arm64/crc32: Implement 4-way interleave using PMULL

Now that kernel mode NEON no longer disables preemption, using FP/SIMD
in library code which is not obviously part of the crypto subsystem is
no longer problematic, as it will no longer incur unexpected latencies.

So accelerate the CRC-32 library code on arm64 to use a 4-way
interleave, using PMULL instructions to implement the folding.

On Apple M2, this results in a speedup of 2 - 2.8x when using input
sizes of 1k - 8k. For smaller sizes, the overhead of preserving and
restoring the FP/SIMD register file may not be worth it, so 1k is used
as a threshold for choosing this code path.

The coefficient tables were generated using code provided by Eric. [0]

[0] https://github.com/ebiggers/libdeflate/blob/master/scripts/gen_crc32_multipliers.c

Cc: Eric Biggers <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Reviewed-by: Eric Biggers <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

diff --git a/arch/arm64/lib/crc32-glue.c b/arch/arm64/lib/crc32-glue.c
index 0b51761d4b755bc672ef544ef90f76ec30305f97..295ae3e6b997ad64293cbf3f3be8e7f3beb750be 100644 (file)
--- a/arch/arm64/lib/crc32-glue.c
+++ b/arch/arm64/lib/crc32-glue.c
@@ -4,16 +4,40 @@
 #include <linux/linkage.h>
 
 #include <asm/alternative.h>
+#include <asm/cpufeature.h>
+#include <asm/neon.h>
+#include <asm/simd.h>
+
+#include <crypto/internal/simd.h>
+
+// The minimum input length to consider the 4-way interleaved code path
+static const size_t min_len = 1024;
 
 asmlinkage u32 crc32_le_arm64(u32 crc, unsigned char const *p, size_t len);
 asmlinkage u32 crc32c_le_arm64(u32 crc, unsigned char const *p, size_t len);
 asmlinkage u32 crc32_be_arm64(u32 crc, unsigned char const *p, size_t len);
 
+asmlinkage u32 crc32_le_arm64_4way(u32 crc, unsigned char const *p, size_t len);
+asmlinkage u32 crc32c_le_arm64_4way(u32 crc, unsigned char const *p, size_t len);
+asmlinkage u32 crc32_be_arm64_4way(u32 crc, unsigned char const *p, size_t len);
+
 u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
 {
        if (!alternative_has_cap_likely(ARM64_HAS_CRC32))
                return crc32_le_base(crc, p, len);
 
+       if (len >= min_len && cpu_have_named_feature(PMULL) && crypto_simd_usable()) {
+               kernel_neon_begin();
+               crc = crc32_le_arm64_4way(crc, p, len);
+               kernel_neon_end();
+
+               p += round_down(len, 64);
+               len %= 64;
+
+               if (!len)
+                       return crc;
+       }
+
        return crc32_le_arm64(crc, p, len);
 }
 
@@ -22,6 +46,18 @@ u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
        if (!alternative_has_cap_likely(ARM64_HAS_CRC32))
                return __crc32c_le_base(crc, p, len);
 
+       if (len >= min_len && cpu_have_named_feature(PMULL) && crypto_simd_usable()) {
+               kernel_neon_begin();
+               crc = crc32c_le_arm64_4way(crc, p, len);
+               kernel_neon_end();
+
+               p += round_down(len, 64);
+               len %= 64;
+
+               if (!len)
+                       return crc;
+       }
+
        return crc32c_le_arm64(crc, p, len);
 }
 
@@ -30,5 +66,17 @@ u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
        if (!alternative_has_cap_likely(ARM64_HAS_CRC32))
                return crc32_be_base(crc, p, len);
 
+       if (len >= min_len && cpu_have_named_feature(PMULL) && crypto_simd_usable()) {
+               kernel_neon_begin();
+               crc = crc32_be_arm64_4way(crc, p, len);
+               kernel_neon_end();
+
+               p += round_down(len, 64);
+               len %= 64;
+
+               if (!len)
+                       return crc;
+       }
+
        return crc32_be_arm64(crc, p, len);
 }

diff --git a/arch/arm64/lib/crc32.S b/arch/arm64/lib/crc32.S
index f9920492f1359858aba3961ce839452b6b8928e3..68825317460fc6e8fd7ca8674151fa67955ee232 100644 (file)
--- a/arch/arm64/lib/crc32.S
+++ b/arch/arm64/lib/crc32.S
@@ -1,14 +1,17 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Accelerated CRC32(C) using AArch64 CRC instructions
+ * Accelerated CRC32(C) using AArch64 CRC and PMULL instructions
  *
- * Copyright (C) 2016 - 2018 Linaro Ltd <[email protected]>
+ * Copyright (C) 2016 - 2018 Linaro Ltd.
+ * Copyright (C) 2024 Google LLC
+ *
+ * Author: Ard Biesheuvel <[email protected]>
  */
 
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 
-       .arch           armv8-a+crc
+       .cpu            generic+crc+crypto
 
        .macro          bitle, reg
        .endm
@@ -135,3 +138,225 @@ SYM_FUNC_END(crc32c_le_arm64)
 SYM_FUNC_START(crc32_be_arm64)
        __crc32         order=be
 SYM_FUNC_END(crc32_be_arm64)
+
+       in              .req    x1
+       len             .req    x2
+
+       /*
+        * w0: input CRC at entry, output CRC at exit
+        * x1: pointer to input buffer
+        * x2: length of input in bytes
+        */
+       .macro          crc4way, insn, table, order=le
+       bit\order       w0
+       lsr             len, len, #6            // len := # of 64-byte blocks
+
+       /* Process up to 64 blocks of 64 bytes at a time */
+.La\@: mov             x3, #64
+       cmp             len, #64
+       csel            x3, x3, len, hi         // x3 := min(len, 64)
+       sub             len, len, x3
+
+       /* Divide the input into 4 contiguous blocks */
+       add             x4, x3, x3, lsl #1      // x4 :=  3 * x3
+       add             x7, in, x3, lsl #4      // x7 := in + 16 * x3
+       add             x8, in, x3, lsl #5      // x8 := in + 32 * x3
+       add             x9, in, x4, lsl #4      // x9 := in + 16 * x4
+
+       /* Load the folding coefficients from the lookup table */
+       adr_l           x5, \table - 12         // entry 0 omitted
+       add             x5, x5, x4, lsl #2      // x5 += 12 * x3
+       ldp             s0, s1, [x5]
+       ldr             s2, [x5, #8]
+
+       /* Zero init partial CRCs for this iteration */
+       mov             w4, wzr
+       mov             w5, wzr
+       mov             w6, wzr
+       mov             x17, xzr
+
+.Lb\@: sub             x3, x3, #1
+       \insn           w6, w6, x17
+       ldp             x10, x11, [in], #16
+       ldp             x12, x13, [x7], #16
+       ldp             x14, x15, [x8], #16
+       ldp             x16, x17, [x9], #16
+
+       \order          x10, x11, x12, x13, x14, x15, x16, x17
+
+       /* Apply the CRC transform to 4 16-byte blocks in parallel */
+       \insn           w0, w0, x10
+       \insn           w4, w4, x12
+       \insn           w5, w5, x14
+       \insn           w6, w6, x16
+       \insn           w0, w0, x11
+       \insn           w4, w4, x13
+       \insn           w5, w5, x15
+       cbnz            x3, .Lb\@
+
+       /* Combine the 4 partial results into w0 */
+       mov             v3.d[0], x0
+       mov             v4.d[0], x4
+       mov             v5.d[0], x5
+       pmull           v0.1q, v0.1d, v3.1d
+       pmull           v1.1q, v1.1d, v4.1d
+       pmull           v2.1q, v2.1d, v5.1d
+       eor             v0.8b, v0.8b, v1.8b
+       eor             v0.8b, v0.8b, v2.8b
+       mov             x5, v0.d[0]
+       eor             x5, x5, x17
+       \insn           w0, w6, x5
+
+       mov             in, x9
+       cbnz            len, .La\@
+
+       bit\order       w0
+       ret
+       .endm
+
+       .align          5
+SYM_FUNC_START(crc32c_le_arm64_4way)
+       crc4way         crc32cx, .L0
+SYM_FUNC_END(crc32c_le_arm64_4way)
+
+       .align          5
+SYM_FUNC_START(crc32_le_arm64_4way)
+       crc4way         crc32x, .L1
+SYM_FUNC_END(crc32_le_arm64_4way)
+
+       .align          5
+SYM_FUNC_START(crc32_be_arm64_4way)
+       crc4way         crc32x, .L1, be
+SYM_FUNC_END(crc32_be_arm64_4way)
+
+       .section        .rodata, "a", %progbits
+       .align          6
+.L0:   .long           0xddc0152b, 0xba4fc28e, 0x493c7d27
+       .long           0x0715ce53, 0x9e4addf8, 0xba4fc28e
+       .long           0xc96cfdc0, 0x0715ce53, 0xddc0152b
+       .long           0xab7aff2a, 0x0d3b6092, 0x9e4addf8
+       .long           0x299847d5, 0x878a92a7, 0x39d3b296
+       .long           0xb6dd949b, 0xab7aff2a, 0x0715ce53
+       .long           0xa60ce07b, 0x83348832, 0x47db8317
+       .long           0xd270f1a2, 0xb9e02b86, 0x0d3b6092
+       .long           0x65863b64, 0xb6dd949b, 0xc96cfdc0
+       .long           0xb3e32c28, 0xbac2fd7b, 0x878a92a7
+       .long           0xf285651c, 0xce7f39f4, 0xdaece73e
+       .long           0x271d9844, 0xd270f1a2, 0xab7aff2a
+       .long           0x6cb08e5c, 0x2b3cac5d, 0x2162d385
+       .long           0xcec3662e, 0x1b03397f, 0x83348832
+       .long           0x8227bb8a, 0xb3e32c28, 0x299847d5
+       .long           0xd7a4825c, 0xdd7e3b0c, 0xb9e02b86
+       .long           0xf6076544, 0x10746f3c, 0x18b33a4e
+       .long           0x98d8d9cb, 0x271d9844, 0xb6dd949b
+       .long           0x57a3d037, 0x93a5f730, 0x78d9ccb7
+       .long           0x3771e98f, 0x6b749fb2, 0xbac2fd7b
+       .long           0xe0ac139e, 0xcec3662e, 0xa60ce07b
+       .long           0x6f345e45, 0xe6fc4e6a, 0xce7f39f4
+       .long           0xa2b73df1, 0xb0cd4768, 0x61d82e56
+       .long           0x86d8e4d2, 0xd7a4825c, 0xd270f1a2
+       .long           0xa90fd27a, 0x0167d312, 0xc619809d
+       .long           0xca6ef3ac, 0x26f6a60a, 0x2b3cac5d
+       .long           0x4597456a, 0x98d8d9cb, 0x65863b64
+       .long           0xc9c8b782, 0x68bce87a, 0x1b03397f
+       .long           0x62ec6c6d, 0x6956fc3b, 0xebb883bd
+       .long           0x2342001e, 0x3771e98f, 0xb3e32c28
+       .long           0xe8b6368b, 0x2178513a, 0x064f7f26
+       .long           0x9ef68d35, 0x170076fa, 0xdd7e3b0c
+       .long           0x0b0bf8ca, 0x6f345e45, 0xf285651c
+       .long           0x02ee03b2, 0xff0dba97, 0x10746f3c
+       .long           0x135c83fd, 0xf872e54c, 0xc7a68855
+       .long           0x00bcf5f6, 0x86d8e4d2, 0x271d9844
+       .long           0x58ca5f00, 0x5bb8f1bc, 0x8e766a0c
+       .long           0xded288f8, 0xb3af077a, 0x93a5f730
+       .long           0x37170390, 0xca6ef3ac, 0x6cb08e5c
+       .long           0xf48642e9, 0xdd66cbbb, 0x6b749fb2
+       .long           0xb25b29f2, 0xe9e28eb4, 0x1393e203
+       .long           0x45cddf4e, 0xc9c8b782, 0xcec3662e
+       .long           0xdfd94fb2, 0x93e106a4, 0x96c515bb
+       .long           0x021ac5ef, 0xd813b325, 0xe6fc4e6a
+       .long           0x8e1450f7, 0x2342001e, 0x8227bb8a
+       .long           0xe0cdcf86, 0x6d9a4957, 0xb0cd4768
+       .long           0x613eee91, 0xd2c3ed1a, 0x39c7ff35
+       .long           0xbedc6ba1, 0x9ef68d35, 0xd7a4825c
+       .long           0x0cd1526a, 0xf2271e60, 0x0ab3844b
+       .long           0xd6c3a807, 0x2664fd8b, 0x0167d312
+       .long           0x1d31175f, 0x02ee03b2, 0xf6076544
+       .long           0x4be7fd90, 0x363bd6b3, 0x26f6a60a
+       .long           0x6eeed1c9, 0x5fabe670, 0xa741c1bf
+       .long           0xb3a6da94, 0x00bcf5f6, 0x98d8d9cb
+       .long           0x2e7d11a7, 0x17f27698, 0x49c3cc9c
+       .long           0x889774e1, 0xaa7c7ad5, 0x68bce87a
+       .long           0x8a074012, 0xded288f8, 0x57a3d037
+       .long           0xbd0bb25f, 0x6d390dec, 0x6956fc3b
+       .long           0x3be3c09b, 0x6353c1cc, 0x42d98888
+       .long           0x465a4eee, 0xf48642e9, 0x3771e98f
+       .long           0x2e5f3c8c, 0xdd35bc8d, 0xb42ae3d9
+       .long           0xa52f58ec, 0x9a5ede41, 0x2178513a
+       .long           0x47972100, 0x45cddf4e, 0xe0ac139e
+       .long           0x359674f7, 0xa51b6135, 0x170076fa
+
+.L1:   .long           0xaf449247, 0x81256527, 0xccaa009e
+       .long           0x57c54819, 0x1d9513d7, 0x81256527
+       .long           0x3f41287a, 0x57c54819, 0xaf449247
+       .long           0xf5e48c85, 0x910eeec1, 0x1d9513d7
+       .long           0x1f0c2cdd, 0x9026d5b1, 0xae0b5394
+       .long           0x71d54a59, 0xf5e48c85, 0x57c54819
+       .long           0x1c63267b, 0xfe807bbd, 0x0cbec0ed
+       .long           0xd31343ea, 0xe95c1271, 0x910eeec1
+       .long           0xf9d9c7ee, 0x71d54a59, 0x3f41287a
+       .long           0x9ee62949, 0xcec97417, 0x9026d5b1
+       .long           0xa55d1514, 0xf183c71b, 0xd1df2327
+       .long           0x21aa2b26, 0xd31343ea, 0xf5e48c85
+       .long           0x9d842b80, 0xeea395c4, 0x3c656ced
+       .long           0xd8110ff1, 0xcd669a40, 0xfe807bbd
+       .long           0x3f9e9356, 0x9ee62949, 0x1f0c2cdd
+       .long           0x1d6708a0, 0x0c30f51d, 0xe95c1271
+       .long           0xef82aa68, 0xdb3935ea, 0xb918a347
+       .long           0xd14bcc9b, 0x21aa2b26, 0x71d54a59
+       .long           0x99cce860, 0x356d209f, 0xff6f2fc2
+       .long           0xd8af8e46, 0xc352f6de, 0xcec97417
+       .long           0xf1996890, 0xd8110ff1, 0x1c63267b
+       .long           0x631bc508, 0xe95c7216, 0xf183c71b
+       .long           0x8511c306, 0x8e031a19, 0x9b9bdbd0
+       .long           0xdb3839f3, 0x1d6708a0, 0xd31343ea
+       .long           0x7a92fffb, 0xf7003835, 0x4470ac44
+       .long           0x6ce68f2a, 0x00eba0c8, 0xeea395c4
+       .long           0x4caaa263, 0xd14bcc9b, 0xf9d9c7ee
+       .long           0xb46f7cff, 0x9a1b53c8, 0xcd669a40
+       .long           0x60290934, 0x81b6f443, 0x6d40f445
+       .long           0x8e976a7d, 0xd8af8e46, 0x9ee62949
+       .long           0xdcf5088a, 0x9dbdc100, 0x145575d5
+       .long           0x1753ab84, 0xbbf2f6d6, 0x0c30f51d
+       .long           0x255b139e, 0x631bc508, 0xa55d1514
+       .long           0xd784eaa8, 0xce26786c, 0xdb3935ea
+       .long           0x6d2c864a, 0x8068c345, 0x2586d334
+       .long           0x02072e24, 0xdb3839f3, 0x21aa2b26
+       .long           0x06689b0a, 0x5efd72f5, 0xe0575528
+       .long           0x1e52f5ea, 0x4117915b, 0x356d209f
+       .long           0x1d3d1db6, 0x6ce68f2a, 0x9d842b80
+       .long           0x3796455c, 0xb8e0e4a8, 0xc352f6de
+       .long           0xdf3a4eb3, 0xc55a2330, 0xb84ffa9c
+       .long           0x28ae0976, 0xb46f7cff, 0xd8110ff1
+       .long           0x9764bc8d, 0xd7e7a22c, 0x712510f0
+       .long           0x13a13e18, 0x3e9a43cd, 0xe95c7216
+       .long           0xb8ee242e, 0x8e976a7d, 0x3f9e9356
+       .long           0x0c540e7b, 0x753c81ff, 0x8e031a19
+       .long           0x9924c781, 0xb9220208, 0x3edcde65
+       .long           0x3954de39, 0x1753ab84, 0x1d6708a0
+       .long           0xf32238b5, 0xbec81497, 0x9e70b943
+       .long           0xbbd2cd2c, 0x0925d861, 0xf7003835
+       .long           0xcc401304, 0xd784eaa8, 0xef82aa68
+       .long           0x4987e684, 0x6044fbb0, 0x00eba0c8
+       .long           0x3aa11427, 0x18fe3b4a, 0x87441142
+       .long           0x297aad60, 0x02072e24, 0xd14bcc9b
+       .long           0xf60c5e51, 0x6ef6f487, 0x5b7fdd0a
+       .long           0x632d78c5, 0x3fc33de4, 0x9a1b53c8
+       .long           0x25b8822a, 0x1e52f5ea, 0x99cce860
+       .long           0xd4fc84bc, 0x1af62fb8, 0x81b6f443
+       .long           0x5690aa32, 0xa91fdefb, 0x688a110e
+       .long           0x1357a093, 0x3796455c, 0xd8af8e46
+       .long           0x798fdd33, 0xaaa18a37, 0x357b9517
+       .long           0xc2815395, 0x54d42691, 0x9dbdc100
+       .long           0x21cfc0f7, 0x28ae0976, 0xf1996890
+       .long           0xa0decef3, 0x7b4aa8b7, 0xbbf2f6d6