criu/cr-restore.c

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <limits.h>
#include <unistd.h>
#include <errno.h>
#include <dirent.h>
#include <string.h>

#include <fcntl.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/vfs.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <sys/file.h>
#include <sys/shm.h>
#include <sys/mount.h>

#include <sched.h>

#include <sys/sendfile.h>

#include "compiler.h"
#include "types.h"

#include "image.h"
#include "util.h"
#include "log.h"
#include "syscall.h"
#include "restorer.h"
#include "sockets.h"
#include "sk-packet.h"
#include "lock.h"
#include "files.h"
#include "files-reg.h"
#include "pipes.h"
#include "fifo.h"
#include "sk-inet.h"
#include "eventfd.h"
#include "eventpoll.h"
#include "signalfd.h"
#include "proc_parse.h"
#include "restorer-blob.h"
#include "crtools.h"
#include "namespaces.h"
#include "shmem.h"
#include "mount.h"
#include "inotify.h"
#include "pstree.h"
#include "net.h"
#include "tty.h"

#include "protobuf.h"
#include "protobuf/sa.pb-c.h"
#include "protobuf/itimer.pb-c.h"
#include "protobuf/vma.pb-c.h"

static struct pstree_item *current;

static int restore_task_with_children(void *);
static int sigreturn_restore(pid_t pid, CoreEntry *core, struct list_head *vmas, int nr_vmas);
static int prepare_restorer_blob(void);

static int shmem_remap(void *old_addr, void *new_addr, unsigned long size)
{
	void *ret;

	ret = mremap(old_addr, size, size,
			MREMAP_FIXED | MREMAP_MAYMOVE, new_addr);
	if (new_addr != ret) {
		pr_perror("mremap failed");
		return -1;
	}

	return 0;
}

static int prepare_shared(void)
{
	int ret = 0;
	struct pstree_item *pi;

	pr_info("Preparing info about shared resources\n");

	if (prepare_shmem_restore())
		return -1;

	if (prepare_shared_fdinfo())
		return -1;

	if (prepare_shared_tty())
		return -1;


	if (collect_reg_files())
		return -1;

	if (collect_pipes())
		return -1;

	if (collect_fifo())
		return -1;

	if (collect_inet_sockets())
		return -1;

	if (collect_unix_sockets())
		return -1;

	if (collect_packet_sockets())
		return -1;

	if (collect_eventfd())
		return -1;

	if (collect_eventpoll())
		return -1;

	if (collect_signalfd())
		return -1;

	if (collect_inotify())
		return -1;

	if (collect_tty())
		return -1;

	for_each_pstree_item(pi) {
		if (pi->state == TASK_HELPER)
			continue;

		ret = prepare_shmem_pid(pi->pid.virt);
		if (ret < 0)
			break;

		ret = prepare_fd_pid(pi->pid.virt, pi->rst);
		if (ret < 0)
			break;

		ret = prepare_ctl_tty(pi->pid.virt, pi->rst, pi->ctl_tty_id);
		if (ret < 0)
			break;
	}

	if (ret < 0)
		goto err;

	mark_pipe_master();

	ret = tty_setup_orphan_slavery(&opts);
	if (ret)
		goto err;

	ret = resolve_unix_peers();
	if (ret)
		goto err;

	ret = prepare_restorer_blob();
	if (ret)
		goto err;

	show_saved_shmems();
	show_saved_files();
err:
	return ret;
}

static int read_and_open_vmas(int pid, struct list_head *vmas, int *nr_vmas)
{
	int fd, ret = -1;

	fd = open_image_ro(CR_FD_VMAS, pid);
	if (fd < 0)
		return fd;

	*nr_vmas = 0;
	while (1) {
		struct vma_area *vma;
		VmaEntry *e;

		ret = -1;
		vma = alloc_vma_area();
		if (!vma)
			break;

		(*nr_vmas)++;
		list_add_tail(&vma->list, vmas);
		ret = pb_read_one_eof(fd, &e, PB_VMAS);
		if (ret <= 0)
			break;

		if (e->fd != -1) {
			ret = -1;
			pr_err("Error in vma->fd setting (%Ld)\n",
					(unsigned long long)e->fd);
			break;
		}

		vma->vma = *e;
		vma_entry__free_unpacked(e, NULL);

		if (!(vma_entry_is(&vma->vma, VMA_AREA_REGULAR)))
			continue;

		pr_info("Opening 0x%016lx-0x%016lx 0x%016lx vma\n",
				vma->vma.start, vma->vma.end, vma->vma.pgoff);

		if (vma_entry_is(&vma->vma, VMA_AREA_SYSVIPC))
			ret = vma->vma.shmid;
		else if (vma_entry_is(&vma->vma, VMA_ANON_SHARED))
			ret = get_shmem_fd(pid, &vma->vma);
		else if (vma_entry_is(&vma->vma, VMA_FILE_PRIVATE) ||
				vma_entry_is(&vma->vma, VMA_FILE_SHARED))
			ret = get_filemap_fd(pid, &vma->vma);
		else
			continue;

		if (ret < 0) {
			pr_err("Can't fixup fd\n");
			break;
		}

		vma->vma.fd = ret;
	}

	close(fd);
	return ret;
}

static int prepare_and_sigreturn(int pid, CoreEntry *core)
{
	int err, nr_vmas;
	LIST_HEAD(vma_list);

	err = read_and_open_vmas(pid, &vma_list, &nr_vmas);
	if (err)
		return err;

	return sigreturn_restore(pid, core, &vma_list, nr_vmas);
}

static rt_sigaction_t sigchld_act;
static int prepare_sigactions(int pid)
{
	rt_sigaction_t act, oact;
	int fd_sigact;
	SaEntry *e;
	int sig;
	int ret = -1;

	fd_sigact = open_image_ro(CR_FD_SIGACT, pid);
	if (fd_sigact < 0)
		return -1;

	for (sig = 1; sig < SIGMAX; sig++) {
		if (sig == SIGKILL || sig == SIGSTOP)
			continue;

		ret = pb_read_one(fd_sigact, &e, PB_SIGACT);
		if (ret < 0)
			break;

		ASSIGN_TYPED(act.rt_sa_handler, e->sigaction);
		ASSIGN_TYPED(act.rt_sa_flags, e->flags);
		ASSIGN_TYPED(act.rt_sa_restorer, e->restorer);
		ASSIGN_TYPED(act.rt_sa_mask.sig[0], e->mask);

		sa_entry__free_unpacked(e, NULL);

		if (sig == SIGCHLD) {
			sigchld_act = act;
			continue;
		}
		/*
		 * A pure syscall is used, because glibc
		 * sigaction overwrites se_restorer.
		 */
		ret = sys_sigaction(sig, &act, &oact, sizeof(rt_sigset_t));
		if (ret == -1) {
			pr_err("%d: Can't restore sigaction: %m\n", pid);
			goto err;
		}
	}

err:
	close_safe(&fd_sigact);
	return ret;
}

static int pstree_wait_helpers()
{
	struct pstree_item *pi;

	list_for_each_entry(pi, &current->children, list) {
		int status, ret;

		if (pi->state != TASK_HELPER)
			continue;

		/* Check, that a helper completed. */
		ret = waitpid(pi->pid.virt, &status, 0);
		if (ret == -1) {
			if (errno == ECHILD)
				continue; /* It has been waited in sigchld_handler */
			pr_err("waitpid(%d) failed\n", pi->pid.virt);
			return -1;
		}
		if (!WIFEXITED(status) || WEXITSTATUS(status)) {
			pr_err("%d exited with non-zero code (%d,%d)", pi->pid.virt,
				WEXITSTATUS(status), WTERMSIG(status));
			return -1;
		}

	}

	return 0;
}


static int restore_one_alive_task(int pid, CoreEntry *core)
{
	pr_info("Restoring resources\n");

	if (pstree_wait_helpers())
		return -1;

	if (prepare_fds(current))
		return -1;

	if (prepare_fs(pid))
		return -1;

	if (prepare_sigactions(pid))
		return -1;

	log_closedir();

	return prepare_and_sigreturn(pid, core);
}

static void zombie_prepare_signals(void)
{
	sigset_t blockmask;
	int sig;
	struct sigaction act;

	sigfillset(&blockmask);
	sigprocmask(SIG_UNBLOCK, &blockmask, NULL);

	memset(&act, 0, sizeof(act));
	act.sa_handler = SIG_DFL;

	for (sig = 1; sig < SIGMAX; sig++)
		sigaction(sig, &act, NULL);
}

#define SIG_FATAL_MASK	(	\
		(1 << SIGHUP)	|\
		(1 << SIGINT)	|\
		(1 << SIGQUIT)	|\
		(1 << SIGILL)	|\
		(1 << SIGTRAP)	|\
		(1 << SIGABRT)	|\
		(1 << SIGIOT)	|\
		(1 << SIGBUS)	|\
		(1 << SIGFPE)	|\
		(1 << SIGKILL)	|\
		(1 << SIGUSR1)	|\
		(1 << SIGSEGV)	|\
		(1 << SIGUSR2)	|\
		(1 << SIGPIPE)	|\
		(1 << SIGALRM)	|\
		(1 << SIGTERM)	|\
		(1 << SIGXCPU)	|\
		(1 << SIGXFSZ)	|\
		(1 << SIGVTALRM)|\
		(1 << SIGPROF)	|\
		(1 << SIGPOLL)	|\
		(1 << SIGIO)	|\
		(1 << SIGSYS)	|\
		(1 << SIGUNUSED)|\
		(1 << SIGSTKFLT)|\
		(1 << SIGPWR)	 \
	)

static inline int sig_fatal(int sig)
{
	return (sig > 0) && (sig < SIGMAX) && (SIG_FATAL_MASK & (1 << sig));
}

struct task_entries *task_entries;

static int restore_one_fake(int pid)
{
	/* We should wait here, otherwise last_pid will be changed. */
	futex_wait_while(&task_entries->start, CR_STATE_FORKING);
	futex_wait_while(&task_entries->start, CR_STATE_RESTORE_PGID);
	return 0;
}

static int restore_one_zombie(int pid, int exit_code)
{
	pr_info("Restoring zombie with %d code\n", exit_code);

	if (task_entries != NULL) {
		futex_dec_and_wake(&task_entries->nr_in_progress);
		futex_wait_while(&task_entries->start, CR_STATE_RESTORE);

		zombie_prepare_signals();

		futex_dec_and_wake(&task_entries->nr_in_progress);
		futex_wait_while(&task_entries->start, CR_STATE_RESTORE_SIGCHLD);
	}

	if (exit_code & 0x7f) {
		int signr;

		signr = exit_code & 0x7F;
		if (!sig_fatal(signr)) {
			pr_warn("Exit with non fatal signal ignored\n");
			signr = SIGABRT;
		}

		if (kill(pid, signr) < 0)
			pr_perror("Can't kill myself, will just exit");

		exit_code = 0;
	}

	exit((exit_code >> 8) & 0x7f);

	/* never reached */
	BUG_ON(1);
	return -1;
}

static int check_core(int pid, CoreEntry *core)
{
	int fd = -1, ret = -1;

	fd = open_image_ro(CR_FD_CORE, pid);
	if (fd < 0)
		return -1;

	if (core->mtype != CORE_ENTRY__MARCH__X86_64) {
		pr_err("Core march mismatch %d\n", (int)core->mtype);
		goto out;
	}

	if (!core->tc) {
		pr_err("Core task state data missed\n");
		goto out;
	}

	if (!core->ids && core->tc->task_state != TASK_DEAD) {
		pr_err("Core IDS data missed for non-zombie\n");
		goto out;
	}

	ret = 0;
out:
	close_safe(&fd);
	return ret < 0 ? ret : 0;
}

static int restore_one_task(int pid)
{
	int fd, ret;
	CoreEntry *core;

	if (current->state == TASK_HELPER)
		return restore_one_fake(pid);

	fd = open_image_ro(CR_FD_CORE, pid);
	if (fd < 0)
		return -1;

	ret = pb_read_one(fd, &core, PB_CORE);
	close(fd);

	if (ret < 0)
		return -1;

	if (check_core(pid, core)) {
		ret = -1;
		goto out;
	}

	switch ((int)core->tc->task_state) {
	case TASK_ALIVE:
		ret = restore_one_alive_task(pid, core);
		break;
	case TASK_DEAD:
		ret = restore_one_zombie(pid, core->tc->exit_code);
		break;
	default:
		pr_err("Unknown state in code %d\n", (int)core->tc->task_state);
		ret = -1;
		break;
	}

out:
	core_entry__free_unpacked(core, NULL);
	return ret;
}

/* All arguments should be above stack, because it grows down */
struct cr_clone_arg {
	char stack[PAGE_SIZE];
	char stack_ptr[0];
	struct pstree_item *item;
	unsigned long clone_flags;
	int fd;
};

static inline int fork_with_pid(struct pstree_item *item, unsigned long ns_clone_flags)
{
	int ret = -1;
	struct cr_clone_arg ca;
	pid_t pid = item->pid.virt;

	pr_info("Forking task with %d pid (flags 0x%lx)\n", pid, ns_clone_flags);

	ca.item = item;
	ca.clone_flags = ns_clone_flags;

	if (!(ca.clone_flags & CLONE_NEWPID)) {
		char buf[32];

		ca.fd = open(LAST_PID_PATH, O_RDWR);
		if (ca.fd < 0) {
			pr_perror("%d: Can't open %s", pid, LAST_PID_PATH);
			goto err;
		}

		if (flock(ca.fd, LOCK_EX)) {
			close(ca.fd);
			pr_perror("%d: Can't lock %s", pid, LAST_PID_PATH);
			goto err;
		}

		snprintf(buf, sizeof(buf), "%d", pid - 1);
		if (write_img_buf(ca.fd, buf, strlen(buf)))
			goto err_unlock;
	} else {
		ca.fd = -1;
		BUG_ON(pid != 1);
	}

	if (ca.clone_flags & CLONE_NEWNET)
		/*
		 * When restoring a net namespace we need to communicate
		 * with the original (i.e. -- init) one. Thus, prepare for
		 * that before we leave the existing namespaces.
		 */
		if (netns_pre_create())
			goto err_unlock;

	ret = clone(restore_task_with_children, ca.stack_ptr,
			ca.clone_flags | SIGCHLD, &ca);

	if (ret < 0)
		pr_perror("Can't fork for %d", pid);

	if (ca.clone_flags & CLONE_NEWPID)
		item->pid.real = ret;

	if (opts.pidfile && root_item == item) {
		int fd;

		fd = open(opts.pidfile, O_WRONLY | O_TRUNC | O_CREAT, 0600);
		if (fd == -1) {
			pr_perror("Can't open %s", opts.pidfile);
			kill(ret, SIGKILL);
		} else {
			dprintf(fd, "%d", ret);
			close(fd);
		}
	}

err_unlock:
	if (ca.fd >= 0) {
		if (flock(ca.fd, LOCK_UN))
			pr_perror("%d: Can't unlock %s", pid, LAST_PID_PATH);

		close(ca.fd);
	}
err:
	return ret;
}

static void sigchld_handler(int signal, siginfo_t *siginfo, void *data)
{
	struct pstree_item *pi;
	pid_t pid = siginfo->si_pid;
	int status;
	int exit;

	exit = siginfo->si_code & CLD_EXITED;
	status = siginfo->si_status;
	if (!current || status)
		goto err;

	/* Skip a helper if it was completed successfully */
	while (pid) {
		pid = waitpid(-1, &status, WNOHANG);
		if (pid <= 0)
			return;

		exit = WIFEXITED(status);
		status = exit ? WEXITSTATUS(status) : WTERMSIG(status);
		if (status)
			break;

		list_for_each_entry(pi, &current->children, list) {
			if (pi->state != TASK_HELPER)
				continue;
			if (pi->pid.virt == siginfo->si_pid)
				break;
		}

		if (&pi->list == &current->children)
			break; /* The process is not a helper */
	}

err:
	if (exit)
		pr_err("%d exited, status=%d\n", pid, status);
	else
		pr_err("%d killed by signal %d\n", pid, status);

	futex_abort_and_wake(&task_entries->nr_in_progress);
}

/*
 * FIXME Din't fail on xid restore failure. MySQL uses runaway
 * pgid and sid and there's nothing we can do about it yet :(
 */

static void xid_fail(void)
{
	exit(1);
}

static void restore_sid(void)
{
	pid_t sid;

	/*
	 * SID can only be reset to pid or inherited from parent.
	 * Thus we restore it right here to let our kids inherit
	 * one in case they need it.
	 *
	 * PGIDs are restored late when all tasks are forked and
	 * we can call setpgid() on custom values.
	 */

	if (current->pid.virt == current->sid) {
		pr_info("Restoring %d to %d sid\n", current->pid.virt, current->sid);
		sid = setsid();
		if (sid != current->sid) {
			pr_perror("Can't restore sid (%d)", sid);
			xid_fail();
		}
	} else {
		sid = getsid(getpid());
		if (sid != current->sid) {
			/* Skip the root task if it's not init */
			if (current == root_item && root_item->pid.virt != 1)
				return;
			pr_err("Requested sid %d doesn't match inherited %d\n",
					current->sid, sid);
			xid_fail();
		}
	}
}

static void restore_pgid(void)
{
	pid_t pgid;

	pr_info("Restoring %d to %d pgid\n", current->pid.virt, current->pgid);

	pgid = getpgrp();
	if (current->pgid == pgid)
		return;

	pr_info("\twill call setpgid, mine pgid is %d\n", pgid);
	if (setpgid(0, current->pgid) != 0) {
		pr_perror("Can't restore pgid (%d/%d->%d)", current->pid.virt, pgid, current->pgid);
		xid_fail();
	}
}

static int mount_proc(void)
{
	int ret;
	char proc_mountpoint[PATH_MAX];

	snprintf(proc_mountpoint, sizeof(proc_mountpoint), "crtools-proc.XXXXXX");
	if (mkdtemp(proc_mountpoint) == NULL) {
		pr_perror("mkdtemp failed %s", proc_mountpoint);
		return -1;
	}

	pr_info("Mount procfs in %s\n", proc_mountpoint);
	if (mount("proc", proc_mountpoint, "proc", MS_MGC_VAL, NULL)) {
		pr_perror("mount failed");
		ret = -1;
		goto out_rmdir;
	}

	ret = set_proc_mountpoint(proc_mountpoint);

	if (umount2(proc_mountpoint, MNT_DETACH) == -1) {
		pr_perror("Can't umount %s", proc_mountpoint);
		return -1;
	}

out_rmdir:
	if (rmdir(proc_mountpoint) == -1) {
		pr_perror("Can't remove %s", proc_mountpoint);
		return -1;
	}

	return ret;
}

static int restore_task_with_children(void *_arg)
{
	struct cr_clone_arg *ca = _arg;
	struct pstree_item *child;
	pid_t pid;
	int ret;
	sigset_t blockmask;

	close_safe(&ca->fd);

	current = ca->item;

	pid = getpid();
	if (current->pid.virt != pid) {
		pr_err("Pid %d do not match expected %d\n", pid, current->pid.virt);
		exit(-1);
	}

	ret = log_init_by_pid();
	if (ret < 0)
		exit(1);

	/* Restore root task */
	if (current->parent == NULL) {
		if (collect_mount_info())
			exit(-1);

		if (prepare_namespace(current->pid.virt, ca->clone_flags))
			exit(-1);

		/*
		 * We need non /proc proc mount for restoring pid and mount
		 * namespaces and do not care for the rest of the cases.
		 * Thus -- mount proc at custom location for any new namespace
		 */
		if (mount_proc())
			exit(-1);

		if (prepare_shared())
			exit(-1);
	}

	/*
	 * The block mask will be restored in sigresturn.
	 *
	 * TODO: This code should be removed, when a freezer will be added.
	 */
	sigfillset(&blockmask);
	sigdelset(&blockmask, SIGCHLD);
	ret = sigprocmask(SIG_BLOCK, &blockmask, NULL);
	if (ret) {
		pr_perror("%d: Can't block signals", current->pid.virt);
		exit(1);
	}

	pr_info("Restoring children:\n");
	list_for_each_entry(child, &current->children, list) {
		if (!restore_before_setsid(child))
			continue;

		BUG_ON(child->born_sid != -1 && getsid(getpid()) != child->born_sid);

		ret = fork_with_pid(child, 0);
		if (ret < 0)
			exit(1);
	}

	restore_sid();

	pr_info("Restoring children:\n");
	list_for_each_entry(child, &current->children, list) {
		if (restore_before_setsid(child))
			continue;
		ret = fork_with_pid(child, 0);
		if (ret < 0)
			exit(1);
	}

	if (current->pgid == current->pid.virt)
		restore_pgid();

	futex_dec_and_wake(&task_entries->nr_in_progress);
	futex_wait_while(&task_entries->start, CR_STATE_FORKING);

	if (current->pgid != current->pid.virt)
		restore_pgid();

	if (current->state != TASK_HELPER) {
		futex_dec_and_wake(&task_entries->nr_in_progress);
		futex_wait_while(&task_entries->start, CR_STATE_RESTORE_PGID);
	}

	return restore_one_task(current->pid.virt);
}

static int restore_root_task(struct pstree_item *init, struct cr_options *opts)
{
	int ret;
	struct sigaction act, old_act;

	ret = sigaction(SIGCHLD, NULL, &act);
	if (ret < 0) {
		pr_perror("sigaction() failed\n");
		return -1;
	}

	act.sa_flags |= SA_NOCLDSTOP | SA_SIGINFO | SA_RESTART;
	act.sa_sigaction = sigchld_handler;
	sigemptyset(&act.sa_mask);
	sigaddset(&act.sa_mask, SIGCHLD);

	ret = sigaction(SIGCHLD, &act, &old_act);
	if (ret < 0) {
		pr_perror("sigaction() failed\n");
		return -1;
	}

	/*
	 * FIXME -- currently we assume that all the tasks live
	 * in the same set of namespaces. This is done to debug
	 * the ns contents dumping/restoring. Need to revisit
	 * this later.
	 */

	if (init->pid.virt == 1) {
		if (!(opts->namespaces_flags & CLONE_NEWPID)) {
			pr_err("This process tree can be restored in a new pid namespace.\n");
			pr_err("crtools should be re-executed with --namespace pid\n");
			return -1;
		}
	} else	if (opts->namespaces_flags & CLONE_NEWPID) {
		pr_err("Can't restore pid namespace without the process init\n");
		return -1;
	}


	ret = fork_with_pid(init, opts->namespaces_flags);
	if (ret < 0)
		return -1;

	pr_info("Wait until all tasks are forked\n");
	futex_wait_while_gt(&task_entries->nr_in_progress, 0);
	ret = (int)futex_get(&task_entries->nr_in_progress);
	if (ret < 0)
		goto out;

	futex_set_and_wake(&task_entries->nr_in_progress, task_entries->nr_tasks);
	futex_set_and_wake(&task_entries->start, CR_STATE_RESTORE_PGID);

	pr_info("Wait until all tasks restored pgid\n");
	futex_wait_while_gt(&task_entries->nr_in_progress, 0);
	ret = (int)futex_get(&task_entries->nr_in_progress);
	if (ret < 0)
		goto out;

	futex_set_and_wake(&task_entries->nr_in_progress, task_entries->nr);
	futex_set_and_wake(&task_entries->start, CR_STATE_RESTORE);

	pr_info("Wait until all tasks are restored\n");
	futex_wait_while_gt(&task_entries->nr_in_progress, 0);
	ret = (int)futex_get(&task_entries->nr_in_progress);

out:
	if (ret < 0) {
		struct pstree_item *pi;
		pr_err("Someone can't be restored\n");

		if (opts->namespaces_flags & CLONE_NEWPID) {
			/* Kill init */
			if (root_item->pid.real > 0)
				kill(root_item->pid.real, SIGKILL);
		} else {
			for_each_pstree_item(pi)
				if (pi->pid.virt > 0)
					kill(pi->pid.virt, SIGKILL);
		}
		return 1;
	}

	futex_set_and_wake(&task_entries->nr_in_progress, task_entries->nr);
	futex_set_and_wake(&task_entries->start, CR_STATE_RESTORE_SIGCHLD);
	futex_wait_until(&task_entries->nr_in_progress, 0);

	ret = sigaction(SIGCHLD, &old_act, NULL);
	if (ret < 0) {
		pr_perror("sigaction() failed\n");
		return -1;
	}

	tcp_unlock_connections();

	pr_info("Go on!!!\n");
	futex_set_and_wake(&task_entries->start, CR_STATE_COMPLETE);

	if (!opts->restore_detach)
		wait(NULL);
	return 0;
}

static int prepare_task_entries()
{
	task_entries = mmap(NULL, TASK_ENTRIES_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, 0, 0);
	if (task_entries == MAP_FAILED) {
		pr_perror("Can't map shmem");
		return -1;
	}
	task_entries->nr = 0;
	task_entries->nr_tasks = 0;
	task_entries->nr_helpers = 0;
	futex_set(&task_entries->start, CR_STATE_FORKING);

	return 0;
}

int cr_restore_tasks(pid_t pid, struct cr_options *opts)
{
	if (check_img_inventory() < 0)
		return -1;

	if (prepare_task_entries() < 0)
		return -1;

	if (prepare_pstree() < 0)
		return -1;

	if (prepare_pstree_ids() < 0)
		return -1;

	futex_set(&task_entries->nr_in_progress, task_entries->nr_tasks + task_entries->nr_helpers);

	return restore_root_task(root_item, opts);
}

#define TASK_SIZE_MAX   ((1UL << 47) - PAGE_SIZE)
static long restorer_get_vma_hint(pid_t pid, struct list_head *tgt_vma_list,
		struct list_head *self_vma_list, long vma_len)
{
	struct vma_area *t_vma, *s_vma;
	long prev_vma_end = 0;
	struct vma_area end_vma;

	end_vma.vma.start = end_vma.vma.end = TASK_SIZE_MAX;
	prev_vma_end = PAGE_SIZE;

	/*
	 * Here we need some heuristics -- the VMA which restorer will
	 * belong to should not be unmapped, so we need to gueess out
	 * where to put it in.
	 */

	s_vma = list_first_entry(self_vma_list, struct vma_area, list);
	t_vma = list_first_entry(tgt_vma_list, struct vma_area, list);

	while (1) {
		if (prev_vma_end + vma_len > s_vma->vma.start) {
			if (s_vma->list.next == self_vma_list) {
				s_vma = &end_vma;
				continue;
			}
			if (s_vma == &end_vma)
				break;
			if (prev_vma_end < s_vma->vma.end)
				prev_vma_end = s_vma->vma.end;
			s_vma = list_entry(s_vma->list.next, struct vma_area, list);
			continue;
		}

		if (prev_vma_end + vma_len > t_vma->vma.start) {
			if (t_vma->list.next == tgt_vma_list) {
				t_vma = &end_vma;
				continue;
			}
			if (t_vma == &end_vma)
				break;
			if (prev_vma_end < t_vma->vma.end)
				prev_vma_end = t_vma->vma.end;
			t_vma = list_entry(t_vma->list.next, struct vma_area, list);
			continue;
		}

		return prev_vma_end;
	}

	return -1;
}

#define USEC_PER_SEC	1000000L

static inline int timeval_valid(struct timeval *tv)
{
	return (tv->tv_sec >= 0) && ((unsigned long)tv->tv_usec < USEC_PER_SEC);
}

static inline int itimer_restore_and_fix(char *n, ItimerEntry *ie,
		struct itimerval *val)
{
	if (ie->isec == 0 && ie->iusec == 0) {
		memzero_p(val);
		return 0;
	}

	val->it_interval.tv_sec = ie->isec;
	val->it_interval.tv_usec = ie->iusec;

	if (!timeval_valid(&val->it_interval)) {
		pr_err("Invalid timer interval\n");
		return -1;
	}

	if (ie->vsec == 0 && ie->vusec == 0) {
		/*
		 * Remaining time was too short. Set it to
		 * interval to make the timer armed and work.
		 */
		val->it_value.tv_sec = ie->isec;
		val->it_value.tv_usec = ie->iusec;
	} else {
		val->it_value.tv_sec = ie->vsec;
		val->it_value.tv_usec = ie->vusec;
	}

	if (!timeval_valid(&val->it_value)) {
		pr_err("Invalid timer value\n");
		return -1;
	}

	pr_info("Restored %s timer to %ld.%ld -> %ld.%ld\n", n,
			val->it_value.tv_sec, val->it_value.tv_usec,
			val->it_interval.tv_sec, val->it_interval.tv_usec);

	return 0;
}

static int prepare_itimers(int pid, struct task_restore_core_args *args)
{
	int fd, ret = -1;
	ItimerEntry *ie;

	fd = open_image_ro(CR_FD_ITIMERS, pid);
	if (fd < 0)
		return fd;

	ret = pb_read_one(fd, &ie, PB_ITIMERS);
	if (ret < 0)
		goto out;
	ret = itimer_restore_and_fix("real", ie, &args->itimers[0]);
	itimer_entry__free_unpacked(ie, NULL);
	if (ret < 0)
		goto out;

	ret = pb_read_one(fd, &ie, PB_ITIMERS);
	if (ret < 0)
		goto out;
	ret = itimer_restore_and_fix("virt", ie, &args->itimers[1]);
	itimer_entry__free_unpacked(ie, NULL);
	if (ret < 0)
		goto out;

	ret = pb_read_one(fd, &ie, PB_ITIMERS);
	if (ret < 0)
		goto out;
	ret = itimer_restore_and_fix("prof", ie, &args->itimers[2]);
	itimer_entry__free_unpacked(ie, NULL);
	if (ret < 0)
		goto out;
out:
	close_safe(&fd);
	return ret;
}

static inline int verify_cap_size(CredsEntry *ce)
{
	return ((ce->n_cap_inh == CR_CAP_SIZE) && (ce->n_cap_eff == CR_CAP_SIZE) &&
		(ce->n_cap_prm == CR_CAP_SIZE) && (ce->n_cap_bnd == CR_CAP_SIZE));
}

static int prepare_creds(int pid, struct task_restore_core_args *args)
{
	int fd, ret;
	CredsEntry *ce;

	fd = open_image_ro(CR_FD_CREDS, pid);
	if (fd < 0)
		return fd;

	ret = pb_read_one(fd, &ce, PB_CREDS);
	close_safe(&fd);

	if (ret < 0)
		return ret;
	if (!verify_cap_size(ce))
		return -1;

	args->creds = *ce;
	args->creds.cap_inh = args->cap_inh;
	memcpy(args->cap_inh, ce->cap_inh, sizeof(args->cap_inh));
	args->creds.cap_eff = args->cap_eff;
	memcpy(args->cap_eff, ce->cap_eff, sizeof(args->cap_eff));
	args->creds.cap_prm = args->cap_prm;
	memcpy(args->cap_prm, ce->cap_prm, sizeof(args->cap_prm));
	args->creds.cap_bnd = args->cap_bnd;
	memcpy(args->cap_bnd, ce->cap_bnd, sizeof(args->cap_bnd));

	creds_entry__free_unpacked(ce, NULL);

	/* XXX -- validate creds here? */

	return 0;
}

static VmaEntry *vma_list_remap(void *addr, unsigned long len, struct list_head *vmas)
{
	VmaEntry *vma, *ret;
	struct vma_area *vma_area;

	ret = vma = mmap(addr, len, PROT_READ | PROT_WRITE,
			MAP_PRIVATE | MAP_ANON | MAP_FIXED, 0, 0);
	if (vma != addr) {
		pr_perror("Can't remap vma area");
		return NULL;
	}

	list_for_each_entry(vma_area, vmas, list) {
		*vma = vma_area->vma;
		vma++;
	}

	vma->start = 0;
	free_mappings(vmas);

	return ret;
}

static int prepare_mm(pid_t pid, struct task_restore_core_args *args)
{
	int fd, exe_fd, ret = -1;
	MmEntry *mm;

	fd = open_image_ro(CR_FD_MM, pid);
	if (fd < 0)
		return -1;

	if (pb_read_one(fd, &mm, PB_MM) < 0)
		return -1;

	args->mm = *mm;
	args->mm.n_mm_saved_auxv = 0;
	args->mm.mm_saved_auxv = NULL;

	if (mm->n_mm_saved_auxv != AT_VECTOR_SIZE) {
		pr_err("Image corrupted on pid %d\n", pid);
		goto out;
	}

	memcpy(args->mm_saved_auxv, mm->mm_saved_auxv,
	       pb_repeated_size(mm, mm_saved_auxv));

	exe_fd = open_reg_by_id(args->mm.exe_file_id);
	if (exe_fd < 0)
		goto out;

	args->fd_exe_link = exe_fd;
	ret = 0;
out:
	mm_entry__free_unpacked(mm, NULL);
	close(fd);
	return ret;
}

static void *restorer;
static unsigned long restorer_len;

static int prepare_restorer_blob(void)
{
	/*
	 * We map anonymous mapping, not mremap the restorer itself later.
	 * Otherwise the resoter vma would be tied to crtools binary which 
	 * in turn will lead to set-exe-file prctl to fail with EBUSY.
	 */

	restorer_len = round_up(sizeof(restorer_blob), PAGE_SIZE);
	restorer = mmap(NULL, restorer_len,
			PROT_READ | PROT_WRITE | PROT_EXEC,
			MAP_PRIVATE | MAP_ANON, 0, 0);
	if (restorer == MAP_FAILED) {
		pr_err("Can't map restorer code");
		return -1;
	}

	memcpy(restorer, &restorer_blob, sizeof(restorer_blob));
	return 0;
}

static int remap_restorer_blob(void *addr)
{
	void *mem;

	mem = mremap(restorer, restorer_len, restorer_len,
			MREMAP_FIXED | MREMAP_MAYMOVE, addr);
	if (mem != addr) {
		pr_perror("Can't remap restorer blob");
		return -1;
	}

	return 0;
}

static int sigreturn_restore(pid_t pid, CoreEntry *core, struct list_head *tgt_vmas, int nr_vmas)
{
	long restore_task_vma_len;
	long restore_thread_vma_len, self_vmas_len, vmas_len;

	void *mem = MAP_FAILED;
	void *restore_thread_exec_start;
	void *restore_task_exec_start;
	void *restore_code_start;

	long new_sp, exec_mem_hint;
	long ret;

	struct task_restore_core_args *task_args;
	struct thread_restore_args *thread_args;

	LIST_HEAD(self_vma_list);
	int fd_pages = -1;
	int i;

	pr_info("Restore via sigreturn\n");

	restore_task_vma_len	= 0;
	restore_thread_vma_len	= 0;

	ret = parse_smaps(pid, &self_vma_list, false);
	close_proc();
	if (ret < 0)
		goto err;

	/* required to unmap stack _with_ guard page */
	mark_stack_vma((long) &self_vma_list, &self_vma_list);

	self_vmas_len = round_up((ret + 1) * sizeof(VmaEntry), PAGE_SIZE);
	vmas_len = round_up((nr_vmas + 1) * sizeof(VmaEntry), PAGE_SIZE);

	/* pr_info_vma_list(&self_vma_list); */

	BUILD_BUG_ON(sizeof(struct task_restore_core_args) & 1);
	BUILD_BUG_ON(sizeof(struct thread_restore_args) & 1);
	BUILD_BUG_ON(SHMEMS_SIZE % PAGE_SIZE);
	BUILD_BUG_ON(TASK_ENTRIES_SIZE % PAGE_SIZE);

	fd_pages = open_image_ro(CR_FD_PAGES, pid);
	if (fd_pages < 0) {
		pr_perror("Can't open pages-%d", pid);
		goto err;
	}

	restore_task_vma_len   = round_up(sizeof(*task_args), PAGE_SIZE);
	restore_thread_vma_len = round_up(sizeof(*thread_args) * current->nr_threads, PAGE_SIZE);

	pr_info("%d threads require %ldK of memory\n",
			current->nr_threads,
			KBYTES(restore_thread_vma_len));

	restore_thread_vma_len = round_up(restore_thread_vma_len, PAGE_SIZE);

	exec_mem_hint = restorer_get_vma_hint(pid, tgt_vmas, &self_vma_list,
					      restorer_len +
					      restore_task_vma_len +
					      restore_thread_vma_len +
					      self_vmas_len + vmas_len +
					      SHMEMS_SIZE + TASK_ENTRIES_SIZE);
	if (exec_mem_hint == -1) {
		pr_err("No suitable area for task_restore bootstrap (%ldK)\n",
		       restore_task_vma_len + restore_thread_vma_len);
		goto err;
	}

	pr_info("Found bootstrap VMA hint at: 0x%lx (needs ~%ldK)\n", exec_mem_hint,
			KBYTES(restore_task_vma_len + restore_thread_vma_len));

	ret = remap_restorer_blob((void *)exec_mem_hint);
	if (ret < 0)
		goto err;

	/*
	 * Prepare a memory map for restorer. Note a thread space
	 * might be completely unused so it's here just for convenience.
	 */
	restore_code_start		= (void *)exec_mem_hint;
	restore_thread_exec_start	= restore_code_start + restorer_blob_offset____export_restore_thread;
	restore_task_exec_start		= restore_code_start + restorer_blob_offset____export_restore_task;

	exec_mem_hint += restorer_len;

	/* VMA we need to run task_restore code */
	mem = mmap((void *)exec_mem_hint,
			restore_task_vma_len + restore_thread_vma_len,
			PROT_READ | PROT_WRITE,
			MAP_PRIVATE | MAP_ANON | MAP_FIXED, 0, 0);
	if (mem != (void *)exec_mem_hint) {
		pr_err("Can't mmap section for restore code\n");
		goto err;
	}

	memzero(mem, restore_task_vma_len + restore_thread_vma_len);
	task_args	= mem;
	thread_args	= mem + restore_task_vma_len;

	/*
	 * Adjust stack.
	 */
	new_sp = RESTORE_ALIGN_STACK((long)task_args->mem_zone.stack, sizeof(task_args->mem_zone.stack));

	/*
	 * Get a reference to shared memory area which is
	 * used to signal if shmem restoration complete
	 * from low-level restore code.
	 *
	 * This shmem area is mapped right after the whole area of
	 * sigreturn rt code. Note we didn't allocated it before
	 * but this area is taken into account for 'hint' memory
	 * address.
	 */

	mem += restore_task_vma_len + restore_thread_vma_len;
	ret = shmem_remap(rst_shmems, mem, SHMEMS_SIZE);
	if (ret < 0)
		goto err;
	task_args->shmems = mem;

	mem += SHMEMS_SIZE;
	ret = shmem_remap(task_entries, mem, TASK_ENTRIES_SIZE);
	if (ret < 0)
		goto err;
	task_args->task_entries = mem;

	mem += TASK_ENTRIES_SIZE;
	task_args->self_vmas = vma_list_remap(mem, self_vmas_len, &self_vma_list);
	if (!task_args->self_vmas)
		goto err;

	mem += self_vmas_len;
	task_args->tgt_vmas = vma_list_remap(mem, vmas_len, tgt_vmas);
	if (!task_args->tgt_vmas)
		goto err;

	/*
	 * Arguments for task restoration.
	 */

	BUG_ON(core->mtype != CORE_ENTRY__MARCH__X86_64);

	task_args->pid		= pid;
	task_args->logfd	= log_get_fd();
	task_args->loglevel	= log_get_loglevel();
	task_args->sigchld_act	= sigchld_act;
	task_args->fd_pages	= fd_pages;

	strncpy(task_args->comm, core->tc->comm, sizeof(task_args->comm));

	task_args->clear_tid_addr	= core->thread_info->clear_tid_addr;
	task_args->ids			= *core->ids;
	task_args->gpregs		= *core->thread_info->gpregs;
	task_args->blk_sigset		= core->tc->blk_sigset;

	if (core->thread_core) {
		task_args->has_futex		= true;
		task_args->futex_rla		= core->thread_core->futex_rla;
		task_args->futex_rla_len	= core->thread_core->futex_rla_len;
	}

	/* No longer need it */
	core_entry__free_unpacked(core, NULL);

	ret = prepare_itimers(pid, task_args);
	if (ret < 0)
		goto err;

	ret = prepare_creds(pid, task_args);
	if (ret < 0)
		goto err;

	ret = prepare_mm(pid, task_args);
	if (ret < 0)
		goto err;

	mutex_init(&task_args->rst_lock);

	/*
	 * Now prepare run-time data for threads restore.
	 */
	task_args->nr_threads		= current->nr_threads;
	task_args->clone_restore_fn	= (void *)restore_thread_exec_start;
	task_args->thread_args		= thread_args;

	/*
	 * Fill up per-thread data.
	 */
	for (i = 0; i < current->nr_threads; i++) {
		int fd_core;
		thread_args[i].pid = current->threads[i].virt;

		/* skip self */
		if (thread_args[i].pid == pid)
			continue;

		fd_core = open_image_ro(CR_FD_CORE, thread_args[i].pid);
		if (fd_core < 0) {
			pr_err("Can't open core data for thread %d\n",
			       thread_args[i].pid);
			goto err;
		}

		ret = pb_read_one(fd_core, &core, PB_CORE);
		close(fd_core);

		if (core->tc || core->ids) {
			pr_err("Thread has optional fields present %d\n",
			       thread_args[i].pid);
			ret = -1;
		}

		if (ret < 0) {
			pr_err("Can't read core data for thread %d\n",
			       thread_args[i].pid);
			goto err;
		}

		thread_args[i].rst_lock		= &task_args->rst_lock;
		thread_args[i].gpregs		= *core->thread_info->gpregs;
		thread_args[i].clear_tid_addr	= core->thread_info->clear_tid_addr;

		if (core->thread_core) {
			thread_args[i].has_futex	= true;
			thread_args[i].futex_rla	= core->thread_core->futex_rla;
			thread_args[i].futex_rla_len	= core->thread_core->futex_rla_len;
		}

		core_entry__free_unpacked(core, NULL);

		pr_info("Thread %4d stack %8p heap %8p rt_sigframe %8p\n",
				i, thread_args[i].mem_zone.stack,
				thread_args[i].mem_zone.heap,
				thread_args[i].mem_zone.rt_sigframe);

	}

	close_image_dir();

	pr_info("task_args: %p\n"
		"task_args->pid: %d\n"
		"task_args->nr_threads: %d\n"
		"task_args->clone_restore_fn: %p\n"
		"task_args->thread_args: %p\n",
		task_args, task_args->pid,
		task_args->nr_threads,
		task_args->clone_restore_fn,
		task_args->thread_args);

	/*
	 * An indirect call to task_restore, note it never resturns
	 * and restoreing core is extremely destructive.
	 */
	asm volatile(
		"movq %0, %%rbx						\n"
		"movq %1, %%rax						\n"
		"movq %2, %%rdi						\n"
		"movq %%rbx, %%rsp					\n"
		"callq *%%rax						\n"
		:
		: "g"(new_sp),
		  "g"(restore_task_exec_start),
		  "g"(task_args)
		: "rsp", "rdi", "rsi", "rbx", "rax", "memory");

err:
	free_mappings(&self_vma_list);

	/* Just to be sure */
	exit(1);
	return -1;
}