arch/x86/lib/crc32-glue.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * x86-optimized CRC32 functions
   4  *
   5  * Copyright (C) 2008 Intel Corporation
   6  * Copyright 2012 Xyratex Technology Limited
   7  * Copyright 2024 Google LLC
   8  */
   9
  10 #include <asm/cpufeatures.h>
  11 #include <asm/simd.h>
  12 #include <crypto/internal/simd.h>
  13 #include <linux/crc32.h>
  14 #include <linux/linkage.h>
  15 #include <linux/module.h>
  16
  17 /* minimum size of buffer for crc32_pclmul_le_16 */
  18 #define CRC32_PCLMUL_MIN_LEN    64
  19
  20 static DEFINE_STATIC_KEY_FALSE(have_crc32);
  21 static DEFINE_STATIC_KEY_FALSE(have_pclmulqdq);
  22
  23 u32 crc32_pclmul_le_16(u32 crc, const u8 *buffer, size_t len);
  24
  25 u32 crc32_le_arch(u32 crc, const u8 *p, size_t len)
  26 {
  27         if (len >= CRC32_PCLMUL_MIN_LEN + 15 &&
  28             static_branch_likely(&have_pclmulqdq) && crypto_simd_usable()) {
  29                 size_t n = -(uintptr_t)p & 15;
  30
  31                 /* align p to 16-byte boundary */
  32                 if (n) {
  33                         crc = crc32_le_base(crc, p, n);
  34                         p += n;
  35                         len -= n;
  36                 }
  37                 n = round_down(len, 16);
  38                 kernel_fpu_begin();
  39                 crc = crc32_pclmul_le_16(crc, p, n);
  40                 kernel_fpu_end();
  41                 p += n;
  42                 len -= n;
  43         }
  44         if (len)
  45                 crc = crc32_le_base(crc, p, len);
  46         return crc;
  47 }
  48 EXPORT_SYMBOL(crc32_le_arch);
  49
  50 #ifdef CONFIG_X86_64
  51 #define CRC32_INST "crc32q %1, %q0"
  52 #else
  53 #define CRC32_INST "crc32l %1, %0"
  54 #endif
  55
  56 /*
  57  * Use carryless multiply version of crc32c when buffer size is >= 512 to
  58  * account for FPU state save/restore overhead.
  59  */
  60 #define CRC32C_PCLMUL_BREAKEVEN 512
  61
  62 asmlinkage u32 crc32c_x86_3way(u32 crc, const u8 *buffer, size_t len);
  63
  64 u32 crc32c_le_arch(u32 crc, const u8 *p, size_t len)
  65 {
  66         size_t num_longs;
  67
  68         if (!static_branch_likely(&have_crc32))
  69                 return crc32c_le_base(crc, p, len);
  70
  71         if (IS_ENABLED(CONFIG_X86_64) && len >= CRC32C_PCLMUL_BREAKEVEN &&
  72             static_branch_likely(&have_pclmulqdq) && crypto_simd_usable()) {
  73                 kernel_fpu_begin();
  74                 crc = crc32c_x86_3way(crc, p, len);
  75                 kernel_fpu_end();
  76                 return crc;
  77         }
  78
  79         for (num_longs = len / sizeof(unsigned long);
  80              num_longs != 0; num_longs--, p += sizeof(unsigned long))
  81                 asm(CRC32_INST : "+r" (crc) : "rm" (*(unsigned long *)p));
  82
  83         for (len %= sizeof(unsigned long); len; len--, p++)
  84                 asm("crc32b %1, %0" : "+r" (crc) : "rm" (*p));
  85
  86         return crc;
  87 }
  88 EXPORT_SYMBOL(crc32c_le_arch);
  89
  90 u32 crc32_be_arch(u32 crc, const u8 *p, size_t len)
  91 {
  92         return crc32_be_base(crc, p, len);
  93 }
  94 EXPORT_SYMBOL(crc32_be_arch);
  95
  96 static int __init crc32_x86_init(void)
  97 {
  98         if (boot_cpu_has(X86_FEATURE_XMM4_2))
  99                 static_branch_enable(&have_crc32);
 100         if (boot_cpu_has(X86_FEATURE_PCLMULQDQ))
 101                 static_branch_enable(&have_pclmulqdq);
 102         return 0;
 103 }
 104 arch_initcall(crc32_x86_init);
 105
 106 static void __exit crc32_x86_exit(void)
 107 {
 108 }
 109 module_exit(crc32_x86_exit);
 110
 111 u32 crc32_optimizations(void)
 112 {
 113         u32 optimizations = 0;
 114
 115         if (static_key_enabled(&have_crc32))
 116                 optimizations |= CRC32C_OPTIMIZATION;
 117         if (static_key_enabled(&have_pclmulqdq))
 118                 optimizations |= CRC32_LE_OPTIMIZATION;
 119         return optimizations;
 120 }
 121 EXPORT_SYMBOL(crc32_optimizations);
 122
 123 MODULE_DESCRIPTION("x86-optimized CRC32 functions");
 124 MODULE_LICENSE("GPL");