1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Macros for accessing the [V]PCLMULQDQ-based CRC functions that are
* instantiated by crc-pclmul-template.S
*
* Copyright 2025 Google LLC
*
* Author: Eric Biggers <ebiggers@google.com>
*/
#ifndef _CRC_PCLMUL_TEMPLATE_H
#define _CRC_PCLMUL_TEMPLATE_H
#include <asm/cpufeatures.h>
#include <asm/simd.h>
#include <crypto/internal/simd.h>
#include <linux/static_call.h>
#include "crc-pclmul-consts.h"
#define DECLARE_CRC_PCLMUL_FUNCS(prefix, crc_t) \
crc_t prefix##_pclmul_sse(crc_t crc, const u8 *p, size_t len, \
const void *consts_ptr); \
crc_t prefix##_vpclmul_avx2(crc_t crc, const u8 *p, size_t len, \
const void *consts_ptr); \
crc_t prefix##_vpclmul_avx512(crc_t crc, const u8 *p, size_t len, \
const void *consts_ptr); \
DEFINE_STATIC_CALL(prefix##_pclmul, prefix##_pclmul_sse)
static inline bool have_vpclmul(void)
{
return boot_cpu_has(X86_FEATURE_VPCLMULQDQ) &&
boot_cpu_has(X86_FEATURE_AVX2) &&
cpu_has_xfeatures(XFEATURE_MASK_YMM, NULL);
}
static inline bool have_avx512(void)
{
return boot_cpu_has(X86_FEATURE_AVX512BW) &&
boot_cpu_has(X86_FEATURE_AVX512VL) &&
!boot_cpu_has(X86_FEATURE_PREFER_YMM) &&
cpu_has_xfeatures(XFEATURE_MASK_AVX512, NULL);
}
/*
* Call a [V]PCLMULQDQ optimized CRC function if the data length is at least 16
* bytes, the CPU has PCLMULQDQ support, and the current context may use SIMD.
*
* 16 bytes is the minimum length supported by the [V]PCLMULQDQ functions.
* There is overhead associated with kernel_fpu_begin() and kernel_fpu_end(),
* varying by CPU and factors such as which parts of the "FPU" state userspace
* has touched, which could result in a larger cutoff being better. Indeed, a
* larger cutoff is usually better for a *single* message. However, the
* overhead of the FPU section gets amortized if multiple FPU sections get
* executed before returning to userspace, since the XSAVE and XRSTOR occur only
* once. Considering that and the fact that the [V]PCLMULQDQ code is lighter on
* the dcache than the table-based code is, a 16-byte cutoff seems to work well.
*/
#define CRC_PCLMUL(crc, p, len, prefix, consts, have_pclmulqdq) \
do { \
if ((len) >= 16 && static_branch_likely(&(have_pclmulqdq)) && \
crypto_simd_usable()) { \
const void *consts_ptr; \
\
consts_ptr = (consts).fold_across_128_bits_consts; \
kernel_fpu_begin(); \
crc = static_call(prefix##_pclmul)((crc), (p), (len), \
consts_ptr); \
kernel_fpu_end(); \
return crc; \
} \
} while (0)
#endif /* _CRC_PCLMUL_TEMPLATE_H */
|
