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