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Subject[PATCH 2/2] crypto: arm64/crct10dif - implement non-Crypto Extensions alternative
Date
The arm64 implementation of the CRC-T10DIF algorithm uses the 64x64 bit
polynomial multiplication instructions, which are optional in the
architecture, and if these instructions are not available, we fall back
to the C routine which is slow and inefficient.

So let's reuse the 64x64 bit PMULL alternative from the GHASH driver that
uses a sequence of ~40 instructions involving 8x8 bit PMULL and some
shifting and masking. This is a lot slower than the original, but it is
still twice as fast as the current [unoptimized] C code on Cortex-A53,
and it is time invariant and much easier on the D-cache.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/arm64/crypto/crct10dif-ce-core.S | 154 ++++++++++++++++++++
arch/arm64/crypto/crct10dif-ce-glue.c | 10 +-
2 files changed, 162 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/crypto/crct10dif-ce-core.S b/arch/arm64/crypto/crct10dif-ce-core.S
index a39951015e86..9e82e8e8ed05 100644
--- a/arch/arm64/crypto/crct10dif-ce-core.S
+++ b/arch/arm64/crypto/crct10dif-ce-core.S
@@ -80,6 +80,145 @@

vzr .req v13

+ ad .req v14
+ bd .req v10
+
+ k00_16 .req v15
+ k32_48 .req v16
+
+ t3 .req v17
+ t4 .req v18
+ t5 .req v19
+ t6 .req v20
+ t7 .req v21
+ t8 .req v22
+ t9 .req v23
+
+ perm1 .req v24
+ perm2 .req v25
+ perm3 .req v26
+ perm4 .req v27
+
+ bd1 .req v28
+ bd2 .req v29
+ bd3 .req v30
+ bd4 .req v31
+
+ .macro __pmull_init_p64
+ .endm
+
+ .macro __pmull_pre_p64, bd
+ .endm
+
+ .macro __pmull_init_p8
+ // k00_16 := 0x0000000000000000_000000000000ffff
+ // k32_48 := 0x00000000ffffffff_0000ffffffffffff
+ movi k32_48.2d, #0xffffffff
+ mov k32_48.h[2], k32_48.h[0]
+ ushr k00_16.2d, k32_48.2d, #32
+
+ // prepare the permutation vectors
+ mov_q x5, 0x080f0e0d0c0b0a09
+ movi perm4.8b, #8
+ dup perm1.2d, x5
+ eor perm1.16b, perm1.16b, perm4.16b
+ ushr perm2.2d, perm1.2d, #8
+ ushr perm3.2d, perm1.2d, #16
+ ushr perm4.2d, perm1.2d, #24
+ sli perm2.2d, perm1.2d, #56
+ sli perm3.2d, perm1.2d, #48
+ sli perm4.2d, perm1.2d, #40
+ .endm
+
+ .macro __pmull_pre_p8, bd
+ tbl bd1.16b, {\bd\().16b}, perm1.16b
+ tbl bd2.16b, {\bd\().16b}, perm2.16b
+ tbl bd3.16b, {\bd\().16b}, perm3.16b
+ tbl bd4.16b, {\bd\().16b}, perm4.16b
+ .endm
+
+__pmull_p8_core:
+.L__pmull_p8_core:
+ ext t4.8b, ad.8b, ad.8b, #1 // A1
+ ext t5.8b, ad.8b, ad.8b, #2 // A2
+ ext t6.8b, ad.8b, ad.8b, #3 // A3
+
+ pmull t4.8h, t4.8b, bd.8b // F = A1*B
+ pmull t8.8h, ad.8b, bd1.8b // E = A*B1
+ pmull t5.8h, t5.8b, bd.8b // H = A2*B
+ pmull t7.8h, ad.8b, bd2.8b // G = A*B2
+ pmull t6.8h, t6.8b, bd.8b // J = A3*B
+ pmull t9.8h, ad.8b, bd3.8b // I = A*B3
+ pmull t3.8h, ad.8b, bd4.8b // K = A*B4
+ b 0f
+
+.L__pmull_p8_core2:
+ tbl t4.16b, {ad.16b}, perm1.16b // A1
+ tbl t5.16b, {ad.16b}, perm2.16b // A2
+ tbl t6.16b, {ad.16b}, perm3.16b // A3
+
+ pmull2 t4.8h, t4.16b, bd.16b // F = A1*B
+ pmull2 t8.8h, ad.16b, bd1.16b // E = A*B1
+ pmull2 t5.8h, t5.16b, bd.16b // H = A2*B
+ pmull2 t7.8h, ad.16b, bd2.16b // G = A*B2
+ pmull2 t6.8h, t6.16b, bd.16b // J = A3*B
+ pmull2 t9.8h, ad.16b, bd3.16b // I = A*B3
+ pmull2 t3.8h, ad.16b, bd4.16b // K = A*B4
+
+0: eor t4.16b, t4.16b, t8.16b // L = E + F
+ eor t5.16b, t5.16b, t7.16b // M = G + H
+ eor t6.16b, t6.16b, t9.16b // N = I + J
+
+ uzp1 t8.2d, t4.2d, t5.2d
+ uzp2 t4.2d, t4.2d, t5.2d
+ uzp1 t7.2d, t6.2d, t3.2d
+ uzp2 t6.2d, t6.2d, t3.2d
+
+ // t4 = (L) (P0 + P1) << 8
+ // t5 = (M) (P2 + P3) << 16
+ eor t8.16b, t8.16b, t4.16b
+ and t4.16b, t4.16b, k32_48.16b
+
+ // t6 = (N) (P4 + P5) << 24
+ // t7 = (K) (P6 + P7) << 32
+ eor t7.16b, t7.16b, t6.16b
+ and t6.16b, t6.16b, k00_16.16b
+
+ eor t8.16b, t8.16b, t4.16b
+ eor t7.16b, t7.16b, t6.16b
+
+ zip2 t5.2d, t8.2d, t4.2d
+ zip1 t4.2d, t8.2d, t4.2d
+ zip2 t3.2d, t7.2d, t6.2d
+ zip1 t6.2d, t7.2d, t6.2d
+
+ ext t4.16b, t4.16b, t4.16b, #15
+ ext t5.16b, t5.16b, t5.16b, #14
+ ext t6.16b, t6.16b, t6.16b, #13
+ ext t3.16b, t3.16b, t3.16b, #12
+
+ eor t4.16b, t4.16b, t5.16b
+ eor t6.16b, t6.16b, t3.16b
+ ret
+ENDPROC(__pmull_p8_core)
+
+ .macro __pmull_p8, rq, ad, bd, i
+ .ifnc \bd, v10
+ .err
+ .endif
+ mov ad.16b, \ad\().16b
+ .ifb \i
+ pmull \rq\().8h, \ad\().8b, bd.8b // D = A*B
+ .else
+ pmull2 \rq\().8h, \ad\().16b, bd.16b // D = A*B
+ .endif
+
+ bl .L__pmull_p8_core\i
+
+ eor \rq\().16b, \rq\().16b, t4.16b
+ eor \rq\().16b, \rq\().16b, t6.16b
+ .endm
+
.macro fold64, p, reg1, reg2
ldp q11, q12, [arg2], #0x20

@@ -106,6 +245,7 @@ CPU_LE( ext v12.16b, v12.16b, v12.16b, #8 )
__pmull_\p \reg, \reg, v10, 2
.ifnb \rk
ldr_l q10, \rk, x8
+ __pmull_pre_\p v10
.endif
eor v7.16b, v7.16b, v8.16b
eor v7.16b, v7.16b, \reg\().16b
@@ -128,6 +268,8 @@ CPU_LE( ext v12.16b, v12.16b, v12.16b, #8 )

movi vzr.16b, #0 // init zero register

+ __pmull_init_\p
+
// adjust the 16-bit initial_crc value, scale it to 32 bits
lsl arg1_low32, arg1_low32, #16

@@ -176,6 +318,7 @@ CPU_LE( ext v7.16b, v7.16b, v7.16b, #8 )
ldr_l q10, rk3, x8 // xmm10 has rk3 and rk4
// type of pmull instruction
// will determine which constant to use
+ __pmull_pre_\p v10

//
// we subtract 256 instead of 128 to save one instruction from the loop
@@ -212,6 +355,8 @@ CPU_LE( ext v7.16b, v7.16b, v7.16b, #8 )
ldp q6, q7, [sp, #.Lframe_local_offset + 96]
ldr_l q10, rk3, x8
movi vzr.16b, #0 // init zero register
+ __pmull_init_\p
+ __pmull_pre_\p v10
endif_yield_neon

b .L_fold_64_B_loop_\@
@@ -225,6 +370,7 @@ CPU_LE( ext v7.16b, v7.16b, v7.16b, #8 )
// constants

ldr_l q10, rk9, x8
+ __pmull_pre_\p v10

fold16 \p, v0, rk11
fold16 \p, v1, rk13
@@ -306,6 +452,7 @@ CPU_LE( ext v1.16b, v1.16b, v1.16b, #8 )
.L_128_done_\@:
// compute crc of a 128-bit value
ldr_l q10, rk5, x8 // rk5 and rk6 in xmm10
+ __pmull_pre_\p v10

// 64b fold
ext v0.16b, vzr.16b, v7.16b, #8
@@ -321,6 +468,7 @@ CPU_LE( ext v1.16b, v1.16b, v1.16b, #8 )

// barrett reduction
ldr_l q10, rk7, x8
+ __pmull_pre_\p v10
mov v0.d[0], v7.d[1]

__pmull_\p v0, v0, v10
@@ -352,6 +500,7 @@ CPU_LE( ext v7.16b, v7.16b, v7.16b, #8 )
b.lt .L_less_than_16_left_\@

ldr_l q10, rk1, x8 // rk1 and rk2 in xmm10
+ __pmull_pre_\p v10

// update the counter. subtract 32 instead of 16 to save one
// instruction from the loop
@@ -372,6 +521,11 @@ CPU_LE( ext v7.16b, v7.16b, v7.16b, #8 )
b .L_128_done_\@
.endm

+ENTRY(crc_t10dif_pmull_p8)
+ crc_t10dif_pmull p8
+ENDPROC(crc_t10dif_pmull_p8)
+
+ .align 5
ENTRY(crc_t10dif_pmull_p64)
crc_t10dif_pmull p64
ENDPROC(crc_t10dif_pmull_p64)
diff --git a/arch/arm64/crypto/crct10dif-ce-glue.c b/arch/arm64/crypto/crct10dif-ce-glue.c
index 343a1e95b11a..b461d62023f2 100644
--- a/arch/arm64/crypto/crct10dif-ce-glue.c
+++ b/arch/arm64/crypto/crct10dif-ce-glue.c
@@ -23,6 +23,7 @@
#define CRC_T10DIF_PMULL_CHUNK_SIZE 16U

asmlinkage u16 crc_t10dif_pmull_p64(u16 init_crc, const u8 buf[], u64 len);
+asmlinkage u16 crc_t10dif_pmull_p8(u16 init_crc, const u8 buf[], u64 len);

static u16 (*crc_t10dif_pmull)(u16 init_crc, const u8 buf[], u64 len);

@@ -87,7 +88,10 @@ static struct shash_alg crc_t10dif_alg = {

static int __init crc_t10dif_mod_init(void)
{
- crc_t10dif_pmull = crc_t10dif_pmull_p64;
+ if (elf_hwcap & HWCAP_PMULL)
+ crc_t10dif_pmull = crc_t10dif_pmull_p64;
+ else
+ crc_t10dif_pmull = crc_t10dif_pmull_p8;

return crypto_register_shash(&crc_t10dif_alg);
}
@@ -97,8 +101,10 @@ static void __exit crc_t10dif_mod_exit(void)
crypto_unregister_shash(&crc_t10dif_alg);
}

-module_cpu_feature_match(PMULL, crc_t10dif_mod_init);
+module_cpu_feature_match(ASIMD, crc_t10dif_mod_init);
module_exit(crc_t10dif_mod_exit);

MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_CRYPTO("crct10dif");
+MODULE_ALIAS_CRYPTO("crct10dif-arm64-ce");
--
2.18.0
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