1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * SHA-256 optimized for x86_64
4 *
5 * Copyright 2025 Google LLC
6 */
7#include <asm/fpu/api.h>
8#include <linux/static_call.h>
9
10static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_sha_ni);
11
12DEFINE_STATIC_CALL(sha256_blocks_x86, sha256_blocks_generic);
13
14#define DEFINE_X86_SHA256_FN(c_fn, asm_fn) \
15 asmlinkage void asm_fn(struct sha256_block_state *state, \
16 const u8 *data, size_t nblocks); \
17 static void c_fn(struct sha256_block_state *state, const u8 *data, \
18 size_t nblocks) \
19 { \
20 if (likely(irq_fpu_usable())) { \
21 kernel_fpu_begin(); \
22 asm_fn(state, data, nblocks); \
23 kernel_fpu_end(); \
24 } else { \
25 sha256_blocks_generic(state, data, nblocks); \
26 } \
27 }
28
29DEFINE_X86_SHA256_FN(sha256_blocks_ssse3, sha256_transform_ssse3);
30DEFINE_X86_SHA256_FN(sha256_blocks_avx, sha256_transform_avx);
31DEFINE_X86_SHA256_FN(sha256_blocks_avx2, sha256_transform_rorx);
32DEFINE_X86_SHA256_FN(sha256_blocks_ni, sha256_ni_transform);
33
34static void sha256_blocks(struct sha256_block_state *state,
35 const u8 *data, size_t nblocks)
36{
37 static_call(sha256_blocks_x86)(state, data, nblocks);
38}
39
40static_assert(offsetof(struct __sha256_ctx, state) == 0);
41static_assert(offsetof(struct __sha256_ctx, bytecount) == 32);
42static_assert(offsetof(struct __sha256_ctx, buf) == 40);
43asmlinkage void sha256_ni_finup2x(const struct __sha256_ctx *ctx,
44 const u8 *data1, const u8 *data2, int len,
45 u8 out1[SHA256_DIGEST_SIZE],
46 u8 out2[SHA256_DIGEST_SIZE]);
47
48#define sha256_finup_2x_arch sha256_finup_2x_arch
49static bool sha256_finup_2x_arch(const struct __sha256_ctx *ctx,
50 const u8 *data1, const u8 *data2, size_t len,
51 u8 out1[SHA256_DIGEST_SIZE],
52 u8 out2[SHA256_DIGEST_SIZE])
53{
54 /*
55 * The assembly requires len >= SHA256_BLOCK_SIZE && len <= INT_MAX.
56 * Further limit len to 65536 to avoid spending too long with preemption
57 * disabled. (Of course, in practice len is nearly always 4096 anyway.)
58 */
59 if (static_branch_likely(&have_sha_ni) && len >= SHA256_BLOCK_SIZE &&
60 len <= 65536 && likely(irq_fpu_usable())) {
61 kernel_fpu_begin();
62 sha256_ni_finup2x(ctx, data1, data2, len, out1, out2);
63 kernel_fpu_end();
64 kmsan_unpoison_memory(address: out1, SHA256_DIGEST_SIZE);
65 kmsan_unpoison_memory(address: out2, SHA256_DIGEST_SIZE);
66 return true;
67 }
68 return false;
69}
70
71static bool sha256_finup_2x_is_optimized_arch(void)
72{
73 return static_key_enabled(&have_sha_ni);
74}
75
76#define sha256_mod_init_arch sha256_mod_init_arch
77static void sha256_mod_init_arch(void)
78{
79 if (boot_cpu_has(X86_FEATURE_SHA_NI)) {
80 static_call_update(sha256_blocks_x86, sha256_blocks_ni);
81 static_branch_enable(&have_sha_ni);
82 } else if (cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM,
83 NULL) &&
84 boot_cpu_has(X86_FEATURE_AVX)) {
85 if (boot_cpu_has(X86_FEATURE_AVX2) &&
86 boot_cpu_has(X86_FEATURE_BMI2))
87 static_call_update(sha256_blocks_x86,
88 sha256_blocks_avx2);
89 else
90 static_call_update(sha256_blocks_x86,
91 sha256_blocks_avx);
92 } else if (boot_cpu_has(X86_FEATURE_SSSE3)) {
93 static_call_update(sha256_blocks_x86, sha256_blocks_ssse3);
94 }
95}
96