output/outas86.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1996-2017 The NASM Authors - All Rights Reserved
   4  *   See the file AUTHORS included with the NASM distribution for
   5  *   the specific copyright holders.
   6  *
   7  *   Redistribution and use in source and binary forms, with or without
   8  *   modification, are permitted provided that the following
   9  *   conditions are met:
  10  *
  11  *   * Redistributions of source code must retain the above copyright
  12  *     notice, this list of conditions and the following disclaimer.
  13  *   * Redistributions in binary form must reproduce the above
  14  *     copyright notice, this list of conditions and the following
  15  *     disclaimer in the documentation and/or other materials provided
  16  *     with the distribution.
  17  *
  18  *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  19  *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  20  *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  21  *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  22  *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  23  *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  25  *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  26  *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  28  *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  29  *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  30  *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  *
  32  * ----------------------------------------------------------------------- */
  33
  34 /*
  35  * outas86.c    output routines for the Netwide Assembler to produce
  36  *              Linux as86 (bin86-0.3) object files
  37  */
  38
  39 #include "compiler.h"
  40
  41 #include "nctype.h"
  42
  43 #include "nasm.h"
  44 #include "nasmlib.h"
  45 #include "error.h"
  46 #include "saa.h"
  47 #include "raa.h"
  48 #include "outform.h"
  49 #include "outlib.h"
  50
  51 #ifdef OF_AS86
  52
  53 struct Piece {
  54     struct Piece *next;
  55     int type;                   /* 0 = absolute, 1 = seg, 2 = sym */
  56     int32_t offset;             /* relative offset */
  57     int number;                 /* symbol/segment number (4=bss) */
  58     int32_t bytes;              /* size of reloc or of absolute data */
  59     bool relative;              /* relative address? */
  60 };
  61
  62 struct Symbol {
  63     int32_t strpos;             /* string table position of name */
  64     int flags;                  /* symbol flags */
  65     int segment;                /* 4=bss at this point */
  66     int32_t value;              /* address, or COMMON variable size */
  67 };
  68
  69 /*
  70  * Section IDs - used in Piece.number and Symbol.segment.
  71  */
  72 #define SECT_TEXT 0             /* text section */
  73 #define SECT_DATA 3             /* data section */
  74 #define SECT_BSS 4              /* bss section */
  75
  76 /*
  77  * Flags used in Symbol.flags.
  78  */
  79 #define SYM_ENTRY (1<<8)
  80 #define SYM_EXPORT (1<<7)
  81 #define SYM_IMPORT (1<<6)
  82 #define SYM_ABSOLUTE (1<<4)
  83
  84 struct Section {
  85     struct SAA *data;
  86     uint32_t datalen, size, len;
  87     int32_t index;
  88     struct Piece *head, *last, **tail;
  89 };
  90
  91 static struct Section stext, sdata;
  92 static uint32_t bsslen;
  93 static int32_t bssindex;
  94
  95 static struct SAA *syms;
  96 static uint32_t nsyms;
  97
  98 static struct RAA *bsym;
  99
 100 static struct SAA *strs;
 101 static size_t strslen;
 102
 103 static int as86_reloc_size;
 104
 105 static void as86_write(void);
 106 static void as86_write_section(struct Section *, int);
 107 static size_t as86_add_string(const char *name);
 108 static void as86_sect_write(struct Section *, const uint8_t *,
 109                             uint32_t);
 110
 111 static void as86_init(void)
 112 {
 113     stext.data = saa_init(1L);
 114     stext.datalen = 0L;
 115     stext.head = stext.last = NULL;
 116     stext.tail = &stext.head;
 117     sdata.data = saa_init(1L);
 118     sdata.datalen = 0L;
 119     sdata.head = sdata.last = NULL;
 120     sdata.tail = &sdata.head;
 121     bsslen =
 122         stext.len = stext.datalen = stext.size =
 123         sdata.len = sdata.datalen = sdata.size = 0;
 124     stext.index = seg_alloc();
 125     sdata.index = seg_alloc();
 126     bssindex = seg_alloc();
 127     syms = saa_init((int32_t)sizeof(struct Symbol));
 128     nsyms = 0;
 129     bsym = raa_init();
 130     strs = saa_init(1L);
 131     strslen = 0;
 132
 133     /* as86 module name = input file minus extension */
 134     as86_add_string(filename_set_extension(inname, ""));
 135 }
 136
 137 static void as86_cleanup(void)
 138 {
 139     struct Piece *p;
 140
 141     as86_write();
 142     saa_free(stext.data);
 143     while (stext.head) {
 144         p = stext.head;
 145         stext.head = stext.head->next;
 146         nasm_free(p);
 147     }
 148     saa_free(sdata.data);
 149     while (sdata.head) {
 150         p = sdata.head;
 151         sdata.head = sdata.head->next;
 152         nasm_free(p);
 153     }
 154     saa_free(syms);
 155     raa_free(bsym);
 156     saa_free(strs);
 157 }
 158
 159 static int32_t as86_section_names(char *name, int *bits)
 160 {
 161     /*
 162      * Default is 16 bits.
 163      */
 164     if (!name) {
 165         *bits = 16;
 166         return stext.index;
 167     }
 168
 169     if (!strcmp(name, ".text"))
 170         return stext.index;
 171     else if (!strcmp(name, ".data"))
 172         return sdata.index;
 173     else if (!strcmp(name, ".bss"))
 174         return bssindex;
 175     else
 176         return NO_SEG;
 177 }
 178
 179 static size_t as86_add_string(const char *name)
 180 {
 181     size_t pos = strslen;
 182     size_t length = strlen(name);
 183
 184     saa_wbytes(strs, name, length + 1);
 185     strslen += 1 + length;
 186
 187     return pos;
 188 }
 189
 190 static void as86_deflabel(char *name, int32_t segment, int64_t offset,
 191                           int is_global, char *special)
 192 {
 193     bool is_start = false;
 194     struct Symbol *sym;
 195
 196     if (special)
 197         nasm_nonfatal("as86 format does not support any"
 198                       " special symbol types");
 199
 200
 201     if (name[0] == '.' && name[1] == '.' && name[2] != '@') {
 202         if (strcmp(name, "..start")) {
 203             nasm_nonfatal("unrecognised special symbol `%s'", name);
 204             return;
 205         } else {
 206             is_start = true;
 207         }
 208     }
 209
 210     sym = saa_wstruct(syms);
 211
 212     sym->strpos = as86_add_string(name);
 213     sym->flags = 0;
 214
 215     if (is_start)
 216       sym->flags = SYM_ENTRY;
 217
 218     if (segment == NO_SEG)
 219         sym->flags |= SYM_ABSOLUTE, sym->segment = 0;
 220     else if (segment == stext.index)
 221         sym->segment = SECT_TEXT;
 222     else if (segment == sdata.index)
 223         sym->segment = SECT_DATA;
 224     else if (segment == bssindex)
 225         sym->segment = SECT_BSS;
 226     else {
 227         sym->flags |= SYM_IMPORT;
 228         sym->segment = 15;
 229     }
 230
 231     if (is_global == 2)
 232         sym->segment = 3;       /* already have IMPORT */
 233
 234     if (is_global && !(sym->flags & SYM_IMPORT))
 235         sym->flags |= SYM_EXPORT;
 236
 237     sym->value = offset;
 238
 239     /*
 240      * define the references from external-symbol segment numbers
 241      * to these symbol records.
 242      */
 243     if (segment != NO_SEG && segment != stext.index &&
 244         segment != sdata.index && segment != bssindex)
 245         bsym = raa_write(bsym, segment, nsyms);
 246
 247     nsyms++;
 248 }
 249
 250 static void as86_add_piece(struct Section *sect, int type, int32_t offset,
 251                            int32_t segment, int32_t bytes, int relative)
 252 {
 253     struct Piece *p;
 254
 255     sect->len += bytes;
 256
 257     if (type == 0 && sect->last && sect->last->type == 0) {
 258         sect->last->bytes += bytes;
 259         return;
 260     }
 261
 262     p = sect->last = *sect->tail = nasm_malloc(sizeof(struct Piece));
 263     sect->tail = &p->next;
 264     p->next = NULL;
 265
 266     p->type = type;
 267     p->offset = offset;
 268     p->bytes = bytes;
 269     p->relative = relative;
 270
 271     if (type == 1 && segment == stext.index)
 272         p->number = SECT_TEXT;
 273     else if (type == 1 && segment == sdata.index)
 274         p->number = SECT_DATA;
 275     else if (type == 1 && segment == bssindex)
 276         p->number = SECT_BSS;
 277     else if (type == 1)
 278         p->number = raa_read(bsym, segment), p->type = 2;
 279 }
 280
 281 static void as86_out(int32_t segto, const void *data,
 282                      enum out_type type, uint64_t size,
 283                      int32_t segment, int32_t wrt)
 284 {
 285     struct Section *s;
 286     int32_t offset;
 287     uint8_t mydata[4], *p;
 288
 289     if (wrt != NO_SEG) {
 290         wrt = NO_SEG;           /* continue to do _something_ */
 291         nasm_nonfatal("WRT not supported by as86 output format");
 292     }
 293
 294     if (segto == stext.index)
 295         s = &stext;
 296     else if (segto == sdata.index)
 297         s = &sdata;
 298     else if (segto == bssindex)
 299         s = NULL;
 300     else {
 301         nasm_warn(WARN_OTHER, "attempt to assemble code in"
 302                   " segment %d: defaulting to `.text'", segto);
 303         s = &stext;
 304     }
 305
 306     if (!s && type != OUT_RESERVE) {
 307         nasm_warn(WARN_OTHER, "attempt to initialize memory in the"
 308                   " BSS section: ignored");
 309         bsslen += realsize(type, size);
 310         return;
 311     }
 312
 313     memset(mydata, 0, sizeof(mydata));
 314
 315     if (type == OUT_RESERVE) {
 316         if (s) {
 317             nasm_warn(WARN_ZEROING, "uninitialized space declared in"
 318                       " %s section: zeroing",
 319                       (segto == stext.index ? "code" : "data"));
 320             as86_sect_write(s, NULL, size);
 321             as86_add_piece(s, 0, 0L, 0L, size, 0);
 322         } else
 323             bsslen += size;
 324     } else if (type == OUT_RAWDATA) {
 325         as86_sect_write(s, data, size);
 326         as86_add_piece(s, 0, 0L, 0L, size, 0);
 327     } else if (type == OUT_ADDRESS) {
 328         int asize = abs((int)size);
 329         if (segment != NO_SEG) {
 330             if (segment % 2) {
 331                 nasm_nonfatal("as86 format does not support"
 332                               " segment base references");
 333             } else {
 334                 offset = *(int64_t *)data;
 335                 as86_add_piece(s, 1, offset, segment, asize, 0);
 336             }
 337         } else {
 338             p = mydata;
 339             WRITELONG(p, *(int64_t *)data);
 340             as86_sect_write(s, data, asize);
 341             as86_add_piece(s, 0, 0L, 0L, asize, 0);
 342         }
 343     } else if (type == OUT_REL2ADR) {
 344         if (segment != NO_SEG) {
 345             if (segment % 2) {
 346                 nasm_nonfatal("as86 format does not support"
 347                               " segment base references");
 348             } else {
 349                 offset = *(int64_t *)data;
 350                 as86_add_piece(s, 1, offset - size + 2, segment, 2L,
 351                                1);
 352             }
 353         }
 354     } else if (type == OUT_REL4ADR) {
 355         if (segment != NO_SEG) {
 356             if (segment % 2) {
 357                 nasm_nonfatal("as86 format does not support"
 358                               " segment base references");
 359             } else {
 360                 offset = *(int64_t *)data;
 361                 as86_add_piece(s, 1, offset - size + 4, segment, 4L,
 362                                1);
 363             }
 364         }
 365     }
 366 }
 367
 368 static void as86_write(void)
 369 {
 370     uint32_t i;
 371     int32_t symlen, seglen, segsize;
 372
 373     /*
 374      * First, go through the symbol records working out how big
 375      * each will be. Also fix up BSS references at this time, and
 376      * set the flags words up completely.
 377      */
 378     symlen = 0;
 379     saa_rewind(syms);
 380     for (i = 0; i < nsyms; i++) {
 381         struct Symbol *sym = saa_rstruct(syms);
 382         if (sym->segment == SECT_BSS)
 383             sym->segment = SECT_DATA, sym->value += sdata.len;
 384         sym->flags |= sym->segment;
 385         if (sym->value == 0)
 386             sym->flags |= 0 << 14, symlen += 4;
 387         else if (sym->value >= 0 && sym->value <= 255)
 388             sym->flags |= 1 << 14, symlen += 5;
 389         else if (sym->value >= 0 && sym->value <= 65535L)
 390             sym->flags |= 2 << 14, symlen += 6;
 391         else
 392             sym->flags |= 3 << 14, symlen += 8;
 393     }
 394
 395     /*
 396      * Now do the same for the segments, and get the segment size
 397      * descriptor word at the same time.
 398      */
 399     seglen = segsize = 0;
 400     if ((uint32_t)stext.len > 65535L)
 401         segsize |= 0x03000000L, seglen += 4;
 402     else
 403         segsize |= 0x02000000L, seglen += 2;
 404     if ((uint32_t)sdata.len > 65535L)
 405         segsize |= 0xC0000000L, seglen += 4;
 406     else
 407         segsize |= 0x80000000L, seglen += 2;
 408
 409     /*
 410      * Emit the as86 header.
 411      */
 412     fwriteint32_t(0x000186A3L, ofile);
 413     fputc(0x2A, ofile);
 414     fwriteint32_t(27 + symlen + seglen + strslen, ofile); /* header length */
 415     fwriteint32_t(stext.len + sdata.len + bsslen, ofile);
 416     fwriteint16_t(strslen, ofile);
 417     fwriteint16_t(0, ofile);     /* class = revision = 0 */
 418     fwriteint32_t(0x55555555L, ofile);    /* segment max sizes: always this */
 419     fwriteint32_t(segsize, ofile);        /* segment size descriptors */
 420     if (segsize & 0x01000000L)
 421         fwriteint32_t(stext.len, ofile);
 422     else
 423         fwriteint16_t(stext.len, ofile);
 424     if (segsize & 0x40000000L)
 425         fwriteint32_t(sdata.len + bsslen, ofile);
 426     else
 427         fwriteint16_t(sdata.len + bsslen, ofile);
 428     fwriteint16_t(nsyms, ofile);
 429
 430     /*
 431      * Write the symbol table.
 432      */
 433     saa_rewind(syms);
 434     for (i = 0; i < nsyms; i++) {
 435         struct Symbol *sym = saa_rstruct(syms);
 436         fwriteint16_t(sym->strpos, ofile);
 437         fwriteint16_t(sym->flags, ofile);
 438         switch (sym->flags & (3 << 14)) {
 439         case 0 << 14:
 440             break;
 441         case 1 << 14:
 442             fputc(sym->value, ofile);
 443             break;
 444         case 2 << 14:
 445             fwriteint16_t(sym->value, ofile);
 446             break;
 447         case 3 << 14:
 448             fwriteint32_t(sym->value, ofile);
 449             break;
 450         }
 451     }
 452
 453     /*
 454      * Write out the string table.
 455      */
 456     saa_fpwrite(strs, ofile);
 457
 458     /*
 459      * Write the program text.
 460      */
 461     as86_reloc_size = -1;
 462     as86_write_section(&stext, SECT_TEXT);
 463     as86_write_section(&sdata, SECT_DATA);
 464     /*
 465      * Append the BSS section to the .data section
 466      */
 467     if (bsslen > 65535L) {
 468         fputc(0x13, ofile);
 469         fwriteint32_t(bsslen, ofile);
 470     } else if (bsslen > 255) {
 471         fputc(0x12, ofile);
 472         fwriteint16_t(bsslen, ofile);
 473     } else if (bsslen) {
 474         fputc(0x11, ofile);
 475         fputc(bsslen, ofile);
 476     }
 477
 478     fputc(0, ofile);           /* termination */
 479 }
 480
 481 static void as86_set_rsize(int size)
 482 {
 483     if (as86_reloc_size != size) {
 484         switch (as86_reloc_size = size) {
 485         case 1:
 486             fputc(0x01, ofile);
 487             break;
 488         case 2:
 489             fputc(0x02, ofile);
 490             break;
 491         case 4:
 492             fputc(0x03, ofile);
 493             break;
 494         default:
 495             nasm_panic("bizarre relocation size %d", size);
 496             break;
 497         }
 498     }
 499 }
 500
 501 static void as86_write_section(struct Section *sect, int index)
 502 {
 503     struct Piece *p;
 504     uint32_t s;
 505     int32_t length;
 506
 507     fputc(0x20 + index, ofile);        /* select the right section */
 508
 509     saa_rewind(sect->data);
 510
 511     for (p = sect->head; p; p = p->next)
 512         switch (p->type) {
 513         case 0:
 514             /*
 515              * Absolute data. Emit it in chunks of at most 64
 516              * bytes.
 517              */
 518             length = p->bytes;
 519             do {
 520                 char buf[64];
 521                 int32_t tmplen = (length > 64 ? 64 : length);
 522                 fputc(0x40 | (tmplen & 0x3F), ofile);
 523                 saa_rnbytes(sect->data, buf, tmplen);
 524                 nasm_write(buf, tmplen, ofile);
 525                 length -= tmplen;
 526             } while (length > 0);
 527             break;
 528         case 1:
 529             /*
 530              * A segment-type relocation. First fix up the BSS.
 531              */
 532             if (p->number == SECT_BSS)
 533                 p->number = SECT_DATA, p->offset += sdata.len;
 534             as86_set_rsize(p->bytes);
 535             fputc(0x80 | (p->relative ? 0x20 : 0) | p->number, ofile);
 536             if (as86_reloc_size == 2)
 537                 fwriteint16_t(p->offset, ofile);
 538             else
 539                 fwriteint32_t(p->offset, ofile);
 540             break;
 541         case 2:
 542             /*
 543              * A symbol-type relocation.
 544              */
 545             as86_set_rsize(p->bytes);
 546             s = p->offset;
 547             if (s > 65535L)
 548                 s = 3;
 549             else if (s > 255)
 550                 s = 2;
 551             else if (s > 0)
 552                 s = 1;
 553             else
 554                 s = 0;
 555             fputc(0xC0 |
 556                   (p->relative ? 0x20 : 0) |
 557                   (p->number > 255 ? 0x04 : 0) | s, ofile);
 558             if (p->number > 255)
 559                 fwriteint16_t(p->number, ofile);
 560             else
 561                 fputc(p->number, ofile);
 562             switch (s) {
 563             case 0:
 564                 break;
 565             case 1:
 566                 fputc(p->offset, ofile);
 567                 break;
 568             case 2:
 569                 fwriteint16_t(p->offset, ofile);
 570                 break;
 571             case 3:
 572                 fwriteint32_t(p->offset, ofile);
 573                 break;
 574             }
 575             break;
 576         }
 577 }
 578
 579 static void as86_sect_write(struct Section *sect,
 580                             const uint8_t *data, uint32_t len)
 581 {
 582     saa_wbytes(sect->data, data, len);
 583     sect->datalen += len;
 584 }
 585
 586 extern macros_t as86_stdmac[];
 587
 588 const struct ofmt of_as86 = {
 589     "Linux as86 (bin86 version 0.3) object files",
 590     "as86",
 591     ".o",
 592     0,
 593     32,
 594     null_debug_arr,
 595     &null_debug_form,
 596     as86_stdmac,
 597     as86_init,
 598     null_reset,
 599     nasm_do_legacy_output,
 600     as86_out,
 601     as86_deflabel,
 602     as86_section_names,
 603     NULL,
 604     null_sectalign,
 605     null_segbase,
 606     null_directive,
 607     as86_cleanup,
 608     NULL                        /* pragma list */
 609 };
 610
 611 #endif                          /* OF_AS86 */