Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 860 insertions, 0 deletions

diff --git a/util/oslib-posix.c b/util/oslib-posix.c
new file mode 100644
index 000000000..e8bdb02e1
--- /dev/null
+++ b/util/oslib-posix.c
@@ -0,0 +1,860 @@
+/*
+ * 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 "qemu/cutils.h"
+#include "qemu/compiler.h"
+
+#ifdef CONFIG_LINUX
+#include <sys/syscall.h>
+#endif
+
+#ifdef __FreeBSD__
+#include <sys/sysctl.h>
+#include <sys/user.h>
+#include <sys/thr.h>
+#include <libutil.h>
+#endif
+
+#ifdef __NetBSD__
+#include <sys/sysctl.h>
+#include <lwp.h>
+#endif
+
+#ifdef __APPLE__
+#include <mach-o/dyld.h>
+#endif
+
+#ifdef __HAIKU__
+#include <kernel/image.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;
+
+static QemuMutex page_mutex;
+static QemuCond page_cond;
+static bool threads_created_flag;
+
+int qemu_get_thread_id(void)
+{
+#if defined(__linux__)
+    return syscall(SYS_gettid);
+#elif defined(__FreeBSD__)
+    /* thread id is up to INT_MAX */
+    long tid;
+    thr_self(&tid);
+    return (int)tid;
+#elif defined(__NetBSD__)
+    return _lwp_self();
+#elif defined(__OpenBSD__)
+    return getthrid();
+#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_old(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*);
+    } else {
+        g_assert(is_power_of_2(alignment));
+    }
+
+#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,
+                          bool noreserve)
+{
+    const uint32_t qemu_map_flags = (shared ? QEMU_MAP_SHARED : 0) |
+                                    (noreserve ? QEMU_MAP_NORESERVE : 0);
+    size_t align = QEMU_VMALLOC_ALIGN;
+    void *ptr = qemu_ram_mmap(-1, size, align, qemu_map_flags, 0);
+
+    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);
+}
+
+int qemu_try_set_nonblock(int fd)
+{
+    int f;
+    f = fcntl(fd, F_GETFL);
+    if (f == -1) {
+        return -errno;
+    }
+    if (fcntl(fd, F_SETFL, f | O_NONBLOCK) == -1) {
+        return -errno;
+    }
+    return 0;
+}
+
+void qemu_set_nonblock(int fd)
+{
+    int f;
+    f = qemu_try_set_nonblock(fd);
+    assert(f == 0);
+}
+
+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)
+{
+    g_autofree char *dir = g_strdup_printf("%s/%s",
+                                           CONFIG_QEMU_LOCALSTATEDIR,
+                                           relative_pathname);
+    return get_relocated_path(dir);
+}
+
+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 const char *exec_dir;
+
+void qemu_init_exec_dir(const char *argv0)
+{
+    char *p = NULL;
+    char buf[PATH_MAX];
+
+    if (exec_dir) {
+        return;
+    }
+
+#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;
+        }
+    }
+#elif defined(__APPLE__)
+    {
+        char fpath[PATH_MAX];
+        uint32_t len = sizeof(fpath);
+        if (_NSGetExecutablePath(fpath, &len) == 0) {
+            p = realpath(fpath, buf);
+            if (!p) {
+                return;
+            }
+        }
+    }
+#elif defined(__HAIKU__)
+    {
+        image_info ii;
+        int32_t c = 0;
+
+        *buf = '\0';
+        while (get_next_image_info(0, &c, &ii) == B_OK) {
+            if (ii.type == B_APP_IMAGE) {
+                strncpy(buf, ii.name, sizeof(buf));
+                buf[sizeof(buf) - 1] = 0;
+                p = buf;
+                break;
+            }
+        }
+    }
+#endif
+    /* If we don't have any way of figuring out the actual executable
+       location then try argv[0].  */
+    if (!p && argv0) {
+        p = realpath(argv0, buf);
+    }
+    if (p) {
+        exec_dir = g_path_get_dirname(p);
+    } else {
+        exec_dir = CONFIG_BINDIR;
+    }
+}
+
+const char *qemu_get_exec_dir(void)
+{
+    return 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;
+
+    /*
+     * On Linux, the page faults from the loop below can cause mmap_sem
+     * contention with allocation of the thread stacks.  Do not start
+     * clearing until all threads have been created.
+     */
+    qemu_mutex_lock(&page_mutex);
+    while(!threads_created_flag){
+        qemu_cond_wait(&page_cond, &page_mutex);
+    }
+    qemu_mutex_unlock(&page_mutex);
+
+    /* 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)
+{
+    static gsize initialized = 0;
+    size_t numpages_per_thread, leftover;
+    char *addr = area;
+    int i = 0;
+
+    if (g_once_init_enter(&initialized)) {
+        qemu_mutex_init(&page_mutex);
+        qemu_cond_init(&page_cond);
+        g_once_init_leave(&initialized, 1);
+    }
+
+    memset_thread_failed = false;
+    threads_created_flag = 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;
+    leftover = numpages % memset_num_threads;
+    for (i = 0; i < memset_num_threads; i++) {
+        memset_thread[i].addr = addr;
+        memset_thread[i].numpages = numpages_per_thread + (i < leftover);
+        memset_thread[i].hpagesize = hpagesize;
+        qemu_thread_create(&memset_thread[i].pgthread, "touch_pages",
+                           do_touch_pages, &memset_thread[i],
+                           QEMU_THREAD_JOINABLE);
+        addr += memset_thread[i].numpages * hpagesize;
+    }
+
+    qemu_mutex_lock(&page_mutex);
+    threads_created_flag = true;
+    qemu_cond_broadcast(&page_cond);
+    qemu_mutex_unlock(&page_mutex);
+
+    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);
+}
+
+/*
+ * Disable CFI checks.
+ * We are going to call a signal hander directly. Such handler may or may not
+ * have been defined in our binary, so there's no guarantee that the pointer
+ * used to set the handler is a cfi-valid pointer. Since the handlers are
+ * stored in kernel memory, changing the handler to an attacker-defined
+ * function requires being able to call a sigaction() syscall,
+ * which is not as easy as overwriting a pointer in memory.
+ */
+QEMU_DISABLE_CFI
+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);
+}
+
+#ifndef HOST_NAME_MAX
+# ifdef _POSIX_HOST_NAME_MAX
+#  define HOST_NAME_MAX _POSIX_HOST_NAME_MAX
+# else
+#  define HOST_NAME_MAX 255
+# endif
+#endif
+
+char *qemu_get_host_name(Error **errp)
+{
+    long len = -1;
+    g_autofree char *hostname = NULL;
+
+#ifdef _SC_HOST_NAME_MAX
+    len = sysconf(_SC_HOST_NAME_MAX);
+#endif /* _SC_HOST_NAME_MAX */
+
+    if (len < 0) {
+        len = HOST_NAME_MAX;
+    }
+
+    /* Unfortunately, gethostname() below does not guarantee a
+     * NULL terminated string. Therefore, allocate one byte more
+     * to be sure. */
+    hostname = g_new0(char, len + 1);
+
+    if (gethostname(hostname, len) < 0) {
+        error_setg_errno(errp, errno,
+                         "cannot get hostname");
+        return NULL;
+    }
+
+    return g_steal_pointer(&hostname);
+}
+
+size_t qemu_get_host_physmem(void)
+{
+#ifdef _SC_PHYS_PAGES
+    long pages = sysconf(_SC_PHYS_PAGES);
+    if (pages > 0) {
+        if (pages > SIZE_MAX / qemu_real_host_page_size) {
+            return SIZE_MAX;
+        } else {
+            return pages * qemu_real_host_page_size;
+        }
+    }
+#endif
+    return 0;
+}