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, 158 insertions, 0 deletions

diff --git a/lib/crypto/x86/poly1305.h b/lib/crypto/x86/poly1305.h
new file mode 100644
index 000000000..ee92e3740
--- /dev/null
+++ b/lib/crypto/x86/poly1305.h
@@ -0,0 +1,158 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#include <asm/cpu_device_id.h>
+#include <asm/fpu/api.h>
+#include <linux/jump_label.h>
+#include <linux/kernel.h>
+#include <linux/sizes.h>
+
+struct poly1305_arch_internal {
+	union {
+		struct {
+			u32 h[5];
+			u32 is_base2_26;
+		};
+		u64 hs[3];
+	};
+	u64 r[2];
+	u64 pad;
+	struct { u32 r2, r1, r4, r3; } rn[9];
+};
+
+/*
+ * The AVX code uses base 2^26, while the scalar code uses base 2^64. If we hit
+ * the unfortunate situation of using AVX and then having to go back to scalar
+ * -- because the user is silly and has called the update function from two
+ * separate contexts -- then we need to convert back to the original base before
+ * proceeding. It is possible to reason that the initial reduction below is
+ * sufficient given the implementation invariants. However, for an avoidance of
+ * doubt and because this is not performance critical, we do the full reduction
+ * anyway. Z3 proof of below function: https://xn--4db.cc/ltPtHCKN/py
+ */
+static void convert_to_base2_64(void *ctx)
+{
+	struct poly1305_arch_internal *state = ctx;
+	u32 cy;
+
+	if (!state->is_base2_26)
+		return;
+
+	cy = state->h[0] >> 26; state->h[0] &= 0x3ffffff; state->h[1] += cy;
+	cy = state->h[1] >> 26; state->h[1] &= 0x3ffffff; state->h[2] += cy;
+	cy = state->h[2] >> 26; state->h[2] &= 0x3ffffff; state->h[3] += cy;
+	cy = state->h[3] >> 26; state->h[3] &= 0x3ffffff; state->h[4] += cy;
+	state->hs[0] = ((u64)state->h[2] << 52) | ((u64)state->h[1] << 26) | state->h[0];
+	state->hs[1] = ((u64)state->h[4] << 40) | ((u64)state->h[3] << 14) | (state->h[2] >> 12);
+	state->hs[2] = state->h[4] >> 24;
+	/* Unsigned Less Than: branchlessly produces 1 if a < b, else 0. */
+#define ULT(a, b) ((a ^ ((a ^ b) | ((a - b) ^ b))) >> (sizeof(a) * 8 - 1))
+	cy = (state->hs[2] >> 2) + (state->hs[2] & ~3ULL);
+	state->hs[2] &= 3;
+	state->hs[0] += cy;
+	state->hs[1] += (cy = ULT(state->hs[0], cy));
+	state->hs[2] += ULT(state->hs[1], cy);
+#undef ULT
+	state->is_base2_26 = 0;
+}
+
+asmlinkage void poly1305_init_x86_64(struct poly1305_block_state *state,
+				     const u8 raw_key[POLY1305_BLOCK_SIZE]);
+asmlinkage void poly1305_blocks_x86_64(struct poly1305_arch_internal *ctx,
+				       const u8 *inp,
+				       const size_t len, const u32 padbit);
+asmlinkage void poly1305_emit_x86_64(const struct poly1305_state *ctx,
+				     u8 mac[POLY1305_DIGEST_SIZE],
+				     const u32 nonce[4]);
+asmlinkage void poly1305_emit_avx(const struct poly1305_state *ctx,
+				  u8 mac[POLY1305_DIGEST_SIZE],
+				  const u32 nonce[4]);
+asmlinkage void poly1305_blocks_avx(struct poly1305_arch_internal *ctx,
+				    const u8 *inp, const size_t len,
+				    const u32 padbit);
+asmlinkage void poly1305_blocks_avx2(struct poly1305_arch_internal *ctx,
+				     const u8 *inp, const size_t len,
+				     const u32 padbit);
+asmlinkage void poly1305_blocks_avx512(struct poly1305_arch_internal *ctx,
+				       const u8 *inp,
+				       const size_t len, const u32 padbit);
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx);
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx2);
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx512);
+
+static void poly1305_block_init(struct poly1305_block_state *state,
+				const u8 raw_key[POLY1305_BLOCK_SIZE])
+{
+	poly1305_init_x86_64(state, raw_key);
+}
+
+static void poly1305_blocks(struct poly1305_block_state *state, const u8 *inp,
+			    unsigned int len, u32 padbit)
+{
+	struct poly1305_arch_internal *ctx =
+		container_of(&state->h.h, struct poly1305_arch_internal, h);
+
+	/* SIMD disables preemption, so relax after processing each page. */
+	BUILD_BUG_ON(SZ_4K < POLY1305_BLOCK_SIZE ||
+		     SZ_4K % POLY1305_BLOCK_SIZE);
+
+	/*
+	 * The AVX implementations have significant setup overhead (e.g. key
+	 * power computation, kernel FPU enabling) which makes them slower for
+	 * short messages.  Fall back to the scalar implementation for messages
+	 * shorter than 288 bytes, unless the AVX-specific key setup has already
+	 * been performed (indicated by ctx->is_base2_26).
+	 */
+	if (!static_branch_likely(&poly1305_use_avx) ||
+	    (len < POLY1305_BLOCK_SIZE * 18 && !ctx->is_base2_26) ||
+	    unlikely(!irq_fpu_usable())) {
+		convert_to_base2_64(ctx);
+		poly1305_blocks_x86_64(ctx, inp, len, padbit);
+		return;
+	}
+
+	do {
+		const unsigned int bytes = min(len, SZ_4K);
+
+		kernel_fpu_begin();
+		if (static_branch_likely(&poly1305_use_avx512))
+			poly1305_blocks_avx512(ctx, inp, bytes, padbit);
+		else if (static_branch_likely(&poly1305_use_avx2))
+			poly1305_blocks_avx2(ctx, inp, bytes, padbit);
+		else
+			poly1305_blocks_avx(ctx, inp, bytes, padbit);
+		kernel_fpu_end();
+
+		len -= bytes;
+		inp += bytes;
+	} while (len);
+}
+
+static void poly1305_emit(const struct poly1305_state *ctx,
+			  u8 mac[POLY1305_DIGEST_SIZE], const u32 nonce[4])
+{
+	if (!static_branch_likely(&poly1305_use_avx))
+		poly1305_emit_x86_64(ctx, mac, nonce);
+	else
+		poly1305_emit_avx(ctx, mac, nonce);
+}
+
+#define poly1305_mod_init_arch poly1305_mod_init_arch
+static void poly1305_mod_init_arch(void)
+{
+	if (boot_cpu_has(X86_FEATURE_AVX) &&
+	    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL))
+		static_branch_enable(&poly1305_use_avx);
+	if (boot_cpu_has(X86_FEATURE_AVX) && boot_cpu_has(X86_FEATURE_AVX2) &&
+	    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL))
+		static_branch_enable(&poly1305_use_avx2);
+	if (boot_cpu_has(X86_FEATURE_AVX) && boot_cpu_has(X86_FEATURE_AVX2) &&
+	    boot_cpu_has(X86_FEATURE_AVX512F) &&
+	    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM | XFEATURE_MASK_AVX512, NULL) &&
+	    /* Skylake downclocks unacceptably much when using zmm, but later generations are fast. */
+	    boot_cpu_data.x86_vfm != INTEL_SKYLAKE_X)
+		static_branch_enable(&poly1305_use_avx512);
+}