kernel: add patch to fix Xavier NX crashes

kernel/0009-Revert-random-use-static-branch-for-crng_ready.patch

@@ -0,0 +1,68 @@
+From 72268945b124cd61336f9b4cac538b0516399a2d Mon Sep 17 00:00:00 2001
+From: "Jason A. Donenfeld" <[email protected]>
+Date: Tue, 7 Jun 2022 10:40:05 +0200
+Subject: [PATCH] Revert "random: use static branch for crng_ready()"
+
+This reverts upstream commit f5bda35fba615ace70a656d4700423fa6c9bebee
+from stable. It's not essential and will take some time during 5.19 to
+work out properly.
+
+Signed-off-by: Jason A. Donenfeld <[email protected]>
+---
+ drivers/char/random.c | 12 ++----------
+ 1 file changed, 2 insertions(+), 10 deletions(-)
+
+diff --git a/drivers/char/random.c b/drivers/char/random.c
+index c206db96f60a..5776dfd4a6fc 100644
+--- a/drivers/char/random.c
++++ b/drivers/char/random.c
+@@ -79,8 +79,7 @@ static enum {
+ 	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)
++#define crng_ready() (likely(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;
+@@ -110,11 +109,6 @@ 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);
+
+@@ -268,7 +262,7 @@ static void crng_reseed(void)
+ 		++next_gen;
+ 	WRITE_ONCE(base_crng.generation, next_gen);
+ 	WRITE_ONCE(base_crng.birth, jiffies);
+-	if (!static_branch_likely(&crng_is_ready))
++	if (!crng_ready())
+ 		crng_init = CRNG_READY;
+ 	spin_unlock_irqrestore(&base_crng.lock, flags);
+ 	memzero_explicit(key, sizeof(key));
+@@ -711,7 +705,6 @@ static void extract_entropy(void *buf, size_t len)
+
+ static void __cold _credit_init_bits(size_t bits)
+ {
+-	static struct execute_work set_ready;
+ 	unsigned int new, orig, add;
+ 	unsigned long flags;
+
+@@ -727,7 +720,6 @@ static void __cold _credit_init_bits(size_t bits)
+
+ 	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);
+ 		process_random_ready_list();
+ 		wake_up_interruptible(&crng_init_wait);
+ 		kill_fasync(&fasync, SIGIO, POLL_IN);
+-- 
+2.44.0
+

kernel/default.nix

@@ -89,6 +89,11 @@ pkgsAarch64.buildLinux (args // {
 
     # Lower priority of tegra-se crypto modules since they're slow and flaky
     { patch = ./0008-Lower-priority-of-tegra-se-crypto.patch; }
+
+    # Include patch from linux-stable that (for some reason) appears to fix
+    # random crashes very early in boot process on Xavier NX specifically
+    # Remove when updating to 35.5.0
+    { patch = ./0009-Revert-random-use-static-branch-for-crng_ready.patch; }
   ] ++ kernelPatches;
 
   structuredExtraConfig = with lib.kernel; {