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2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc 
 kernel/arch/arm/crypto/crct10dif-ce-core.S
....@@ -2,12 +2,14 @@
22 // Accelerated CRC-T10DIF using ARM NEON and Crypto Extensions instructions
33 //
44 // Copyright (C) 2016 Linaro Ltd <ard.biesheuvel@linaro.org>
5
+// Copyright (C) 2019 Google LLC <ebiggers@google.com>
56 //
67 // This program is free software; you can redistribute it and/or modify
78 // it under the terms of the GNU General Public License version 2 as
89 // published by the Free Software Foundation.
910 //
1011 
12
+// Derived from the x86 version:
1113 //
1214 // Implement fast CRC-T10DIF computation with SSE and PCLMULQDQ instructions
1315 //
....@@ -54,18 +56,10 @@
5456 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
5557 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
5658 //
57
-//       Function API:
58
-//       UINT16 crc_t10dif_pcl(
59
-//               UINT16 init_crc, //initial CRC value, 16 bits
60
-//               const unsigned char *buf, //buffer pointer to calculate CRC on
61
-//               UINT64 len //buffer length in bytes (64-bit data)
62
-//       );
63
-//
6459 //       Reference paper titled "Fast CRC Computation for Generic
6560 //	Polynomials Using PCLMULQDQ Instruction"
6661 //       URL: http://www.intel.com/content/dam/www/public/us/en/documents
6762 //  /white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf
68
-//
6963 //
7064 
7165 #include <linux/linkage.h>
....@@ -78,13 +72,14 @@
7872 #endif
7973 
8074 	.text
75
+	.arch		armv8-a
8176 	.fpu		crypto-neon-fp-armv8
8277 
83
-	arg1_low32	.req	r0
84
-	arg2		.req	r1
85
-	arg3		.req	r2
78
+	init_crc	.req	r0
79
+	buf		.req	r1
80
+	len		.req	r2
8681 
87
-	qzr		.req	q13
82
+	fold_consts_ptr	.req	ip
8883 
8984 	q0l		.req	d0
9085 	q0h		.req	d1
....@@ -102,82 +97,35 @@
10297 	q6h		.req	d13
10398 	q7l		.req	d14
10499 	q7h		.req	d15
100
+	q8l		.req	d16
101
+	q8h		.req	d17
102
+	q9l		.req	d18
103
+	q9h		.req	d19
104
+	q10l		.req	d20
105
+	q10h		.req	d21
106
+	q11l		.req	d22
107
+	q11h		.req	d23
108
+	q12l		.req	d24
109
+	q12h		.req	d25
105110 
106
-ENTRY(crc_t10dif_pmull)
107
-	vmov.i8		qzr, #0			// init zero register
111
+	FOLD_CONSTS	.req	q10
112
+	FOLD_CONST_L	.req	q10l
113
+	FOLD_CONST_H	.req	q10h
108114 
109
-	// adjust the 16-bit initial_crc value, scale it to 32 bits
110
-	lsl		arg1_low32, arg1_low32, #16
115
+	// Fold reg1, reg2 into the next 32 data bytes, storing the result back
116
+	// into reg1, reg2.
117
+	.macro		fold_32_bytes, reg1, reg2
118
+	vld1.64		{q11-q12}, [buf]!
111119 
112
-	// check if smaller than 256
113
-	cmp		arg3, #256
120
+	vmull.p64	q8, \reg1\()h, FOLD_CONST_H
121
+	vmull.p64	\reg1, \reg1\()l, FOLD_CONST_L
122
+	vmull.p64	q9, \reg2\()h, FOLD_CONST_H
123
+	vmull.p64	\reg2, \reg2\()l, FOLD_CONST_L
114124 
115
-	// for sizes less than 128, we can't fold 64B at a time...
116
-	blt		_less_than_128
117
-
118
-	// load the initial crc value
119
-	// crc value does not need to be byte-reflected, but it needs
120
-	// to be moved to the high part of the register.
121
-	// because data will be byte-reflected and will align with
122
-	// initial crc at correct place.
123
-	vmov		s0, arg1_low32		// initial crc
124
-	vext.8		q10, qzr, q0, #4
125
-
126
-	// receive the initial 64B data, xor the initial crc value
127
-	vld1.64		{q0-q1}, [arg2]!
128
-	vld1.64		{q2-q3}, [arg2]!
129
-	vld1.64		{q4-q5}, [arg2]!
130
-	vld1.64		{q6-q7}, [arg2]!
131
-CPU_LE(	vrev64.8	q0, q0			)
132
-CPU_LE(	vrev64.8	q1, q1			)
133
-CPU_LE(	vrev64.8	q2, q2			)
134
-CPU_LE(	vrev64.8	q3, q3			)
135
-CPU_LE(	vrev64.8	q4, q4			)
136
-CPU_LE(	vrev64.8	q5, q5			)
137
-CPU_LE(	vrev64.8	q6, q6			)
138
-CPU_LE(	vrev64.8	q7, q7			)
139
-
140
-	vswp		d0, d1
141
-	vswp		d2, d3
142
-	vswp		d4, d5
143
-	vswp		d6, d7
144
-	vswp		d8, d9
145
-	vswp		d10, d11
146
-	vswp		d12, d13
147
-	vswp		d14, d15
148
-
149
-	// XOR the initial_crc value
150
-	veor.8		q0, q0, q10
151
-
152
-	adr		ip, rk3
153
-	vld1.64		{q10}, [ip, :128]	// xmm10 has rk3 and rk4
154
-
155
-	//
156
-	// we subtract 256 instead of 128 to save one instruction from the loop
157
-	//
158
-	sub		arg3, arg3, #256
159
-
160
-	// at this section of the code, there is 64*x+y (0<=y<64) bytes of
161
-	// buffer. The _fold_64_B_loop will fold 64B at a time
162
-	// until we have 64+y Bytes of buffer
163
-
164
-
165
-	// fold 64B at a time. This section of the code folds 4 vector
166
-	// registers in parallel
167
-_fold_64_B_loop:
168
-
169
-	.macro		fold64, reg1, reg2
170
-	vld1.64		{q11-q12}, [arg2]!
171
-
172
-	vmull.p64	q8, \reg1\()h, d21
173
-	vmull.p64	\reg1, \reg1\()l, d20
174
-	vmull.p64	q9, \reg2\()h, d21
175
-	vmull.p64	\reg2, \reg2\()l, d20
176
-
177
-CPU_LE(	vrev64.8	q11, q11		)
178
-CPU_LE(	vrev64.8	q12, q12		)
179
-	vswp		d22, d23
180
-	vswp		d24, d25
125
+CPU_LE(	vrev64.8	q11, q11	)
126
+CPU_LE(	vrev64.8	q12, q12	)
127
+	vswp		q11l, q11h
128
+	vswp		q12l, q12h
181129 
182130 	veor.8		\reg1, \reg1, q8
183131 	veor.8		\reg2, \reg2, q9
....@@ -185,242 +133,248 @@
185133 	veor.8		\reg2, \reg2, q12
186134 	.endm
187135 
188
-	fold64		q0, q1
189
-	fold64		q2, q3
190
-	fold64		q4, q5
191
-	fold64		q6, q7
192
-
193
-	subs		arg3, arg3, #128
194
-
195
-	// check if there is another 64B in the buffer to be able to fold
196
-	bge		_fold_64_B_loop
197
-
198
-	// at this point, the buffer pointer is pointing at the last y Bytes
199
-	// of the buffer the 64B of folded data is in 4 of the vector
200
-	// registers: v0, v1, v2, v3
201
-
202
-	// fold the 8 vector registers to 1 vector register with different
203
-	// constants
204
-
205
-	adr		ip, rk9
206
-	vld1.64		{q10}, [ip, :128]!
207
-
208
-	.macro		fold16, reg, rk
209
-	vmull.p64	q8, \reg\()l, d20
210
-	vmull.p64	\reg, \reg\()h, d21
211
-	.ifnb		\rk
212
-	vld1.64		{q10}, [ip, :128]!
136
+	// Fold src_reg into dst_reg, optionally loading the next fold constants
137
+	.macro		fold_16_bytes, src_reg, dst_reg, load_next_consts
138
+	vmull.p64	q8, \src_reg\()l, FOLD_CONST_L
139
+	vmull.p64	\src_reg, \src_reg\()h, FOLD_CONST_H
140
+	.ifnb		\load_next_consts
141
+	vld1.64		{FOLD_CONSTS}, [fold_consts_ptr, :128]!
213142 	.endif
214
-	veor.8		q7, q7, q8
215
-	veor.8		q7, q7, \reg
143
+	veor.8		\dst_reg, \dst_reg, q8
144
+	veor.8		\dst_reg, \dst_reg, \src_reg
216145 	.endm
217146 
218
-	fold16		q0, rk11
219
-	fold16		q1, rk13
220
-	fold16		q2, rk15
221
-	fold16		q3, rk17
222
-	fold16		q4, rk19
223
-	fold16		q5, rk1
224
-	fold16		q6
147
+	.macro		__adrl, out, sym
148
+	movw		\out, #:lower16:\sym
149
+	movt		\out, #:upper16:\sym
150
+	.endm
225151 
226
-	// instead of 64, we add 48 to the loop counter to save 1 instruction
227
-	// from the loop instead of a cmp instruction, we use the negative
228
-	// flag with the jl instruction
229
-	adds		arg3, arg3, #(128-16)
230
-	blt		_final_reduction_for_128
152
+//
153
+// u16 crc_t10dif_pmull(u16 init_crc, const u8 *buf, size_t len);
154
+//
155
+// Assumes len >= 16.
156
+//
157
+ENTRY(crc_t10dif_pmull)
231158 
232
-	// now we have 16+y bytes left to reduce. 16 Bytes is in register v7
233
-	// and the rest is in memory. We can fold 16 bytes at a time if y>=16
234
-	// continue folding 16B at a time
159
+	// For sizes less than 256 bytes, we can't fold 128 bytes at a time.
160
+	cmp		len, #256
161
+	blt		.Lless_than_256_bytes
235162 
236
-_16B_reduction_loop:
237
-	vmull.p64	q8, d14, d20
238
-	vmull.p64	q7, d15, d21
163
+	__adrl		fold_consts_ptr, .Lfold_across_128_bytes_consts
164
+
165
+	// Load the first 128 data bytes.  Byte swapping is necessary to make
166
+	// the bit order match the polynomial coefficient order.
167
+	vld1.64		{q0-q1}, [buf]!
168
+	vld1.64		{q2-q3}, [buf]!
169
+	vld1.64		{q4-q5}, [buf]!
170
+	vld1.64		{q6-q7}, [buf]!
171
+CPU_LE(	vrev64.8	q0, q0	)
172
+CPU_LE(	vrev64.8	q1, q1	)
173
+CPU_LE(	vrev64.8	q2, q2	)
174
+CPU_LE(	vrev64.8	q3, q3	)
175
+CPU_LE(	vrev64.8	q4, q4	)
176
+CPU_LE(	vrev64.8	q5, q5	)
177
+CPU_LE(	vrev64.8	q6, q6	)
178
+CPU_LE(	vrev64.8	q7, q7	)
179
+	vswp		q0l, q0h
180
+	vswp		q1l, q1h
181
+	vswp		q2l, q2h
182
+	vswp		q3l, q3h
183
+	vswp		q4l, q4h
184
+	vswp		q5l, q5h
185
+	vswp		q6l, q6h
186
+	vswp		q7l, q7h
187
+
188
+	// XOR the first 16 data *bits* with the initial CRC value.
189
+	vmov.i8		q8h, #0
190
+	vmov.u16	q8h[3], init_crc
191
+	veor		q0h, q0h, q8h
192
+
193
+	// Load the constants for folding across 128 bytes.
194
+	vld1.64		{FOLD_CONSTS}, [fold_consts_ptr, :128]!
195
+
196
+	// Subtract 128 for the 128 data bytes just consumed.  Subtract another
197
+	// 128 to simplify the termination condition of the following loop.
198
+	sub		len, len, #256
199
+
200
+	// While >= 128 data bytes remain (not counting q0-q7), fold the 128
201
+	// bytes q0-q7 into them, storing the result back into q0-q7.
202
+.Lfold_128_bytes_loop:
203
+	fold_32_bytes	q0, q1
204
+	fold_32_bytes	q2, q3
205
+	fold_32_bytes	q4, q5
206
+	fold_32_bytes	q6, q7
207
+	subs		len, len, #128
208
+	bge		.Lfold_128_bytes_loop
209
+
210
+	// Now fold the 112 bytes in q0-q6 into the 16 bytes in q7.
211
+
212
+	// Fold across 64 bytes.
213
+	vld1.64		{FOLD_CONSTS}, [fold_consts_ptr, :128]!
214
+	fold_16_bytes	q0, q4
215
+	fold_16_bytes	q1, q5
216
+	fold_16_bytes	q2, q6
217
+	fold_16_bytes	q3, q7, 1
218
+	// Fold across 32 bytes.
219
+	fold_16_bytes	q4, q6
220
+	fold_16_bytes	q5, q7, 1
221
+	// Fold across 16 bytes.
222
+	fold_16_bytes	q6, q7
223
+
224
+	// Add 128 to get the correct number of data bytes remaining in 0...127
225
+	// (not counting q7), following the previous extra subtraction by 128.
226
+	// Then subtract 16 to simplify the termination condition of the
227
+	// following loop.
228
+	adds		len, len, #(128-16)
229
+
230
+	// While >= 16 data bytes remain (not counting q7), fold the 16 bytes q7
231
+	// into them, storing the result back into q7.
232
+	blt		.Lfold_16_bytes_loop_done
233
+.Lfold_16_bytes_loop:
234
+	vmull.p64	q8, q7l, FOLD_CONST_L
235
+	vmull.p64	q7, q7h, FOLD_CONST_H
239236 	veor.8		q7, q7, q8
240
-
241
-	vld1.64		{q0}, [arg2]!
242
-CPU_LE(	vrev64.8	q0, q0		)
243
-	vswp		d0, d1
237
+	vld1.64		{q0}, [buf]!
238
+CPU_LE(	vrev64.8	q0, q0	)
239
+	vswp		q0l, q0h
244240 	veor.8		q7, q7, q0
245
-	subs		arg3, arg3, #16
241
+	subs		len, len, #16
242
+	bge		.Lfold_16_bytes_loop
246243 
247
-	// instead of a cmp instruction, we utilize the flags with the
248
-	// jge instruction equivalent of: cmp arg3, 16-16
249
-	// check if there is any more 16B in the buffer to be able to fold
250
-	bge		_16B_reduction_loop
244
+.Lfold_16_bytes_loop_done:
245
+	// Add 16 to get the correct number of data bytes remaining in 0...15
246
+	// (not counting q7), following the previous extra subtraction by 16.
247
+	adds		len, len, #16
248
+	beq		.Lreduce_final_16_bytes
251249 
252
-	// now we have 16+z bytes left to reduce, where 0<= z < 16.
253
-	// first, we reduce the data in the xmm7 register
250
+.Lhandle_partial_segment:
251
+	// Reduce the last '16 + len' bytes where 1 <= len <= 15 and the first
252
+	// 16 bytes are in q7 and the rest are the remaining data in 'buf'.  To
253
+	// do this without needing a fold constant for each possible 'len',
254
+	// redivide the bytes into a first chunk of 'len' bytes and a second
255
+	// chunk of 16 bytes, then fold the first chunk into the second.
254256 
255
-_final_reduction_for_128:
256
-	// check if any more data to fold. If not, compute the CRC of
257
-	// the final 128 bits
258
-	adds		arg3, arg3, #16
259
-	beq		_128_done
257
+	// q0 = last 16 original data bytes
258
+	add		buf, buf, len
259
+	sub		buf, buf, #16
260
+	vld1.64		{q0}, [buf]
261
+CPU_LE(	vrev64.8	q0, q0	)
262
+	vswp		q0l, q0h
260263 
261
-	// here we are getting data that is less than 16 bytes.
262
-	// since we know that there was data before the pointer, we can
263
-	// offset the input pointer before the actual point, to receive
264
-	// exactly 16 bytes. after that the registers need to be adjusted.
265
-_get_last_two_regs:
266
-	add		arg2, arg2, arg3
267
-	sub		arg2, arg2, #16
268
-	vld1.64		{q1}, [arg2]
269
-CPU_LE(	vrev64.8	q1, q1			)
270
-	vswp		d2, d3
264
+	// q1 = high order part of second chunk: q7 left-shifted by 'len' bytes.
265
+	__adrl		r3, .Lbyteshift_table + 16
266
+	sub		r3, r3, len
267
+	vld1.8		{q2}, [r3]
268
+	vtbl.8		q1l, {q7l-q7h}, q2l
269
+	vtbl.8		q1h, {q7l-q7h}, q2h
271270 
272
-	// get rid of the extra data that was loaded before
273
-	// load the shift constant
274
-	adr		ip, tbl_shf_table + 16
275
-	sub		ip, ip, arg3
276
-	vld1.8		{q0}, [ip]
271
+	// q3 = first chunk: q7 right-shifted by '16-len' bytes.
272
+	vmov.i8		q3, #0x80
273
+	veor.8		q2, q2, q3
274
+	vtbl.8		q3l, {q7l-q7h}, q2l
275
+	vtbl.8		q3h, {q7l-q7h}, q2h
277276 
278
-	// shift v2 to the left by arg3 bytes
279
-	vtbl.8		d4, {d14-d15}, d0
280
-	vtbl.8		d5, {d14-d15}, d1
277
+	// Convert to 8-bit masks: 'len' 0x00 bytes, then '16-len' 0xff bytes.
278
+	vshr.s8		q2, q2, #7
281279 
282
-	// shift v7 to the right by 16-arg3 bytes
283
-	vmov.i8		q9, #0x80
284
-	veor.8		q0, q0, q9
285
-	vtbl.8		d18, {d14-d15}, d0
286
-	vtbl.8		d19, {d14-d15}, d1
280
+	// q2 = second chunk: 'len' bytes from q0 (low-order bytes),
281
+	// then '16-len' bytes from q1 (high-order bytes).
282
+	vbsl.8		q2, q1, q0
287283 
288
-	// blend
289
-	vshr.s8		q0, q0, #7		// convert to 8-bit mask
290
-	vbsl.8		q0, q2, q1
291
-
292
-	// fold 16 Bytes
293
-	vmull.p64	q8, d18, d20
294
-	vmull.p64	q7, d19, d21
295
-	veor.8		q7, q7, q8
284
+	// Fold the first chunk into the second chunk, storing the result in q7.
285
+	vmull.p64	q0, q3l, FOLD_CONST_L
286
+	vmull.p64	q7, q3h, FOLD_CONST_H
296287 	veor.8		q7, q7, q0
288
+	veor.8		q7, q7, q2
297289 
298
-_128_done:
299
-	// compute crc of a 128-bit value
300
-	vldr		d20, rk5
301
-	vldr		d21, rk6		// rk5 and rk6 in xmm10
290
+.Lreduce_final_16_bytes:
291
+	// Reduce the 128-bit value M(x), stored in q7, to the final 16-bit CRC.
302292 
303
-	// 64b fold
304
-	vext.8		q0, qzr, q7, #8
305
-	vmull.p64	q7, d15, d20
306
-	veor.8		q7, q7, q0
293
+	// Load 'x^48 * (x^48 mod G(x))' and 'x^48 * (x^80 mod G(x))'.
294
+	vld1.64		{FOLD_CONSTS}, [fold_consts_ptr, :128]!
307295 
308
-	// 32b fold
309
-	vext.8		q0, q7, qzr, #12
310
-	vmov		s31, s3
311
-	vmull.p64	q0, d0, d21
312
-	veor.8		q7, q0, q7
296
+	// Fold the high 64 bits into the low 64 bits, while also multiplying by
297
+	// x^64.  This produces a 128-bit value congruent to x^64 * M(x) and
298
+	// whose low 48 bits are 0.
299
+	vmull.p64	q0, q7h, FOLD_CONST_H	// high bits * x^48 * (x^80 mod G(x))
300
+	veor.8		q0h, q0h, q7l		// + low bits * x^64
313301 
314
-	// barrett reduction
315
-_barrett:
316
-	vldr		d20, rk7
317
-	vldr		d21, rk8
302
+	// Fold the high 32 bits into the low 96 bits.  This produces a 96-bit
303
+	// value congruent to x^64 * M(x) and whose low 48 bits are 0.
304
+	vmov.i8		q1, #0
305
+	vmov		s4, s3			// extract high 32 bits
306
+	vmov		s3, s5			// zero high 32 bits
307
+	vmull.p64	q1, q1l, FOLD_CONST_L	// high 32 bits * x^48 * (x^48 mod G(x))
308
+	veor.8		q0, q0, q1		// + low bits
318309 
319
-	vmull.p64	q0, d15, d20
320
-	vext.8		q0, qzr, q0, #12
321
-	vmull.p64	q0, d1, d21
322
-	vext.8		q0, qzr, q0, #12
323
-	veor.8		q7, q7, q0
324
-	vmov		r0, s29
310
+	// Load G(x) and floor(x^48 / G(x)).
311
+	vld1.64		{FOLD_CONSTS}, [fold_consts_ptr, :128]
325312 
326
-_cleanup:
327
-	// scale the result back to 16 bits
328
-	lsr		r0, r0, #16
313
+	// Use Barrett reduction to compute the final CRC value.
314
+	vmull.p64	q1, q0h, FOLD_CONST_H	// high 32 bits * floor(x^48 / G(x))
315
+	vshr.u64	q1l, q1l, #32		// /= x^32
316
+	vmull.p64	q1, q1l, FOLD_CONST_L	// *= G(x)
317
+	vshr.u64	q0l, q0l, #48
318
+	veor.8		q0l, q0l, q1l		// + low 16 nonzero bits
319
+	// Final CRC value (x^16 * M(x)) mod G(x) is in low 16 bits of q0.
320
+
321
+	vmov.u16	r0, q0l[0]
329322 	bx		lr
330323 
331
-_less_than_128:
332
-	teq		arg3, #0
333
-	beq		_cleanup
324
+.Lless_than_256_bytes:
325
+	// Checksumming a buffer of length 16...255 bytes
334326 
335
-	vmov.i8		q0, #0
336
-	vmov		s3, arg1_low32		// get the initial crc value
327
+	__adrl		fold_consts_ptr, .Lfold_across_16_bytes_consts
337328 
338
-	vld1.64		{q7}, [arg2]!
339
-CPU_LE(	vrev64.8	q7, q7		)
340
-	vswp		d14, d15
341
-	veor.8		q7, q7, q0
329
+	// Load the first 16 data bytes.
330
+	vld1.64		{q7}, [buf]!
331
+CPU_LE(	vrev64.8	q7, q7	)
332
+	vswp		q7l, q7h
342333 
343
-	cmp		arg3, #16
344
-	beq		_128_done		// exactly 16 left
345
-	blt		_less_than_16_left
334
+	// XOR the first 16 data *bits* with the initial CRC value.
335
+	vmov.i8		q0h, #0
336
+	vmov.u16	q0h[3], init_crc
337
+	veor.8		q7h, q7h, q0h
346338 
347
-	// now if there is, load the constants
348
-	vldr		d20, rk1
349
-	vldr		d21, rk2		// rk1 and rk2 in xmm10
339
+	// Load the fold-across-16-bytes constants.
340
+	vld1.64		{FOLD_CONSTS}, [fold_consts_ptr, :128]!
350341 
351
-	// check if there is enough buffer to be able to fold 16B at a time
352
-	subs		arg3, arg3, #32
353
-	addlt		arg3, arg3, #16
354
-	blt		_get_last_two_regs
355
-	b		_16B_reduction_loop
356
-
357
-_less_than_16_left:
358
-	// shl r9, 4
359
-	adr		ip, tbl_shf_table + 16
360
-	sub		ip, ip, arg3
361
-	vld1.8		{q0}, [ip]
362
-	vmov.i8		q9, #0x80
363
-	veor.8		q0, q0, q9
364
-	vtbl.8		d18, {d14-d15}, d0
365
-	vtbl.8		d15, {d14-d15}, d1
366
-	vmov		d14, d18
367
-	b		_128_done
342
+	cmp		len, #16
343
+	beq		.Lreduce_final_16_bytes		// len == 16
344
+	subs		len, len, #32
345
+	addlt		len, len, #16
346
+	blt		.Lhandle_partial_segment	// 17 <= len <= 31
347
+	b		.Lfold_16_bytes_loop		// 32 <= len <= 255
368348 ENDPROC(crc_t10dif_pmull)
369349 
370
-// precomputed constants
371
-// these constants are precomputed from the poly:
372
-// 0x8bb70000 (0x8bb7 scaled to 32 bits)
350
+	.section	".rodata", "a"
373351 	.align		4
374
-// Q = 0x18BB70000
375
-// rk1 = 2^(32*3) mod Q << 32
376
-// rk2 = 2^(32*5) mod Q << 32
377
-// rk3 = 2^(32*15) mod Q << 32
378
-// rk4 = 2^(32*17) mod Q << 32
379
-// rk5 = 2^(32*3) mod Q << 32
380
-// rk6 = 2^(32*2) mod Q << 32
381
-// rk7 = floor(2^64/Q)
382
-// rk8 = Q
383352 
384
-rk3:	.quad		0x9d9d000000000000
385
-rk4:	.quad		0x7cf5000000000000
386
-rk5:	.quad		0x2d56000000000000
387
-rk6:	.quad		0x1368000000000000
388
-rk7:	.quad		0x00000001f65a57f8
389
-rk8:	.quad		0x000000018bb70000
390
-rk9:	.quad		0xceae000000000000
391
-rk10:	.quad		0xbfd6000000000000
392
-rk11:	.quad		0x1e16000000000000
393
-rk12:	.quad		0x713c000000000000
394
-rk13:	.quad		0xf7f9000000000000
395
-rk14:	.quad		0x80a6000000000000
396
-rk15:	.quad		0x044c000000000000
397
-rk16:	.quad		0xe658000000000000
398
-rk17:	.quad		0xad18000000000000
399
-rk18:	.quad		0xa497000000000000
400
-rk19:	.quad		0x6ee3000000000000
401
-rk20:	.quad		0xe7b5000000000000
402
-rk1:	.quad		0x2d56000000000000
403
-rk2:	.quad		0x06df000000000000
353
+// Fold constants precomputed from the polynomial 0x18bb7
354
+// G(x) = x^16 + x^15 + x^11 + x^9 + x^8 + x^7 + x^5 + x^4 + x^2 + x^1 + x^0
355
+.Lfold_across_128_bytes_consts:
356
+	.quad		0x0000000000006123	// x^(8*128)	mod G(x)
357
+	.quad		0x0000000000002295	// x^(8*128+64)	mod G(x)
358
+// .Lfold_across_64_bytes_consts:
359
+	.quad		0x0000000000001069	// x^(4*128)	mod G(x)
360
+	.quad		0x000000000000dd31	// x^(4*128+64)	mod G(x)
361
+// .Lfold_across_32_bytes_consts:
362
+	.quad		0x000000000000857d	// x^(2*128)	mod G(x)
363
+	.quad		0x0000000000007acc	// x^(2*128+64)	mod G(x)
364
+.Lfold_across_16_bytes_consts:
365
+	.quad		0x000000000000a010	// x^(1*128)	mod G(x)
366
+	.quad		0x0000000000001faa	// x^(1*128+64)	mod G(x)
367
+// .Lfinal_fold_consts:
368
+	.quad		0x1368000000000000	// x^48 * (x^48 mod G(x))
369
+	.quad		0x2d56000000000000	// x^48 * (x^80 mod G(x))
370
+// .Lbarrett_reduction_consts:
371
+	.quad		0x0000000000018bb7	// G(x)
372
+	.quad		0x00000001f65a57f8	// floor(x^48 / G(x))
404373 
405
-tbl_shf_table:
406
-// use these values for shift constants for the tbl/tbx instruction
407
-// different alignments result in values as shown:
408
-//	DDQ 0x008f8e8d8c8b8a898887868584838281 # shl 15 (16-1) / shr1
409
-//	DDQ 0x01008f8e8d8c8b8a8988878685848382 # shl 14 (16-3) / shr2
410
-//	DDQ 0x0201008f8e8d8c8b8a89888786858483 # shl 13 (16-4) / shr3
411
-//	DDQ 0x030201008f8e8d8c8b8a898887868584 # shl 12 (16-4) / shr4
412
-//	DDQ 0x04030201008f8e8d8c8b8a8988878685 # shl 11 (16-5) / shr5
413
-//	DDQ 0x0504030201008f8e8d8c8b8a89888786 # shl 10 (16-6) / shr6
414
-//	DDQ 0x060504030201008f8e8d8c8b8a898887 # shl 9  (16-7) / shr7
415
-//	DDQ 0x07060504030201008f8e8d8c8b8a8988 # shl 8  (16-8) / shr8
416
-//	DDQ 0x0807060504030201008f8e8d8c8b8a89 # shl 7  (16-9) / shr9
417
-//	DDQ 0x090807060504030201008f8e8d8c8b8a # shl 6  (16-10) / shr10
418
-//	DDQ 0x0a090807060504030201008f8e8d8c8b # shl 5  (16-11) / shr11
419
-//	DDQ 0x0b0a090807060504030201008f8e8d8c # shl 4  (16-12) / shr12
420
-//	DDQ 0x0c0b0a090807060504030201008f8e8d # shl 3  (16-13) / shr13
421
-//	DDQ 0x0d0c0b0a090807060504030201008f8e # shl 2  (16-14) / shr14
422
-//	DDQ 0x0e0d0c0b0a090807060504030201008f # shl 1  (16-15) / shr15
423
-
374
+// For 1 <= len <= 15, the 16-byte vector beginning at &byteshift_table[16 -
375
+// len] is the index vector to shift left by 'len' bytes, and is also {0x80,
376
+// ..., 0x80} XOR the index vector to shift right by '16 - len' bytes.
377
+.Lbyteshift_table:
424378 	.byte		 0x0, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87
425379 	.byte		0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f
426380 	.byte		 0x0,  0x1,  0x2,  0x3,  0x4,  0x5,  0x6,  0x7