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
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
|
C x86_64/salsa20-crypt.asm
ifelse(<
Copyright (C) 2012 Niels Möller
This file is part of GNU Nettle.
GNU Nettle is free software: you can redistribute it and/or
modify it under the terms of either:
* the GNU Lesser General Public License as published by the Free
Software Foundation; either version 3 of the License, or (at your
option) any later version.
or
* the GNU General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your
option) any later version.
or both in parallel, as here.
GNU Nettle is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received copies of the GNU General Public License and
the GNU Lesser General Public License along with this program. If
not, see http://www.gnu.org/licenses/.
>)
define(<CTX>, <%rdi>)
define(<LENGTH>, <%rsi>)
define(<DST>, <%rdx>)
define(<SRC>, <%rcx>)
define(<T64>, <%r8>)
define(<POS>, <%r9>)
define(<X0>, <%xmm0>)
define(<X1>, <%xmm1>)
define(<X2>, <%xmm2>)
define(<X3>, <%xmm3>)
define(<T0>, <%xmm4>)
define(<T1>, <%xmm5>)
define(<M0101>, <%xmm6>)
define(<M0110>, <%xmm7>)
define(<M0011>, <%xmm8>)
define(<COUNT>, <%rax>)
include_src(<x86_64/salsa20.m4>)
C Possible improvements:
C
C Do two blocks (or more) at a time in parallel, to avoid limitations
C due to data dependencies.
C
C Avoid redoing the permutation of the input for each block (all but
C the two counter words are constant). Could also keep the input in
C registers.
.file "salsa20-crypt.asm"
C salsa20_crypt(struct salsa20_ctx *ctx, size_t length,
C uint8_t *dst, const uint8_t *src)
.text
ALIGN(16)
PROLOGUE(nettle_salsa20_crypt)
W64_ENTRY(4, 9)
test LENGTH, LENGTH
jz .Lend
C Load mask registers
mov $-1, XREG(COUNT)
movd XREG(COUNT), M0101
pshufd $0x09, M0101, M0011 C 01 01 00 00
pshufd $0x41, M0101, M0110 C 01 00 00 01
pshufd $0x22, M0101, M0101 C 01 00 01 00
.Lblock_loop:
movups (CTX), X0
movups 16(CTX), X1
movups 32(CTX), X2
movups 48(CTX), X3
C On input, each xmm register is one row. We start with
C
C 0 1 2 3 C K K K
C 4 5 6 7 K C I I
C 8 9 10 11 B B C K
C 12 13 14 15 K K K C
C
C Diagrams are in little-endian order, with least significant word to
C the left. We rotate the columns, to get instead
C
C 0 5 10 15 C C C C
C 4 9 14 3 K B K K
C 8 13 2 7 B K K I
C 12 1 6 11 K K I K
C
C The original rows are now diagonals.
SWAP(X0, X1, M0101)
SWAP(X2, X3, M0101)
SWAP(X1, X3, M0110)
SWAP(X0, X2, M0011)
movl $10, XREG(COUNT)
ALIGN(16)
.Loop:
QROUND(X0, X1, X2, X3)
C For the row operations, we first rotate the rows, to get
C
C 0 5 10 15
C 3 4 9 14
C 2 7 8 13
C 1 6 11 12
C
C Now the original rows are turned into into columns. (This
C SIMD hack described in djb's papers).
pshufd $0x93, X1, X1 C 11 00 01 10 (least sign. left)
pshufd $0x4e, X2, X2 C 10 11 00 01
pshufd $0x39, X3, X3 C 01 10 11 00
QROUND(X0, X3, X2, X1)
C Inverse rotation of the rows
pshufd $0x39, X1, X1 C 01 10 11 00
pshufd $0x4e, X2, X2 C 10 11 00 01
pshufd $0x93, X3, X3 C 11 00 01 10
decl XREG(COUNT)
jnz .Loop
SWAP(X0, X2, M0011)
SWAP(X1, X3, M0110)
SWAP(X0, X1, M0101)
SWAP(X2, X3, M0101)
movups (CTX), T0
movups 16(CTX), T1
paddd T0, X0
paddd T1, X1
movups 32(CTX), T0
movups 48(CTX), T1
paddd T0, X2
paddd T1, X3
C Increment block counter
incq 32(CTX)
cmp $64, LENGTH
jc .Lfinal_xor
movups 48(SRC), T1
pxor T1, X3
movups X3, 48(DST)
.Lxor3:
movups 32(SRC), T0
pxor T0, X2
movups X2, 32(DST)
.Lxor2:
movups 16(SRC), T1
pxor T1, X1
movups X1, 16(DST)
.Lxor1:
movups (SRC), T0
pxor T0, X0
movups X0, (DST)
lea 64(SRC), SRC
lea 64(DST), DST
sub $64, LENGTH
ja .Lblock_loop
.Lend:
W64_EXIT(4, 9)
ret
.Lfinal_xor:
cmp $32, LENGTH
jz .Lxor2
jc .Llt32
cmp $48, LENGTH
jz .Lxor3
jc .Llt48
movaps X3, T0
call .Lpartial
jmp .Lxor3
.Llt48:
movaps X2, T0
call .Lpartial
jmp .Lxor2
.Llt32:
cmp $16, LENGTH
jz .Lxor1
jc .Llt16
movaps X1, T0
call .Lpartial
jmp .Lxor1
.Llt16:
movaps X0, T0
call .Lpartial
jmp .Lend
.Lpartial:
mov LENGTH, POS
and $-16, POS
test $8, LENGTH
jz .Llt8
C This "movd" instruction should assemble to
C 66 49 0f 7e e0 movq %xmm4,%r8
C Apparently, assemblers treat movd and movq (with the
C arguments we use) in the same way, except for osx, which
C barfs at movq.
movd T0, T64
xor (SRC, POS), T64
mov T64, (DST, POS)
lea 8(POS), POS
pshufd $0xee, T0, T0 C 10 11 10 11
.Llt8:
C And this is also really a movq.
movd T0, T64
test $4, LENGTH
jz .Llt4
mov XREG(T64), XREG(COUNT)
xor (SRC, POS), XREG(COUNT)
mov XREG(COUNT), (DST, POS)
lea 4(POS), POS
shr $32, T64
.Llt4:
test $2, LENGTH
jz .Llt2
mov WREG(T64), WREG(COUNT)
xor (SRC, POS), WREG(COUNT)
mov WREG(COUNT), (DST, POS)
lea 2(POS), POS
shr $16, XREG(T64)
.Llt2:
test $1, LENGTH
jz .Lret
xor (SRC, POS), LREG(T64)
mov LREG(T64), (DST, POS)
.Lret:
ret
EPILOGUE(nettle_salsa20_crypt)
|