semihosting/syscalls.c

   1 /*
   2  * Syscall implementations for semihosting.
   3  *
   4  * Copyright (c) 2022 Linaro
   5  *
   6  * SPDX-License-Identifier: GPL-2.0-or-later
   7  */
   8
   9 #include "qemu/osdep.h"
  10 #include "cpu.h"
  11 #include "gdbstub/syscalls.h"
  12 #include "semihosting/guestfd.h"
  13 #include "semihosting/syscalls.h"
  14 #include "semihosting/console.h"
  15 #ifdef CONFIG_USER_ONLY
  16 #include "qemu.h"
  17 #else
  18 #include "semihosting/softmmu-uaccess.h"
  19 #endif
  20
  21
  22 /*
  23  * Validate or compute the length of the string (including terminator).
  24  */
  25 static int validate_strlen(CPUState *cs, target_ulong str, target_ulong tlen)
  26 {
  27     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
  28     char c;
  29
  30     if (tlen == 0) {
  31         ssize_t slen = target_strlen(str);
  32
  33         if (slen < 0) {
  34             return -EFAULT;
  35         }
  36         if (slen >= INT32_MAX) {
  37             return -ENAMETOOLONG;
  38         }
  39         return slen + 1;
  40     }
  41     if (tlen > INT32_MAX) {
  42         return -ENAMETOOLONG;
  43     }
  44     if (get_user_u8(c, str + tlen - 1)) {
  45         return -EFAULT;
  46     }
  47     if (c != 0) {
  48         return -EINVAL;
  49     }
  50     return tlen;
  51 }
  52
  53 static int validate_lock_user_string(char **pstr, CPUState *cs,
  54                                      target_ulong tstr, target_ulong tlen)
  55 {
  56     int ret = validate_strlen(cs, tstr, tlen);
  57     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
  58     char *str = NULL;
  59
  60     if (ret > 0) {
  61         str = lock_user(VERIFY_READ, tstr, ret, true);
  62         ret = str ? 0 : -EFAULT;
  63     }
  64     *pstr = str;
  65     return ret;
  66 }
  67
  68 /*
  69  * TODO: Note that gdb always stores the stat structure big-endian.
  70  * So far, that's ok, as the only two targets using this are also
  71  * big-endian.  Until we do something with gdb, also produce the
  72  * same big-endian result from the host.
  73  */
  74 static int copy_stat_to_user(CPUState *cs, target_ulong addr,
  75                              const struct stat *s)
  76 {
  77     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
  78     struct gdb_stat *p;
  79
  80     if (s->st_dev != (uint32_t)s->st_dev ||
  81         s->st_ino != (uint32_t)s->st_ino) {
  82         return -EOVERFLOW;
  83     }
  84
  85     p = lock_user(VERIFY_WRITE, addr, sizeof(struct gdb_stat), 0);
  86     if (!p) {
  87         return -EFAULT;
  88     }
  89
  90     p->gdb_st_dev = cpu_to_be32(s->st_dev);
  91     p->gdb_st_ino = cpu_to_be32(s->st_ino);
  92     p->gdb_st_mode = cpu_to_be32(s->st_mode);
  93     p->gdb_st_nlink = cpu_to_be32(s->st_nlink);
  94     p->gdb_st_uid = cpu_to_be32(s->st_uid);
  95     p->gdb_st_gid = cpu_to_be32(s->st_gid);
  96     p->gdb_st_rdev = cpu_to_be32(s->st_rdev);
  97     p->gdb_st_size = cpu_to_be64(s->st_size);
  98 #ifdef _WIN32
  99     /* Windows stat is missing some fields.  */
 100     p->gdb_st_blksize = 0;
 101     p->gdb_st_blocks = 0;
 102 #else
 103     p->gdb_st_blksize = cpu_to_be64(s->st_blksize);
 104     p->gdb_st_blocks = cpu_to_be64(s->st_blocks);
 105 #endif
 106     p->gdb_st_atime = cpu_to_be32(s->st_atime);
 107     p->gdb_st_mtime = cpu_to_be32(s->st_mtime);
 108     p->gdb_st_ctime = cpu_to_be32(s->st_ctime);
 109
 110     unlock_user(p, addr, sizeof(struct gdb_stat));
 111     return 0;
 112 }
 113
 114 /*
 115  * GDB semihosting syscall implementations.
 116  */
 117
 118 static gdb_syscall_complete_cb gdb_open_complete;
 119
 120 static void gdb_open_cb(CPUState *cs, uint64_t ret, int err)
 121 {
 122     if (!err) {
 123         int guestfd = alloc_guestfd();
 124         associate_guestfd(guestfd, ret);
 125         ret = guestfd;
 126     }
 127     gdb_open_complete(cs, ret, err);
 128 }
 129
 130 static void gdb_open(CPUState *cs, gdb_syscall_complete_cb complete,
 131                      target_ulong fname, target_ulong fname_len,
 132                      int gdb_flags, int mode)
 133 {
 134     int len = validate_strlen(cs, fname, fname_len);
 135     if (len < 0) {
 136         complete(cs, -1, -len);
 137         return;
 138     }
 139
 140     gdb_open_complete = complete;
 141     gdb_do_syscall(gdb_open_cb, "open,%s,%x,%x",
 142                    (uint64_t)fname, (uint32_t)len,
 143                    (uint32_t)gdb_flags, (uint32_t)mode);
 144 }
 145
 146 static void gdb_close(CPUState *cs, gdb_syscall_complete_cb complete,
 147                       GuestFD *gf)
 148 {
 149     gdb_do_syscall(complete, "close,%x", (uint32_t)gf->hostfd);
 150 }
 151
 152 static void gdb_read(CPUState *cs, gdb_syscall_complete_cb complete,
 153                      GuestFD *gf, target_ulong buf, target_ulong len)
 154 {
 155     gdb_do_syscall(complete, "read,%x,%lx,%lx",
 156                    (uint32_t)gf->hostfd, (uint64_t)buf, (uint64_t)len);
 157 }
 158
 159 static void gdb_write(CPUState *cs, gdb_syscall_complete_cb complete,
 160                       GuestFD *gf, target_ulong buf, target_ulong len)
 161 {
 162     gdb_do_syscall(complete, "write,%x,%lx,%lx",
 163                    (uint32_t)gf->hostfd, (uint64_t)buf, (uint64_t)len);
 164 }
 165
 166 static void gdb_lseek(CPUState *cs, gdb_syscall_complete_cb complete,
 167                       GuestFD *gf, int64_t off, int gdb_whence)
 168 {
 169     gdb_do_syscall(complete, "lseek,%x,%lx,%x",
 170                    (uint32_t)gf->hostfd, off, (uint32_t)gdb_whence);
 171 }
 172
 173 static void gdb_isatty(CPUState *cs, gdb_syscall_complete_cb complete,
 174                        GuestFD *gf)
 175 {
 176     gdb_do_syscall(complete, "isatty,%x", (uint32_t)gf->hostfd);
 177 }
 178
 179 static void gdb_fstat(CPUState *cs, gdb_syscall_complete_cb complete,
 180                       GuestFD *gf, target_ulong addr)
 181 {
 182     gdb_do_syscall(complete, "fstat,%x,%lx",
 183                    (uint32_t)gf->hostfd, (uint64_t)addr);
 184 }
 185
 186 static void gdb_stat(CPUState *cs, gdb_syscall_complete_cb complete,
 187                      target_ulong fname, target_ulong fname_len,
 188                      target_ulong addr)
 189 {
 190     int len = validate_strlen(cs, fname, fname_len);
 191     if (len < 0) {
 192         complete(cs, -1, -len);
 193         return;
 194     }
 195
 196     gdb_do_syscall(complete, "stat,%s,%lx",
 197                    (uint64_t)fname, (uint32_t)len, (uint64_t)addr);
 198 }
 199
 200 static void gdb_remove(CPUState *cs, gdb_syscall_complete_cb complete,
 201                        target_ulong fname, target_ulong fname_len)
 202 {
 203     int len = validate_strlen(cs, fname, fname_len);
 204     if (len < 0) {
 205         complete(cs, -1, -len);
 206         return;
 207     }
 208
 209     gdb_do_syscall(complete, "unlink,%s", (uint64_t)fname, (uint32_t)len);
 210 }
 211
 212 static void gdb_rename(CPUState *cs, gdb_syscall_complete_cb complete,
 213                        target_ulong oname, target_ulong oname_len,
 214                        target_ulong nname, target_ulong nname_len)
 215 {
 216     int olen, nlen;
 217
 218     olen = validate_strlen(cs, oname, oname_len);
 219     if (olen < 0) {
 220         complete(cs, -1, -olen);
 221         return;
 222     }
 223     nlen = validate_strlen(cs, nname, nname_len);
 224     if (nlen < 0) {
 225         complete(cs, -1, -nlen);
 226         return;
 227     }
 228
 229     gdb_do_syscall(complete, "rename,%s,%s",
 230                    (uint64_t)oname, (uint32_t)olen,
 231                    (uint64_t)nname, (uint32_t)nlen);
 232 }
 233
 234 static void gdb_system(CPUState *cs, gdb_syscall_complete_cb complete,
 235                        target_ulong cmd, target_ulong cmd_len)
 236 {
 237     int len = validate_strlen(cs, cmd, cmd_len);
 238     if (len < 0) {
 239         complete(cs, -1, -len);
 240         return;
 241     }
 242
 243     gdb_do_syscall(complete, "system,%s", (uint64_t)cmd, (uint32_t)len);
 244 }
 245
 246 static void gdb_gettimeofday(CPUState *cs, gdb_syscall_complete_cb complete,
 247                              target_ulong tv_addr, target_ulong tz_addr)
 248 {
 249     gdb_do_syscall(complete, "gettimeofday,%lx,%lx",
 250                    (uint64_t)tv_addr, (uint64_t)tz_addr);
 251 }
 252
 253 /*
 254  * Host semihosting syscall implementations.
 255  */
 256
 257 static void host_open(CPUState *cs, gdb_syscall_complete_cb complete,
 258                       target_ulong fname, target_ulong fname_len,
 259                       int gdb_flags, int mode)
 260 {
 261     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
 262     char *p;
 263     int ret, host_flags = O_BINARY;
 264
 265     ret = validate_lock_user_string(&p, cs, fname, fname_len);
 266     if (ret < 0) {
 267         complete(cs, -1, -ret);
 268         return;
 269     }
 270
 271     if (gdb_flags & GDB_O_WRONLY) {
 272         host_flags |= O_WRONLY;
 273     } else if (gdb_flags & GDB_O_RDWR) {
 274         host_flags |= O_RDWR;
 275     } else {
 276         host_flags |= O_RDONLY;
 277     }
 278     if (gdb_flags & GDB_O_CREAT) {
 279         host_flags |= O_CREAT;
 280     }
 281     if (gdb_flags & GDB_O_TRUNC) {
 282         host_flags |= O_TRUNC;
 283     }
 284     if (gdb_flags & GDB_O_EXCL) {
 285         host_flags |= O_EXCL;
 286     }
 287
 288     ret = open(p, host_flags, mode);
 289     if (ret < 0) {
 290         complete(cs, -1, errno);
 291     } else {
 292         int guestfd = alloc_guestfd();
 293         associate_guestfd(guestfd, ret);
 294         complete(cs, guestfd, 0);
 295     }
 296     unlock_user(p, fname, 0);
 297 }
 298
 299 static void host_close(CPUState *cs, gdb_syscall_complete_cb complete,
 300                        GuestFD *gf)
 301 {
 302     /*
 303      * Only close the underlying host fd if it's one we opened on behalf
 304      * of the guest in SYS_OPEN.
 305      */
 306     if (gf->hostfd != STDIN_FILENO &&
 307         gf->hostfd != STDOUT_FILENO &&
 308         gf->hostfd != STDERR_FILENO &&
 309         close(gf->hostfd) < 0) {
 310         complete(cs, -1, errno);
 311     } else {
 312         complete(cs, 0, 0);
 313     }
 314 }
 315
 316 static void host_read(CPUState *cs, gdb_syscall_complete_cb complete,
 317                       GuestFD *gf, target_ulong buf, target_ulong len)
 318 {
 319     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
 320     void *ptr = lock_user(VERIFY_WRITE, buf, len, 0);
 321     ssize_t ret;
 322
 323     if (!ptr) {
 324         complete(cs, -1, EFAULT);
 325         return;
 326     }
 327     ret = RETRY_ON_EINTR(read(gf->hostfd, ptr, len));
 328     if (ret == -1) {
 329         unlock_user(ptr, buf, 0);
 330         complete(cs, -1, errno);
 331     } else {
 332         unlock_user(ptr, buf, ret);
 333         complete(cs, ret, 0);
 334     }
 335 }
 336
 337 static void host_write(CPUState *cs, gdb_syscall_complete_cb complete,
 338                        GuestFD *gf, target_ulong buf, target_ulong len)
 339 {
 340     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
 341     void *ptr = lock_user(VERIFY_READ, buf, len, 1);
 342     ssize_t ret;
 343
 344     if (!ptr) {
 345         complete(cs, -1, EFAULT);
 346         return;
 347     }
 348     ret = write(gf->hostfd, ptr, len);
 349     unlock_user(ptr, buf, 0);
 350     complete(cs, ret, ret == -1 ? errno : 0);
 351 }
 352
 353 static void host_lseek(CPUState *cs, gdb_syscall_complete_cb complete,
 354                        GuestFD *gf, int64_t off, int whence)
 355 {
 356     /* So far, all hosts use the same values. */
 357     QEMU_BUILD_BUG_ON(GDB_SEEK_SET != SEEK_SET);
 358     QEMU_BUILD_BUG_ON(GDB_SEEK_CUR != SEEK_CUR);
 359     QEMU_BUILD_BUG_ON(GDB_SEEK_END != SEEK_END);
 360
 361     off_t ret = off;
 362     int err = 0;
 363
 364     if (ret == off) {
 365         ret = lseek(gf->hostfd, ret, whence);
 366         if (ret == -1) {
 367             err = errno;
 368         }
 369     } else {
 370         ret = -1;
 371         err = EINVAL;
 372     }
 373     complete(cs, ret, err);
 374 }
 375
 376 static void host_isatty(CPUState *cs, gdb_syscall_complete_cb complete,
 377                         GuestFD *gf)
 378 {
 379     int ret = isatty(gf->hostfd);
 380     complete(cs, ret, ret ? 0 : errno);
 381 }
 382
 383 static void host_flen(CPUState *cs, gdb_syscall_complete_cb complete,
 384                       GuestFD *gf)
 385 {
 386     struct stat buf;
 387
 388     if (fstat(gf->hostfd, &buf) < 0) {
 389         complete(cs, -1, errno);
 390     } else {
 391         complete(cs, buf.st_size, 0);
 392     }
 393 }
 394
 395 static void host_fstat(CPUState *cs, gdb_syscall_complete_cb complete,
 396                        GuestFD *gf, target_ulong addr)
 397 {
 398     struct stat buf;
 399     int ret;
 400
 401     ret = fstat(gf->hostfd, &buf);
 402     if (ret) {
 403         complete(cs, -1, errno);
 404         return;
 405     }
 406     ret = copy_stat_to_user(cs, addr, &buf);
 407     complete(cs, ret ? -1 : 0, ret ? -ret : 0);
 408 }
 409
 410 static void host_stat(CPUState *cs, gdb_syscall_complete_cb complete,
 411                       target_ulong fname, target_ulong fname_len,
 412                       target_ulong addr)
 413 {
 414     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
 415     struct stat buf;
 416     char *name;
 417     int ret, err;
 418
 419     ret = validate_lock_user_string(&name, cs, fname, fname_len);
 420     if (ret < 0) {
 421         complete(cs, -1, -ret);
 422         return;
 423     }
 424
 425     ret = stat(name, &buf);
 426     if (ret) {
 427         err = errno;
 428     } else {
 429         ret = copy_stat_to_user(cs, addr, &buf);
 430         err = 0;
 431         if (ret < 0) {
 432             err = -ret;
 433             ret = -1;
 434         }
 435     }
 436     unlock_user(name, fname, 0);
 437     complete(cs, ret, err);
 438 }
 439
 440 static void host_remove(CPUState *cs, gdb_syscall_complete_cb complete,
 441                         target_ulong fname, target_ulong fname_len)
 442 {
 443     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
 444     char *p;
 445     int ret;
 446
 447     ret = validate_lock_user_string(&p, cs, fname, fname_len);
 448     if (ret < 0) {
 449         complete(cs, -1, -ret);
 450         return;
 451     }
 452
 453     ret = remove(p);
 454     unlock_user(p, fname, 0);
 455     complete(cs, ret, ret ? errno : 0);
 456 }
 457
 458 static void host_rename(CPUState *cs, gdb_syscall_complete_cb complete,
 459                         target_ulong oname, target_ulong oname_len,
 460                         target_ulong nname, target_ulong nname_len)
 461 {
 462     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
 463     char *ostr, *nstr;
 464     int ret;
 465
 466     ret = validate_lock_user_string(&ostr, cs, oname, oname_len);
 467     if (ret < 0) {
 468         complete(cs, -1, -ret);
 469         return;
 470     }
 471     ret = validate_lock_user_string(&nstr, cs, nname, nname_len);
 472     if (ret < 0) {
 473         unlock_user(ostr, oname, 0);
 474         complete(cs, -1, -ret);
 475         return;
 476     }
 477
 478     ret = rename(ostr, nstr);
 479     unlock_user(ostr, oname, 0);
 480     unlock_user(nstr, nname, 0);
 481     complete(cs, ret, ret ? errno : 0);
 482 }
 483
 484 static void host_system(CPUState *cs, gdb_syscall_complete_cb complete,
 485                         target_ulong cmd, target_ulong cmd_len)
 486 {
 487     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
 488     char *p;
 489     int ret;
 490
 491     ret = validate_lock_user_string(&p, cs, cmd, cmd_len);
 492     if (ret < 0) {
 493         complete(cs, -1, -ret);
 494         return;
 495     }
 496
 497     ret = system(p);
 498     unlock_user(p, cmd, 0);
 499     complete(cs, ret, ret == -1 ? errno : 0);
 500 }
 501
 502 static void host_gettimeofday(CPUState *cs, gdb_syscall_complete_cb complete,
 503                               target_ulong tv_addr, target_ulong tz_addr)
 504 {
 505     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
 506     struct gdb_timeval *p;
 507     int64_t rt;
 508
 509     /* GDB fails on non-null TZ, so be consistent. */
 510     if (tz_addr != 0) {
 511         complete(cs, -1, EINVAL);
 512         return;
 513     }
 514
 515     p = lock_user(VERIFY_WRITE, tv_addr, sizeof(struct gdb_timeval), 0);
 516     if (!p) {
 517         complete(cs, -1, EFAULT);
 518         return;
 519     }
 520
 521     /* TODO: Like stat, gdb always produces big-endian results; match it. */
 522     rt = g_get_real_time();
 523     p->tv_sec = cpu_to_be32(rt / G_USEC_PER_SEC);
 524     p->tv_usec = cpu_to_be64(rt % G_USEC_PER_SEC);
 525     unlock_user(p, tv_addr, sizeof(struct gdb_timeval));
 526 }
 527
 528 #ifndef CONFIG_USER_ONLY
 529 static void host_poll_one(CPUState *cs, gdb_syscall_complete_cb complete,
 530                           GuestFD *gf, GIOCondition cond, int timeout)
 531 {
 532     /*
 533      * Since this is only used by xtensa in system mode, and stdio is
 534      * handled through GuestFDConsole, and there are no semihosting
 535      * system calls for sockets and the like, that means this descriptor
 536      * must be a normal file.  Normal files never block and are thus
 537      * always ready.
 538      */
 539     complete(cs, cond & (G_IO_IN | G_IO_OUT), 0);
 540 }
 541 #endif
 542
 543 /*
 544  * Static file semihosting syscall implementations.
 545  */
 546
 547 static void staticfile_read(CPUState *cs, gdb_syscall_complete_cb complete,
 548                             GuestFD *gf, target_ulong buf, target_ulong len)
 549 {
 550     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
 551     target_ulong rest = gf->staticfile.len - gf->staticfile.off;
 552     void *ptr;
 553
 554     if (len > rest) {
 555         len = rest;
 556     }
 557     ptr = lock_user(VERIFY_WRITE, buf, len, 0);
 558     if (!ptr) {
 559         complete(cs, -1, EFAULT);
 560         return;
 561     }
 562     memcpy(ptr, gf->staticfile.data + gf->staticfile.off, len);
 563     gf->staticfile.off += len;
 564     unlock_user(ptr, buf, len);
 565     complete(cs, len, 0);
 566 }
 567
 568 static void staticfile_lseek(CPUState *cs, gdb_syscall_complete_cb complete,
 569                              GuestFD *gf, int64_t off, int gdb_whence)
 570 {
 571     int64_t ret;
 572
 573     switch (gdb_whence) {
 574     case GDB_SEEK_SET:
 575         ret = off;
 576         break;
 577     case GDB_SEEK_CUR:
 578         ret = gf->staticfile.off + off;
 579         break;
 580     case GDB_SEEK_END:
 581         ret = gf->staticfile.len + off;
 582         break;
 583     default:
 584         ret = -1;
 585         break;
 586     }
 587     if (ret >= 0 && ret <= gf->staticfile.len) {
 588         gf->staticfile.off = ret;
 589         complete(cs, ret, 0);
 590     } else {
 591         complete(cs, -1, EINVAL);
 592     }
 593 }
 594
 595 static void staticfile_flen(CPUState *cs, gdb_syscall_complete_cb complete,
 596                             GuestFD *gf)
 597 {
 598     complete(cs, gf->staticfile.len, 0);
 599 }
 600
 601 /*
 602  * Console semihosting syscall implementations.
 603  */
 604
 605 static void console_read(CPUState *cs, gdb_syscall_complete_cb complete,
 606                          GuestFD *gf, target_ulong buf, target_ulong len)
 607 {
 608     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
 609     char *ptr;
 610     int ret;
 611
 612     ptr = lock_user(VERIFY_WRITE, buf, len, 0);
 613     if (!ptr) {
 614         complete(cs, -1, EFAULT);
 615         return;
 616     }
 617     ret = qemu_semihosting_console_read(cs, ptr, len);
 618     unlock_user(ptr, buf, ret);
 619     complete(cs, ret, 0);
 620 }
 621
 622 static void console_write(CPUState *cs, gdb_syscall_complete_cb complete,
 623                           GuestFD *gf, target_ulong buf, target_ulong len)
 624 {
 625     CPUArchState *env G_GNUC_UNUSED = cs->env_ptr;
 626     char *ptr = lock_user(VERIFY_READ, buf, len, 1);
 627     int ret;
 628
 629     if (!ptr) {
 630         complete(cs, -1, EFAULT);
 631         return;
 632     }
 633     ret = qemu_semihosting_console_write(ptr, len);
 634     unlock_user(ptr, buf, 0);
 635     complete(cs, ret ? ret : -1, ret ? 0 : EIO);
 636 }
 637
 638 static void console_fstat(CPUState *cs, gdb_syscall_complete_cb complete,
 639                           GuestFD *gf, target_ulong addr)
 640 {
 641     static const struct stat tty_buf = {
 642         .st_mode = 020666,  /* S_IFCHR, ugo+rw */
 643         .st_rdev = 5,       /* makedev(5, 0) -- linux /dev/tty */
 644     };
 645     int ret;
 646
 647     ret = copy_stat_to_user(cs, addr, &tty_buf);
 648     complete(cs, ret ? -1 : 0, ret ? -ret : 0);
 649 }
 650
 651 #ifndef CONFIG_USER_ONLY
 652 static void console_poll_one(CPUState *cs, gdb_syscall_complete_cb complete,
 653                              GuestFD *gf, GIOCondition cond, int timeout)
 654 {
 655     /* The semihosting console does not support urgent data or errors. */
 656     cond &= G_IO_IN | G_IO_OUT;
 657
 658     /*
 659      * Since qemu_semihosting_console_write never blocks, we can
 660      * consider output always ready -- leave G_IO_OUT alone.
 661      * All that remains is to conditionally signal input ready.
 662      * Since output ready causes an immediate return, only block
 663      * for G_IO_IN alone.
 664      *
 665      * TODO: Implement proper timeout.  For now, only support
 666      * indefinite wait or immediate poll.
 667      */
 668     if (cond == G_IO_IN && timeout < 0) {
 669         qemu_semihosting_console_block_until_ready(cs);
 670         /* We returned -- input must be ready. */
 671     } else if ((cond & G_IO_IN) && !qemu_semihosting_console_ready()) {
 672         cond &= ~G_IO_IN;
 673     }
 674
 675     complete(cs, cond, 0);
 676 }
 677 #endif
 678
 679 /*
 680  * Syscall entry points.
 681  */
 682
 683 void semihost_sys_open(CPUState *cs, gdb_syscall_complete_cb complete,
 684                        target_ulong fname, target_ulong fname_len,
 685                        int gdb_flags, int mode)
 686 {
 687     if (use_gdb_syscalls()) {
 688         gdb_open(cs, complete, fname, fname_len, gdb_flags, mode);
 689     } else {
 690         host_open(cs, complete, fname, fname_len, gdb_flags, mode);
 691     }
 692 }
 693
 694 void semihost_sys_close(CPUState *cs, gdb_syscall_complete_cb complete, int fd)
 695 {
 696     GuestFD *gf = get_guestfd(fd);
 697
 698     if (!gf) {
 699         complete(cs, -1, EBADF);
 700         return;
 701     }
 702     switch (gf->type) {
 703     case GuestFDGDB:
 704         gdb_close(cs, complete, gf);
 705         break;
 706     case GuestFDHost:
 707         host_close(cs, complete, gf);
 708         break;
 709     case GuestFDStatic:
 710     case GuestFDConsole:
 711         complete(cs, 0, 0);
 712         break;
 713     default:
 714         g_assert_not_reached();
 715     }
 716     dealloc_guestfd(fd);
 717 }
 718
 719 void semihost_sys_read_gf(CPUState *cs, gdb_syscall_complete_cb complete,
 720                           GuestFD *gf, target_ulong buf, target_ulong len)
 721 {
 722     /*
 723      * Bound length for 64-bit guests on 32-bit hosts, not overflowing ssize_t.
 724      * Note the Linux kernel does this with MAX_RW_COUNT, so it's not a bad
 725      * idea to do this unconditionally.
 726      */
 727     if (len > INT32_MAX) {
 728         len = INT32_MAX;
 729     }
 730     switch (gf->type) {
 731     case GuestFDGDB:
 732         gdb_read(cs, complete, gf, buf, len);
 733         break;
 734     case GuestFDHost:
 735         host_read(cs, complete, gf, buf, len);
 736         break;
 737     case GuestFDStatic:
 738         staticfile_read(cs, complete, gf, buf, len);
 739         break;
 740     case GuestFDConsole:
 741         console_read(cs, complete, gf, buf, len);
 742         break;
 743     default:
 744         g_assert_not_reached();
 745     }
 746 }
 747
 748 void semihost_sys_read(CPUState *cs, gdb_syscall_complete_cb complete,
 749                        int fd, target_ulong buf, target_ulong len)
 750 {
 751     GuestFD *gf = get_guestfd(fd);
 752
 753     if (gf) {
 754         semihost_sys_read_gf(cs, complete, gf, buf, len);
 755     } else {
 756         complete(cs, -1, EBADF);
 757     }
 758 }
 759
 760 void semihost_sys_write_gf(CPUState *cs, gdb_syscall_complete_cb complete,
 761                            GuestFD *gf, target_ulong buf, target_ulong len)
 762 {
 763     /*
 764      * Bound length for 64-bit guests on 32-bit hosts, not overflowing ssize_t.
 765      * Note the Linux kernel does this with MAX_RW_COUNT, so it's not a bad
 766      * idea to do this unconditionally.
 767      */
 768     if (len > INT32_MAX) {
 769         len = INT32_MAX;
 770     }
 771     switch (gf->type) {
 772     case GuestFDGDB:
 773         gdb_write(cs, complete, gf, buf, len);
 774         break;
 775     case GuestFDHost:
 776         host_write(cs, complete, gf, buf, len);
 777         break;
 778     case GuestFDConsole:
 779         console_write(cs, complete, gf, buf, len);
 780         break;
 781     case GuestFDStatic:
 782         /* Static files are never open for writing: EBADF. */
 783         complete(cs, -1, EBADF);
 784         break;
 785     default:
 786         g_assert_not_reached();
 787     }
 788 }
 789
 790 void semihost_sys_write(CPUState *cs, gdb_syscall_complete_cb complete,
 791                         int fd, target_ulong buf, target_ulong len)
 792 {
 793     GuestFD *gf = get_guestfd(fd);
 794
 795     if (gf) {
 796         semihost_sys_write_gf(cs, complete, gf, buf, len);
 797     } else {
 798         complete(cs, -1, EBADF);
 799     }
 800 }
 801
 802 void semihost_sys_lseek(CPUState *cs, gdb_syscall_complete_cb complete,
 803                         int fd, int64_t off, int gdb_whence)
 804 {
 805     GuestFD *gf = get_guestfd(fd);
 806
 807     if (!gf) {
 808         complete(cs, -1, EBADF);
 809         return;
 810     }
 811     switch (gf->type) {
 812     case GuestFDGDB:
 813         gdb_lseek(cs, complete, gf, off, gdb_whence);
 814         return;
 815     case GuestFDHost:
 816         host_lseek(cs, complete, gf, off, gdb_whence);
 817         break;
 818     case GuestFDStatic:
 819         staticfile_lseek(cs, complete, gf, off, gdb_whence);
 820         break;
 821     case GuestFDConsole:
 822         complete(cs, -1, ESPIPE);
 823         break;
 824     default:
 825         g_assert_not_reached();
 826     }
 827 }
 828
 829 void semihost_sys_isatty(CPUState *cs, gdb_syscall_complete_cb complete, int fd)
 830 {
 831     GuestFD *gf = get_guestfd(fd);
 832
 833     if (!gf) {
 834         complete(cs, 0, EBADF);
 835         return;
 836     }
 837     switch (gf->type) {
 838     case GuestFDGDB:
 839         gdb_isatty(cs, complete, gf);
 840         break;
 841     case GuestFDHost:
 842         host_isatty(cs, complete, gf);
 843         break;
 844     case GuestFDStatic:
 845         complete(cs, 0, ENOTTY);
 846         break;
 847     case GuestFDConsole:
 848         complete(cs, 1, 0);
 849         break;
 850     default:
 851         g_assert_not_reached();
 852     }
 853 }
 854
 855 void semihost_sys_flen(CPUState *cs, gdb_syscall_complete_cb fstat_cb,
 856                        gdb_syscall_complete_cb flen_cb, int fd,
 857                        target_ulong fstat_addr)
 858 {
 859     GuestFD *gf = get_guestfd(fd);
 860
 861     if (!gf) {
 862         flen_cb(cs, -1, EBADF);
 863         return;
 864     }
 865     switch (gf->type) {
 866     case GuestFDGDB:
 867         gdb_fstat(cs, fstat_cb, gf, fstat_addr);
 868         break;
 869     case GuestFDHost:
 870         host_flen(cs, flen_cb, gf);
 871         break;
 872     case GuestFDStatic:
 873         staticfile_flen(cs, flen_cb, gf);
 874         break;
 875     case GuestFDConsole:
 876     default:
 877         g_assert_not_reached();
 878     }
 879 }
 880
 881 void semihost_sys_fstat(CPUState *cs, gdb_syscall_complete_cb complete,
 882                         int fd, target_ulong addr)
 883 {
 884     GuestFD *gf = get_guestfd(fd);
 885
 886     if (!gf) {
 887         complete(cs, -1, EBADF);
 888         return;
 889     }
 890     switch (gf->type) {
 891     case GuestFDGDB:
 892         gdb_fstat(cs, complete, gf, addr);
 893         break;
 894     case GuestFDHost:
 895         host_fstat(cs, complete, gf, addr);
 896         break;
 897     case GuestFDConsole:
 898         console_fstat(cs, complete, gf, addr);
 899         break;
 900     case GuestFDStatic:
 901     default:
 902         g_assert_not_reached();
 903     }
 904 }
 905
 906 void semihost_sys_stat(CPUState *cs, gdb_syscall_complete_cb complete,
 907                        target_ulong fname, target_ulong fname_len,
 908                        target_ulong addr)
 909 {
 910     if (use_gdb_syscalls()) {
 911         gdb_stat(cs, complete, fname, fname_len, addr);
 912     } else {
 913         host_stat(cs, complete, fname, fname_len, addr);
 914     }
 915 }
 916
 917 void semihost_sys_remove(CPUState *cs, gdb_syscall_complete_cb complete,
 918                          target_ulong fname, target_ulong fname_len)
 919 {
 920     if (use_gdb_syscalls()) {
 921         gdb_remove(cs, complete, fname, fname_len);
 922     } else {
 923         host_remove(cs, complete, fname, fname_len);
 924     }
 925 }
 926
 927 void semihost_sys_rename(CPUState *cs, gdb_syscall_complete_cb complete,
 928                          target_ulong oname, target_ulong oname_len,
 929                          target_ulong nname, target_ulong nname_len)
 930 {
 931     if (use_gdb_syscalls()) {
 932         gdb_rename(cs, complete, oname, oname_len, nname, nname_len);
 933     } else {
 934         host_rename(cs, complete, oname, oname_len, nname, nname_len);
 935     }
 936 }
 937
 938 void semihost_sys_system(CPUState *cs, gdb_syscall_complete_cb complete,
 939                          target_ulong cmd, target_ulong cmd_len)
 940 {
 941     if (use_gdb_syscalls()) {
 942         gdb_system(cs, complete, cmd, cmd_len);
 943     } else {
 944         host_system(cs, complete, cmd, cmd_len);
 945     }
 946 }
 947
 948 void semihost_sys_gettimeofday(CPUState *cs, gdb_syscall_complete_cb complete,
 949                                target_ulong tv_addr, target_ulong tz_addr)
 950 {
 951     if (use_gdb_syscalls()) {
 952         gdb_gettimeofday(cs, complete, tv_addr, tz_addr);
 953     } else {
 954         host_gettimeofday(cs, complete, tv_addr, tz_addr);
 955     }
 956 }
 957
 958 #ifndef CONFIG_USER_ONLY
 959 void semihost_sys_poll_one(CPUState *cs, gdb_syscall_complete_cb complete,
 960                            int fd, GIOCondition cond, int timeout)
 961 {
 962     GuestFD *gf = get_guestfd(fd);
 963
 964     if (!gf) {
 965         complete(cs, G_IO_NVAL, 1);
 966         return;
 967     }
 968     switch (gf->type) {
 969     case GuestFDGDB:
 970         complete(cs, G_IO_NVAL, 1);
 971         break;
 972     case GuestFDHost:
 973         host_poll_one(cs, complete, gf, cond, timeout);
 974         break;
 975     case GuestFDConsole:
 976         console_poll_one(cs, complete, gf, cond, timeout);
 977         break;
 978     case GuestFDStatic:
 979     default:
 980         g_assert_not_reached();
 981     }
 982 }
 983 #endif