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 #elif defined(__OpenBSD__)
 104     return getthrid();
 105 #else
 106     return getpid();
 107 #endif
 108 }
 109
 110 int qemu_daemon(int nochdir, int noclose)
 111 {
 112     return daemon(nochdir, noclose);
 113 }
 114
 115 bool qemu_write_pidfile(const char *path, Error **errp)
 116 {
 117     int fd;
 118     char pidstr[32];
 119
 120     while (1) {
 121         struct stat a, b;
 122         struct flock lock = {
 123             .l_type = F_WRLCK,
 124             .l_whence = SEEK_SET,
 125             .l_len = 0,
 126         };
 127
 128         fd = qemu_open_old(path, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR);
 129         if (fd == -1) {
 130             error_setg_errno(errp, errno, "Cannot open pid file");
 131             return false;
 132         }
 133
 134         if (fstat(fd, &b) < 0) {
 135             error_setg_errno(errp, errno, "Cannot stat file");
 136             goto fail_close;
 137         }
 138
 139         if (fcntl(fd, F_SETLK, &lock)) {
 140             error_setg_errno(errp, errno, "Cannot lock pid file");
 141             goto fail_close;
 142         }
 143
 144         /*
 145          * Now make sure the path we locked is the same one that now
 146          * exists on the filesystem.
 147          */
 148         if (stat(path, &a) < 0) {
 149             /*
 150              * PID file disappeared, someone else must be racing with
 151              * us, so try again.
 152              */
 153             close(fd);
 154             continue;
 155         }
 156
 157         if (a.st_ino == b.st_ino) {
 158             break;
 159         }
 160
 161         /*
 162          * PID file was recreated, someone else must be racing with
 163          * us, so try again.
 164          */
 165         close(fd);
 166     }
 167
 168     if (ftruncate(fd, 0) < 0) {
 169         error_setg_errno(errp, errno, "Failed to truncate pid file");
 170         goto fail_unlink;
 171     }
 172
 173     snprintf(pidstr, sizeof(pidstr), FMT_pid "\n", getpid());
 174     if (write(fd, pidstr, strlen(pidstr)) != strlen(pidstr)) {
 175         error_setg(errp, "Failed to write pid file");
 176         goto fail_unlink;
 177     }
 178
 179     return true;
 180
 181 fail_unlink:
 182     unlink(path);
 183 fail_close:
 184     close(fd);
 185     return false;
 186 }
 187
 188 void *qemu_oom_check(void *ptr)
 189 {
 190     if (ptr == NULL) {
 191         fprintf(stderr, "Failed to allocate memory: %s\n", strerror(errno));
 192         abort();
 193     }
 194     return ptr;
 195 }
 196
 197 void *qemu_try_memalign(size_t alignment, size_t size)
 198 {
 199     void *ptr;
 200
 201     if (alignment < sizeof(void*)) {
 202         alignment = sizeof(void*);
 203     }
 204
 205 #if defined(CONFIG_POSIX_MEMALIGN)
 206     int ret;
 207     ret = posix_memalign(&ptr, alignment, size);
 208     if (ret != 0) {
 209         errno = ret;
 210         ptr = NULL;
 211     }
 212 #elif defined(CONFIG_BSD)
 213     ptr = valloc(size);
 214 #else
 215     ptr = memalign(alignment, size);
 216 #endif
 217     trace_qemu_memalign(alignment, size, ptr);
 218     return ptr;
 219 }
 220
 221 void *qemu_memalign(size_t alignment, size_t size)
 222 {
 223     return qemu_oom_check(qemu_try_memalign(alignment, size));
 224 }
 225
 226 /* alloc shared memory pages */
 227 void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment, bool shared)
 228 {
 229     size_t align = QEMU_VMALLOC_ALIGN;
 230     void *ptr = qemu_ram_mmap(-1, size, align, shared, false);
 231
 232     if (ptr == MAP_FAILED) {
 233         return NULL;
 234     }
 235
 236     if (alignment) {
 237         *alignment = align;
 238     }
 239
 240     trace_qemu_anon_ram_alloc(size, ptr);
 241     return ptr;
 242 }
 243
 244 void qemu_vfree(void *ptr)
 245 {
 246     trace_qemu_vfree(ptr);
 247     free(ptr);
 248 }
 249
 250 void qemu_anon_ram_free(void *ptr, size_t size)
 251 {
 252     trace_qemu_anon_ram_free(ptr, size);
 253     qemu_ram_munmap(-1, ptr, size);
 254 }
 255
 256 void qemu_set_block(int fd)
 257 {
 258     int f;
 259     f = fcntl(fd, F_GETFL);
 260     assert(f != -1);
 261     f = fcntl(fd, F_SETFL, f & ~O_NONBLOCK);
 262     assert(f != -1);
 263 }
 264
 265 int qemu_try_set_nonblock(int fd)
 266 {
 267     int f;
 268     f = fcntl(fd, F_GETFL);
 269     if (f == -1) {
 270         return -errno;
 271     }
 272     if (fcntl(fd, F_SETFL, f | O_NONBLOCK) == -1) {
 273 #ifdef __OpenBSD__
 274         /*
 275          * Previous to OpenBSD 6.3, fcntl(F_SETFL) is not permitted on
 276          * memory devices and sets errno to ENODEV.
 277          * It's OK if we fail to set O_NONBLOCK on devices like /dev/null,
 278          * because they will never block anyway.
 279          */
 280         if (errno == ENODEV) {
 281             return 0;
 282         }
 283 #endif
 284         return -errno;
 285     }
 286     return 0;
 287 }
 288
 289 void qemu_set_nonblock(int fd)
 290 {
 291     int f;
 292     f = qemu_try_set_nonblock(fd);
 293     assert(f == 0);
 294 }
 295
 296 int socket_set_fast_reuse(int fd)
 297 {
 298     int val = 1, ret;
 299
 300     ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
 301                      (const char *)&val, sizeof(val));
 302
 303     assert(ret == 0);
 304
 305     return ret;
 306 }
 307
 308 void qemu_set_cloexec(int fd)
 309 {
 310     int f;
 311     f = fcntl(fd, F_GETFD);
 312     assert(f != -1);
 313     f = fcntl(fd, F_SETFD, f | FD_CLOEXEC);
 314     assert(f != -1);
 315 }
 316
 317 /*
 318  * Creates a pipe with FD_CLOEXEC set on both file descriptors
 319  */
 320 int qemu_pipe(int pipefd[2])
 321 {
 322     int ret;
 323
 324 #ifdef CONFIG_PIPE2
 325     ret = pipe2(pipefd, O_CLOEXEC);
 326     if (ret != -1 || errno != ENOSYS) {
 327         return ret;
 328     }
 329 #endif
 330     ret = pipe(pipefd);
 331     if (ret == 0) {
 332         qemu_set_cloexec(pipefd[0]);
 333         qemu_set_cloexec(pipefd[1]);
 334     }
 335
 336     return ret;
 337 }
 338
 339 char *
 340 qemu_get_local_state_pathname(const char *relative_pathname)
 341 {
 342     g_autofree char *dir = g_strdup_printf("%s/%s",
 343                                            CONFIG_QEMU_LOCALSTATEDIR,
 344                                            relative_pathname);
 345     return get_relocated_path(dir);
 346 }
 347
 348 void qemu_set_tty_echo(int fd, bool echo)
 349 {
 350     struct termios tty;
 351
 352     tcgetattr(fd, &tty);
 353
 354     if (echo) {
 355         tty.c_lflag |= ECHO | ECHONL | ICANON | IEXTEN;
 356     } else {
 357         tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
 358     }
 359
 360     tcsetattr(fd, TCSANOW, &tty);
 361 }
 362
 363 static const char *exec_dir;
 364
 365 void qemu_init_exec_dir(const char *argv0)
 366 {
 367     char *p = NULL;
 368     char buf[PATH_MAX];
 369
 370     if (exec_dir) {
 371         return;
 372     }
 373
 374 #if defined(__linux__)
 375     {
 376         int len;
 377         len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
 378         if (len > 0) {
 379             buf[len] = 0;
 380             p = buf;
 381         }
 382     }
 383 #elif defined(__FreeBSD__) \
 384       || (defined(__NetBSD__) && defined(KERN_PROC_PATHNAME))
 385     {
 386 #if defined(__FreeBSD__)
 387         static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
 388 #else
 389         static int mib[4] = {CTL_KERN, KERN_PROC_ARGS, -1, KERN_PROC_PATHNAME};
 390 #endif
 391         size_t len = sizeof(buf) - 1;
 392
 393         *buf = '\0';
 394         if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
 395             *buf) {
 396             buf[sizeof(buf) - 1] = '\0';
 397             p = buf;
 398         }
 399     }
 400 #elif defined(__APPLE__)
 401     {
 402         char fpath[PATH_MAX];
 403         uint32_t len = sizeof(fpath);
 404         if (_NSGetExecutablePath(fpath, &len) == 0) {
 405             p = realpath(fpath, buf);
 406             if (!p) {
 407                 return;
 408             }
 409         }
 410     }
 411 #elif defined(__HAIKU__)
 412     {
 413         image_info ii;
 414         int32_t c = 0;
 415
 416         *buf = '\0';
 417         while (get_next_image_info(0, &c, &ii) == B_OK) {
 418             if (ii.type == B_APP_IMAGE) {
 419                 strncpy(buf, ii.name, sizeof(buf));
 420                 buf[sizeof(buf) - 1] = 0;
 421                 p = buf;
 422                 break;
 423             }
 424         }
 425     }
 426 #endif
 427     /* If we don't have any way of figuring out the actual executable
 428        location then try argv[0].  */
 429     if (!p && argv0) {
 430         p = realpath(argv0, buf);
 431     }
 432     if (p) {
 433         exec_dir = g_path_get_dirname(p);
 434     } else {
 435         exec_dir = CONFIG_BINDIR;
 436     }
 437 }
 438
 439 const char *qemu_get_exec_dir(void)
 440 {
 441     return exec_dir;
 442 }
 443
 444 static void sigbus_handler(int signal)
 445 {
 446     int i;
 447     if (memset_thread) {
 448         for (i = 0; i < memset_num_threads; i++) {
 449             if (qemu_thread_is_self(&memset_thread[i].pgthread)) {
 450                 siglongjmp(memset_thread[i].env, 1);
 451             }
 452         }
 453     }
 454 }
 455
 456 static void *do_touch_pages(void *arg)
 457 {
 458     MemsetThread *memset_args = (MemsetThread *)arg;
 459     sigset_t set, oldset;
 460
 461     /*
 462      * On Linux, the page faults from the loop below can cause mmap_sem
 463      * contention with allocation of the thread stacks.  Do not start
 464      * clearing until all threads have been created.
 465      */
 466     qemu_mutex_lock(&page_mutex);
 467     while(!threads_created_flag){
 468         qemu_cond_wait(&page_cond, &page_mutex);
 469     }
 470     qemu_mutex_unlock(&page_mutex);
 471
 472     /* unblock SIGBUS */
 473     sigemptyset(&set);
 474     sigaddset(&set, SIGBUS);
 475     pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
 476
 477     if (sigsetjmp(memset_args->env, 1)) {
 478         memset_thread_failed = true;
 479     } else {
 480         char *addr = memset_args->addr;
 481         size_t numpages = memset_args->numpages;
 482         size_t hpagesize = memset_args->hpagesize;
 483         size_t i;
 484         for (i = 0; i < numpages; i++) {
 485             /*
 486              * Read & write back the same value, so we don't
 487              * corrupt existing user/app data that might be
 488              * stored.
 489              *
 490              * 'volatile' to stop compiler optimizing this away
 491              * to a no-op
 492              *
 493              * TODO: get a better solution from kernel so we
 494              * don't need to write at all so we don't cause
 495              * wear on the storage backing the region...
 496              */
 497             *(volatile char *)addr = *addr;
 498             addr += hpagesize;
 499         }
 500     }
 501     pthread_sigmask(SIG_SETMASK, &oldset, NULL);
 502     return NULL;
 503 }
 504
 505 static inline int get_memset_num_threads(int smp_cpus)
 506 {
 507     long host_procs = sysconf(_SC_NPROCESSORS_ONLN);
 508     int ret = 1;
 509
 510     if (host_procs > 0) {
 511         ret = MIN(MIN(host_procs, MAX_MEM_PREALLOC_THREAD_COUNT), smp_cpus);
 512     }
 513     /* In case sysconf() fails, we fall back to single threaded */
 514     return ret;
 515 }
 516
 517 static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages,
 518                             int smp_cpus)
 519 {
 520     static gsize initialized = 0;
 521     size_t numpages_per_thread, leftover;
 522     char *addr = area;
 523     int i = 0;
 524
 525     if (g_once_init_enter(&initialized)) {
 526         qemu_mutex_init(&page_mutex);
 527         qemu_cond_init(&page_cond);
 528         g_once_init_leave(&initialized, 1);
 529     }
 530
 531     memset_thread_failed = false;
 532     threads_created_flag = false;
 533     memset_num_threads = get_memset_num_threads(smp_cpus);
 534     memset_thread = g_new0(MemsetThread, memset_num_threads);
 535     numpages_per_thread = numpages / memset_num_threads;
 536     leftover = numpages % memset_num_threads;
 537     for (i = 0; i < memset_num_threads; i++) {
 538         memset_thread[i].addr = addr;
 539         memset_thread[i].numpages = numpages_per_thread + (i < leftover);
 540         memset_thread[i].hpagesize = hpagesize;
 541         qemu_thread_create(&memset_thread[i].pgthread, "touch_pages",
 542                            do_touch_pages, &memset_thread[i],
 543                            QEMU_THREAD_JOINABLE);
 544         addr += memset_thread[i].numpages * hpagesize;
 545     }
 546
 547     qemu_mutex_lock(&page_mutex);
 548     threads_created_flag = true;
 549     qemu_cond_broadcast(&page_cond);
 550     qemu_mutex_unlock(&page_mutex);
 551
 552     for (i = 0; i < memset_num_threads; i++) {
 553         qemu_thread_join(&memset_thread[i].pgthread);
 554     }
 555     g_free(memset_thread);
 556     memset_thread = NULL;
 557
 558     return memset_thread_failed;
 559 }
 560
 561 void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
 562                      Error **errp)
 563 {
 564     int ret;
 565     struct sigaction act, oldact;
 566     size_t hpagesize = qemu_fd_getpagesize(fd);
 567     size_t numpages = DIV_ROUND_UP(memory, hpagesize);
 568
 569     memset(&act, 0, sizeof(act));
 570     act.sa_handler = &sigbus_handler;
 571     act.sa_flags = 0;
 572
 573     ret = sigaction(SIGBUS, &act, &oldact);
 574     if (ret) {
 575         error_setg_errno(errp, errno,
 576             "os_mem_prealloc: failed to install signal handler");
 577         return;
 578     }
 579
 580     /* touch pages simultaneously */
 581     if (touch_all_pages(area, hpagesize, numpages, smp_cpus)) {
 582         error_setg(errp, "os_mem_prealloc: Insufficient free host memory "
 583             "pages available to allocate guest RAM");
 584     }
 585
 586     ret = sigaction(SIGBUS, &oldact, NULL);
 587     if (ret) {
 588         /* Terminate QEMU since it can't recover from error */
 589         perror("os_mem_prealloc: failed to reinstall signal handler");
 590         exit(1);
 591     }
 592 }
 593
 594 char *qemu_get_pid_name(pid_t pid)
 595 {
 596     char *name = NULL;
 597
 598 #if defined(__FreeBSD__)
 599     /* BSDs don't have /proc, but they provide a nice substitute */
 600     struct kinfo_proc *proc = kinfo_getproc(pid);
 601
 602     if (proc) {
 603         name = g_strdup(proc->ki_comm);
 604         free(proc);
 605     }
 606 #else
 607     /* Assume a system with reasonable procfs */
 608     char *pid_path;
 609     size_t len;
 610
 611     pid_path = g_strdup_printf("/proc/%d/cmdline", pid);
 612     g_file_get_contents(pid_path, &name, &len, NULL);
 613     g_free(pid_path);
 614 #endif
 615
 616     return name;
 617 }
 618
 619
 620 pid_t qemu_fork(Error **errp)
 621 {
 622     sigset_t oldmask, newmask;
 623     struct sigaction sig_action;
 624     int saved_errno;
 625     pid_t pid;
 626
 627     /*
 628      * Need to block signals now, so that child process can safely
 629      * kill off caller's signal handlers without a race.
 630      */
 631     sigfillset(&newmask);
 632     if (pthread_sigmask(SIG_SETMASK, &newmask, &oldmask) != 0) {
 633         error_setg_errno(errp, errno,
 634                          "cannot block signals");
 635         return -1;
 636     }
 637
 638     pid = fork();
 639     saved_errno = errno;
 640
 641     if (pid < 0) {
 642         /* attempt to restore signal mask, but ignore failure, to
 643          * avoid obscuring the fork failure */
 644         (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
 645         error_setg_errno(errp, saved_errno,
 646                          "cannot fork child process");
 647         errno = saved_errno;
 648         return -1;
 649     } else if (pid) {
 650         /* parent process */
 651
 652         /* Restore our original signal mask now that the child is
 653          * safely running. Only documented failures are EFAULT (not
 654          * possible, since we are using just-grabbed mask) or EINVAL
 655          * (not possible, since we are using correct arguments).  */
 656         (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
 657     } else {
 658         /* child process */
 659         size_t i;
 660
 661         /* Clear out all signal handlers from parent so nothing
 662          * unexpected can happen in our child once we unblock
 663          * signals */
 664         sig_action.sa_handler = SIG_DFL;
 665         sig_action.sa_flags = 0;
 666         sigemptyset(&sig_action.sa_mask);
 667
 668         for (i = 1; i < NSIG; i++) {
 669             /* Only possible errors are EFAULT or EINVAL The former
 670              * won't happen, the latter we expect, so no need to check
 671              * return value */
 672             (void)sigaction(i, &sig_action, NULL);
 673         }
 674
 675         /* Unmask all signals in child, since we've no idea what the
 676          * caller's done with their signal mask and don't want to
 677          * propagate that to children */
 678         sigemptyset(&newmask);
 679         if (pthread_sigmask(SIG_SETMASK, &newmask, NULL) != 0) {
 680             Error *local_err = NULL;
 681             error_setg_errno(&local_err, errno,
 682                              "cannot unblock signals");
 683             error_report_err(local_err);
 684             _exit(1);
 685         }
 686     }
 687     return pid;
 688 }
 689
 690 void *qemu_alloc_stack(size_t *sz)
 691 {
 692     void *ptr, *guardpage;
 693     int flags;
 694 #ifdef CONFIG_DEBUG_STACK_USAGE
 695     void *ptr2;
 696 #endif
 697     size_t pagesz = qemu_real_host_page_size;
 698 #ifdef _SC_THREAD_STACK_MIN
 699     /* avoid stacks smaller than _SC_THREAD_STACK_MIN */
 700     long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN);
 701     *sz = MAX(MAX(min_stack_sz, 0), *sz);
 702 #endif
 703     /* adjust stack size to a multiple of the page size */
 704     *sz = ROUND_UP(*sz, pagesz);
 705     /* allocate one extra page for the guard page */
 706     *sz += pagesz;
 707
 708     flags = MAP_PRIVATE | MAP_ANONYMOUS;
 709 #if defined(MAP_STACK) && defined(__OpenBSD__)
 710     /* Only enable MAP_STACK on OpenBSD. Other OS's such as
 711      * Linux/FreeBSD/NetBSD have a flag with the same name
 712      * but have differing functionality. OpenBSD will SEGV
 713      * if it spots execution with a stack pointer pointing
 714      * at memory that was not allocated with MAP_STACK.
 715      */
 716     flags |= MAP_STACK;
 717 #endif
 718
 719     ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE, flags, -1, 0);
 720     if (ptr == MAP_FAILED) {
 721         perror("failed to allocate memory for stack");
 722         abort();
 723     }
 724
 725 #if defined(HOST_IA64)
 726     /* separate register stack */
 727     guardpage = ptr + (((*sz - pagesz) / 2) & ~pagesz);
 728 #elif defined(HOST_HPPA)
 729     /* stack grows up */
 730     guardpage = ptr + *sz - pagesz;
 731 #else
 732     /* stack grows down */
 733     guardpage = ptr;
 734 #endif
 735     if (mprotect(guardpage, pagesz, PROT_NONE) != 0) {
 736         perror("failed to set up stack guard page");
 737         abort();
 738     }
 739
 740 #ifdef CONFIG_DEBUG_STACK_USAGE
 741     for (ptr2 = ptr + pagesz; ptr2 < ptr + *sz; ptr2 += sizeof(uint32_t)) {
 742         *(uint32_t *)ptr2 = 0xdeadbeaf;
 743     }
 744 #endif
 745
 746     return ptr;
 747 }
 748
 749 #ifdef CONFIG_DEBUG_STACK_USAGE
 750 static __thread unsigned int max_stack_usage;
 751 #endif
 752
 753 void qemu_free_stack(void *stack, size_t sz)
 754 {
 755 #ifdef CONFIG_DEBUG_STACK_USAGE
 756     unsigned int usage;
 757     void *ptr;
 758
 759     for (ptr = stack + qemu_real_host_page_size; ptr < stack + sz;
 760          ptr += sizeof(uint32_t)) {
 761         if (*(uint32_t *)ptr != 0xdeadbeaf) {
 762             break;
 763         }
 764     }
 765     usage = sz - (uintptr_t) (ptr - stack);
 766     if (usage > max_stack_usage) {
 767         error_report("thread %d max stack usage increased from %u to %u",
 768                      qemu_get_thread_id(), max_stack_usage, usage);
 769         max_stack_usage = usage;
 770     }
 771 #endif
 772
 773     munmap(stack, sz);
 774 }
 775
 776 void sigaction_invoke(struct sigaction *action,
 777                       struct qemu_signalfd_siginfo *info)
 778 {
 779     siginfo_t si = {};
 780     si.si_signo = info->ssi_signo;
 781     si.si_errno = info->ssi_errno;
 782     si.si_code = info->ssi_code;
 783
 784     /* Convert the minimal set of fields defined by POSIX.
 785      * Positive si_code values are reserved for kernel-generated
 786      * signals, where the valid siginfo fields are determined by
 787      * the signal number.  But according to POSIX, it is unspecified
 788      * whether SI_USER and SI_QUEUE have values less than or equal to
 789      * zero.
 790      */
 791     if (info->ssi_code == SI_USER || info->ssi_code == SI_QUEUE ||
 792         info->ssi_code <= 0) {
 793         /* SIGTERM, etc.  */
 794         si.si_pid = info->ssi_pid;
 795         si.si_uid = info->ssi_uid;
 796     } else if (info->ssi_signo == SIGILL || info->ssi_signo == SIGFPE ||
 797                info->ssi_signo == SIGSEGV || info->ssi_signo == SIGBUS) {
 798         si.si_addr = (void *)(uintptr_t)info->ssi_addr;
 799     } else if (info->ssi_signo == SIGCHLD) {
 800         si.si_pid = info->ssi_pid;
 801         si.si_status = info->ssi_status;
 802         si.si_uid = info->ssi_uid;
 803     }
 804     action->sa_sigaction(info->ssi_signo, &si, NULL);
 805 }
 806
 807 #ifndef HOST_NAME_MAX
 808 # ifdef _POSIX_HOST_NAME_MAX
 809 #  define HOST_NAME_MAX _POSIX_HOST_NAME_MAX
 810 # else
 811 #  define HOST_NAME_MAX 255
 812 # endif
 813 #endif
 814
 815 char *qemu_get_host_name(Error **errp)
 816 {
 817     long len = -1;
 818     g_autofree char *hostname = NULL;
 819
 820 #ifdef _SC_HOST_NAME_MAX
 821     len = sysconf(_SC_HOST_NAME_MAX);
 822 #endif /* _SC_HOST_NAME_MAX */
 823
 824     if (len < 0) {
 825         len = HOST_NAME_MAX;
 826     }
 827
 828     /* Unfortunately, gethostname() below does not guarantee a
 829      * NULL terminated string. Therefore, allocate one byte more
 830      * to be sure. */
 831     hostname = g_new0(char, len + 1);
 832
 833     if (gethostname(hostname, len) < 0) {
 834         error_setg_errno(errp, errno,
 835                          "cannot get hostname");
 836         return NULL;
 837     }
 838
 839     return g_steal_pointer(&hostname);
 840 }
 841
 842 size_t qemu_get_host_physmem(void)
 843 {
 844 #ifdef _SC_PHYS_PAGES
 845     long pages = sysconf(_SC_PHYS_PAGES);
 846     if (pages > 0) {
 847         if (pages > SIZE_MAX / qemu_real_host_page_size) {
 848             return SIZE_MAX;
 849         } else {
 850             return pages * qemu_real_host_page_size;
 851         }
 852     }
 853 #endif
 854     return 0;
 855 }