sha256.h

 1/* SPDX-License-Identifier: GPL-2.0-or-later */
 2/*
 3 * SHA-256 optimized for ARM64
 4 *
 5 * Copyright 2025 Google LLC
 6 */
 7#include <asm/simd.h>
 8#include <linux/cpufeature.h>
 9
10static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
11static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_ce);
12
13asmlinkage void sha256_block_data_order(struct sha256_block_state *state,
14					const u8 *data, size_t nblocks);
15asmlinkage void sha256_block_neon(struct sha256_block_state *state,
16				  const u8 *data, size_t nblocks);
17asmlinkage size_t __sha256_ce_transform(struct sha256_block_state *state,
18					const u8 *data, size_t nblocks);
19
20static void sha256_blocks(struct sha256_block_state *state,
21			  const u8 *data, size_t nblocks)
22{
23	if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) &&
24	    static_branch_likely(&have_neon) && likely(may_use_simd())) {
25		if (static_branch_likely(&have_ce)) {
26			do {
27				size_t rem;
28
29				scoped_ksimd()
30					rem = __sha256_ce_transform(state, data,
31								    nblocks);
32
33				data += (nblocks - rem) * SHA256_BLOCK_SIZE;
34				nblocks = rem;
35			} while (nblocks);
36		} else {
37			scoped_ksimd()
38				sha256_block_neon(state, data, nblocks);
39		}
40	} else {
41		sha256_block_data_order(state, data, nblocks);
42	}
43}
44
45static_assert(offsetof(struct __sha256_ctx, state) == 0);
46static_assert(offsetof(struct __sha256_ctx, bytecount) == 32);
47static_assert(offsetof(struct __sha256_ctx, buf) == 40);
48asmlinkage void sha256_ce_finup2x(const struct __sha256_ctx *ctx,
49				  const u8 *data1, const u8 *data2, int len,
50				  u8 out1[SHA256_DIGEST_SIZE],
51				  u8 out2[SHA256_DIGEST_SIZE]);
52
53#define sha256_finup_2x_arch sha256_finup_2x_arch
54static bool sha256_finup_2x_arch(const struct __sha256_ctx *ctx,
55				 const u8 *data1, const u8 *data2, size_t len,
56				 u8 out1[SHA256_DIGEST_SIZE],
57				 u8 out2[SHA256_DIGEST_SIZE])
58{
59	/*
60	 * The assembly requires len >= SHA256_BLOCK_SIZE && len <= INT_MAX.
61	 * Further limit len to 65536 to avoid spending too long with preemption
62	 * disabled.  (Of course, in practice len is nearly always 4096 anyway.)
63	 */
64	if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) &&
65	    static_branch_likely(&have_ce) && len >= SHA256_BLOCK_SIZE &&
66	    len <= 65536 && likely(may_use_simd())) {
67		scoped_ksimd()
68			sha256_ce_finup2x(ctx, data1, data2, len, out1, out2);
69		kmsan_unpoison_memory(out1, SHA256_DIGEST_SIZE);
70		kmsan_unpoison_memory(out2, SHA256_DIGEST_SIZE);
71		return true;
72	}
73	return false;
74}
75
76static bool sha256_finup_2x_is_optimized_arch(void)
77{
78	return static_key_enabled(&have_ce);
79}
80
81#ifdef CONFIG_KERNEL_MODE_NEON
82#define sha256_mod_init_arch sha256_mod_init_arch
83static void sha256_mod_init_arch(void)
84{
85	if (cpu_have_named_feature(ASIMD)) {
86		static_branch_enable(&have_neon);
87		if (cpu_have_named_feature(SHA2))
88			static_branch_enable(&have_ce);
89	}
90}
91#endif /* CONFIG_KERNEL_MODE_NEON */