int parasite_map_exchange(struct parasite_ctl *ctl, unsigned long size)
{
int fd;
ctl->remote_map = mmap_seized(ctl, NULL, size,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_ANONYMOUS | MAP_SHARED, -1, 0);
if (!ctl->remote_map) {
pr_err("Can't allocate memory for parasite blob (pid: %d)\n", ctl->pid.real);
return -1;
}
ctl->map_length = round_up(size, PAGE_SIZE);
fd = open_proc_rw(ctl->pid.real, "map_files/%p-%p",
ctl->remote_map, ctl->remote_map + ctl->map_length);
if (fd < 0)
return -1;
ctl->local_map = mmap(NULL, size, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_FILE, fd, 0);
close(fd);
if (ctl->local_map == MAP_FAILED) {
ctl->local_map = NULL;
pr_perror("Can't map remote parasite map");
return -1;
}
return 0;
}
int get_shmem_fd(int pid, VmaEntry *vi)
{
struct shmem_info *si;
void *addr;
int f;
si = find_shmem_by_id(vi->shmid);
pr_info("Search for 0x%016"PRIx64" shmem 0x%"PRIx64" %p/%d\n", vi->start, vi->shmid, si, si ? si->pid : -1);
if (!si) {
pr_err("Can't find my shmem 0x%016"PRIx64"\n", vi->start);
return -1;
}
if (si->pid != pid)
return shmem_wait_and_open(pid, si);
if (si->fd != -1)
return dup(si->fd);
/*
* The following hack solves problems:
* vi->pgoff may be not zero in a target process.
* This mapping may be mapped more then once.
* The restorer doesn't have snprintf.
* Here is a good place to restore content
*/
addr = mmap(NULL, si->size,
PROT_WRITE | PROT_READ,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (addr == MAP_FAILED) {
pr_err("Can't mmap shmid=0x%"PRIx64" size=%ld\n",
vi->shmid, si->size);
return -1;
}
if (restore_shmem_content(addr, si) < 0) {
pr_err("Can't restore shmem content\n");
return -1;
}
f = open_proc_rw(getpid(), "map_files/%lx-%lx",
(unsigned long) addr,
(unsigned long) addr + si->size);
munmap(addr, si->size);
if (f < 0)
return -1;
si->fd = f;
return f;
}
static int shmem_wait_and_open(int pid, struct shmem_info *si)
{
char path[128];
int ret;
snprintf(path, sizeof(path), "/proc/%d/map_files/%lx-%lx",
si->pid, si->start, si->end);
pr_info("Waiting for [%s] to appear\n", path);
futex_wait_until(&si->lock, 1);
pr_info("Opening shmem [%s] \n", path);
ret = open_proc_rw(si->pid, "map_files/%lx-%lx", si->start, si->end);
if (ret < 0)
pr_perror(" %d: Can't stat shmem at %s",
si->pid, path);
return ret;
}
static int shmem_wait_and_open(int pid, struct shmem_info *si)
{
char path[128];
int ret;
pr_info("Waiting for the %lx shmem to appear\n", si->shmid);
futex_wait_while(&si->lock, 0);
snprintf(path, sizeof(path), "/proc/%d/fd/%d",
si->pid, si->fd);
pr_info("Opening shmem [%s] \n", path);
ret = open_proc_rw(si->pid, "fd/%d", si->fd);
if (ret < 0)
pr_perror(" %d: Can't stat shmem at %s",
si->pid, path);
futex_inc_and_wake(&si->lock);
return ret;
}
int get_shmem_fd(int pid, VmaEntry *vi)
{
struct shmem_info *si;
void *addr = MAP_FAILED;
int f = -1;
int flags;
si = find_shmem_by_id(vi->shmid);
pr_info("Search for 0x%016"PRIx64" shmem 0x%"PRIx64" %p/%d\n", vi->start, vi->shmid, si, si ? si->pid : -1);
if (!si) {
pr_err("Can't find my shmem 0x%016"PRIx64"\n", vi->start);
return -1;
}
if (si->pid != pid)
return shmem_wait_and_open(pid, si);
if (si->fd != -1)
return dup(si->fd);
flags = MAP_SHARED;
if (kdat.has_memfd) {
f = sys_memfd_create("", 0);
if (f < 0) {
pr_perror("Unable to create memfd");
goto err;
}
if (ftruncate(f, si->size)) {
pr_perror("Unable to truncate memfd");
goto err;
}
flags |= MAP_FILE;
} else
flags |= MAP_ANONYMOUS;
/*
* The following hack solves problems:
* vi->pgoff may be not zero in a target process.
* This mapping may be mapped more then once.
* The restorer doesn't have snprintf.
* Here is a good place to restore content
*/
addr = mmap(NULL, si->size, PROT_WRITE | PROT_READ, flags, f, 0);
if (addr == MAP_FAILED) {
pr_err("Can't mmap shmid=0x%"PRIx64" size=%ld\n",
vi->shmid, si->size);
goto err;
}
if (restore_shmem_content(addr, si) < 0) {
pr_err("Can't restore shmem content\n");
goto err;
}
if (f == -1) {
f = open_proc_rw(getpid(), "map_files/%lx-%lx",
(unsigned long) addr,
(unsigned long) addr + si->size);
if (f < 0)
goto err;
}
munmap(addr, si->size);
si->fd = f;
/* Send signal to slaves, that they can open fd for this shmem */
futex_inc_and_wake(&si->lock);
/*
* All other regions in this process will duplicate
* the file descriptor, so we don't wait them.
*/
futex_wait_until(&si->lock, si->count - si->self_count + 1);
return f;
err:
if (addr != MAP_FAILED)
munmap(addr, si->size);
close_safe(&f);
return -1;
}
