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, 120 insertions, 0 deletions

diff --git a/lib/crypto/x86/sha256.h b/lib/crypto/x86/sha256.h
new file mode 100644
index 000000000..0ee69d8e3
--- /dev/null
+++ b/lib/crypto/x86/sha256.h
@@ -0,0 +1,120 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * SHA-256 optimized for x86_64
+ *
+ * Copyright 2025 Google LLC
+ */
+#include <asm/fpu/api.h>
+#include <linux/static_call.h>
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_sha_ni);
+
+DEFINE_STATIC_CALL(sha256_blocks_x86, sha256_blocks_generic);
+
+#define DEFINE_X86_SHA256_FN(c_fn, asm_fn)                                 \
+	asmlinkage void asm_fn(struct sha256_block_state *state,           \
+			       const u8 *data, size_t nblocks);            \
+	static void c_fn(struct sha256_block_state *state, const u8 *data, \
+			 size_t nblocks)                                   \
+	{                                                                  \
+		if (likely(irq_fpu_usable())) {                            \
+			kernel_fpu_begin();                                \
+			asm_fn(state, data, nblocks);                      \
+			kernel_fpu_end();                                  \
+		} else {                                                   \
+			sha256_blocks_generic(state, data, nblocks);       \
+		}                                                          \
+	}
+
+DEFINE_X86_SHA256_FN(sha256_blocks_ssse3, sha256_transform_ssse3);
+DEFINE_X86_SHA256_FN(sha256_blocks_avx, sha256_transform_avx);
+DEFINE_X86_SHA256_FN(sha256_blocks_avx2, sha256_transform_rorx);
+DEFINE_X86_SHA256_FN(sha256_blocks_ni, sha256_ni_transform);
+
+#define PHE_ALIGNMENT 16
+static void sha256_blocks_phe(struct sha256_block_state *state,
+			      const u8 *data, size_t nblocks)
+{
+	/*
+	 * On Zhaoxin processors, XSHA256 requires the %rdi register
+	 * in 64-bit mode (or %edi in 32-bit mode) to point to
+	 * a 32-byte, 16-byte-aligned buffer.
+	 */
+	u8 buf[32 + PHE_ALIGNMENT - 1];
+	u8 *dst = PTR_ALIGN(&buf[0], PHE_ALIGNMENT);
+	size_t padding = -1;
+
+	memcpy(dst, state, SHA256_DIGEST_SIZE);
+	asm volatile(".byte 0xf3,0x0f,0xa6,0xd0" /* REP XSHA256 */
+		     : "+a"(padding), "+c"(nblocks), "+S"(data)
+		     : "D"(dst)
+		     : "memory");
+	memcpy(state, dst, SHA256_DIGEST_SIZE);
+}
+
+static void sha256_blocks(struct sha256_block_state *state,
+			  const u8 *data, size_t nblocks)
+{
+	static_call(sha256_blocks_x86)(state, data, nblocks);
+}
+
+static_assert(offsetof(struct __sha256_ctx, state) == 0);
+static_assert(offsetof(struct __sha256_ctx, bytecount) == 32);
+static_assert(offsetof(struct __sha256_ctx, buf) == 40);
+asmlinkage void sha256_ni_finup2x(const struct __sha256_ctx *ctx,
+				  const u8 *data1, const u8 *data2, int len,
+				  u8 out1[SHA256_DIGEST_SIZE],
+				  u8 out2[SHA256_DIGEST_SIZE]);
+
+#define sha256_finup_2x_arch sha256_finup_2x_arch
+static bool sha256_finup_2x_arch(const struct __sha256_ctx *ctx,
+				 const u8 *data1, const u8 *data2, size_t len,
+				 u8 out1[SHA256_DIGEST_SIZE],
+				 u8 out2[SHA256_DIGEST_SIZE])
+{
+	/*
+	 * The assembly requires len >= SHA256_BLOCK_SIZE && len <= INT_MAX.
+	 * Further limit len to 65536 to avoid spending too long with preemption
+	 * disabled.  (Of course, in practice len is nearly always 4096 anyway.)
+	 */
+	if (static_branch_likely(&have_sha_ni) && len >= SHA256_BLOCK_SIZE &&
+	    len <= 65536 && likely(irq_fpu_usable())) {
+		kernel_fpu_begin();
+		sha256_ni_finup2x(ctx, data1, data2, len, out1, out2);
+		kernel_fpu_end();
+		kmsan_unpoison_memory(out1, SHA256_DIGEST_SIZE);
+		kmsan_unpoison_memory(out2, SHA256_DIGEST_SIZE);
+		return true;
+	}
+	return false;
+}
+
+static bool sha256_finup_2x_is_optimized_arch(void)
+{
+	return static_key_enabled(&have_sha_ni);
+}
+
+#define sha256_mod_init_arch sha256_mod_init_arch
+static void sha256_mod_init_arch(void)
+{
+	if (boot_cpu_has(X86_FEATURE_SHA_NI)) {
+		static_call_update(sha256_blocks_x86, sha256_blocks_ni);
+		static_branch_enable(&have_sha_ni);
+	} else if (IS_ENABLED(CONFIG_CPU_SUP_ZHAOXIN) &&
+		   boot_cpu_has(X86_FEATURE_PHE_EN) &&
+		   boot_cpu_data.x86 >= 0x07) {
+		static_call_update(sha256_blocks_x86, sha256_blocks_phe);
+	} else if (cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM,
+				     NULL) &&
+		   boot_cpu_has(X86_FEATURE_AVX)) {
+		if (boot_cpu_has(X86_FEATURE_AVX2) &&
+		    boot_cpu_has(X86_FEATURE_BMI2))
+			static_call_update(sha256_blocks_x86,
+					   sha256_blocks_avx2);
+		else
+			static_call_update(sha256_blocks_x86,
+					   sha256_blocks_avx);
+	} else if (boot_cpu_has(X86_FEATURE_SSSE3)) {
+		static_call_update(sha256_blocks_x86, sha256_blocks_ssse3);
+	}
+}