bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 39 insertions, 0 deletions

diff --git a/lib/crypto/x86/sm3.h b/lib/crypto/x86/sm3.h
new file mode 100644
index 000000000..3834780f2
--- /dev/null
+++ b/lib/crypto/x86/sm3.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * SM3 optimized for x86_64
+ *
+ * Copyright 2026 Google LLC
+ */
+#include <asm/fpu/api.h>
+#include <linux/static_call.h>
+
+asmlinkage void sm3_transform_avx(struct sm3_block_state *state,
+				  const u8 *data, size_t nblocks);
+
+static void sm3_blocks_avx(struct sm3_block_state *state,
+			   const u8 *data, size_t nblocks)
+{
+	if (likely(irq_fpu_usable())) {
+		kernel_fpu_begin();
+		sm3_transform_avx(state, data, nblocks);
+		kernel_fpu_end();
+	} else {
+		sm3_blocks_generic(state, data, nblocks);
+	}
+}
+
+DEFINE_STATIC_CALL(sm3_blocks_x86, sm3_blocks_generic);
+
+static void sm3_blocks(struct sm3_block_state *state,
+		       const u8 *data, size_t nblocks)
+{
+	static_call(sm3_blocks_x86)(state, data, nblocks);
+}
+
+#define sm3_mod_init_arch sm3_mod_init_arch
+static void sm3_mod_init_arch(void)
+{
+	if (boot_cpu_has(X86_FEATURE_AVX) && boot_cpu_has(X86_FEATURE_BMI2) &&
+	    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL))
+		static_call_update(sm3_blocks_x86, sm3_blocks_avx);
+}