sha256.h

 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(out1, SHA256_DIGEST_SIZE);
65		kmsan_unpoison_memory(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}