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