/* * os-posix-lib.c * * Copyright (c) 2003-2008 Fabrice Bellard * Copyright (c) 2010 Red Hat, Inc. * * QEMU library functions on POSIX which are shared between QEMU and * the QEMU tools. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include "qemu/osdep.h" #include <termios.h> #include <glib/gprintf.h> #include "qemu-common.h" #include "sysemu/sysemu.h" #include "trace.h" #include "qapi/error.h" #include "qemu/sockets.h" #include "qemu/thread.h" #include <libgen.h> #include <sys/signal.h> #include "qemu/cutils.h" #ifdef CONFIG_LINUX #include <sys/syscall.h> #endif #ifdef __FreeBSD__ #include <sys/sysctl.h> #include <sys/user.h> #include <libutil.h> #endif #ifdef __NetBSD__ #include <sys/sysctl.h> #endif #include "qemu/mmap-alloc.h" #ifdef CONFIG_DEBUG_STACK_USAGE #include "qemu/error-report.h" #endif #define MAX_MEM_PREALLOC_THREAD_COUNT 16 struct MemsetThread { char *addr; size_t numpages; size_t hpagesize; QemuThread pgthread; sigjmp_buf env; }; typedef struct MemsetThread MemsetThread; static MemsetThread *memset_thread; static int memset_num_threads; static bool memset_thread_failed; int qemu_get_thread_id(void) { #if defined(__linux__) return syscall(SYS_gettid); #else return getpid(); #endif } int qemu_daemon(int nochdir, int noclose) { return daemon(nochdir, noclose); } bool qemu_write_pidfile(const char *path, Error **errp) { int fd; char pidstr[32]; while (1) { struct stat a, b; struct flock lock = { .l_type = F_WRLCK, .l_whence = SEEK_SET, .l_len = 0, }; fd = qemu_open(path, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR); if (fd == -1) { error_setg_errno(errp, errno, "Cannot open pid file"); return false; } if (fstat(fd, &b) < 0) { error_setg_errno(errp, errno, "Cannot stat file"); goto fail_close; } if (fcntl(fd, F_SETLK, &lock)) { error_setg_errno(errp, errno, "Cannot lock pid file"); goto fail_close; } /* * Now make sure the path we locked is the same one that now * exists on the filesystem. */ if (stat(path, &a) < 0) { /* * PID file disappeared, someone else must be racing with * us, so try again. */ close(fd); continue; } if (a.st_ino == b.st_ino) { break; } /* * PID file was recreated, someone else must be racing with * us, so try again. */ close(fd); } if (ftruncate(fd, 0) < 0) { error_setg_errno(errp, errno, "Failed to truncate pid file"); goto fail_unlink; } snprintf(pidstr, sizeof(pidstr), FMT_pid "\n", getpid()); if (write(fd, pidstr, strlen(pidstr)) != strlen(pidstr)) { error_setg(errp, "Failed to write pid file"); goto fail_unlink; } return true; fail_unlink: unlink(path); fail_close: close(fd); return false; } void *qemu_oom_check(void *ptr) { if (ptr == NULL) { fprintf(stderr, "Failed to allocate memory: %s\n", strerror(errno)); abort(); } return ptr; } void *qemu_try_memalign(size_t alignment, size_t size) { void *ptr; if (alignment < sizeof(void*)) { alignment = sizeof(void*); } #if defined(CONFIG_POSIX_MEMALIGN) int ret; ret = posix_memalign(&ptr, alignment, size); if (ret != 0) { errno = ret; ptr = NULL; } #elif defined(CONFIG_BSD) ptr = valloc(size); #else ptr = memalign(alignment, size); #endif trace_qemu_memalign(alignment, size, ptr); return ptr; } void *qemu_memalign(size_t alignment, size_t size) { return qemu_oom_check(qemu_try_memalign(alignment, size)); } /* alloc shared memory pages */ void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment, bool shared) { size_t align = QEMU_VMALLOC_ALIGN; void *ptr = qemu_ram_mmap(-1, size, align, shared, false); if (ptr == MAP_FAILED) { return NULL; } if (alignment) { *alignment = align; } trace_qemu_anon_ram_alloc(size, ptr); return ptr; } void qemu_vfree(void *ptr) { trace_qemu_vfree(ptr); free(ptr); } void qemu_anon_ram_free(void *ptr, size_t size) { trace_qemu_anon_ram_free(ptr, size); qemu_ram_munmap(-1, ptr, size); } void qemu_set_block(int fd) { int f; f = fcntl(fd, F_GETFL); assert(f != -1); f = fcntl(fd, F_SETFL, f & ~O_NONBLOCK); assert(f != -1); } void qemu_set_nonblock(int fd) { int f; f = fcntl(fd, F_GETFL); assert(f != -1); f = fcntl(fd, F_SETFL, f | O_NONBLOCK); #ifdef __OpenBSD__ if (f == -1) { /* * Previous to OpenBSD 6.3, fcntl(F_SETFL) is not permitted on * memory devices and sets errno to ENODEV. * It's OK if we fail to set O_NONBLOCK on devices like /dev/null, * because they will never block anyway. */ assert(errno == ENODEV); } #else assert(f != -1); #endif } int socket_set_fast_reuse(int fd) { int val = 1, ret; ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (const char *)&val, sizeof(val)); assert(ret == 0); return ret; } void qemu_set_cloexec(int fd) { int f; f = fcntl(fd, F_GETFD); assert(f != -1); f = fcntl(fd, F_SETFD, f | FD_CLOEXEC); assert(f != -1); } /* * Creates a pipe with FD_CLOEXEC set on both file descriptors */ int qemu_pipe(int pipefd[2]) { int ret; #ifdef CONFIG_PIPE2 ret = pipe2(pipefd, O_CLOEXEC); if (ret != -1 || errno != ENOSYS) { return ret; } #endif ret = pipe(pipefd); if (ret == 0) { qemu_set_cloexec(pipefd[0]); qemu_set_cloexec(pipefd[1]); } return ret; } char * qemu_get_local_state_pathname(const char *relative_pathname) { return g_strdup_printf("%s/%s", CONFIG_QEMU_LOCALSTATEDIR, relative_pathname); } void qemu_set_tty_echo(int fd, bool echo) { struct termios tty; tcgetattr(fd, &tty); if (echo) { tty.c_lflag |= ECHO | ECHONL | ICANON | IEXTEN; } else { tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN); } tcsetattr(fd, TCSANOW, &tty); } static char exec_dir[PATH_MAX]; void qemu_init_exec_dir(const char *argv0) { char *dir; char *p = NULL; char buf[PATH_MAX]; assert(!exec_dir[0]); #if defined(__linux__) { int len; len = readlink("/proc/self/exe", buf, sizeof(buf) - 1); if (len > 0) { buf[len] = 0; p = buf; } } #elif defined(__FreeBSD__) \ || (defined(__NetBSD__) && defined(KERN_PROC_PATHNAME)) { #if defined(__FreeBSD__) static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1}; #else static int mib[4] = {CTL_KERN, KERN_PROC_ARGS, -1, KERN_PROC_PATHNAME}; #endif size_t len = sizeof(buf) - 1; *buf = '\0'; if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) && *buf) { buf[sizeof(buf) - 1] = '\0'; p = buf; } } #endif /* If we don't have any way of figuring out the actual executable location then try argv[0]. */ if (!p) { if (!argv0) { return; } p = realpath(argv0, buf); if (!p) { return; } } dir = g_path_get_dirname(p); pstrcpy(exec_dir, sizeof(exec_dir), dir); g_free(dir); } char *qemu_get_exec_dir(void) { return g_strdup(exec_dir); } static void sigbus_handler(int signal) { int i; if (memset_thread) { for (i = 0; i < memset_num_threads; i++) { if (qemu_thread_is_self(&memset_thread[i].pgthread)) { siglongjmp(memset_thread[i].env, 1); } } } } static void *do_touch_pages(void *arg) { MemsetThread *memset_args = (MemsetThread *)arg; sigset_t set, oldset; /* unblock SIGBUS */ sigemptyset(&set); sigaddset(&set, SIGBUS); pthread_sigmask(SIG_UNBLOCK, &set, &oldset); if (sigsetjmp(memset_args->env, 1)) { memset_thread_failed = true; } else { char *addr = memset_args->addr; size_t numpages = memset_args->numpages; size_t hpagesize = memset_args->hpagesize; size_t i; for (i = 0; i < numpages; i++) { /* * Read & write back the same value, so we don't * corrupt existing user/app data that might be * stored. * * 'volatile' to stop compiler optimizing this away * to a no-op * * TODO: get a better solution from kernel so we * don't need to write at all so we don't cause * wear on the storage backing the region... */ *(volatile char *)addr = *addr; addr += hpagesize; } } pthread_sigmask(SIG_SETMASK, &oldset, NULL); return NULL; } static inline int get_memset_num_threads(int smp_cpus) { long host_procs = sysconf(_SC_NPROCESSORS_ONLN); int ret = 1; if (host_procs > 0) { ret = MIN(MIN(host_procs, MAX_MEM_PREALLOC_THREAD_COUNT), smp_cpus); } /* In case sysconf() fails, we fall back to single threaded */ return ret; } static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages, int smp_cpus) { size_t numpages_per_thread; size_t size_per_thread; char *addr = area; int i = 0; memset_thread_failed = false; memset_num_threads = get_memset_num_threads(smp_cpus); memset_thread = g_new0(MemsetThread, memset_num_threads); numpages_per_thread = (numpages / memset_num_threads); size_per_thread = (hpagesize * numpages_per_thread); for (i = 0; i < memset_num_threads; i++) { memset_thread[i].addr = addr; memset_thread[i].numpages = (i == (memset_num_threads - 1)) ? numpages : numpages_per_thread; memset_thread[i].hpagesize = hpagesize; qemu_thread_create(&memset_thread[i].pgthread, "touch_pages", do_touch_pages, &memset_thread[i], QEMU_THREAD_JOINABLE); addr += size_per_thread; numpages -= numpages_per_thread; } for (i = 0; i < memset_num_threads; i++) { qemu_thread_join(&memset_thread[i].pgthread); } g_free(memset_thread); memset_thread = NULL; return memset_thread_failed; } void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus, Error **errp) { int ret; struct sigaction act, oldact; size_t hpagesize = qemu_fd_getpagesize(fd); size_t numpages = DIV_ROUND_UP(memory, hpagesize); memset(&act, 0, sizeof(act)); act.sa_handler = &sigbus_handler; act.sa_flags = 0; ret = sigaction(SIGBUS, &act, &oldact); if (ret) { error_setg_errno(errp, errno, "os_mem_prealloc: failed to install signal handler"); return; } /* touch pages simultaneously */ if (touch_all_pages(area, hpagesize, numpages, smp_cpus)) { error_setg(errp, "os_mem_prealloc: Insufficient free host memory " "pages available to allocate guest RAM"); } ret = sigaction(SIGBUS, &oldact, NULL); if (ret) { /* Terminate QEMU since it can't recover from error */ perror("os_mem_prealloc: failed to reinstall signal handler"); exit(1); } } char *qemu_get_pid_name(pid_t pid) { char *name = NULL; #if defined(__FreeBSD__) /* BSDs don't have /proc, but they provide a nice substitute */ struct kinfo_proc *proc = kinfo_getproc(pid); if (proc) { name = g_strdup(proc->ki_comm); free(proc); } #else /* Assume a system with reasonable procfs */ char *pid_path; size_t len; pid_path = g_strdup_printf("/proc/%d/cmdline", pid); g_file_get_contents(pid_path, &name, &len, NULL); g_free(pid_path); #endif return name; } pid_t qemu_fork(Error **errp) { sigset_t oldmask, newmask; struct sigaction sig_action; int saved_errno; pid_t pid; /* * Need to block signals now, so that child process can safely * kill off caller's signal handlers without a race. */ sigfillset(&newmask); if (pthread_sigmask(SIG_SETMASK, &newmask, &oldmask) != 0) { error_setg_errno(errp, errno, "cannot block signals"); return -1; } pid = fork(); saved_errno = errno; if (pid < 0) { /* attempt to restore signal mask, but ignore failure, to * avoid obscuring the fork failure */ (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL); error_setg_errno(errp, saved_errno, "cannot fork child process"); errno = saved_errno; return -1; } else if (pid) { /* parent process */ /* Restore our original signal mask now that the child is * safely running. Only documented failures are EFAULT (not * possible, since we are using just-grabbed mask) or EINVAL * (not possible, since we are using correct arguments). */ (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL); } else { /* child process */ size_t i; /* Clear out all signal handlers from parent so nothing * unexpected can happen in our child once we unblock * signals */ sig_action.sa_handler = SIG_DFL; sig_action.sa_flags = 0; sigemptyset(&sig_action.sa_mask); for (i = 1; i < NSIG; i++) { /* Only possible errors are EFAULT or EINVAL The former * won't happen, the latter we expect, so no need to check * return value */ (void)sigaction(i, &sig_action, NULL); } /* Unmask all signals in child, since we've no idea what the * caller's done with their signal mask and don't want to * propagate that to children */ sigemptyset(&newmask); if (pthread_sigmask(SIG_SETMASK, &newmask, NULL) != 0) { Error *local_err = NULL; error_setg_errno(&local_err, errno, "cannot unblock signals"); error_report_err(local_err); _exit(1); } } return pid; } void *qemu_alloc_stack(size_t *sz) { void *ptr, *guardpage; int flags; #ifdef CONFIG_DEBUG_STACK_USAGE void *ptr2; #endif size_t pagesz = qemu_real_host_page_size; #ifdef _SC_THREAD_STACK_MIN /* avoid stacks smaller than _SC_THREAD_STACK_MIN */ long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN); *sz = MAX(MAX(min_stack_sz, 0), *sz); #endif /* adjust stack size to a multiple of the page size */ *sz = ROUND_UP(*sz, pagesz); /* allocate one extra page for the guard page */ *sz += pagesz; flags = MAP_PRIVATE | MAP_ANONYMOUS; #if defined(MAP_STACK) && defined(__OpenBSD__) /* Only enable MAP_STACK on OpenBSD. Other OS's such as * Linux/FreeBSD/NetBSD have a flag with the same name * but have differing functionality. OpenBSD will SEGV * if it spots execution with a stack pointer pointing * at memory that was not allocated with MAP_STACK. */ flags |= MAP_STACK; #endif ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE, flags, -1, 0); if (ptr == MAP_FAILED) { perror("failed to allocate memory for stack"); abort(); } #if defined(HOST_IA64) /* separate register stack */ guardpage = ptr + (((*sz - pagesz) / 2) & ~pagesz); #elif defined(HOST_HPPA) /* stack grows up */ guardpage = ptr + *sz - pagesz; #else /* stack grows down */ guardpage = ptr; #endif if (mprotect(guardpage, pagesz, PROT_NONE) != 0) { perror("failed to set up stack guard page"); abort(); } #ifdef CONFIG_DEBUG_STACK_USAGE for (ptr2 = ptr + pagesz; ptr2 < ptr + *sz; ptr2 += sizeof(uint32_t)) { *(uint32_t *)ptr2 = 0xdeadbeaf; } #endif return ptr; } #ifdef CONFIG_DEBUG_STACK_USAGE static __thread unsigned int max_stack_usage; #endif void qemu_free_stack(void *stack, size_t sz) { #ifdef CONFIG_DEBUG_STACK_USAGE unsigned int usage; void *ptr; for (ptr = stack + qemu_real_host_page_size; ptr < stack + sz; ptr += sizeof(uint32_t)) { if (*(uint32_t *)ptr != 0xdeadbeaf) { break; } } usage = sz - (uintptr_t) (ptr - stack); if (usage > max_stack_usage) { error_report("thread %d max stack usage increased from %u to %u", qemu_get_thread_id(), max_stack_usage, usage); max_stack_usage = usage; } #endif munmap(stack, sz); } void sigaction_invoke(struct sigaction *action, struct qemu_signalfd_siginfo *info) { siginfo_t si = {}; si.si_signo = info->ssi_signo; si.si_errno = info->ssi_errno; si.si_code = info->ssi_code; /* Convert the minimal set of fields defined by POSIX. * Positive si_code values are reserved for kernel-generated * signals, where the valid siginfo fields are determined by * the signal number. But according to POSIX, it is unspecified * whether SI_USER and SI_QUEUE have values less than or equal to * zero. */ if (info->ssi_code == SI_USER || info->ssi_code == SI_QUEUE || info->ssi_code <= 0) { /* SIGTERM, etc. */ si.si_pid = info->ssi_pid; si.si_uid = info->ssi_uid; } else if (info->ssi_signo == SIGILL || info->ssi_signo == SIGFPE || info->ssi_signo == SIGSEGV || info->ssi_signo == SIGBUS) { si.si_addr = (void *)(uintptr_t)info->ssi_addr; } else if (info->ssi_signo == SIGCHLD) { si.si_pid = info->ssi_pid; si.si_status = info->ssi_status; si.si_uid = info->ssi_uid; } action->sa_sigaction(info->ssi_signo, &si, NULL); }