1/* SPDX-License-Identifier: GPL-2.0+ 2 * 3 * $Id: checksum.S,v 1.10 2001/07/06 13:11:32 gniibe Exp $ 4 * 5 * INET An implementation of the TCP/IP protocol suite for the LINUX 6 * operating system. INET is implemented using the BSD Socket 7 * interface as the means of communication with the user level. 8 * 9 * IP/TCP/UDP checksumming routines 10 * 11 * Authors: Jorge Cwik, <jorge@laser.satlink.net> 12 * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 13 * Tom May, <ftom@netcom.com> 14 * Pentium Pro/II routines: 15 * Alexander Kjeldaas <astor@guardian.no> 16 * Finn Arne Gangstad <finnag@guardian.no> 17 * Lots of code moved from tcp.c and ip.c; see those files 18 * for more names. 19 * 20 * Changes: Ingo Molnar, converted csum_partial_copy() to 2.1 exception 21 * handling. 22 * Andi Kleen, add zeroing on error 23 * converted to pure assembler 24 * 25 * SuperH version: Copyright (C) 1999 Niibe Yutaka 26 */ 27 28#include <asm/errno.h> 29#include <linux/linkage.h> 30 31/* 32 * computes a partial checksum, e.g. for TCP/UDP fragments 33 */ 34 35/* 36 * asmlinkage __wsum csum_partial(const void *buf, int len, __wsum sum); 37 */ 38 39.text 40ENTRY(csum_partial) 41 /* 42 * Experiments with Ethernet and SLIP connections show that buff 43 * is aligned on either a 2-byte or 4-byte boundary. We get at 44 * least a twofold speedup on 486 and Pentium if it is 4-byte aligned. 45 * Fortunately, it is easy to convert 2-byte alignment to 4-byte 46 * alignment for the unrolled loop. 47 */ 48 mov r4, r0 49 tst #3, r0 ! Check alignment. 50 bt/s 2f ! Jump if alignment is ok. 51 mov r4, r7 ! Keep a copy to check for alignment 52 ! 53 tst #1, r0 ! Check alignment. 54 bt 21f ! Jump if alignment is boundary of 2bytes. 55 56 ! buf is odd 57 tst r5, r5 58 add #-1, r5 59 bt 9f 60 mov.b @r4+, r0 61 extu.b r0, r0 62 addc r0, r6 ! t=0 from previous tst 63 mov r6, r0 64 shll8 r6 65 shlr16 r0 66 shlr8 r0 67 or r0, r6 68 mov r4, r0 69 tst #2, r0 70 bt 2f 7121: 72 ! buf is 2 byte aligned (len could be 0) 73 add #-2, r5 ! Alignment uses up two bytes. 74 cmp/pz r5 ! 75 bt/s 1f ! Jump if we had at least two bytes. 76 clrt 77 bra 6f 78 add #2, r5 ! r5 was < 2. Deal with it. 791: 80 mov.w @r4+, r0 81 extu.w r0, r0 82 addc r0, r6 83 bf 2f 84 add #1, r6 852: 86 ! buf is 4 byte aligned (len could be 0) 87 mov r5, r1 88 mov #-5, r0 89 shld r0, r1 90 tst r1, r1 91 bt/s 4f ! if it's =0, go to 4f 92 clrt 93 .align 2 943: 95 mov.l @r4+, r0 96 mov.l @r4+, r2 97 mov.l @r4+, r3 98 addc r0, r6 99 mov.l @r4+, r0 100 addc r2, r6 101 mov.l @r4+, r2 102 addc r3, r6 103 mov.l @r4+, r3 104 addc r0, r6 105 mov.l @r4+, r0 106 addc r2, r6 107 mov.l @r4+, r2 108 addc r3, r6 109 addc r0, r6 110 addc r2, r6 111 movt r0 112 dt r1 113 bf/s 3b 114 cmp/eq #1, r0 115 ! here, we know r1==0 116 addc r1, r6 ! add carry to r6 1174: 118 mov r5, r0 119 and #0x1c, r0 120 tst r0, r0 121 bt 6f 122 ! 4 bytes or more remaining 123 mov r0, r1 124 shlr2 r1 125 mov #0, r2 1265: 127 addc r2, r6 128 mov.l @r4+, r2 129 movt r0 130 dt r1 131 bf/s 5b 132 cmp/eq #1, r0 133 addc r2, r6 134 addc r1, r6 ! r1==0 here, so it means add carry-bit 1356: 136 ! 3 bytes or less remaining 137 mov #3, r0 138 and r0, r5 139 tst r5, r5 140 bt 9f ! if it's =0 go to 9f 141 mov #2, r1 142 cmp/hs r1, r5 143 bf 7f 144 mov.w @r4+, r0 145 extu.w r0, r0 146 cmp/eq r1, r5 147 bt/s 8f 148 clrt 149 shll16 r0 150 addc r0, r6 1517: 152 mov.b @r4+, r0 153 extu.b r0, r0 154#ifndef __LITTLE_ENDIAN__ 155 shll8 r0 156#endif 1578: 158 addc r0, r6 159 mov #0, r0 160 addc r0, r6 1619: 162 ! Check if the buffer was misaligned, if so realign sum 163 mov r7, r0 164 tst #1, r0 165 bt 10f 166 mov r6, r0 167 shll8 r6 168 shlr16 r0 169 shlr8 r0 170 or r0, r6 17110: 172 rts 173 mov r6, r0 174 175/* 176unsigned int csum_partial_copy_generic (const char *src, char *dst, int len) 177 */ 178 179/* 180 * Copy from ds while checksumming, otherwise like csum_partial with initial 181 * sum being ~0U 182 */ 183 184#define EXC(...) \ 185 9999: __VA_ARGS__ ; \ 186 .section __ex_table, "a"; \ 187 .long 9999b, 6001f ; \ 188 .previous 189 190! 191! r4: const char *SRC 192! r5: char *DST 193! r6: int LEN 194! 195ENTRY(csum_partial_copy_generic) 196 mov #-1,r7 197 mov #3,r0 ! Check src and dest are equally aligned 198 mov r4,r1 199 and r0,r1 200 and r5,r0 201 cmp/eq r1,r0 202 bf 3f ! Different alignments, use slow version 203 tst #1,r0 ! Check dest word aligned 204 bf 3f ! If not, do it the slow way 205 206 mov #2,r0 207 tst r0,r5 ! Check dest alignment. 208 bt 2f ! Jump if alignment is ok. 209 add #-2,r6 ! Alignment uses up two bytes. 210 cmp/pz r6 ! Jump if we had at least two bytes. 211 bt/s 1f 212 clrt 213 add #2,r6 ! r6 was < 2. Deal with it. 214 bra 4f 215 mov r6,r2 216 2173: ! Handle different src and dest alignments. 218 ! This is not common, so simple byte by byte copy will do. 219 mov r6,r2 220 shlr r6 221 tst r6,r6 222 bt 4f 223 clrt 224 .align 2 2255: 226EXC( mov.b @r4+,r1 ) 227EXC( mov.b @r4+,r0 ) 228 extu.b r1,r1 229EXC( mov.b r1,@r5 ) 230EXC( mov.b r0,@(1,r5) ) 231 extu.b r0,r0 232 add #2,r5 233 234#ifdef __LITTLE_ENDIAN__ 235 shll8 r0 236#else 237 shll8 r1 238#endif 239 or r1,r0 240 241 addc r0,r7 242 movt r0 243 dt r6 244 bf/s 5b 245 cmp/eq #1,r0 246 mov #0,r0 247 addc r0, r7 248 249 mov r2, r0 250 tst #1, r0 251 bt 7f 252 bra 5f 253 clrt 254 255 ! src and dest equally aligned, but to a two byte boundary. 256 ! Handle first two bytes as a special case 257 .align 2 2581: 259EXC( mov.w @r4+,r0 ) 260EXC( mov.w r0,@r5 ) 261 add #2,r5 262 extu.w r0,r0 263 addc r0,r7 264 mov #0,r0 265 addc r0,r7 2662: 267 mov r6,r2 268 mov #-5,r0 269 shld r0,r6 270 tst r6,r6 271 bt/s 2f 272 clrt 273 .align 2 2741: 275EXC( mov.l @r4+,r0 ) 276EXC( mov.l @r4+,r1 ) 277 addc r0,r7 278EXC( mov.l r0,@r5 ) 279EXC( mov.l r1,@(4,r5) ) 280 addc r1,r7 281 282EXC( mov.l @r4+,r0 ) 283EXC( mov.l @r4+,r1 ) 284 addc r0,r7 285EXC( mov.l r0,@(8,r5) ) 286EXC( mov.l r1,@(12,r5) ) 287 addc r1,r7 288 289EXC( mov.l @r4+,r0 ) 290EXC( mov.l @r4+,r1 ) 291 addc r0,r7 292EXC( mov.l r0,@(16,r5) ) 293EXC( mov.l r1,@(20,r5) ) 294 addc r1,r7 295 296EXC( mov.l @r4+,r0 ) 297EXC( mov.l @r4+,r1 ) 298 addc r0,r7 299EXC( mov.l r0,@(24,r5) ) 300EXC( mov.l r1,@(28,r5) ) 301 addc r1,r7 302 add #32,r5 303 movt r0 304 dt r6 305 bf/s 1b 306 cmp/eq #1,r0 307 mov #0,r0 308 addc r0,r7 309 3102: mov r2,r6 311 mov #0x1c,r0 312 and r0,r6 313 cmp/pl r6 314 bf/s 4f 315 clrt 316 shlr2 r6 3173: 318EXC( mov.l @r4+,r0 ) 319 addc r0,r7 320EXC( mov.l r0,@r5 ) 321 add #4,r5 322 movt r0 323 dt r6 324 bf/s 3b 325 cmp/eq #1,r0 326 mov #0,r0 327 addc r0,r7 3284: mov r2,r6 329 mov #3,r0 330 and r0,r6 331 cmp/pl r6 332 bf 7f 333 mov #2,r1 334 cmp/hs r1,r6 335 bf 5f 336EXC( mov.w @r4+,r0 ) 337EXC( mov.w r0,@r5 ) 338 extu.w r0,r0 339 add #2,r5 340 cmp/eq r1,r6 341 bt/s 6f 342 clrt 343 shll16 r0 344 addc r0,r7 3455: 346EXC( mov.b @r4+,r0 ) 347EXC( mov.b r0,@r5 ) 348 extu.b r0,r0 349#ifndef __LITTLE_ENDIAN__ 350 shll8 r0 351#endif 3526: addc r0,r7 353 mov #0,r0 354 addc r0,r7 3557: 356 357# Exception handler: 358.section .fixup, "ax" 359 3606001: 361 rts 362 mov #0,r0 363.previous 364 rts 365 mov r7,r0 366