arch/x86/lib/checksum_32.S

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              IP/TCP/UDP checksumming routines
   7  *
   8  * Authors:     Jorge Cwik, <jorge@laser.satlink.net>
   9  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  10  *              Tom May, <ftom@netcom.com>
  11  *              Pentium Pro/II routines:
  12  *              Alexander Kjeldaas <astor@guardian.no>
  13  *              Finn Arne Gangstad <finnag@guardian.no>
  14  *              Lots of code moved from tcp.c and ip.c; see those files
  15  *              for more names.
  16  *
  17  * Changes:     Ingo Molnar, converted csum_partial_copy() to 2.1 exception
  18  *                           handling.
  19  *              Andi Kleen,  add zeroing on error
  20  *                   converted to pure assembler
  21  *
  22  *              This program is free software; you can redistribute it and/or
  23  *              modify it under the terms of the GNU General Public License
  24  *              as published by the Free Software Foundation; either version
  25  *              2 of the License, or (at your option) any later version.
  26  */
  27
  28 #include <linux/linkage.h>
  29 #include <asm/errno.h>
  30 #include <asm/asm.h>
  31
  32 /*
  33  * computes a partial checksum, e.g. for TCP/UDP fragments
  34  */
  35
  36 /*
  37 unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
  38  */
  39
  40 .text
  41
  42 #ifndef CONFIG_X86_USE_PPRO_CHECKSUM
  43
  44           /*
  45            * Experiments with Ethernet and SLIP connections show that buff
  46            * is aligned on either a 2-byte or 4-byte boundary.  We get at
  47            * least a twofold speedup on 486 and Pentium if it is 4-byte aligned.
  48            * Fortunately, it is easy to convert 2-byte alignment to 4-byte
  49            * alignment for the unrolled loop.
  50            */
  51 ENTRY(csum_partial)
  52         pushl %esi
  53         pushl %ebx
  54         movl 20(%esp),%eax      # Function arg: unsigned int sum
  55         movl 16(%esp),%ecx      # Function arg: int len
  56         movl 12(%esp),%esi      # Function arg: unsigned char *buff
  57         testl $3, %esi          # Check alignment.
  58         jz 2f                   # Jump if alignment is ok.
  59         testl $1, %esi          # Check alignment.
  60         jz 10f                  # Jump if alignment is boundary of 2 bytes.
  61
  62         # buf is odd
  63         dec %ecx
  64         jl 8f
  65         movzbl (%esi), %ebx
  66         adcl %ebx, %eax
  67         roll $8, %eax
  68         inc %esi
  69         testl $2, %esi
  70         jz 2f
  71 10:
  72         subl $2, %ecx           # Alignment uses up two bytes.
  73         jae 1f                  # Jump if we had at least two bytes.
  74         addl $2, %ecx           # ecx was < 2.  Deal with it.
  75         jmp 4f
  76 1:      movw (%esi), %bx
  77         addl $2, %esi
  78         addw %bx, %ax
  79         adcl $0, %eax
  80 2:
  81         movl %ecx, %edx
  82         shrl $5, %ecx
  83         jz 2f
  84         testl %esi, %esi
  85 1:      movl (%esi), %ebx
  86         adcl %ebx, %eax
  87         movl 4(%esi), %ebx
  88         adcl %ebx, %eax
  89         movl 8(%esi), %ebx
  90         adcl %ebx, %eax
  91         movl 12(%esi), %ebx
  92         adcl %ebx, %eax
  93         movl 16(%esi), %ebx
  94         adcl %ebx, %eax
  95         movl 20(%esi), %ebx
  96         adcl %ebx, %eax
  97         movl 24(%esi), %ebx
  98         adcl %ebx, %eax
  99         movl 28(%esi), %ebx
 100         adcl %ebx, %eax
 101         lea 32(%esi), %esi
 102         dec %ecx
 103         jne 1b
 104         adcl $0, %eax
 105 2:      movl %edx, %ecx
 106         andl $0x1c, %edx
 107         je 4f
 108         shrl $2, %edx           # This clears CF
 109 3:      adcl (%esi), %eax
 110         lea 4(%esi), %esi
 111         dec %edx
 112         jne 3b
 113         adcl $0, %eax
 114 4:      andl $3, %ecx
 115         jz 7f
 116         cmpl $2, %ecx
 117         jb 5f
 118         movw (%esi),%cx
 119         leal 2(%esi),%esi
 120         je 6f
 121         shll $16,%ecx
 122 5:      movb (%esi),%cl
 123 6:      addl %ecx,%eax
 124         adcl $0, %eax
 125 7:
 126         testb $1, 12(%esp)
 127         jz 8f
 128         roll $8, %eax
 129 8:
 130         popl %ebx
 131         popl %esi
 132         ret
 133 ENDPROC(csum_partial)
 134
 135 #else
 136
 137 /* Version for PentiumII/PPro */
 138
 139 ENTRY(csum_partial)
 140         pushl %esi
 141         pushl %ebx
 142         movl 20(%esp),%eax      # Function arg: unsigned int sum
 143         movl 16(%esp),%ecx      # Function arg: int len
 144         movl 12(%esp),%esi      # Function arg: const unsigned char *buf
 145
 146         testl $3, %esi
 147         jnz 25f
 148 10:
 149         movl %ecx, %edx
 150         movl %ecx, %ebx
 151         andl $0x7c, %ebx
 152         shrl $7, %ecx
 153         addl %ebx,%esi
 154         shrl $2, %ebx
 155         negl %ebx
 156         lea 45f(%ebx,%ebx,2), %ebx
 157         testl %esi, %esi
 158         jmp *%ebx
 159
 160         # Handle 2-byte-aligned regions
 161 20:     addw (%esi), %ax
 162         lea 2(%esi), %esi
 163         adcl $0, %eax
 164         jmp 10b
 165 25:
 166         testl $1, %esi
 167         jz 30f
 168         # buf is odd
 169         dec %ecx
 170         jl 90f
 171         movzbl (%esi), %ebx
 172         addl %ebx, %eax
 173         adcl $0, %eax
 174         roll $8, %eax
 175         inc %esi
 176         testl $2, %esi
 177         jz 10b
 178
 179 30:     subl $2, %ecx
 180         ja 20b
 181         je 32f
 182         addl $2, %ecx
 183         jz 80f
 184         movzbl (%esi),%ebx      # csumming 1 byte, 2-aligned
 185         addl %ebx, %eax
 186         adcl $0, %eax
 187         jmp 80f
 188 32:
 189         addw (%esi), %ax        # csumming 2 bytes, 2-aligned
 190         adcl $0, %eax
 191         jmp 80f
 192
 193 40:
 194         addl -128(%esi), %eax
 195         adcl -124(%esi), %eax
 196         adcl -120(%esi), %eax
 197         adcl -116(%esi), %eax
 198         adcl -112(%esi), %eax
 199         adcl -108(%esi), %eax
 200         adcl -104(%esi), %eax
 201         adcl -100(%esi), %eax
 202         adcl -96(%esi), %eax
 203         adcl -92(%esi), %eax
 204         adcl -88(%esi), %eax
 205         adcl -84(%esi), %eax
 206         adcl -80(%esi), %eax
 207         adcl -76(%esi), %eax
 208         adcl -72(%esi), %eax
 209         adcl -68(%esi), %eax
 210         adcl -64(%esi), %eax
 211         adcl -60(%esi), %eax
 212         adcl -56(%esi), %eax
 213         adcl -52(%esi), %eax
 214         adcl -48(%esi), %eax
 215         adcl -44(%esi), %eax
 216         adcl -40(%esi), %eax
 217         adcl -36(%esi), %eax
 218         adcl -32(%esi), %eax
 219         adcl -28(%esi), %eax
 220         adcl -24(%esi), %eax
 221         adcl -20(%esi), %eax
 222         adcl -16(%esi), %eax
 223         adcl -12(%esi), %eax
 224         adcl -8(%esi), %eax
 225         adcl -4(%esi), %eax
 226 45:
 227         lea 128(%esi), %esi
 228         adcl $0, %eax
 229         dec %ecx
 230         jge 40b
 231         movl %edx, %ecx
 232 50:     andl $3, %ecx
 233         jz 80f
 234
 235         # Handle the last 1-3 bytes without jumping
 236         notl %ecx               # 1->2, 2->1, 3->0, higher bits are masked
 237         movl $0xffffff,%ebx     # by the shll and shrl instructions
 238         shll $3,%ecx
 239         shrl %cl,%ebx
 240         andl -128(%esi),%ebx    # esi is 4-aligned so should be ok
 241         addl %ebx,%eax
 242         adcl $0,%eax
 243 80:
 244         testb $1, 12(%esp)
 245         jz 90f
 246         roll $8, %eax
 247 90:
 248         popl %ebx
 249         popl %esi
 250         ret
 251 ENDPROC(csum_partial)
 252
 253 #endif
 254
 255 /*
 256 unsigned int csum_partial_copy_generic (const char *src, char *dst,
 257                                   int len, int sum, int *src_err_ptr, int *dst_err_ptr)
 258  */
 259
 260 /*
 261  * Copy from ds while checksumming, otherwise like csum_partial
 262  *
 263  * The macros SRC and DST specify the type of access for the instruction.
 264  * thus we can call a custom exception handler for all access types.
 265  *
 266  * FIXME: could someone double-check whether I haven't mixed up some SRC and
 267  *        DST definitions? It's damn hard to trigger all cases.  I hope I got
 268  *        them all but there's no guarantee.
 269  */
 270
 271 #define SRC(y...)                       \
 272         9999: y;                        \
 273         _ASM_EXTABLE(9999b, 6001f)
 274
 275 #define DST(y...)                       \
 276         9999: y;                        \
 277         _ASM_EXTABLE(9999b, 6002f)
 278
 279 #ifndef CONFIG_X86_USE_PPRO_CHECKSUM
 280
 281 #define ARGBASE 16
 282 #define FP              12
 283
 284 ENTRY(csum_partial_copy_generic)
 285         subl  $4,%esp
 286         pushl %edi
 287         pushl %esi
 288         pushl %ebx
 289         movl ARGBASE+16(%esp),%eax      # sum
 290         movl ARGBASE+12(%esp),%ecx      # len
 291         movl ARGBASE+4(%esp),%esi       # src
 292         movl ARGBASE+8(%esp),%edi       # dst
 293
 294         testl $2, %edi                  # Check alignment.
 295         jz 2f                           # Jump if alignment is ok.
 296         subl $2, %ecx                   # Alignment uses up two bytes.
 297         jae 1f                          # Jump if we had at least two bytes.
 298         addl $2, %ecx                   # ecx was < 2.  Deal with it.
 299         jmp 4f
 300 SRC(1:  movw (%esi), %bx        )
 301         addl $2, %esi
 302 DST(    movw %bx, (%edi)        )
 303         addl $2, %edi
 304         addw %bx, %ax
 305         adcl $0, %eax
 306 2:
 307         movl %ecx, FP(%esp)
 308         shrl $5, %ecx
 309         jz 2f
 310         testl %esi, %esi
 311 SRC(1:  movl (%esi), %ebx       )
 312 SRC(    movl 4(%esi), %edx      )
 313         adcl %ebx, %eax
 314 DST(    movl %ebx, (%edi)       )
 315         adcl %edx, %eax
 316 DST(    movl %edx, 4(%edi)      )
 317
 318 SRC(    movl 8(%esi), %ebx      )
 319 SRC(    movl 12(%esi), %edx     )
 320         adcl %ebx, %eax
 321 DST(    movl %ebx, 8(%edi)      )
 322         adcl %edx, %eax
 323 DST(    movl %edx, 12(%edi)     )
 324
 325 SRC(    movl 16(%esi), %ebx     )
 326 SRC(    movl 20(%esi), %edx     )
 327         adcl %ebx, %eax
 328 DST(    movl %ebx, 16(%edi)     )
 329         adcl %edx, %eax
 330 DST(    movl %edx, 20(%edi)     )
 331
 332 SRC(    movl 24(%esi), %ebx     )
 333 SRC(    movl 28(%esi), %edx     )
 334         adcl %ebx, %eax
 335 DST(    movl %ebx, 24(%edi)     )
 336         adcl %edx, %eax
 337 DST(    movl %edx, 28(%edi)     )
 338
 339         lea 32(%esi), %esi
 340         lea 32(%edi), %edi
 341         dec %ecx
 342         jne 1b
 343         adcl $0, %eax
 344 2:      movl FP(%esp), %edx
 345         movl %edx, %ecx
 346         andl $0x1c, %edx
 347         je 4f
 348         shrl $2, %edx                   # This clears CF
 349 SRC(3:  movl (%esi), %ebx       )
 350         adcl %ebx, %eax
 351 DST(    movl %ebx, (%edi)       )
 352         lea 4(%esi), %esi
 353         lea 4(%edi), %edi
 354         dec %edx
 355         jne 3b
 356         adcl $0, %eax
 357 4:      andl $3, %ecx
 358         jz 7f
 359         cmpl $2, %ecx
 360         jb 5f
 361 SRC(    movw (%esi), %cx        )
 362         leal 2(%esi), %esi
 363 DST(    movw %cx, (%edi)        )
 364         leal 2(%edi), %edi
 365         je 6f
 366         shll $16,%ecx
 367 SRC(5:  movb (%esi), %cl        )
 368 DST(    movb %cl, (%edi)        )
 369 6:      addl %ecx, %eax
 370         adcl $0, %eax
 371 7:
 372 5000:
 373
 374 # Exception handler:
 375 .section .fixup, "ax"
 376
 377 6001:
 378         movl ARGBASE+20(%esp), %ebx     # src_err_ptr
 379         movl $-EFAULT, (%ebx)
 380
 381         # zero the complete destination - computing the rest
 382         # is too much work
 383         movl ARGBASE+8(%esp), %edi      # dst
 384         movl ARGBASE+12(%esp), %ecx     # len
 385         xorl %eax,%eax
 386         rep ; stosb
 387
 388         jmp 5000b
 389
 390 6002:
 391         movl ARGBASE+24(%esp), %ebx     # dst_err_ptr
 392         movl $-EFAULT,(%ebx)
 393         jmp 5000b
 394
 395 .previous
 396
 397         popl %ebx
 398         popl %esi
 399         popl %edi
 400         popl %ecx                       # equivalent to addl $4,%esp
 401         ret
 402 ENDPROC(csum_partial_copy_generic)
 403
 404 #else
 405
 406 /* Version for PentiumII/PPro */
 407
 408 #define ROUND1(x) \
 409         SRC(movl x(%esi), %ebx  )       ;       \
 410         addl %ebx, %eax                 ;       \
 411         DST(movl %ebx, x(%edi)  )       ;
 412
 413 #define ROUND(x) \
 414         SRC(movl x(%esi), %ebx  )       ;       \
 415         adcl %ebx, %eax                 ;       \
 416         DST(movl %ebx, x(%edi)  )       ;
 417
 418 #define ARGBASE 12
 419
 420 ENTRY(csum_partial_copy_generic)
 421         pushl %ebx
 422         pushl %edi
 423         pushl %esi
 424         movl ARGBASE+4(%esp),%esi       #src
 425         movl ARGBASE+8(%esp),%edi       #dst
 426         movl ARGBASE+12(%esp),%ecx      #len
 427         movl ARGBASE+16(%esp),%eax      #sum
 428 #       movl %ecx, %edx
 429         movl %ecx, %ebx
 430         movl %esi, %edx
 431         shrl $6, %ecx
 432         andl $0x3c, %ebx
 433         negl %ebx
 434         subl %ebx, %esi
 435         subl %ebx, %edi
 436         lea  -1(%esi),%edx
 437         andl $-32,%edx
 438         lea 3f(%ebx,%ebx), %ebx
 439         testl %esi, %esi
 440         jmp *%ebx
 441 1:      addl $64,%esi
 442         addl $64,%edi
 443         SRC(movb -32(%edx),%bl) ; SRC(movb (%edx),%bl)
 444         ROUND1(-64) ROUND(-60) ROUND(-56) ROUND(-52)
 445         ROUND (-48) ROUND(-44) ROUND(-40) ROUND(-36)
 446         ROUND (-32) ROUND(-28) ROUND(-24) ROUND(-20)
 447         ROUND (-16) ROUND(-12) ROUND(-8)  ROUND(-4)
 448 3:      adcl $0,%eax
 449         addl $64, %edx
 450         dec %ecx
 451         jge 1b
 452 4:      movl ARGBASE+12(%esp),%edx      #len
 453         andl $3, %edx
 454         jz 7f
 455         cmpl $2, %edx
 456         jb 5f
 457 SRC(    movw (%esi), %dx         )
 458         leal 2(%esi), %esi
 459 DST(    movw %dx, (%edi)         )
 460         leal 2(%edi), %edi
 461         je 6f
 462         shll $16,%edx
 463 5:
 464 SRC(    movb (%esi), %dl         )
 465 DST(    movb %dl, (%edi)         )
 466 6:      addl %edx, %eax
 467         adcl $0, %eax
 468 7:
 469 .section .fixup, "ax"
 470 6001:   movl    ARGBASE+20(%esp), %ebx  # src_err_ptr
 471         movl $-EFAULT, (%ebx)
 472         # zero the complete destination (computing the rest is too much work)
 473         movl ARGBASE+8(%esp),%edi       # dst
 474         movl ARGBASE+12(%esp),%ecx      # len
 475         xorl %eax,%eax
 476         rep; stosb
 477         jmp 7b
 478 6002:   movl ARGBASE+24(%esp), %ebx     # dst_err_ptr
 479         movl $-EFAULT, (%ebx)
 480         jmp  7b
 481 .previous
 482
 483         popl %esi
 484         popl %edi
 485         popl %ebx
 486         ret
 487 ENDPROC(csum_partial_copy_generic)
 488
 489 #undef ROUND
 490 #undef ROUND1
 491
 492 #endif