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