util/oslib-posix.c

   1 /*
   2  * os-posix-lib.c
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  * Copyright (c) 2010 Red Hat, Inc.
   6  *
   7  * QEMU library functions on POSIX which are shared between QEMU and
   8  * the QEMU tools.
   9  *
  10  * Permission is hereby granted, free of charge, to any person obtaining a copy
  11  * of this software and associated documentation files (the "Software"), to deal
  12  * in the Software without restriction, including without limitation the rights
  13  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14  * copies of the Software, and to permit persons to whom the Software is
  15  * furnished to do so, subject to the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be included in
  18  * all copies or substantial portions of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  23  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  25  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  26  * THE SOFTWARE.
  27  */
  28
  29 #include "qemu/osdep.h"
  30 #include <termios.h>
  31
  32 #include <glib/gprintf.h>
  33
  34 #include "qemu-common.h"
  35 #include "sysemu/sysemu.h"
  36 #include "trace.h"
  37 #include "qapi/error.h"
  38 #include "qemu/sockets.h"
  39 #include "qemu/thread.h"
  40 #include <libgen.h>
  41 #include "qemu/cutils.h"
  42
  43 #ifdef CONFIG_LINUX
  44 #include <sys/syscall.h>
  45 #endif
  46
  47 #ifdef __FreeBSD__
  48 #include <sys/sysctl.h>
  49 #include <sys/user.h>
  50 #include <sys/thr.h>
  51 #include <libutil.h>
  52 #endif
  53
  54 #ifdef __NetBSD__
  55 #include <sys/sysctl.h>
  56 #include <lwp.h>
  57 #endif
  58
  59 #ifdef __APPLE__
  60 #include <mach-o/dyld.h>
  61 #endif
  62
  63 #ifdef __HAIKU__
  64 #include <kernel/image.h>
  65 #endif
  66
  67 #include "qemu/mmap-alloc.h"
  68
  69 #ifdef CONFIG_DEBUG_STACK_USAGE
  70 #include "qemu/error-report.h"
  71 #endif
  72
  73 #define MAX_MEM_PREALLOC_THREAD_COUNT 16
  74
  75 struct MemsetThread {
  76     char *addr;
  77     size_t numpages;
  78     size_t hpagesize;
  79     QemuThread pgthread;
  80     sigjmp_buf env;
  81 };
  82 typedef struct MemsetThread MemsetThread;
  83
  84 static MemsetThread *memset_thread;
  85 static int memset_num_threads;
  86 static bool memset_thread_failed;
  87
  88 static QemuMutex page_mutex;
  89 static QemuCond page_cond;
  90 static bool threads_created_flag;
  91
  92 int qemu_get_thread_id(void)
  93 {
  94 #if defined(__linux__)
  95     return syscall(SYS_gettid);
  96 #elif defined(__FreeBSD__)
  97     /* thread id is up to INT_MAX */
  98     long tid;
  99     thr_self(&tid);
 100     return (int)tid;
 101 #elif defined(__NetBSD__)
 102     return _lwp_self();
 103 #else
 104     return getpid();
 105 #endif
 106 }
 107
 108 int qemu_daemon(int nochdir, int noclose)
 109 {
 110     return daemon(nochdir, noclose);
 111 }
 112
 113 bool qemu_write_pidfile(const char *path, Error **errp)
 114 {
 115     int fd;
 116     char pidstr[32];
 117
 118     while (1) {
 119         struct stat a, b;
 120         struct flock lock = {
 121             .l_type = F_WRLCK,
 122             .l_whence = SEEK_SET,
 123             .l_len = 0,
 124         };
 125
 126         fd = qemu_open(path, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR);
 127         if (fd == -1) {
 128             error_setg_errno(errp, errno, "Cannot open pid file");
 129             return false;
 130         }
 131
 132         if (fstat(fd, &b) < 0) {
 133             error_setg_errno(errp, errno, "Cannot stat file");
 134             goto fail_close;
 135         }
 136
 137         if (fcntl(fd, F_SETLK, &lock)) {
 138             error_setg_errno(errp, errno, "Cannot lock pid file");
 139             goto fail_close;
 140         }
 141
 142         /*
 143          * Now make sure the path we locked is the same one that now
 144          * exists on the filesystem.
 145          */
 146         if (stat(path, &a) < 0) {
 147             /*
 148              * PID file disappeared, someone else must be racing with
 149              * us, so try again.
 150              */
 151             close(fd);
 152             continue;
 153         }
 154
 155         if (a.st_ino == b.st_ino) {
 156             break;
 157         }
 158
 159         /*
 160          * PID file was recreated, someone else must be racing with
 161          * us, so try again.
 162          */
 163         close(fd);
 164     }
 165
 166     if (ftruncate(fd, 0) < 0) {
 167         error_setg_errno(errp, errno, "Failed to truncate pid file");
 168         goto fail_unlink;
 169     }
 170
 171     snprintf(pidstr, sizeof(pidstr), FMT_pid "\n", getpid());
 172     if (write(fd, pidstr, strlen(pidstr)) != strlen(pidstr)) {
 173         error_setg(errp, "Failed to write pid file");
 174         goto fail_unlink;
 175     }
 176
 177     return true;
 178
 179 fail_unlink:
 180     unlink(path);
 181 fail_close:
 182     close(fd);
 183     return false;
 184 }
 185
 186 void *qemu_oom_check(void *ptr)
 187 {
 188     if (ptr == NULL) {
 189         fprintf(stderr, "Failed to allocate memory: %s\n", strerror(errno));
 190         abort();
 191     }
 192     return ptr;
 193 }
 194
 195 void *qemu_try_memalign(size_t alignment, size_t size)
 196 {
 197     void *ptr;
 198
 199     if (alignment < sizeof(void*)) {
 200         alignment = sizeof(void*);
 201     }
 202
 203 #if defined(CONFIG_POSIX_MEMALIGN)
 204     int ret;
 205     ret = posix_memalign(&ptr, alignment, size);
 206     if (ret != 0) {
 207         errno = ret;
 208         ptr = NULL;
 209     }
 210 #elif defined(CONFIG_BSD)
 211     ptr = valloc(size);
 212 #else
 213     ptr = memalign(alignment, size);
 214 #endif
 215     trace_qemu_memalign(alignment, size, ptr);
 216     return ptr;
 217 }
 218
 219 void *qemu_memalign(size_t alignment, size_t size)
 220 {
 221     return qemu_oom_check(qemu_try_memalign(alignment, size));
 222 }
 223
 224 /* alloc shared memory pages */
 225 void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment, bool shared)
 226 {
 227     size_t align = QEMU_VMALLOC_ALIGN;
 228     void *ptr = qemu_ram_mmap(-1, size, align, shared, false);
 229
 230     if (ptr == MAP_FAILED) {
 231         return NULL;
 232     }
 233
 234     if (alignment) {
 235         *alignment = align;
 236     }
 237
 238     trace_qemu_anon_ram_alloc(size, ptr);
 239     return ptr;
 240 }
 241
 242 void qemu_vfree(void *ptr)
 243 {
 244     trace_qemu_vfree(ptr);
 245     free(ptr);
 246 }
 247
 248 void qemu_anon_ram_free(void *ptr, size_t size)
 249 {
 250     trace_qemu_anon_ram_free(ptr, size);
 251     qemu_ram_munmap(-1, ptr, size);
 252 }
 253
 254 void qemu_set_block(int fd)
 255 {
 256     int f;
 257     f = fcntl(fd, F_GETFL);
 258     assert(f != -1);
 259     f = fcntl(fd, F_SETFL, f & ~O_NONBLOCK);
 260     assert(f != -1);
 261 }
 262
 263 int qemu_try_set_nonblock(int fd)
 264 {
 265     int f;
 266     f = fcntl(fd, F_GETFL);
 267     if (f == -1) {
 268         return -errno;
 269     }
 270     if (fcntl(fd, F_SETFL, f | O_NONBLOCK) == -1) {
 271 #ifdef __OpenBSD__
 272         /*
 273          * Previous to OpenBSD 6.3, fcntl(F_SETFL) is not permitted on
 274          * memory devices and sets errno to ENODEV.
 275          * It's OK if we fail to set O_NONBLOCK on devices like /dev/null,
 276          * because they will never block anyway.
 277          */
 278         if (errno == ENODEV) {
 279             return 0;
 280         }
 281 #endif
 282         return -errno;
 283     }
 284     return 0;
 285 }
 286
 287 void qemu_set_nonblock(int fd)
 288 {
 289     int f;
 290     f = qemu_try_set_nonblock(fd);
 291     assert(f == 0);
 292 }
 293
 294 int socket_set_fast_reuse(int fd)
 295 {
 296     int val = 1, ret;
 297
 298     ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
 299                      (const char *)&val, sizeof(val));
 300
 301     assert(ret == 0);
 302
 303     return ret;
 304 }
 305
 306 void qemu_set_cloexec(int fd)
 307 {
 308     int f;
 309     f = fcntl(fd, F_GETFD);
 310     assert(f != -1);
 311     f = fcntl(fd, F_SETFD, f | FD_CLOEXEC);
 312     assert(f != -1);
 313 }
 314
 315 /*
 316  * Creates a pipe with FD_CLOEXEC set on both file descriptors
 317  */
 318 int qemu_pipe(int pipefd[2])
 319 {
 320     int ret;
 321
 322 #ifdef CONFIG_PIPE2
 323     ret = pipe2(pipefd, O_CLOEXEC);
 324     if (ret != -1 || errno != ENOSYS) {
 325         return ret;
 326     }
 327 #endif
 328     ret = pipe(pipefd);
 329     if (ret == 0) {
 330         qemu_set_cloexec(pipefd[0]);
 331         qemu_set_cloexec(pipefd[1]);
 332     }
 333
 334     return ret;
 335 }
 336
 337 char *
 338 qemu_get_local_state_pathname(const char *relative_pathname)
 339 {
 340     return g_strdup_printf("%s/%s", CONFIG_QEMU_LOCALSTATEDIR,
 341                            relative_pathname);
 342 }
 343
 344 void qemu_set_tty_echo(int fd, bool echo)
 345 {
 346     struct termios tty;
 347
 348     tcgetattr(fd, &tty);
 349
 350     if (echo) {
 351         tty.c_lflag |= ECHO | ECHONL | ICANON | IEXTEN;
 352     } else {
 353         tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
 354     }
 355
 356     tcsetattr(fd, TCSANOW, &tty);
 357 }
 358
 359 static char exec_dir[PATH_MAX];
 360
 361 void qemu_init_exec_dir(const char *argv0)
 362 {
 363     char *dir;
 364     char *p = NULL;
 365     char buf[PATH_MAX];
 366
 367     assert(!exec_dir[0]);
 368
 369 #if defined(__linux__)
 370     {
 371         int len;
 372         len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
 373         if (len > 0) {
 374             buf[len] = 0;
 375             p = buf;
 376         }
 377     }
 378 #elif defined(__FreeBSD__) \
 379       || (defined(__NetBSD__) && defined(KERN_PROC_PATHNAME))
 380     {
 381 #if defined(__FreeBSD__)
 382         static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
 383 #else
 384         static int mib[4] = {CTL_KERN, KERN_PROC_ARGS, -1, KERN_PROC_PATHNAME};
 385 #endif
 386         size_t len = sizeof(buf) - 1;
 387
 388         *buf = '\0';
 389         if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
 390             *buf) {
 391             buf[sizeof(buf) - 1] = '\0';
 392             p = buf;
 393         }
 394     }
 395 #elif defined(__APPLE__)
 396     {
 397         char fpath[PATH_MAX];
 398         uint32_t len = sizeof(fpath);
 399         if (_NSGetExecutablePath(fpath, &len) == 0) {
 400             p = realpath(fpath, buf);
 401             if (!p) {
 402                 return;
 403             }
 404         }
 405     }
 406 #elif defined(__HAIKU__)
 407     {
 408         image_info ii;
 409         int32_t c = 0;
 410
 411         *buf = '\0';
 412         while (get_next_image_info(0, &c, &ii) == B_OK) {
 413             if (ii.type == B_APP_IMAGE) {
 414                 strncpy(buf, ii.name, sizeof(buf));
 415                 buf[sizeof(buf) - 1] = 0;
 416                 p = buf;
 417                 break;
 418             }
 419         }
 420     }
 421 #endif
 422     /* If we don't have any way of figuring out the actual executable
 423        location then try argv[0].  */
 424     if (!p) {
 425         if (!argv0) {
 426             return;
 427         }
 428         p = realpath(argv0, buf);
 429         if (!p) {
 430             return;
 431         }
 432     }
 433     dir = g_path_get_dirname(p);
 434
 435     pstrcpy(exec_dir, sizeof(exec_dir), dir);
 436
 437     g_free(dir);
 438 }
 439
 440 char *qemu_get_exec_dir(void)
 441 {
 442     return g_strdup(exec_dir);
 443 }
 444
 445 static void sigbus_handler(int signal)
 446 {
 447     int i;
 448     if (memset_thread) {
 449         for (i = 0; i < memset_num_threads; i++) {
 450             if (qemu_thread_is_self(&memset_thread[i].pgthread)) {
 451                 siglongjmp(memset_thread[i].env, 1);
 452             }
 453         }
 454     }
 455 }
 456
 457 static void *do_touch_pages(void *arg)
 458 {
 459     MemsetThread *memset_args = (MemsetThread *)arg;
 460     sigset_t set, oldset;
 461
 462     /*
 463      * On Linux, the page faults from the loop below can cause mmap_sem
 464      * contention with allocation of the thread stacks.  Do not start
 465      * clearing until all threads have been created.
 466      */
 467     qemu_mutex_lock(&page_mutex);
 468     while(!threads_created_flag){
 469         qemu_cond_wait(&page_cond, &page_mutex);
 470     }
 471     qemu_mutex_unlock(&page_mutex);
 472
 473     /* unblock SIGBUS */
 474     sigemptyset(&set);
 475     sigaddset(&set, SIGBUS);
 476     pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
 477
 478     if (sigsetjmp(memset_args->env, 1)) {
 479         memset_thread_failed = true;
 480     } else {
 481         char *addr = memset_args->addr;
 482         size_t numpages = memset_args->numpages;
 483         size_t hpagesize = memset_args->hpagesize;
 484         size_t i;
 485         for (i = 0; i < numpages; i++) {
 486             /*
 487              * Read & write back the same value, so we don't
 488              * corrupt existing user/app data that might be
 489              * stored.
 490              *
 491              * 'volatile' to stop compiler optimizing this away
 492              * to a no-op
 493              *
 494              * TODO: get a better solution from kernel so we
 495              * don't need to write at all so we don't cause
 496              * wear on the storage backing the region...
 497              */
 498             *(volatile char *)addr = *addr;
 499             addr += hpagesize;
 500         }
 501     }
 502     pthread_sigmask(SIG_SETMASK, &oldset, NULL);
 503     return NULL;
 504 }
 505
 506 static inline int get_memset_num_threads(int smp_cpus)
 507 {
 508     long host_procs = sysconf(_SC_NPROCESSORS_ONLN);
 509     int ret = 1;
 510
 511     if (host_procs > 0) {
 512         ret = MIN(MIN(host_procs, MAX_MEM_PREALLOC_THREAD_COUNT), smp_cpus);
 513     }
 514     /* In case sysconf() fails, we fall back to single threaded */
 515     return ret;
 516 }
 517
 518 static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages,
 519                             int smp_cpus)
 520 {
 521     static gsize initialized = 0;
 522     size_t numpages_per_thread, leftover;
 523     char *addr = area;
 524     int i = 0;
 525
 526     if (g_once_init_enter(&initialized)) {
 527         qemu_mutex_init(&page_mutex);
 528         qemu_cond_init(&page_cond);
 529         g_once_init_leave(&initialized, 1);
 530     }
 531
 532     memset_thread_failed = false;
 533     threads_created_flag = false;
 534     memset_num_threads = get_memset_num_threads(smp_cpus);
 535     memset_thread = g_new0(MemsetThread, memset_num_threads);
 536     numpages_per_thread = numpages / memset_num_threads;
 537     leftover = numpages % memset_num_threads;
 538     for (i = 0; i < memset_num_threads; i++) {
 539         memset_thread[i].addr = addr;
 540         memset_thread[i].numpages = numpages_per_thread + (i < leftover);
 541         memset_thread[i].hpagesize = hpagesize;
 542         qemu_thread_create(&memset_thread[i].pgthread, "touch_pages",
 543                            do_touch_pages, &memset_thread[i],
 544                            QEMU_THREAD_JOINABLE);
 545         addr += memset_thread[i].numpages * hpagesize;
 546     }
 547
 548     qemu_mutex_lock(&page_mutex);
 549     threads_created_flag = true;
 550     qemu_cond_broadcast(&page_cond);
 551     qemu_mutex_unlock(&page_mutex);
 552
 553     for (i = 0; i < memset_num_threads; i++) {
 554         qemu_thread_join(&memset_thread[i].pgthread);
 555     }
 556     g_free(memset_thread);
 557     memset_thread = NULL;
 558
 559     return memset_thread_failed;
 560 }
 561
 562 void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
 563                      Error **errp)
 564 {
 565     int ret;
 566     struct sigaction act, oldact;
 567     size_t hpagesize = qemu_fd_getpagesize(fd);
 568     size_t numpages = DIV_ROUND_UP(memory, hpagesize);
 569
 570     memset(&act, 0, sizeof(act));
 571     act.sa_handler = &sigbus_handler;
 572     act.sa_flags = 0;
 573
 574     ret = sigaction(SIGBUS, &act, &oldact);
 575     if (ret) {
 576         error_setg_errno(errp, errno,
 577             "os_mem_prealloc: failed to install signal handler");
 578         return;
 579     }
 580
 581     /* touch pages simultaneously */
 582     if (touch_all_pages(area, hpagesize, numpages, smp_cpus)) {
 583         error_setg(errp, "os_mem_prealloc: Insufficient free host memory "
 584             "pages available to allocate guest RAM");
 585     }
 586
 587     ret = sigaction(SIGBUS, &oldact, NULL);
 588     if (ret) {
 589         /* Terminate QEMU since it can't recover from error */
 590         perror("os_mem_prealloc: failed to reinstall signal handler");
 591         exit(1);
 592     }
 593 }
 594
 595 char *qemu_get_pid_name(pid_t pid)
 596 {
 597     char *name = NULL;
 598
 599 #if defined(__FreeBSD__)
 600     /* BSDs don't have /proc, but they provide a nice substitute */
 601     struct kinfo_proc *proc = kinfo_getproc(pid);
 602
 603     if (proc) {
 604         name = g_strdup(proc->ki_comm);
 605         free(proc);
 606     }
 607 #else
 608     /* Assume a system with reasonable procfs */
 609     char *pid_path;
 610     size_t len;
 611
 612     pid_path = g_strdup_printf("/proc/%d/cmdline", pid);
 613     g_file_get_contents(pid_path, &name, &len, NULL);
 614     g_free(pid_path);
 615 #endif
 616
 617     return name;
 618 }
 619
 620
 621 pid_t qemu_fork(Error **errp)
 622 {
 623     sigset_t oldmask, newmask;
 624     struct sigaction sig_action;
 625     int saved_errno;
 626     pid_t pid;
 627
 628     /*
 629      * Need to block signals now, so that child process can safely
 630      * kill off caller's signal handlers without a race.
 631      */
 632     sigfillset(&newmask);
 633     if (pthread_sigmask(SIG_SETMASK, &newmask, &oldmask) != 0) {
 634         error_setg_errno(errp, errno,
 635                          "cannot block signals");
 636         return -1;
 637     }
 638
 639     pid = fork();
 640     saved_errno = errno;
 641
 642     if (pid < 0) {
 643         /* attempt to restore signal mask, but ignore failure, to
 644          * avoid obscuring the fork failure */
 645         (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
 646         error_setg_errno(errp, saved_errno,
 647                          "cannot fork child process");
 648         errno = saved_errno;
 649         return -1;
 650     } else if (pid) {
 651         /* parent process */
 652
 653         /* Restore our original signal mask now that the child is
 654          * safely running. Only documented failures are EFAULT (not
 655          * possible, since we are using just-grabbed mask) or EINVAL
 656          * (not possible, since we are using correct arguments).  */
 657         (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
 658     } else {
 659         /* child process */
 660         size_t i;
 661
 662         /* Clear out all signal handlers from parent so nothing
 663          * unexpected can happen in our child once we unblock
 664          * signals */
 665         sig_action.sa_handler = SIG_DFL;
 666         sig_action.sa_flags = 0;
 667         sigemptyset(&sig_action.sa_mask);
 668
 669         for (i = 1; i < NSIG; i++) {
 670             /* Only possible errors are EFAULT or EINVAL The former
 671              * won't happen, the latter we expect, so no need to check
 672              * return value */
 673             (void)sigaction(i, &sig_action, NULL);
 674         }
 675
 676         /* Unmask all signals in child, since we've no idea what the
 677          * caller's done with their signal mask and don't want to
 678          * propagate that to children */
 679         sigemptyset(&newmask);
 680         if (pthread_sigmask(SIG_SETMASK, &newmask, NULL) != 0) {
 681             Error *local_err = NULL;
 682             error_setg_errno(&local_err, errno,
 683                              "cannot unblock signals");
 684             error_report_err(local_err);
 685             _exit(1);
 686         }
 687     }
 688     return pid;
 689 }
 690
 691 void *qemu_alloc_stack(size_t *sz)
 692 {
 693     void *ptr, *guardpage;
 694     int flags;
 695 #ifdef CONFIG_DEBUG_STACK_USAGE
 696     void *ptr2;
 697 #endif
 698     size_t pagesz = qemu_real_host_page_size;
 699 #ifdef _SC_THREAD_STACK_MIN
 700     /* avoid stacks smaller than _SC_THREAD_STACK_MIN */
 701     long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN);
 702     *sz = MAX(MAX(min_stack_sz, 0), *sz);
 703 #endif
 704     /* adjust stack size to a multiple of the page size */
 705     *sz = ROUND_UP(*sz, pagesz);
 706     /* allocate one extra page for the guard page */
 707     *sz += pagesz;
 708
 709     flags = MAP_PRIVATE | MAP_ANONYMOUS;
 710 #if defined(MAP_STACK) && defined(__OpenBSD__)
 711     /* Only enable MAP_STACK on OpenBSD. Other OS's such as
 712      * Linux/FreeBSD/NetBSD have a flag with the same name
 713      * but have differing functionality. OpenBSD will SEGV
 714      * if it spots execution with a stack pointer pointing
 715      * at memory that was not allocated with MAP_STACK.
 716      */
 717     flags |= MAP_STACK;
 718 #endif
 719
 720     ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE, flags, -1, 0);
 721     if (ptr == MAP_FAILED) {
 722         perror("failed to allocate memory for stack");
 723         abort();
 724     }
 725
 726 #if defined(HOST_IA64)
 727     /* separate register stack */
 728     guardpage = ptr + (((*sz - pagesz) / 2) & ~pagesz);
 729 #elif defined(HOST_HPPA)
 730     /* stack grows up */
 731     guardpage = ptr + *sz - pagesz;
 732 #else
 733     /* stack grows down */
 734     guardpage = ptr;
 735 #endif
 736     if (mprotect(guardpage, pagesz, PROT_NONE) != 0) {
 737         perror("failed to set up stack guard page");
 738         abort();
 739     }
 740
 741 #ifdef CONFIG_DEBUG_STACK_USAGE
 742     for (ptr2 = ptr + pagesz; ptr2 < ptr + *sz; ptr2 += sizeof(uint32_t)) {
 743         *(uint32_t *)ptr2 = 0xdeadbeaf;
 744     }
 745 #endif
 746
 747     return ptr;
 748 }
 749
 750 #ifdef CONFIG_DEBUG_STACK_USAGE
 751 static __thread unsigned int max_stack_usage;
 752 #endif
 753
 754 void qemu_free_stack(void *stack, size_t sz)
 755 {
 756 #ifdef CONFIG_DEBUG_STACK_USAGE
 757     unsigned int usage;
 758     void *ptr;
 759
 760     for (ptr = stack + qemu_real_host_page_size; ptr < stack + sz;
 761          ptr += sizeof(uint32_t)) {
 762         if (*(uint32_t *)ptr != 0xdeadbeaf) {
 763             break;
 764         }
 765     }
 766     usage = sz - (uintptr_t) (ptr - stack);
 767     if (usage > max_stack_usage) {
 768         error_report("thread %d max stack usage increased from %u to %u",
 769                      qemu_get_thread_id(), max_stack_usage, usage);
 770         max_stack_usage = usage;
 771     }
 772 #endif
 773
 774     munmap(stack, sz);
 775 }
 776
 777 void sigaction_invoke(struct sigaction *action,
 778                       struct qemu_signalfd_siginfo *info)
 779 {
 780     siginfo_t si = {};
 781     si.si_signo = info->ssi_signo;
 782     si.si_errno = info->ssi_errno;
 783     si.si_code = info->ssi_code;
 784
 785     /* Convert the minimal set of fields defined by POSIX.
 786      * Positive si_code values are reserved for kernel-generated
 787      * signals, where the valid siginfo fields are determined by
 788      * the signal number.  But according to POSIX, it is unspecified
 789      * whether SI_USER and SI_QUEUE have values less than or equal to
 790      * zero.
 791      */
 792     if (info->ssi_code == SI_USER || info->ssi_code == SI_QUEUE ||
 793         info->ssi_code <= 0) {
 794         /* SIGTERM, etc.  */
 795         si.si_pid = info->ssi_pid;
 796         si.si_uid = info->ssi_uid;
 797     } else if (info->ssi_signo == SIGILL || info->ssi_signo == SIGFPE ||
 798                info->ssi_signo == SIGSEGV || info->ssi_signo == SIGBUS) {
 799         si.si_addr = (void *)(uintptr_t)info->ssi_addr;
 800     } else if (info->ssi_signo == SIGCHLD) {
 801         si.si_pid = info->ssi_pid;
 802         si.si_status = info->ssi_status;
 803         si.si_uid = info->ssi_uid;
 804     }
 805     action->sa_sigaction(info->ssi_signo, &si, NULL);
 806 }
 807
 808 #ifndef HOST_NAME_MAX
 809 # ifdef _POSIX_HOST_NAME_MAX
 810 #  define HOST_NAME_MAX _POSIX_HOST_NAME_MAX
 811 # else
 812 #  define HOST_NAME_MAX 255
 813 # endif
 814 #endif
 815
 816 char *qemu_get_host_name(Error **errp)
 817 {
 818     long len = -1;
 819     g_autofree char *hostname = NULL;
 820
 821 #ifdef _SC_HOST_NAME_MAX
 822     len = sysconf(_SC_HOST_NAME_MAX);
 823 #endif /* _SC_HOST_NAME_MAX */
 824
 825     if (len < 0) {
 826         len = HOST_NAME_MAX;
 827     }
 828
 829     /* Unfortunately, gethostname() below does not guarantee a
 830      * NULL terminated string. Therefore, allocate one byte more
 831      * to be sure. */
 832     hostname = g_new0(char, len + 1);
 833
 834     if (gethostname(hostname, len) < 0) {
 835         error_setg_errno(errp, errno,
 836                          "cannot get hostname");
 837         return NULL;
 838     }
 839
 840     return g_steal_pointer(&hostname);
 841 }