ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 85 insertions, 0 deletions

diff --git a/lib/crypto/x86/aes.h b/lib/crypto/x86/aes.h
new file mode 100644
index 000000000..b047dee94
--- /dev/null
+++ b/lib/crypto/x86/aes.h
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * AES block cipher using AES-NI instructions
+ *
+ * Copyright 2026 Google LLC
+ */
+
+#include <asm/fpu/api.h>
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_aes);
+
+void aes128_expandkey_aesni(u32 rndkeys[], u32 *inv_rndkeys,
+			    const u8 in_key[AES_KEYSIZE_128]);
+void aes256_expandkey_aesni(u32 rndkeys[], u32 *inv_rndkeys,
+			    const u8 in_key[AES_KEYSIZE_256]);
+void aes_encrypt_aesni(const u32 rndkeys[], int nrounds,
+		       u8 out[AES_BLOCK_SIZE], const u8 in[AES_BLOCK_SIZE]);
+void aes_decrypt_aesni(const u32 inv_rndkeys[], int nrounds,
+		       u8 out[AES_BLOCK_SIZE], const u8 in[AES_BLOCK_SIZE]);
+
+/*
+ * Expand an AES key using AES-NI if supported and usable or generic code
+ * otherwise.  The expanded key format is compatible between the two cases.  The
+ * outputs are @k->rndkeys (required) and @inv_k->inv_rndkeys (optional).
+ *
+ * We could just always use the generic key expansion code.  AES key expansion
+ * is usually less performance-critical than AES en/decryption.  However,
+ * there's still *some* value in speed here, as well as in non-key-dependent
+ * execution time which AES-NI provides.  So, do use AES-NI to expand AES-128
+ * and AES-256 keys.  (Don't bother with AES-192, as it's almost never used.)
+ */
+static void aes_preparekey_arch(union aes_enckey_arch *k,
+				union aes_invkey_arch *inv_k,
+				const u8 *in_key, int key_len, int nrounds)
+{
+	u32 *rndkeys = k->rndkeys;
+	u32 *inv_rndkeys = inv_k ? inv_k->inv_rndkeys : NULL;
+
+	if (static_branch_likely(&have_aes) && key_len != AES_KEYSIZE_192 &&
+	    irq_fpu_usable()) {
+		kernel_fpu_begin();
+		if (key_len == AES_KEYSIZE_128)
+			aes128_expandkey_aesni(rndkeys, inv_rndkeys, in_key);
+		else
+			aes256_expandkey_aesni(rndkeys, inv_rndkeys, in_key);
+		kernel_fpu_end();
+	} else {
+		aes_expandkey_generic(rndkeys, inv_rndkeys, in_key, key_len);
+	}
+}
+
+static void aes_encrypt_arch(const struct aes_enckey *key,
+			     u8 out[AES_BLOCK_SIZE],
+			     const u8 in[AES_BLOCK_SIZE])
+{
+	if (static_branch_likely(&have_aes) && irq_fpu_usable()) {
+		kernel_fpu_begin();
+		aes_encrypt_aesni(key->k.rndkeys, key->nrounds, out, in);
+		kernel_fpu_end();
+	} else {
+		aes_encrypt_generic(key->k.rndkeys, key->nrounds, out, in);
+	}
+}
+
+static void aes_decrypt_arch(const struct aes_key *key,
+			     u8 out[AES_BLOCK_SIZE],
+			     const u8 in[AES_BLOCK_SIZE])
+{
+	if (static_branch_likely(&have_aes) && irq_fpu_usable()) {
+		kernel_fpu_begin();
+		aes_decrypt_aesni(key->inv_k.inv_rndkeys, key->nrounds,
+				  out, in);
+		kernel_fpu_end();
+	} else {
+		aes_decrypt_generic(key->inv_k.inv_rndkeys, key->nrounds,
+				    out, in);
+	}
+}
+
+#define aes_mod_init_arch aes_mod_init_arch
+static void aes_mod_init_arch(void)
+{
+	if (boot_cpu_has(X86_FEATURE_AES))
+		static_branch_enable(&have_aes);
+}