		printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n",
-				func_name, caller, crng_init);
-}
+#define warn_unseeded_randomness() \
+	if (IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM) && !crng_ready()) \
+		printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", \
+				__func__, (void *)_RET_IP_, crng_init)
 
 
 /*********************************************************************
@@ -216,7 +156,7 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller, void
  *
  * There are a few exported interfaces for use by other drivers:
  *
- *	void get_random_bytes(void *buf, size_t nbytes)
+ *	void get_random_bytes(void *buf, size_t len)
  *	u32 get_random_u32()
  *	u64 get_random_u64()
  *	unsigned int get_random_int()
@@ -232,8 +172,8 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller, void
  *********************************************************************/
 
 enum {
-	CRNG_RESEED_INTERVAL = 300 * HZ,
-	CRNG_INIT_CNT_THRESH = 2 * CHACHA_KEY_SIZE
+	CRNG_RESEED_START_INTERVAL = HZ,
+	CRNG_RESEED_INTERVAL = 60 * HZ
 };
 
 static struct {
@@ -256,24 +196,17 @@ static DEFINE_PER_CPU(struct crng, crngs) = {
 	.lock = INIT_LOCAL_LOCK(crngs.lock),
 };
 
-/* Used by crng_reseed() to extract a new seed from the input pool. */
-static bool drain_entropy(void *buf, size_t nbytes, bool force);
+/* Used by crng_reseed() and crng_make_state() to extract a new seed from the input pool. */
+static void extract_entropy(void *buf, size_t len);
 
-/*
- * This extracts a new crng key from the input pool, but only if there is a
- * sufficient amount of entropy available or force is true, in order to
- * mitigate bruteforcing of newly added bits.
- */
-static void crng_reseed(bool force)
+/* This extracts a new crng key from the input pool. */
+static void crng_reseed(void)
 {
 	unsigned long flags;
 	unsigned long next_gen;
 	u8 key[CHACHA_KEY_SIZE];
-	bool finalize_init = false;
 
-	/* Only reseed if we can, to prevent brute forcing a small amount of new bits. */
-	if (!drain_entropy(key, sizeof(key), force))
-		return;
+	extract_entropy(key, sizeof(key));
 
 	/*
 	 * We copy the new key into the base_crng, overwriting the old one,
@@ -288,28 +221,10 @@ static void crng_reseed(bool force)
 		++next_gen;
 	WRITE_ONCE(base_crng.generation, next_gen);
 	WRITE_ONCE(base_crng.birth, jiffies);
-	if (!crng_ready()) {
-		crng_init = 2;
-		finalize_init = true;
-	}
+	if (!static_branch_likely(&crng_is_ready))
+		crng_init = CRNG_READY;
 	spin_unlock_irqrestore(&base_crng.lock, flags);
 	memzero_explicit(key, sizeof(key));
-	if (finalize_init) {
-		process_random_ready_list();
-		wake_up_interruptible(&crng_init_wait);
-		kill_fasync(&fasync, SIGIO, POLL_IN);
-		pr_notice("crng init done\n");
-		if (unseeded_warning.missed) {
-			pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
-				  unseeded_warning.missed);
-			unseeded_warning.missed = 0;
-		}
-		if (urandom_warning.missed) {
-			pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
-				  urandom_warning.missed);
-			urandom_warning.missed = 0;
-		}
-	}
 }
 
 /*
@@ -345,10 +260,10 @@ static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE],
 }
 
 /*
- * Return whether the crng seed is considered to be sufficiently
- * old that a reseeding might be attempted. This happens if the last
- * reseeding was CRNG_RESEED_INTERVAL ago, or during early boot, at
- * an interval proportional to the uptime.
+ * Return whether the crng seed is considered to be sufficiently old
+ * that a reseeding is needed. This happens if the last reseeding
+ * was CRNG_RESEED_INTERVAL ago, or during early boot, at an interval
+ * proportional to the uptime.
  */
 static bool crng_has_old_seed(void)
 {
@@ -360,10 +275,10 @@ static bool crng_has_old_seed(void)
 		if (uptime >= CRNG_RESEED_INTERVAL / HZ * 2)
 			WRITE_ONCE(early_boot, false);
 		else
-			interval = max_t(unsigned int, 5 * HZ,
+			interval = max_t(unsigned int, CRNG_RESEED_START_INTERVAL,
 					 (unsigned int)uptime / 2 * HZ);
 	}
-	return time_after(jiffies, READ_ONCE(base_crng.birth) + interval);
+	return time_is_before_jiffies(READ_ONCE(base_crng.birth) + interval);
 }
 
 /*
@@ -382,28 +297,31 @@ static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS],
 	/*
 	 * For the fast path, we check whether we're ready, unlocked first, and
 	 * then re-check once locked later. In the case where we're really not
-	 * ready, we do fast key erasure with the base_crng directly, because
-	 * this is what crng_pre_init_inject() mutates during early init.
+	 * ready, we do fast key erasure with the base_crng directly, extracting
+	 * when crng_init is CRNG_EMPTY.
 	 */
 	if (!crng_ready()) {
 		bool ready;
 
 		spin_lock_irqsave(&base_crng.lock, flags);
 		ready = crng_ready();
-		if (!ready)
+		if (!ready) {
+			if (crng_init == CRNG_EMPTY)
+				extract_entropy(base_crng.key, sizeof(base_crng.key));
 			crng_fast_key_erasure(base_crng.key, chacha_state,
 					      random_data, random_data_len);
+		}
 		spin_unlock_irqrestore(&base_crng.lock, flags);
 		if (!ready)
 			return;
 	}
 
 	/*
-	 * If the base_crng is old enough, we try to reseed, which in turn
-	 * bumps the generation counter that we check below.
+	 * If the base_crng is old enough, we reseed, which in turn bumps the
+	 * generation counter that we check below.
 	 */
 	if (unlikely(crng_has_old_seed()))
-		crng_reseed(false);
+		crng_reseed();
 
 	local_lock_irqsave(&crngs.lock, flags);
 	crng = raw_cpu_ptr(&crngs);
@@ -433,68 +351,24 @@ static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS],
 	local_unlock_irqrestore(&crngs.lock, flags);
 }
 
-/*
- * This function is for crng_init == 0 only. It loads entropy directly
- * into the crng's key, without going through the input pool. It is,
- * generally speaking, not very safe, but we use this only at early
- * boot time when it's better to have something there rather than
- * nothing.
- *
- * If account is set, then the crng_init_cnt counter is incremented.
- * This shouldn't be set by functions like add_device_randomness(),
- * where we can't trust the buffer passed to it is guaranteed to be
- * unpredictable (so it might not have any entropy at all).
- */
-static void crng_pre_init_inject(const void *input, size_t len, bool account)
-{
-	static int crng_init_cnt = 0;
-	struct blake2s_state hash;
-	unsigned long flags;
-
-	blake2s_init(&hash, sizeof(base_crng.key));
-
-	spin_lock_irqsave(&base_crng.lock, flags);
-	if (crng_init != 0) {
-		spin_unlock_irqrestore(&base_crng.lock, flags);
-		return;
-	}
-
-	blake2s_update(&hash, base_crng.key, sizeof(base_crng.key));
-	blake2s_update(&hash, input, len);
-	blake2s_final(&hash, base_crng.key);
-
-	if (account) {
-		crng_init_cnt += min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt);
-		if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
-			++base_crng.generation;
-			crng_init = 1;
-		}
-	}
-
-	spin_unlock_irqrestore(&base_crng.lock, flags);
-
-	if (crng_init == 1)
-		pr_notice("fast init done\n");
-}
-
-static void _get_random_bytes(void *buf, size_t nbytes)
+static void _get_random_bytes(void *buf, size_t len)
 {
 	u32 chacha_state[CHACHA_STATE_WORDS];
 	u8 tmp[CHACHA_BLOCK_SIZE];
-	size_t len;
+	size_t first_block_len;
 
-	if (!nbytes)
+	if (!len)
 		return;
 
-	len = min_t(size_t, 32, nbytes);
-	crng_make_state(chacha_state, buf, len);
-	nbytes -= len;
-	buf += len;
+	first_block_len = min_t(size_t, 32, len);
+	crng_make_state(chacha_state, buf, first_block_len);
+	len -= first_block_len;
+	buf += first_block_len;
 
-	while (nbytes) {
-		if (nbytes < CHACHA_BLOCK_SIZE) {
+	while (len) {
+		if (len < CHACHA_BLOCK_SIZE) {
 			chacha20_block(chacha_state, tmp);
-			memcpy(buf, tmp, nbytes);
+			memcpy(buf, tmp, len);
 			memzero_explicit(tmp, sizeof(tmp));
 			break;
 		}
@@ -502,7 +376,7 @@ static void _get_random_bytes(void *buf, size_t nbytes)
 		chacha20_block(chacha_state, buf);
 		if (unlikely(chacha_state[12] == 0))
 			++chacha_state[13];
-		nbytes -= CHACHA_BLOCK_SIZE;
+		len -= CHACHA_BLOCK_SIZE;
 		buf += CHACHA_BLOCK_SIZE;
 	}
 
@@ -512,29 +386,24 @@ static void _get_random_bytes(void *buf, size_t nbytes)
 /*
  * This function is the exported kernel interface.  It returns some
  * number of good random numbers, suitable for key generation, seeding
- * TCP sequence numbers, etc.  It does not rely on the hardware random
- * number generator.  For random bytes direct from the hardware RNG
- * (when available), use get_random_bytes_arch(). In order to ensure
- * that the randomness provided by this function is okay, the function
- * wait_for_random_bytes() should be called and return 0 at least once
- * at any point prior.
+ * TCP sequence numbers, etc. In order to ensure that the randomness
+ * by this function is okay, the function wait_for_random_bytes()
+ * should be called and return 0 at least once at any point prior.
  */
-void get_random_bytes(void *buf, size_t nbytes)
+void get_random_bytes(void *buf, size_t len)
 {
-	static void *previous;
-
-	warn_unseeded_randomness(&previous);
-	_get_random_bytes(buf, nbytes);
+	warn_unseeded_randomness();
+	_get_random_bytes(buf, len);
 }
 EXPORT_SYMBOL(get_random_bytes);
 
-static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes)
+static ssize_t get_random_bytes_user(struct iov_iter *iter)
 {
-	size_t len, left, ret = 0;
 	u32 chacha_state[CHACHA_STATE_WORDS];
-	u8 output[CHACHA_BLOCK_SIZE];
+	u8 block[CHACHA_BLOCK_SIZE];
+	size_t ret = 0, copied;
 
-	if (!nbytes)
+	if (unlikely(!iov_iter_count(iter)))
 		return 0;
 
 	/*
@@ -548,30 +417,22 @@ static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes)
 	 * use chacha_state after, so we can simply return those bytes to
 	 * the user directly.
 	 */
-	if (nbytes <= CHACHA_KEY_SIZE) {
-		ret = nbytes - copy_to_user(buf, &chacha_state[4], nbytes);
+	if (iov_iter_count(iter) <= CHACHA_KEY_SIZE) {
+		ret = copy_to_iter(&chacha_state[4], CHACHA_KEY_SIZE, iter);
 		goto out_zero_chacha;
 	}
 
 	for (;;) {
-		chacha20_block(chacha_state, output);
+		chacha20_block(chacha_state, block);
 		if (unlikely(chacha_state[12] == 0))
 			++chacha_state[13];
 
-		len = min_t(size_t, nbytes, CHACHA_BLOCK_SIZE);
-		left = copy_to_user(buf, output, len);
-		if (left) {
-			ret += len - left;
-			break;
-		}
-
-		buf += len;
-		ret += len;
-		nbytes -= len;
-		if (!nbytes)
+		copied = copy_to_iter(block, sizeof(block), iter);
+		ret += copied;
+		if (!iov_iter_count(iter) || copied != sizeof(block))
 			break;
 
-		BUILD_BUG_ON(PAGE_SIZE % CHACHA_BLOCK_SIZE != 0);
+		BUILD_BUG_ON(PAGE_SIZE % sizeof(block) != 0);
 		if (ret % PAGE_SIZE == 0) {
 			if (signal_pending(current))
 				break;
@@ -579,7 +440,7 @@ static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes)
 		}
 	}
 
-	memzero_explicit(output, sizeof(output));
+	memzero_explicit(block, sizeof(block));
 out_zero_chacha:
 	memzero_explicit(chacha_state, sizeof(chacha_state));
 	return ret ? ret : -EFAULT;
@@ -591,98 +452,69 @@ out_zero_chacha:
  * provided by this function is okay, the function wait_for_random_bytes()
  * should be called and return 0 at least once at any point prior.
  */
-struct batched_entropy {
-	union {
-		/*
-		 * We make this 1.5x a ChaCha block, so that we get the
-		 * remaining 32 bytes from fast key erasure, plus one full
-		 * block from the detached ChaCha state. We can increase
-		 * the size of this later if needed so long as we keep the
-		 * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE.
-		 */
-		u64 entropy_u64[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u64))];
-		u32 entropy_u32[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(u32))];
-	};
-	local_lock_t lock;
-	unsigned long generation;
-	unsigned int position;
-};
-
 
-static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = {
-	.lock = INIT_LOCAL_LOCK(batched_entropy_u64.lock),
-	.position = UINT_MAX
-};
-
-u64 get_random_u64(void)
-{
-	u64 ret;
-	unsigned long flags;
-	struct batched_entropy *batch;
-	static void *previous;
-	unsigned long next_gen;
-
-	warn_unseeded_randomness(&previous);
-
-	local_lock_irqsave(&batched_entropy_u64.lock, flags);
-	batch = raw_cpu_ptr(&batched_entropy_u64);
-
-	next_gen = READ_ONCE(base_crng.generation);
-	if (batch->position >= ARRAY_SIZE(batch->entropy_u64) ||
-	    next_gen != batch->generation) {
-		_get_random_bytes(batch->entropy_u64, sizeof(batch->entropy_u64));
-		batch->position = 0;
-		batch->generation = next_gen;
-	}
-
-	ret = batch->entropy_u64[batch->position];
-	batch->entropy_u64[batch->position] = 0;
-	++batch->position;
-	local_unlock_irqrestore(&batched_entropy_u64.lock, flags);
-	return ret;
-}
-EXPORT_SYMBOL(get_random_u64);
-
-static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = {
-	.lock = INIT_LOCAL_LOCK(batched_entropy_u32.lock),
-	.position = UINT_MAX
-};
-
-u32 get_random_u32(void)
-{
-	u32 ret;
-	unsigned long flags;
-	struct batched_entropy *batch;
-	static void *previous;
-	unsigned long next_gen;
-
-	warn_unseeded_randomness(&previous);
-
-	local_lock_irqsave(&batched_entropy_u32.lock, flags);
-	batch = raw_cpu_ptr(&batched_entropy_u32);
-
-	next_gen = READ_ONCE(base_crng.generation);
-	if (batch->position >= ARRAY_SIZE(batch->entropy_u32) ||
-	    next_gen != batch->generation) {
-		_get_random_bytes(batch->entropy_u32, sizeof(batch->entropy_u32));
-		batch->position = 0;
-		batch->generation = next_gen;
-	}
-
-	ret = batch->entropy_u32[batch->position];
-	batch->entropy_u32[batch->position] = 0;
-	++batch->position;
-	local_unlock_irqrestore(&batched_entropy_u32.lock, flags);
-	return ret;
-}
-EXPORT_SYMBOL(get_random_u32);
+#define DEFINE_BATCHED_ENTROPY(type)						\
+struct batch_ ##type {								\
+	/*									\
+	 * We make this 1.5x a ChaCha block, so that we get the			\
+	 * remaining 32 bytes from fast key erasure, plus one full		\
+	 * block from the detached ChaCha state. We can increase		\
+	 * the size of this later if needed so long as we keep the		\
+	 * formula of (integer_blocks + 0.5) * CHACHA_BLOCK_SIZE.		\
+	 */									\
+	type entropy[CHACHA_BLOCK_SIZE * 3 / (2 * sizeof(type))];		\
+	local_lock_t lock;							\
+	unsigned long generation;						\
+	unsigned int position;							\
+};										\
+										\
+static DEFINE_PER_CPU(struct batch_ ##type, batched_entropy_ ##type) = {	\
+	.lock = INIT_LOCAL_LOCK(batched_entropy_ ##type.lock),			\
+	.position = UINT_MAX							\
+};										\
+										\
+type get_random_ ##type(void)							\
+{										\
+	type ret;								\
+	unsigned long flags;							\
+	struct batch_ ##type *batch;						\
+	unsigned long next_gen;							\
+										\
+	warn_unseeded_randomness();						\
+										\
+	if  (!crng_ready()) {							\
+		_get_random_bytes(&ret, sizeof(ret));				\
+		return ret;							\
+	}									\
+										\
+	local_lock_irqsave(&batched_entropy_ ##type.lock, flags);		\
+	batch = raw_cpu_ptr(&batched_entropy_##type);				\
+										\
+	next_gen = READ_ONCE(base_crng.generation);				\
+	if (batch->position >= ARRAY_SIZE(batch->entropy) ||			\
+	    next_gen != batch->generation) {					\
+		_get_random_bytes(batch->entropy, sizeof(batch->entropy));	\
+		batch->position = 0;						\
+		batch->generation = next_gen;					\
+	}									\
+										\
+	ret = batch->entropy[batch->position];					\
+	batch->entropy[batch->position] = 0;					\
+	++batch->position;							\
+	local_unlock_irqrestore(&batched_entropy_ ##type.lock, flags);		\
+	return ret;								\
+}										\
+EXPORT_SYMBOL(get_random_ ##type);
+
+DEFINE_BATCHED_ENTROPY(u64)
+DEFINE_BATCHED_ENTROPY(u32)
 
 #ifdef CONFIG_SMP
 /*
  * This function is called when the CPU is coming up, with entry
  * CPUHP_RANDOM_PREPARE, which comes before CPUHP_WORKQUEUE_PREP.
  */
-int random_prepare_cpu(unsigned int cpu)
+int __cold random_prepare_cpu(unsigned int cpu)
 {
 	/*
 	 * When the cpu comes back online, immediately invalidate both
@@ -696,65 +528,6 @@ int random_prepare_cpu(unsigned int cpu)
 }
 #endif
 
-/**
- * randomize_page - Generate a random, page aligned address
- * @start:	The smallest acceptable address the caller will take.
- * @range:	The size of the area, starting at @start, within which the
- *		random address must fall.
- *
- * If @start + @range would overflow, @range is capped.
- *
- * NOTE: Historical use of randomize_range, which this replaces, presumed that
- * @start was already page aligned.  We now align it regardless.
- *
- * Return: A page aligned address within [start, start + range).  On error,
- * @start is returned.
- */
-unsigned long randomize_page(unsigned long start, unsigned long range)
-{
-	if (!PAGE_ALIGNED(start)) {
-		range -= PAGE_ALIGN(start) - start;
-		start = PAGE_ALIGN(start);
-	}
-
-	if (start > ULONG_MAX - range)
-		range = ULONG_MAX - start;
-
-	range >>= PAGE_SHIFT;
-
-	if (range == 0)
-		return start;
-
-	return start + (get_random_long() % range << PAGE_SHIFT);
-}
-
-/*
- * This function will use the architecture-specific hardware random
- * number generator if it is available. It is not recommended for
- * use. Use get_random_bytes() instead. It returns the number of
- * bytes filled in.
- */
-size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes)
-{
-	size_t left = nbytes;
-	u8 *p = buf;
-
-	while (left) {
-		unsigned long v;
-		size_t chunk = min_t(size_t, left, sizeof(unsigned long));
-
-		if (!arch_get_random_long(&v))
-			break;
-
-		memcpy(p, &v, chunk);
-		p += chunk;
-		left -= chunk;
-	}
-
-	return nbytes - left;
-}
-EXPORT_SYMBOL(get_random_bytes_arch);
-
 
 /**********************************************************************
  *
@@ -762,33 +535,28 @@ EXPORT_SYMBOL(get_random_bytes_arch);
  *
  * Callers may add entropy via:
  *
- *     static void mix_pool_bytes(const void *in, size_t nbytes)
+ *     static void mix_pool_bytes(const void *buf, size_t len)
  *
  * After which, if added entropy should be credited:
  *
- *     static void credit_entropy_bits(size_t nbits)
+ *     static void credit_init_bits(size_t bits)
  *
- * Finally, extract entropy via these two, with the latter one
- * setting the entropy count to zero and extracting only if there
- * is POOL_MIN_BITS entropy credited prior or force is true:
+ * Finally, extract entropy via:
  *
- *     static void extract_entropy(void *buf, size_t nbytes)
- *     static bool drain_entropy(void *buf, size_t nbytes, bool force)
+ *     static void extract_entropy(void *buf, size_t len)
  *
  **********************************************************************/
 
 enum {
 	POOL_BITS = BLAKE2S_HASH_SIZE * 8,
-	POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
+	POOL_READY_BITS = POOL_BITS, /* When crng_init->CRNG_READY */
+	POOL_EARLY_BITS = POOL_READY_BITS / 2 /* When crng_init->CRNG_EARLY */
 };
 
-/* For notifying userspace should write into /dev/random. */
-static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
-
 static struct {
 	struct blake2s_state hash;
 	spinlock_t lock;
-	unsigned int entropy_count;
+	unsigned int init_bits;
 } input_pool = {
 	.hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE),
 		    BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4,
@@ -797,48 +565,30 @@ static struct {
 	.lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
 };
 
-static void _mix_pool_bytes(const void *in, size_t nbytes)
+static void _mix_pool_bytes(const void *buf, size_t len)
 {
-	blake2s_update(&input_pool.hash, in, nbytes);
+	blake2s_update(&input_pool.hash, buf, len);
 }
 
 /*
- * This function adds bytes into the entropy "pool".  It does not
- * update the entropy estimate.  The caller should call
- * credit_entropy_bits if this is appropriate.
+ * This function adds bytes into the input pool. It does not
+ * update the initialization bit counter; the caller should call
+ * credit_init_bits if this is appropriate.
  */
-static void mix_pool_bytes(const void *in, size_t nbytes)
+static void mix_pool_bytes(const void *buf, size_t len)
 {
 	unsigned long flags;
 
 	spin_lock_irqsave(&input_pool.lock, flags);
-	_mix_pool_bytes(in, nbytes);
+	_mix_pool_bytes(buf, len);
 	spin_unlock_irqrestore(&input_pool.lock, flags);
 }
 
-static void credit_entropy_bits(size_t nbits)
-{
-	unsigned int entropy_count, orig, add;
-
-	if (!nbits)
-		return;
-
-	add = min_t(size_t, nbits, POOL_BITS);
-
-	do {
-		orig = READ_ONCE(input_pool.entropy_count);
-		entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
-	} while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
-
-	if (!crng_ready() && entropy_count >= POOL_MIN_BITS)
-		crng_reseed(false);
-}
-
 /*
  * This is an HKDF-like construction for using the hashed collected entropy
  * as a PRF key, that's then expanded block-by-block.
  */
-static void extract_entropy(void *buf, size_t nbytes)
+static void extract_entropy(void *buf, size_t len)
 {
 	unsigned long flags;
 	u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE];
@@ -867,12 +617,12 @@ static void extract_entropy(void *buf, size_t nbytes)
 	spin_unlock_irqrestore(&input_pool.lock, flags);
 	memzero_explicit(next_key, sizeof(next_key));
 
-	while (nbytes) {
-		i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE);
+	while (len) {
+		i = min_t(size_t, len, BLAKE2S_HASH_SIZE);
 		/* output = HASHPRF(seed, RDSEED || ++counter) */
 		++block.counter;
 		blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed));
-		nbytes -= i;
+		len -= i;
 		buf += i;
 	}
 
@@ -880,23 +630,42 @@ static void extract_entropy(void *buf, size_t nbytes)
 	memzero_explicit(&block, sizeof(block));
 }
 
-/*
- * First we make sure we have POOL_MIN_BITS of entropy in the pool unless force
- * is true, and then we set the entropy count to zero (but don't actually touch
- * any data). Only then can we extract a new key with extract_entropy().
- */
-static bool drain_entropy(void *buf, size_t nbytes, bool force)
+#define credit_init_bits(bits) if (!crng_ready()) _credit_init_bits(bits)
+
+static void __cold _credit_init_bits(size_t bits)
 {
-	unsigned int entropy_count;
+	static struct execute_work set_ready;
+	unsigned int new, orig, add;
+	unsigned long flags;
+
+	if (!bits)
+		return;
+
+	add = min_t(size_t, bits, POOL_BITS);
+
 	do {
-		entropy_count = READ_ONCE(input_pool.entropy_count);
-		if (!force && entropy_count < POOL_MIN_BITS)
-			return false;
-	} while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count);
-	extract_entropy(buf, nbytes);
-	wake_up_interruptible(&random_write_wait);
-	kill_fasync(&fasync, SIGIO, POLL_OUT);
-	return true;
+		orig = READ_ONCE(input_pool.init_bits);
+		new = min_t(unsigned int, POOL_BITS, orig + add);
+	} while (cmpxchg(&input_pool.init_bits, orig, new) != orig);
+
+	if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
+		crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */
+		execute_in_process_context(crng_set_ready, &set_ready);
+		wake_up_interruptible(&crng_init_wait);
+		kill_fasync(&fasync, SIGIO, POLL_IN);
+		pr_notice("crng init done\n");
+		if (urandom_warning.missed)
+			pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
+				  urandom_warning.missed);
+	} else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
+		spin_lock_irqsave(&base_crng.lock, flags);
+		/* Check if crng_init is CRNG_EMPTY, to avoid race with crng_reseed(). */
+		if (crng_init == CRNG_EMPTY) {
+			extract_entropy(base_crng.key, sizeof(base_crng.key));
+			crng_init = CRNG_EARLY;
+		}
+		spin_unlock_irqrestore(&base_crng.lock, flags);
+	}
 }
 
 
@@ -907,15 +676,13 @@ static bool drain_entropy(void *buf, size_t nbytes, bool force)
  * The following exported functions are used for pushing entropy into
  * the above entropy accumulation routines:
  *
- *	void add_device_randomness(const void *buf, size_t size);
- *	void add_input_randomness(unsigned int type, unsigned int code,
- *	                          unsigned int value);
- *	void add_disk_randomness(struct gendisk *disk);
- *	void add_hwgenerator_randomness(const void *buffer, size_t count,
- *					size_t entropy);
- *	void add_bootloader_randomness(const void *buf, size_t size);
- *	void add_vmfork_randomness(const void *unique_vm_id, size_t size);
+ *	void add_device_randomness(const void *buf, size_t len);
+ *	void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy);
+ *	void add_bootloader_randomness(const void *buf, size_t len);
+ *	void add_vmfork_randomness(const void *unique_vm_id, size_t len);
  *	void add_interrupt_randomness(int irq);
+ *	void add_input_randomness(unsigned int type, unsigned int code, unsigned int value);
+ *	void add_disk_randomness(struct gendisk *disk);
  *
  * add_device_randomness() adds data to the input pool that
  * is likely to differ between two devices (or possibly even per boot).
@@ -925,26 +692,13 @@ static bool drain_entropy(void *buf, size_t nbytes, bool force)
  * that might otherwise be identical and have very little entropy
  * available to them (particularly common in the embedded world).
  *
- * add_input_randomness() uses the input layer interrupt timing, as well
- * as the event type information from the hardware.
- *
- * add_disk_randomness() uses what amounts to the seek time of block
- * layer request events, on a per-disk_devt basis, as input to the
- * entropy pool. Note that high-speed solid state drives with very low
- * seek times do not make for good sources of entropy, as their seek
- * times are usually fairly consistent.
- *
- * The above two routines try to estimate how many bits of entropy
- * to credit. They do this by keeping track of the first and second
- * order deltas of the event timings.
- *
  * add_hwgenerator_randomness() is for true hardware RNGs, and will credit
  * entropy as specified by the caller. If the entropy pool is full it will
  * block until more entropy is needed.
  *
- * add_bootloader_randomness() is the same as add_hwgenerator_randomness() or
- * add_device_randomness(), depending on whether or not the configuration
- * option CONFIG_RANDOM_TRUST_BOOTLOADER is set.
+ * add_bootloader_randomness() is called by bootloader drivers, such as EFI
+ * and device tree, and credits its input depending on whether or not the
+ * configuration option CONFIG_RANDOM_TRUST_BOOTLOADER is set.
  *
  * add_vmfork_randomness() adds a unique (but not necessarily secret) ID
  * representing the current instance of a VM to the pool, without crediting,
@@ -955,8 +709,22 @@ static bool drain_entropy(void *buf, size_t nbytes, bool force)
  * as inputs, it feeds the input pool roughly once a second or after 64
  * interrupts, crediting 1 bit of entropy for whichever comes first.
  *
+ * add_input_randomness() uses the input layer interrupt timing, as well
+ * as the event type information from the hardware.
+ *
+ * add_disk_randomness() uses what amounts to the seek time of block
+ * layer request events, on a per-disk_devt basis, as input to the
+ * entropy pool. Note that high-speed solid state drives with very low
+ * seek times do not make for good sources of entropy, as their seek
+ * times are usually fairly consistent.
+ *
+ * The last two routines try to estimate how many bits of entropy
+ * to credit. They do this by keeping track of the first and second
+ * order deltas of the event timings.
+ *
  **********************************************************************/
 
+static bool used_arch_random;
 static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
 static bool trust_bootloader __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER);
 static int __init parse_trust_cpu(char *arg)
@@ -970,52 +738,91 @@ static int __init parse_trust_bootloader(char *arg)
 early_param("random.trust_cpu", parse_trust_cpu);
 early_param("random.trust_bootloader", parse_trust_bootloader);
 
+static int random_pm_notification(struct notifier_block *nb, unsigned long action, void *data)
+{
+	unsigned long flags, entropy = random_get_entropy();
+
+	/*
+	 * Encode a representation of how long the system has been suspended,
+	 * in a way that is distinct from prior system suspends.
+	 */
+	ktime_t stamps[] = { ktime_get(), ktime_get_boottime(), ktime_get_real() };
+
+	spin_lock_irqsave(&input_pool.lock, flags);
+	_mix_pool_bytes(&action, sizeof(action));
+	_mix_pool_bytes(stamps, sizeof(stamps));
+	_mix_pool_bytes(&entropy, sizeof(entropy));
+	spin_unlock_irqrestore(&input_pool.lock, flags);
+
+	if (crng_ready() && (action == PM_RESTORE_PREPARE ||
+	    (action == PM_POST_SUSPEND &&
+	     !IS_ENABLED(CONFIG_PM_AUTOSLEEP) && !IS_ENABLED(CONFIG_ANDROID)))) {
+		crng_reseed();
+		pr_notice("crng reseeded on system resumption\n");
+	}
+	return 0;
+}
+
+static struct notifier_block pm_notifier = { .notifier_call = random_pm_notification };
+
 /*
  * The first collection of entropy occurs at system boot while interrupts
- * are still turned off. Here we push in RDSEED, a timestamp, and utsname().
- * Depending on the above configuration knob, RDSEED may be considered
- * sufficient for initialization. Note that much earlier setup may already
- * have pushed entropy into the input pool by the time we get here.
+ * are still turned off. Here we push in latent entropy, RDSEED, a timestamp,
+ * utsname(), and the command line. Depending on the above configuration knob,
+ * RDSEED may be considered sufficient for initialization. Note that much
+ * earlier setup may already have pushed entropy into the input pool by the
+ * time we get here.
  */
-int __init rand_initialize(void)
+int __init random_init(const char *command_line)
 {
-	size_t i;
 	ktime_t now = ktime_get_real();
-	bool arch_init = true;
-	unsigned long rv;
+	unsigned int i, arch_bytes;
+	unsigned long entropy;
 
 #if defined(LATENT_ENTROPY_PLUGIN)
 	static const u8 compiletime_seed[BLAKE2S_BLOCK_SIZE] __initconst __latent_entropy;
 	_mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed));
 #endif
 
-	for (i = 0; i < BLAKE2S_BLOCK_SIZE; i += sizeof(rv)) {
-		if (!arch_get_random_seed_long_early(&rv) &&
-		    !arch_get_random_long_early(&rv)) {
-			rv = random_get_entropy();
-			arch_init = false;
+	for (i = 0, arch_bytes = BLAKE2S_BLOCK_SIZE;
+	     i < BLAKE2S_BLOCK_SIZE; i += sizeof(entropy)) {
+		if (!arch_get_random_seed_long_early(&entropy) &&
+		    !arch_get_random_long_early(&entropy)) {
+			entropy = random_get_entropy();
+			arch_bytes -= sizeof(entropy);
 		}
-		_mix_pool_bytes(&rv, sizeof(rv));
+		_mix_pool_bytes(&entropy, sizeof(entropy));
 	}
 	_mix_pool_bytes(&now, sizeof(now));
 	_mix_pool_bytes(utsname(), sizeof(*(utsname())));
+	_mix_pool_bytes(command_line, strlen(command_line));
+	add_latent_entropy();
 
-	extract_entropy(base_crng.key, sizeof(base_crng.key));
-	++base_crng.generation;
+	if (crng_ready())
+		crng_reseed();
+	else if (trust_cpu)
+		credit_init_bits(arch_bytes * 8);
+	used_arch_random = arch_bytes * 8 >= POOL_READY_BITS;
 
-	if (arch_init && trust_cpu && !crng_ready()) {
-		crng_init = 2;
-		pr_notice("crng init done (trusting CPU's manufacturer)\n");
-	}
+	WARN_ON(register_pm_notifier(&pm_notifier));
 
-	if (ratelimit_disable) {
-		urandom_warning.interval = 0;
-		unseeded_warning.interval = 0;
-	}
+	WARN(!random_get_entropy(), "Missing cycle counter and fallback timer; RNG "
+				    "entropy collection will consequently suffer.");
 	return 0;
 }
 
 /*
+ * Returns whether arch randomness has been mixed into the initial
+ * state of the RNG, regardless of whether or not that randomness
+ * was credited. Knowing this is only good for a very limited set
+ * of uses, such as early init printk pointer obfuscation.
+ */
+bool rng_has_arch_random(void)
+{
+	return used_arch_random;
+}
+
+/*
  * Add device- or boot-specific data to the input pool to help
  * initialize it.
  *
@@ -1023,164 +830,46 @@ int __init rand_initialize(void)
  * the entropy pool having similar initial state across largely
  * identical devices.
  */
-void add_device_randomness(const void *buf, size_t size)
+void add_device_randomness(const void *buf, size_t len)
 {
-	unsigned long cycles = random_get_entropy();
-	unsigned long flags, now = jiffies;
-
-	if (crng_init == 0 && size)
-		crng_pre_init_inject(buf, size, false);
+	unsigned long entropy = random_get_entropy();
+	unsigned long flags;
 
 	spin_lock_irqsave(&input_pool.lock, flags);
-	_mix_pool_bytes(&cycles, sizeof(cycles));
-	_mix_pool_bytes(&now, sizeof(now));
-	_mix_pool_bytes(buf, size);
+	_mix_pool_bytes(&entropy, sizeof(entropy));
+	_mix_pool_bytes(buf, len);
 	spin_unlock_irqrestore(&input_pool.lock, flags);
 }
 EXPORT_SYMBOL(add_device_randomness);
 
-/* There is one of these per entropy source */
-struct timer_rand_state {
-	unsigned long last_time;
-	long last_delta, last_delta2;
-};
-
-/*
- * This function adds entropy to the entropy "pool" by using timing
- * delays.  It uses the timer_rand_state structure to make an estimate
- * of how many bits of entropy this call has added to the pool.
- *
- * The number "num" is also added to the pool - it should somehow describe
- * the type of event which just happened.  This is currently 0-255 for
- * keyboard scan codes, and 256 upwards for interrupts.
- */
-static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)
-{
-	unsigned long cycles = random_get_entropy(), now = jiffies, flags;
-	long delta, delta2, delta3;
-
-	spin_lock_irqsave(&input_pool.lock, flags);
-	_mix_pool_bytes(&cycles, sizeof(cycles));
-	_mix_pool_bytes(&now, sizeof(now));
-	_mix_pool_bytes(&num, sizeof(num));
-	spin_unlock_irqrestore(&input_pool.lock, flags);
-
-	/*
-	 * Calculate number of bits of randomness we probably added.
-	 * We take into account the first, second and third-order deltas
-	 * in order to make our estimate.
-	 */
-	delta = now - READ_ONCE(state->last_time);
-	WRITE_ONCE(state->last_time, now);
-
-	delta2 = delta - READ_ONCE(state->last_delta);
-	WRITE_ONCE(state->last_delta, delta);
-
-	delta3 = delta2 - READ_ONCE(state->last_delta2);
-	WRITE_ONCE(state->last_delta2, delta2);
-
-	if (delta < 0)
-		delta = -delta;
-	if (delta2 < 0)
-		delta2 = -delta2;
-	if (delta3 < 0)
-		delta3 = -delta3;
-	if (delta > delta2)
-		delta = delta2;
-	if (delta > delta3)
-		delta = delta3;
-
-	/*
-	 * delta is now minimum absolute delta.
-	 * Round down by 1 bit on general principles,
-	 * and limit entropy estimate to 12 bits.
-	 */
-	credit_entropy_bits(min_t(unsigned int, fls(delta >> 1), 11));
-}
-
-void add_input_randomness(unsigned int type, unsigned int code,
-			  unsigned int value)
-{
-	static unsigned char last_value;
-	static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES };
-
-	/* Ignore autorepeat and the like. */
-	if (value == last_value)
-		return;
-
-	last_value = value;
-	add_timer_randomness(&input_timer_state,
-			     (type << 4) ^ code ^ (code >> 4) ^ value);
-}
-EXPORT_SYMBOL_GPL(add_input_randomness);
-
-#ifdef CONFIG_BLOCK
-void add_disk_randomness(struct gendisk *disk)
-{
-	if (!disk || !disk->random)
-		return;
-	/* First major is 1, so we get >= 0x200 here. */
-	add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
-}
-EXPORT_SYMBOL_GPL(add_disk_randomness);
-
-void rand_initialize_disk(struct gendisk *disk)
-{
-	struct timer_rand_state *state;
-
-	/*
-	 * If kzalloc returns null, we just won't use that entropy
-	 * source.
-	 */
-	state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
-	if (state) {
-		state->last_time = INITIAL_JIFFIES;
-		disk->random = state;
-	}
-}
-#endif
-
 /*
  * Interface for in-kernel drivers of true hardware RNGs.
  * Those devices may produce endless random bits and will be throttled
  * when our pool is full.
  */
-void add_hwgenerator_randomness(const void *buffer, size_t count,
-				size_t entropy)
+void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy)
 {
-	if (unlikely(crng_init == 0 && entropy < POOL_MIN_BITS)) {
-		crng_pre_init_inject(buffer, count, true);
-		mix_pool_bytes(buffer, count);
-		return;
-	}
+	mix_pool_bytes(buf, len);
+	credit_init_bits(entropy);
 
 	/*
-	 * Throttle writing if we're above the trickle threshold.
-	 * We'll be woken up again once below POOL_MIN_BITS, when
-	 * the calling thread is about to terminate, or once
-	 * CRNG_RESEED_INTERVAL has elapsed.
+	 * Throttle writing to once every CRNG_RESEED_INTERVAL, unless
+	 * we're not yet initialized.
 	 */
-	wait_event_interruptible_timeout(random_write_wait,
-			!system_wq || kthread_should_stop() ||
-			input_pool.entropy_count < POOL_MIN_BITS,
-			CRNG_RESEED_INTERVAL);
-	mix_pool_bytes(buffer, count);
-	credit_entropy_bits(entropy);
+	if (!kthread_should_stop() && crng_ready())
+		schedule_timeout_interruptible(CRNG_RESEED_INTERVAL);
 }
 EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
 
 /*
- * Handle random seed passed by bootloader.
- * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise
- * it would be regarded as device data.
- * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER.
+ * Handle random seed passed by bootloader, and credit it if
+ * CONFIG_RANDOM_TRUST_BOOTLOADER is set.
  */
-void add_bootloader_randomness(const void *buf, size_t size)
+void __cold add_bootloader_randomness(const void *buf, size_t len)
 {
+	mix_pool_bytes(buf, len);
 	if (trust_bootloader)
-		add_hwgenerator_randomness(buf, size, size * 8);
-	else
-		add_device_randomness(buf, size);
+		credit_init_bits(len * 8);
 }
 EXPORT_SYMBOL_GPL(add_bootloader_randomness);
 
@@ -1192,11 +881,11 @@ static BLOCKING_NOTIFIER_HEAD(vmfork_chain);
  * don't credit it, but we do immediately force a reseed after so
  * that it's used by the crng posthaste.
  */
-void add_vmfork_randomness(const void *unique_vm_id, size_t size)
+void __cold add_vmfork_randomness(const void *unique_vm_id, size_t len)
 {
-	add_device_randomness(unique_vm_id, size);
+	add_device_randomness(unique_vm_id, len);
 	if (crng_ready()) {
-		crng_reseed(true);
+		crng_reseed();
 		pr_notice("crng reseeded due to virtual machine fork\n");
 	}
 	blocking_notifier_call_chain(&vmfork_chain, 0, NULL);
@@ -1205,13 +894,13 @@ void add_vmfork_randomness(const void *unique_vm_id, size_t size)
 EXPORT_SYMBOL_GPL(add_vmfork_randomness);
 #endif
 
-int register_random_vmfork_notifier(struct notifier_block *nb)
+int __cold register_random_vmfork_notifier(struct notifier_block *nb)
 {
 	return blocking_notifier_chain_register(&vmfork_chain, nb);
 }
 EXPORT_SYMBOL_GPL(register_random_vmfork_notifier);
 
-int unregister_random_vmfork_notifier(struct notifier_block *nb)
+int __cold unregister_random_vmfork_notifier(struct notifier_block *nb)
 {
 	return blocking_notifier_chain_unregister(&vmfork_chain, nb);
 }
@@ -1223,17 +912,15 @@ struct fast_pool {
 	unsigned long pool[4];
 	unsigned long last;
 	unsigned int count;
-	u16 reg_idx;
 };
 
 static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = {
 #ifdef CONFIG_64BIT
-	/* SipHash constants */
-	.pool = { 0x736f6d6570736575UL, 0x646f72616e646f6dUL,
-		  0x6c7967656e657261UL, 0x7465646279746573UL }
+#define FASTMIX_PERM SIPHASH_PERMUTATION
+	.pool = { SIPHASH_CONST_0, SIPHASH_CONST_1, SIPHASH_CONST_2, SIPHASH_CONST_3 }
 #else
-	/* HalfSipHash constants */
-	.pool = { 0, 0, 0x6c796765U, 0x74656462U }
+#define FASTMIX_PERM HSIPHASH_PERMUTATION
+	.pool = { HSIPHASH_CONST_0, HSIPHASH_CONST_1, HSIPHASH_CONST_2, HSIPHASH_CONST_3 }
 #endif
 };
 
@@ -1241,27 +928,16 @@ static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = {
  * This is [Half]SipHash-1-x, starting from an empty key. Because
  * the key is fixed, it assumes that its inputs are non-malicious,
  * and therefore this has no security on its own. s represents the
- * 128 or 256-bit SipHash state, while v represents a 128-bit input.
+ * four-word SipHash state, while v represents a two-word input.
  */
-static void fast_mix(unsigned long s[4], const unsigned long *v)
+static void fast_mix(unsigned long s[4], unsigned long v1, unsigned long v2)
 {
-	size_t i;
-
-	for (i = 0; i < 16 / sizeof(long); ++i) {
-		s[3] ^= v[i];
-#ifdef CONFIG_64BIT
-		s[0] += s[1]; s[1] = rol64(s[1], 13); s[1] ^= s[0]; s[0] = rol64(s[0], 32);
-		s[2] += s[3]; s[3] = rol64(s[3], 16); s[3] ^= s[2];
-		s[0] += s[3]; s[3] = rol64(s[3], 21); s[3] ^= s[0];
-		s[2] += s[1]; s[1] = rol64(s[1], 17); s[1] ^= s[2]; s[2] = rol64(s[2], 32);
-#else
-		s[0] += s[1]; s[1] = rol32(s[1],  5); s[1] ^= s[0]; s[0] = rol32(s[0], 16);
-		s[2] += s[3]; s[3] = rol32(s[3],  8); s[3] ^= s[2];
-		s[0] += s[3]; s[3] = rol32(s[3],  7); s[3] ^= s[0];
-		s[2] += s[1]; s[1] = rol32(s[1], 13); s[1] ^= s[2]; s[2] = rol32(s[2], 16);
-#endif
-		s[0] ^= v[i];
-	}
+	s[3] ^= v1;
+	FASTMIX_PERM(s[0], s[1], s[2], s[3]);
+	s[0] ^= v1;
+	s[3] ^= v2;
+	FASTMIX_PERM(s[0], s[1], s[2], s[3]);
+	s[0] ^= v2;
 }
 
 #ifdef CONFIG_SMP
@@ -1269,7 +945,7 @@ static void fast_mix(unsigned long s[4], const unsigned long *v)
  * This function is called when the CPU has just come online, with
  * entry CPUHP_AP_RANDOM_ONLINE, just after CPUHP_AP_WORKQUEUE_ONLINE.
  */
-int random_online_cpu(unsigned int cpu)
+int __cold random_online_cpu(unsigned int cpu)
 {
 	/*
 	 * During CPU shutdown and before CPU onlining, add_interrupt_
@@ -1287,33 +963,18 @@ int random_online_cpu(unsigned int cpu)
 }
 #endif
 
-static unsigned long get_reg(struct fast_pool *f, struct pt_regs *regs)
-{
-	unsigned long *ptr = (unsigned long *)regs;
-	unsigned int idx;
-
-	if (regs == NULL)
-		return 0;
-	idx = READ_ONCE(f->reg_idx);
-	if (idx >= sizeof(struct pt_regs) / sizeof(unsigned long))
-		idx = 0;
-	ptr += idx++;
-	WRITE_ONCE(f->reg_idx, idx);
-	return *ptr;
-}
-
 static void mix_interrupt_randomness(struct work_struct *work)
 {
 	struct fast_pool *fast_pool = container_of(work, struct fast_pool, mix);
 	/*
-	 * The size of the copied stack pool is explicitly 16 bytes so that we
-	 * tax mix_pool_byte()'s compression function the same amount on all
-	 * platforms. This means on 64-bit we copy half the pool into this,
-	 * while on 32-bit we copy all of it. The entropy is supposed to be
-	 * sufficiently dispersed between bits that in the sponge-like
-	 * half case, on average we don't wind up "losing" some.
+	 * The size of the copied stack pool is explicitly 2 longs so that we
+	 * only ever ingest half of the siphash output each time, retaining
+	 * the other half as the next "key" that carries over. The entropy is
+	 * supposed to be sufficiently dispersed between bits so on average
+	 * we don't wind up "losing" some.
 	 */
-	u8 pool[16];
+	unsigned long pool[2];
+	unsigned int count;
 
 	/* Check to see if we're running on the wrong CPU due to hotplug. */
 	local_irq_disable();
@@ -1327,17 +988,13 @@ static void mix_interrupt_randomness(struct work_struct *work)
 	 * consistent view, before we reenable irqs again.
 	 */
 	memcpy(pool, fast_pool->pool, sizeof(pool));
+	count = fast_pool->count;
 	fast_pool->count = 0;
 	fast_pool->last = jiffies;
 	local_irq_enable();
 
-	if (unlikely(crng_init == 0)) {
-		crng_pre_init_inject(pool, sizeof(pool), true);
-		mix_pool_bytes(pool, sizeof(pool));
-	} else {
-		mix_pool_bytes(pool, sizeof(pool));
-		credit_entropy_bits(1);
-	}
+	mix_pool_bytes(pool, sizeof(pool));
+	credit_init_bits(max(1u, (count & U16_MAX) / 64));
 
 	memzero_explicit(pool, sizeof(pool));
 }
@@ -1345,37 +1002,19 @@ static void mix_interrupt_randomness(struct work_struct *work)
 void add_interrupt_randomness(int irq)
 {
 	enum { MIX_INFLIGHT = 1U << 31 };
-	unsigned long cycles = random_get_entropy(), now = jiffies;
+	unsigned long entropy = random_get_entropy();
 	struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
 	struct pt_regs *regs = get_irq_regs();
 	unsigned int new_count;
-	union {
-		u32 u32[4];
-		u64 u64[2];
-		unsigned long longs[16 / sizeof(long)];
-	} irq_data;
-
-	if (cycles == 0)
-		cycles = get_reg(fast_pool, regs);
-
-	if (sizeof(unsigned long) == 8) {
-		irq_data.u64[0] = cycles ^ rol64(now, 32) ^ irq;
-		irq_data.u64[1] = regs ? instruction_pointer(regs) : _RET_IP_;
-	} else {
-		irq_data.u32[0] = cycles ^ irq;
-		irq_data.u32[1] = now;
-		irq_data.u32[2] = regs ? instruction_pointer(regs) : _RET_IP_;
-		irq_data.u32[3] = get_reg(fast_pool, regs);
-	}
 
-	fast_mix(fast_pool->pool, irq_data.longs);
+	fast_mix(fast_pool->pool, entropy,
+		 (regs ? instruction_pointer(regs) : _RET_IP_) ^ swab(irq));
 	new_count = ++fast_pool->count;
 
 	if (new_count & MIX_INFLIGHT)
 		return;
 
-	if (new_count < 64 && (!time_after(now, fast_pool->last + HZ) ||
-			       unlikely(crng_init == 0)))
+	if (new_count < 64 && !time_is_before_jiffies(fast_pool->last + HZ))
 		return;
 
 	if (unlikely(!fast_pool->mix.func))
@@ -1385,6 +1024,132 @@ void add_interrupt_randomness(int irq)
 }
 EXPORT_SYMBOL_GPL(add_interrupt_randomness);
 
+/* There is one of these per entropy source */
+struct timer_rand_state {
+	unsigned long last_time;
+	long last_delta, last_delta2;
+};
+
+/*
+ * This function adds entropy to the entropy "pool" by using timing
+ * delays. It uses the timer_rand_state structure to make an estimate
+ * of how many bits of entropy this call has added to the pool. The
+ * value "num" is also added to the pool; it should somehow describe
+ * the type of event that just happened.
+ */
+static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)
+{
+	unsigned long entropy = random_get_entropy(), now = jiffies, flags;
+	long delta, delta2, delta3;
+	unsigned int bits;
+
+	/*
+	 * If we're in a hard IRQ, add_interrupt_randomness() will be called
+	 * sometime after, so mix into the fast pool.
+	 */
+	if (in_hardirq()) {
+		fast_mix(this_cpu_ptr(&irq_randomness)->pool, entropy, num);
+	} else {
+		spin_lock_irqsave(&input_pool.lock, flags);
+		_mix_pool_bytes(&entropy, sizeof(entropy));
+		_mix_pool_bytes(&num, sizeof(num));
+		spin_unlock_irqrestore(&input_pool.lock, flags);
+	}
+
+	if (crng_ready())
+		return;
+
+	/*
+	 * Calculate number of bits of randomness we probably added.
+	 * We take into account the first, second and third-order deltas
+	 * in order to make our estimate.
+	 */
+	delta = now - READ_ONCE(state->last_time);
+	WRITE_ONCE(state->last_time, now);
+
+	delta2 = delta - READ_ONCE(state->last_delta);
+	WRITE_ONCE(state->last_delta, delta);
+
+	delta3 = delta2 - READ_ONCE(state->last_delta2);
+	WRITE_ONCE(state->last_delta2, delta2);
+
+	if (delta < 0)
+		delta = -delta;
+	if (delta2 < 0)
+		delta2 = -delta2;
+	if (delta3 < 0)
+		delta3 = -delta3;
+	if (delta > delta2)
+		delta = delta2;
+	if (delta > delta3)
+		delta = delta3;
+
+	/*
+	 * delta is now minimum absolute delta. Round down by 1 bit
+	 * on general principles, and limit entropy estimate to 11 bits.
+	 */
+	bits = min(fls(delta >> 1), 11);
+
+	/*
+	 * As mentioned above, if we're in a hard IRQ, add_interrupt_randomness()
+	 * will run after this, which uses a different crediting scheme of 1 bit
+	 * per every 64 interrupts. In order to let that function do accounting
+	 * close to the one in this function, we credit a full 64/64 bit per bit,
+	 * and then subtract one to account for the extra one added.
+	 */
+	if (in_hardirq())
+		this_cpu_ptr(&irq_randomness)->count += max(1u, bits * 64) - 1;
+	else
+		_credit_init_bits(bits);
+}
+
+void add_input_randomness(unsigned int type, unsigned int code, unsigned int value)
+{
+	static unsigned char last_value;
+	static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES };
+
+	/* Ignore autorepeat and the like. */
+	if (value == last_value)
+		return;
+
+	last_value = value;
+	add_timer_randomness(&input_timer_state,
+			     (type << 4) ^ code ^ (code >> 4) ^ value);
+}
+EXPORT_SYMBOL_GPL(add_input_randomness);
+
+#ifdef CONFIG_BLOCK
+void add_disk_randomness(struct gendisk *disk)
+{
+	if (!disk || !disk->random)
+		return;
+	/* First major is 1, so we get >= 0x200 here. */
+	add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
+}
+EXPORT_SYMBOL_GPL(add_disk_randomness);
+
+void __cold rand_initialize_disk(struct gendisk *disk)
+{
+	struct timer_rand_state *state;
+
+	/*
+	 * If kzalloc returns null, we just won't use that entropy
+	 * source.
+	 */
+	state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
+	if (state) {
+		state->last_time = INITIAL_JIFFIES;
+		disk->random = state;
+	}
+}
+#endif
+
+struct entropy_timer_state {
+	unsigned long entropy;
+	struct timer_list timer;
+	unsigned int samples, samples_per_bit;
+};
+
 /*
  * Each time the timer fires, we expect that we got an unpredictable
  * jump in the cycle counter. Even if the timer is running on another
@@ -1398,40 +1163,50 @@ EXPORT_SYMBOL_GPL(add_interrupt_randomness);
  *
  * So the re-arming always happens in the entropy loop itself.
  */
-static void entropy_timer(struct timer_list *t)
+static void __cold entropy_timer(struct timer_list *timer)
 {
-	credit_entropy_bits(1);
+	struct entropy_timer_state *state = container_of(timer, struct entropy_timer_state, timer);
+
+	if (++state->samples == state->samples_per_bit) {
+		credit_init_bits(1);
+		state->samples = 0;
+	}
 }
 
 /*
  * If we have an actual cycle counter, see if we can
  * generate enough entropy with timing noise
  */
-static void try_to_generate_entropy(void)
+static void __cold try_to_generate_entropy(void)
 {
-	struct {
-		unsigned long cycles;
-		struct timer_list timer;
-	} stack;
-
-	stack.cycles = random_get_entropy();
-
-	/* Slow counter - or none. Don't even bother */
-	if (stack.cycles == random_get_entropy())
+	enum { NUM_TRIAL_SAMPLES = 8192, MAX_SAMPLES_PER_BIT = 32 };
+	struct entropy_timer_state stack;
+	unsigned int i, num_different = 0;
+	unsigned long last = random_get_entropy();
+
+	for (i = 0; i < NUM_TRIAL_SAMPLES - 1; ++i) {
+		stack.entropy = random_get_entropy();
+		if (stack.entropy != last)
+			++num_different;
+		last = stack.entropy;
+	}
+	stack.samples_per_bit = DIV_ROUND_UP(NUM_TRIAL_SAMPLES, num_different + 1);
+	if (stack.samples_per_bit > MAX_SAMPLES_PER_BIT)
 		return;
 
+	stack.samples = 0;
 	timer_setup_on_stack(&stack.timer, entropy_timer, 0);
 	while (!crng_ready() && !signal_pending(current)) {
 		if (!timer_pending(&stack.timer))
 			mod_timer(&stack.timer, jiffies + 1);
-		mix_pool_bytes(&stack.cycles, sizeof(stack.cycles));
+		mix_pool_bytes(&stack.entropy, sizeof(stack.entropy));
 		schedule();
-		stack.cycles = random_get_entropy();
+		stack.entropy = random_get_entropy();
 	}
 
 	del_timer_sync(&stack.timer);
 	destroy_timer_on_stack(&stack.timer);
-	mix_pool_bytes(&stack.cycles, sizeof(stack.cycles));
+	mix_pool_bytes(&stack.entropy, sizeof(stack.entropy));
 }
 
 
@@ -1463,9 +1238,12 @@ static void try_to_generate_entropy(void)
  *
  **********************************************************************/
 
-SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int,
-		flags)
+SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len, unsigned int, flags)
 {
+	struct iov_iter iter;
+	struct iovec iov;
+	int ret;
+
 	if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE))
 		return -EINVAL;
 
@@ -1476,72 +1254,60 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count, unsigned int,
 	if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM))
 		return -EINVAL;
 
-	if (count > INT_MAX)
-		count = INT_MAX;
-
-	if (!(flags & GRND_INSECURE) && !crng_ready()) {
-		int ret;
-
+	if (!crng_ready() && !(flags & GRND_INSECURE)) {
 		if (flags & GRND_NONBLOCK)
 			return -EAGAIN;
 		ret = wait_for_random_bytes();
 		if (unlikely(ret))
 			return ret;
 	}
-	return get_random_bytes_user(buf, count);
+
+	ret = import_single_range(READ, ubuf, len, &iov, &iter);
+	if (unlikely(ret))
+		return ret;
+	return get_random_bytes_user(&iter);
 }
 
 static __poll_t random_poll(struct file *file, poll_table *wait)
 {
-	__poll_t mask;
-
 	poll_wait(file, &crng_init_wait, wait);
-	poll_wait(file, &random_write_wait, wait);
-	mask = 0;
-	if (crng_ready())
-		mask |= EPOLLIN | EPOLLRDNORM;
-	if (input_pool.entropy_count < POOL_MIN_BITS)
-		mask |= EPOLLOUT | EPOLLWRNORM;
-	return mask;
+	return crng_ready() ? EPOLLIN | EPOLLRDNORM : EPOLLOUT | EPOLLWRNORM;
 }
 
-static int write_pool(const char __user *ubuf, size_t count)
+static ssize_t write_pool_user(struct iov_iter *iter)
 {
-	size_t len;
-	int ret = 0;
 	u8 block[BLAKE2S_BLOCK_SIZE];
+	ssize_t ret = 0;
+	size_t copied;
+
+	if (unlikely(!iov_iter_count(iter)))
+		return 0;
+
+	for (;;) {
+		copied = copy_from_iter(block, sizeof(block), iter);
+		ret += copied;
+		mix_pool_bytes(block, copied);
+		if (!iov_iter_count(iter) || copied != sizeof(block))
+			break;
 
-	while (count) {
-		len = min(count, sizeof(block));
-		if (copy_from_user(block, ubuf, len)) {
-			ret = -EFAULT;
-			goto out;
+		BUILD_BUG_ON(PAGE_SIZE % sizeof(block) != 0);
+		if (ret % PAGE_SIZE == 0) {
+			if (signal_pending(current))
+				break;
+			cond_resched();
 		}
-		count -= len;
-		ubuf += len;
-		mix_pool_bytes(block, len);
-		cond_resched();
 	}
 
-out:
 	memzero_explicit(block, sizeof(block));
-	return ret;
+	return ret ? ret : -EFAULT;
 }
 
-static ssize_t random_write(struct file *file, const char __user *buffer,
-			    size_t count, loff_t *ppos)
+static ssize_t random_write_iter(struct kiocb *kiocb, struct iov_iter *iter)
 {
-	int ret;
-
-	ret = write_pool(buffer, count);
-	if (ret)
-		return ret;
-
-	return (ssize_t)count;
+	return write_pool_user(iter);
 }
 
-static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes,
-			    loff_t *ppos)
+static ssize_t urandom_read_iter(struct kiocb *kiocb, struct iov_iter *iter)
 {
 	static int maxwarn = 10;
 
@@ -1552,37 +1318,38 @@ static ssize_t urandom_read(struct file *file, char __user *buf, size_t nbytes,
 	if (!crng_ready())
 		try_to_generate_entropy();
 
-	if (!crng_ready() && maxwarn > 0) {
-		maxwarn--;
-		if (__ratelimit(&urandom_warning))
-			pr_notice("%s: uninitialized urandom read (%zd bytes read)\n",
-				  current->comm, nbytes);
+	if (!crng_ready()) {
+		if (!ratelimit_disable && maxwarn <= 0)
+			++urandom_warning.missed;
+		else if (ratelimit_disable || __ratelimit(&urandom_warning)) {
+			--maxwarn;
+			pr_notice("%s: uninitialized urandom read (%zu bytes read)\n",
+				  current->comm, iov_iter_count(iter));
+		}
 	}
 
-	return get_random_bytes_user(buf, nbytes);
+	return get_random_bytes_user(iter);
 }
 
-static ssize_t random_read(struct file *file, char __user *buf, size_t nbytes,
-			   loff_t *ppos)
+static ssize_t random_read_iter(struct kiocb *kiocb, struct iov_iter *iter)
 {
 	int ret;
 
 	ret = wait_for_random_bytes();
 	if (ret != 0)
 		return ret;
-	return get_random_bytes_user(buf, nbytes);
+	return get_random_bytes_user(iter);
 }
 
 static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
 {
-	int size, ent_count;
 	int __user *p = (int __user *)arg;
-	int retval;
+	int ent_count;
 
 	switch (cmd) {
 	case RNDGETENTCNT:
 		/* Inherently racy, no point locking. */
-		if (put_user(input_pool.entropy_count, p))
+		if (put_user(input_pool.init_bits, p))
 			return -EFAULT;
 		return 0;
 	case RNDADDTOENTCNT:
@@ -1592,41 +1359,46 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
 			return -EFAULT;
 		if (ent_count < 0)
 			return -EINVAL;
-		credit_entropy_bits(ent_count);
+		credit_init_bits(ent_count);
 		return 0;
-	case RNDADDENTROPY:
+	case RNDADDENTROPY: {
+		struct iov_iter iter;
+		struct iovec iov;
+		ssize_t ret;
+		int len;
+
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
 		if (get_user(ent_count, p++))
 			return -EFAULT;
 		if (ent_count < 0)
 			return -EINVAL;
-		if (get_user(size, p++))
+		if (get_user(len, p++))
 			return -EFAULT;
-		retval = write_pool((const char __user *)p, size);
-		if (retval < 0)
-			return retval;
-		credit_entropy_bits(ent_count);
+		ret = import_single_range(WRITE, p, len, &iov, &iter);
+		if (unlikely(ret))
+			return ret;
+		ret = write_pool_user(&iter);
+		if (unlikely(ret < 0))
+			return ret;
+		/* Since we're crediting, enforce that it was all written into the pool. */
+		if (unlikely(ret != len))
+			return -EFAULT;
+		credit_init_bits(ent_count);
 		return 0;
+	}
 	case RNDZAPENTCNT:
 	case RNDCLEARPOOL:
-		/*
-		 * Clear the entropy pool counters. We no longer clear
-		 * the entropy pool, as that's silly.
-		 */
+		/* No longer has any effect. */
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
-		if (xchg(&input_pool.entropy_count, 0) >= POOL_MIN_BITS) {
-			wake_up_interruptible(&random_write_wait);
-			kill_fasync(&fasync, SIGIO, POLL_OUT);
-		}
 		return 0;
 	case RNDRESEEDCRNG:
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
 		if (!crng_ready())
 			return -ENODATA;
-		crng_reseed(false);
+		crng_reseed();
 		return 0;
 	default:
 		return -EINVAL;
@@ -1639,22 +1411,26 @@ static int random_fasync(int fd, struct file *filp, int on)
 }
 
 const struct file_operations random_fops = {
-	.read = random_read,
-	.write = random_write,
+	.read_iter = random_read_iter,
+	.write_iter = random_write_iter,
 	.poll = random_poll,
 	.unlocked_ioctl = random_ioctl,
 	.compat_ioctl = compat_ptr_ioctl,
 	.fasync = random_fasync,
 	.llseek = noop_llseek,
+	.splice_read = generic_file_splice_read,
+	.splice_write = iter_file_splice_write,
 };
 
 const struct file_operations urandom_fops = {
-	.read = urandom_read,
-	.write = random_write,
+	.read_iter = urandom_read_iter,
+	.write_iter = random_write_iter,
 	.unlocked_ioctl = random_ioctl,
 	.compat_ioctl = compat_ptr_ioctl,
 	.fasync = random_fasync,
 	.llseek = noop_llseek,
+	.splice_read = generic_file_splice_read,
+	.splice_write = iter_file_splice_write,
 };
 
 
@@ -1678,7 +1454,7 @@ const struct file_operations urandom_fops = {
  *
  * - write_wakeup_threshold - the amount of entropy in the input pool
  *   below which write polls to /dev/random will unblock, requesting
- *   more entropy, tied to the POOL_MIN_BITS constant. It is writable
+ *   more entropy, tied to the POOL_READY_BITS constant. It is writable
  *   to avoid breaking old userspaces, but writing to it does not
  *   change any behavior of the RNG.
  *
@@ -1693,7 +1469,7 @@ const struct file_operations urandom_fops = {
 #include <linux/sysctl.h>
 
 static int sysctl_random_min_urandom_seed = CRNG_RESEED_INTERVAL / HZ;
-static int sysctl_random_write_wakeup_bits = POOL_MIN_BITS;
+static int sysctl_random_write_wakeup_bits = POOL_READY_BITS;
 static int sysctl_poolsize = POOL_BITS;
 static u8 sysctl_bootid[UUID_SIZE];
 
@@ -1702,7 +1478,7 @@ static u8 sysctl_bootid[UUID_SIZE];
  * UUID. The difference is in whether table->data is NULL; if it is,
  * then a new UUID is generated and returned to the user.
  */
-static int proc_do_uuid(struct ctl_table *table, int write, void *buffer,
+static int proc_do_uuid(struct ctl_table *table, int write, void *buf,
 			size_t *lenp, loff_t *ppos)
 {
 	u8 tmp_uuid[UUID_SIZE], *uuid;
@@ -1729,14 +1505,14 @@ static int proc_do_uuid(struct ctl_table *table, int write, void *buffer,
 	}
 
 	snprintf(uuid_string, sizeof(uuid_string), "%pU", uuid);
-	return proc_dostring(&fake_table, 0, buffer, lenp, ppos);
+	return proc_dostring(&fake_table, 0, buf, lenp, ppos);
 }
 
 /* The same as proc_dointvec, but writes don't change anything. */
-static int proc_do_rointvec(struct ctl_table *table, int write, void *buffer,
+static int proc_do_rointvec(struct ctl_table *table, int write, void *buf,
 			    size_t *lenp, loff_t *ppos)
 {
-	return write ? 0 : proc_dointvec(table, 0, buffer, lenp, ppos);
+	return write ? 0 : proc_dointvec(table, 0, buf, lenp, ppos);
 }
 
 static struct ctl_table random_table[] = {
@@ -1749,7 +1525,7 @@ static struct ctl_table random_table[] = {
 	},
 	{
 		.procname	= "entropy_avail",
-		.data		= &input_pool.entropy_count,
+		.data		= &input_pool.init_bits,
 		.maxlen		= sizeof(int),
 		.mode		= 0444,
 		.proc_handler	= proc_dointvec,
@@ -1783,8 +1559,8 @@ static struct ctl_table random_table[] = {
 };
 
 /*
- * rand_initialize() is called before sysctl_init(),
- * so we cannot call register_sysctl_init() in rand_initialize()
+ * random_init() is called before sysctl_init(),
+ * so we cannot call register_sysctl_init() in random_init()
  */
 static int __init random_sysctls_init(void)
 {