xen: introduce new 'XenBus' and 'XenDevice' object hierarchy
[qemu.git] / util / oslib-posix.c
blobc1bee2a581429bbe4e4a808b42415b2e52b776e1
1 /*
2 * os-posix-lib.c
4 * Copyright (c) 2003-2008 Fabrice Bellard
5 * Copyright (c) 2010 Red Hat, Inc.
7 * QEMU library functions on POSIX which are shared between QEMU and
8 * the QEMU tools.
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:
17 * The above copyright notice and this permission notice shall be included in
18 * all copies or substantial portions of the Software.
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.
29 #include "qemu/osdep.h"
30 #include <termios.h>
32 #include <glib/gprintf.h>
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"
42 #ifdef CONFIG_LINUX
43 #include <sys/syscall.h>
44 #endif
46 #ifdef __FreeBSD__
47 #include <sys/sysctl.h>
48 #include <sys/user.h>
49 #include <libutil.h>
50 #endif
52 #ifdef __NetBSD__
53 #include <sys/sysctl.h>
54 #endif
56 #include "qemu/mmap-alloc.h"
58 #ifdef CONFIG_DEBUG_STACK_USAGE
59 #include "qemu/error-report.h"
60 #endif
62 #define MAX_MEM_PREALLOC_THREAD_COUNT 16
64 struct MemsetThread {
65 char *addr;
66 size_t numpages;
67 size_t hpagesize;
68 QemuThread pgthread;
69 sigjmp_buf env;
71 typedef struct MemsetThread MemsetThread;
73 static MemsetThread *memset_thread;
74 static int memset_num_threads;
75 static bool memset_thread_failed;
77 int qemu_get_thread_id(void)
79 #if defined(__linux__)
80 return syscall(SYS_gettid);
81 #else
82 return getpid();
83 #endif
86 int qemu_daemon(int nochdir, int noclose)
88 return daemon(nochdir, noclose);
91 bool qemu_write_pidfile(const char *path, Error **errp)
93 int fd;
94 char pidstr[32];
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,
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;
110 if (fstat(fd, &b) < 0) {
111 error_setg_errno(errp, errno, "Cannot stat file");
112 goto fail_close;
115 if (fcntl(fd, F_SETLK, &lock)) {
116 error_setg_errno(errp, errno, "Cannot lock pid file");
117 goto fail_close;
121 * Now make sure the path we locked is the same one that now
122 * exists on the filesystem.
124 if (stat(path, &a) < 0) {
126 * PID file disappeared, someone else must be racing with
127 * us, so try again.
129 close(fd);
130 continue;
133 if (a.st_ino == b.st_ino) {
134 break;
138 * PID file was recreated, someone else must be racing with
139 * us, so try again.
141 close(fd);
144 if (ftruncate(fd, 0) < 0) {
145 error_setg_errno(errp, errno, "Failed to truncate pid file");
146 goto fail_unlink;
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;
155 return true;
157 fail_unlink:
158 unlink(path);
159 fail_close:
160 close(fd);
161 return false;
164 void *qemu_oom_check(void *ptr)
166 if (ptr == NULL) {
167 fprintf(stderr, "Failed to allocate memory: %s\n", strerror(errno));
168 abort();
170 return ptr;
173 void *qemu_try_memalign(size_t alignment, size_t size)
175 void *ptr;
177 if (alignment < sizeof(void*)) {
178 alignment = sizeof(void*);
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;
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;
197 void *qemu_memalign(size_t alignment, size_t size)
199 return qemu_oom_check(qemu_try_memalign(alignment, size));
202 /* alloc shared memory pages */
203 void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment, bool shared)
205 size_t align = QEMU_VMALLOC_ALIGN;
206 void *ptr = qemu_ram_mmap(-1, size, align, shared);
208 if (ptr == MAP_FAILED) {
209 return NULL;
212 if (alignment) {
213 *alignment = align;
216 trace_qemu_anon_ram_alloc(size, ptr);
217 return ptr;
220 void qemu_vfree(void *ptr)
222 trace_qemu_vfree(ptr);
223 free(ptr);
226 void qemu_anon_ram_free(void *ptr, size_t size)
228 trace_qemu_anon_ram_free(ptr, size);
229 qemu_ram_munmap(ptr, size);
232 void qemu_set_block(int fd)
234 int f;
235 f = fcntl(fd, F_GETFL);
236 fcntl(fd, F_SETFL, f & ~O_NONBLOCK);
239 void qemu_set_nonblock(int fd)
241 int f;
242 f = fcntl(fd, F_GETFL);
243 fcntl(fd, F_SETFL, f | O_NONBLOCK);
246 int socket_set_fast_reuse(int fd)
248 int val = 1, ret;
250 ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
251 (const char *)&val, sizeof(val));
253 assert(ret == 0);
255 return ret;
258 void qemu_set_cloexec(int fd)
260 int f;
261 f = fcntl(fd, F_GETFD);
262 assert(f != -1);
263 f = fcntl(fd, F_SETFD, f | FD_CLOEXEC);
264 assert(f != -1);
268 * Creates a pipe with FD_CLOEXEC set on both file descriptors
270 int qemu_pipe(int pipefd[2])
272 int ret;
274 #ifdef CONFIG_PIPE2
275 ret = pipe2(pipefd, O_CLOEXEC);
276 if (ret != -1 || errno != ENOSYS) {
277 return ret;
279 #endif
280 ret = pipe(pipefd);
281 if (ret == 0) {
282 qemu_set_cloexec(pipefd[0]);
283 qemu_set_cloexec(pipefd[1]);
286 return ret;
289 char *
290 qemu_get_local_state_pathname(const char *relative_pathname)
292 return g_strdup_printf("%s/%s", CONFIG_QEMU_LOCALSTATEDIR,
293 relative_pathname);
296 void qemu_set_tty_echo(int fd, bool echo)
298 struct termios tty;
300 tcgetattr(fd, &tty);
302 if (echo) {
303 tty.c_lflag |= ECHO | ECHONL | ICANON | IEXTEN;
304 } else {
305 tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
308 tcsetattr(fd, TCSANOW, &tty);
311 static char exec_dir[PATH_MAX];
313 void qemu_init_exec_dir(const char *argv0)
315 char *dir;
316 char *p = NULL;
317 char buf[PATH_MAX];
319 assert(!exec_dir[0]);
321 #if defined(__linux__)
323 int len;
324 len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
325 if (len > 0) {
326 buf[len] = 0;
327 p = buf;
330 #elif defined(__FreeBSD__) \
331 || (defined(__NetBSD__) && defined(KERN_PROC_PATHNAME))
333 #if defined(__FreeBSD__)
334 static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
335 #else
336 static int mib[4] = {CTL_KERN, KERN_PROC_ARGS, -1, KERN_PROC_PATHNAME};
337 #endif
338 size_t len = sizeof(buf) - 1;
340 *buf = '\0';
341 if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
342 *buf) {
343 buf[sizeof(buf) - 1] = '\0';
344 p = buf;
347 #endif
348 /* If we don't have any way of figuring out the actual executable
349 location then try argv[0]. */
350 if (!p) {
351 if (!argv0) {
352 return;
354 p = realpath(argv0, buf);
355 if (!p) {
356 return;
359 dir = g_path_get_dirname(p);
361 pstrcpy(exec_dir, sizeof(exec_dir), dir);
363 g_free(dir);
366 char *qemu_get_exec_dir(void)
368 return g_strdup(exec_dir);
371 static void sigbus_handler(int signal)
373 int i;
374 if (memset_thread) {
375 for (i = 0; i < memset_num_threads; i++) {
376 if (qemu_thread_is_self(&memset_thread[i].pgthread)) {
377 siglongjmp(memset_thread[i].env, 1);
383 static void *do_touch_pages(void *arg)
385 MemsetThread *memset_args = (MemsetThread *)arg;
386 sigset_t set, oldset;
388 /* unblock SIGBUS */
389 sigemptyset(&set);
390 sigaddset(&set, SIGBUS);
391 pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
393 if (sigsetjmp(memset_args->env, 1)) {
394 memset_thread_failed = true;
395 } else {
396 char *addr = memset_args->addr;
397 size_t numpages = memset_args->numpages;
398 size_t hpagesize = memset_args->hpagesize;
399 size_t i;
400 for (i = 0; i < numpages; i++) {
402 * Read & write back the same value, so we don't
403 * corrupt existing user/app data that might be
404 * stored.
406 * 'volatile' to stop compiler optimizing this away
407 * to a no-op
409 * TODO: get a better solution from kernel so we
410 * don't need to write at all so we don't cause
411 * wear on the storage backing the region...
413 *(volatile char *)addr = *addr;
414 addr += hpagesize;
417 pthread_sigmask(SIG_SETMASK, &oldset, NULL);
418 return NULL;
421 static inline int get_memset_num_threads(int smp_cpus)
423 long host_procs = sysconf(_SC_NPROCESSORS_ONLN);
424 int ret = 1;
426 if (host_procs > 0) {
427 ret = MIN(MIN(host_procs, MAX_MEM_PREALLOC_THREAD_COUNT), smp_cpus);
429 /* In case sysconf() fails, we fall back to single threaded */
430 return ret;
433 static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages,
434 int smp_cpus)
436 size_t numpages_per_thread;
437 size_t size_per_thread;
438 char *addr = area;
439 int i = 0;
441 memset_thread_failed = false;
442 memset_num_threads = get_memset_num_threads(smp_cpus);
443 memset_thread = g_new0(MemsetThread, memset_num_threads);
444 numpages_per_thread = (numpages / memset_num_threads);
445 size_per_thread = (hpagesize * numpages_per_thread);
446 for (i = 0; i < memset_num_threads; i++) {
447 memset_thread[i].addr = addr;
448 memset_thread[i].numpages = (i == (memset_num_threads - 1)) ?
449 numpages : numpages_per_thread;
450 memset_thread[i].hpagesize = hpagesize;
451 qemu_thread_create(&memset_thread[i].pgthread, "touch_pages",
452 do_touch_pages, &memset_thread[i],
453 QEMU_THREAD_JOINABLE);
454 addr += size_per_thread;
455 numpages -= numpages_per_thread;
457 for (i = 0; i < memset_num_threads; i++) {
458 qemu_thread_join(&memset_thread[i].pgthread);
460 g_free(memset_thread);
461 memset_thread = NULL;
463 return memset_thread_failed;
466 void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
467 Error **errp)
469 int ret;
470 struct sigaction act, oldact;
471 size_t hpagesize = qemu_fd_getpagesize(fd);
472 size_t numpages = DIV_ROUND_UP(memory, hpagesize);
474 memset(&act, 0, sizeof(act));
475 act.sa_handler = &sigbus_handler;
476 act.sa_flags = 0;
478 ret = sigaction(SIGBUS, &act, &oldact);
479 if (ret) {
480 error_setg_errno(errp, errno,
481 "os_mem_prealloc: failed to install signal handler");
482 return;
485 /* touch pages simultaneously */
486 if (touch_all_pages(area, hpagesize, numpages, smp_cpus)) {
487 error_setg(errp, "os_mem_prealloc: Insufficient free host memory "
488 "pages available to allocate guest RAM");
491 ret = sigaction(SIGBUS, &oldact, NULL);
492 if (ret) {
493 /* Terminate QEMU since it can't recover from error */
494 perror("os_mem_prealloc: failed to reinstall signal handler");
495 exit(1);
500 char *qemu_get_pid_name(pid_t pid)
502 char *name = NULL;
504 #if defined(__FreeBSD__)
505 /* BSDs don't have /proc, but they provide a nice substitute */
506 struct kinfo_proc *proc = kinfo_getproc(pid);
508 if (proc) {
509 name = g_strdup(proc->ki_comm);
510 free(proc);
512 #else
513 /* Assume a system with reasonable procfs */
514 char *pid_path;
515 size_t len;
517 pid_path = g_strdup_printf("/proc/%d/cmdline", pid);
518 g_file_get_contents(pid_path, &name, &len, NULL);
519 g_free(pid_path);
520 #endif
522 return name;
526 pid_t qemu_fork(Error **errp)
528 sigset_t oldmask, newmask;
529 struct sigaction sig_action;
530 int saved_errno;
531 pid_t pid;
534 * Need to block signals now, so that child process can safely
535 * kill off caller's signal handlers without a race.
537 sigfillset(&newmask);
538 if (pthread_sigmask(SIG_SETMASK, &newmask, &oldmask) != 0) {
539 error_setg_errno(errp, errno,
540 "cannot block signals");
541 return -1;
544 pid = fork();
545 saved_errno = errno;
547 if (pid < 0) {
548 /* attempt to restore signal mask, but ignore failure, to
549 * avoid obscuring the fork failure */
550 (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
551 error_setg_errno(errp, saved_errno,
552 "cannot fork child process");
553 errno = saved_errno;
554 return -1;
555 } else if (pid) {
556 /* parent process */
558 /* Restore our original signal mask now that the child is
559 * safely running. Only documented failures are EFAULT (not
560 * possible, since we are using just-grabbed mask) or EINVAL
561 * (not possible, since we are using correct arguments). */
562 (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
563 } else {
564 /* child process */
565 size_t i;
567 /* Clear out all signal handlers from parent so nothing
568 * unexpected can happen in our child once we unblock
569 * signals */
570 sig_action.sa_handler = SIG_DFL;
571 sig_action.sa_flags = 0;
572 sigemptyset(&sig_action.sa_mask);
574 for (i = 1; i < NSIG; i++) {
575 /* Only possible errors are EFAULT or EINVAL The former
576 * won't happen, the latter we expect, so no need to check
577 * return value */
578 (void)sigaction(i, &sig_action, NULL);
581 /* Unmask all signals in child, since we've no idea what the
582 * caller's done with their signal mask and don't want to
583 * propagate that to children */
584 sigemptyset(&newmask);
585 if (pthread_sigmask(SIG_SETMASK, &newmask, NULL) != 0) {
586 Error *local_err = NULL;
587 error_setg_errno(&local_err, errno,
588 "cannot unblock signals");
589 error_report_err(local_err);
590 _exit(1);
593 return pid;
596 void *qemu_alloc_stack(size_t *sz)
598 void *ptr, *guardpage;
599 int flags;
600 #ifdef CONFIG_DEBUG_STACK_USAGE
601 void *ptr2;
602 #endif
603 size_t pagesz = getpagesize();
604 #ifdef _SC_THREAD_STACK_MIN
605 /* avoid stacks smaller than _SC_THREAD_STACK_MIN */
606 long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN);
607 *sz = MAX(MAX(min_stack_sz, 0), *sz);
608 #endif
609 /* adjust stack size to a multiple of the page size */
610 *sz = ROUND_UP(*sz, pagesz);
611 /* allocate one extra page for the guard page */
612 *sz += pagesz;
614 flags = MAP_PRIVATE | MAP_ANONYMOUS;
615 #if defined(MAP_STACK) && defined(__OpenBSD__)
616 /* Only enable MAP_STACK on OpenBSD. Other OS's such as
617 * Linux/FreeBSD/NetBSD have a flag with the same name
618 * but have differing functionality. OpenBSD will SEGV
619 * if it spots execution with a stack pointer pointing
620 * at memory that was not allocated with MAP_STACK.
622 flags |= MAP_STACK;
623 #endif
625 ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE, flags, -1, 0);
626 if (ptr == MAP_FAILED) {
627 perror("failed to allocate memory for stack");
628 abort();
631 #if defined(HOST_IA64)
632 /* separate register stack */
633 guardpage = ptr + (((*sz - pagesz) / 2) & ~pagesz);
634 #elif defined(HOST_HPPA)
635 /* stack grows up */
636 guardpage = ptr + *sz - pagesz;
637 #else
638 /* stack grows down */
639 guardpage = ptr;
640 #endif
641 if (mprotect(guardpage, pagesz, PROT_NONE) != 0) {
642 perror("failed to set up stack guard page");
643 abort();
646 #ifdef CONFIG_DEBUG_STACK_USAGE
647 for (ptr2 = ptr + pagesz; ptr2 < ptr + *sz; ptr2 += sizeof(uint32_t)) {
648 *(uint32_t *)ptr2 = 0xdeadbeaf;
650 #endif
652 return ptr;
655 #ifdef CONFIG_DEBUG_STACK_USAGE
656 static __thread unsigned int max_stack_usage;
657 #endif
659 void qemu_free_stack(void *stack, size_t sz)
661 #ifdef CONFIG_DEBUG_STACK_USAGE
662 unsigned int usage;
663 void *ptr;
665 for (ptr = stack + getpagesize(); ptr < stack + sz;
666 ptr += sizeof(uint32_t)) {
667 if (*(uint32_t *)ptr != 0xdeadbeaf) {
668 break;
671 usage = sz - (uintptr_t) (ptr - stack);
672 if (usage > max_stack_usage) {
673 error_report("thread %d max stack usage increased from %u to %u",
674 qemu_get_thread_id(), max_stack_usage, usage);
675 max_stack_usage = usage;
677 #endif
679 munmap(stack, sz);
682 void sigaction_invoke(struct sigaction *action,
683 struct qemu_signalfd_siginfo *info)
685 siginfo_t si = {};
686 si.si_signo = info->ssi_signo;
687 si.si_errno = info->ssi_errno;
688 si.si_code = info->ssi_code;
690 /* Convert the minimal set of fields defined by POSIX.
691 * Positive si_code values are reserved for kernel-generated
692 * signals, where the valid siginfo fields are determined by
693 * the signal number. But according to POSIX, it is unspecified
694 * whether SI_USER and SI_QUEUE have values less than or equal to
695 * zero.
697 if (info->ssi_code == SI_USER || info->ssi_code == SI_QUEUE ||
698 info->ssi_code <= 0) {
699 /* SIGTERM, etc. */
700 si.si_pid = info->ssi_pid;
701 si.si_uid = info->ssi_uid;
702 } else if (info->ssi_signo == SIGILL || info->ssi_signo == SIGFPE ||
703 info->ssi_signo == SIGSEGV || info->ssi_signo == SIGBUS) {
704 si.si_addr = (void *)(uintptr_t)info->ssi_addr;
705 } else if (info->ssi_signo == SIGCHLD) {
706 si.si_pid = info->ssi_pid;
707 si.si_status = info->ssi_status;
708 si.si_uid = info->ssi_uid;
710 action->sa_sigaction(info->ssi_signo, &si, NULL);