UFFDIO_COPY(2const)                                        UFFDIO_COPY(2const)

NAME
       UFFDIO_COPY - atomically copy a continuous memory chunk into the
       userfault registered range

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <linux/userfaultfd.h>  /* Definition of UFFD* constants */
       #include <sys/ioctl.h>

       int ioctl(int fd, UFFDIO_COPY, struct uffdio_copy *argp);

       #include <linux/userfaultfd.h>

       struct uffdio_copy {
           __u64  dst;   /* Destination of copy */
           __u64  src;   /* Source of copy */
           __u64  len;   /* Number of bytes to copy */
           __u64  mode;  /* Flags controlling behavior of copy */
           __s64  copy;  /* Number of bytes copied, or negated error */
       };

DESCRIPTION
       Atomically copy a continuous memory chunk into the userfault registered
       range and optionally wake up the blocked thread.

       The following value may be bitwise ORed in mode to change the behavior
       of the UFFDIO_COPY operation:

       UFFDIO_COPY_MODE_DONTWAKE
              Do not wake up the thread that waits for page-fault resolution

       UFFDIO_COPY_MODE_WP
              Copy the page with read-only permission.  This allows the user
              to trap the next write to the page, which will block and
              generate another write-protect userfault message.  This is used
              only when both UFFDIO_REGISTER_MODE_MISSING and
              UFFDIO_REGISTER_MODE_WP modes are enabled for the registered
              range.

       The copy field is used by the kernel to return the number of bytes that
       was actually copied, or an error (a negated errno-style value).  The
       copy field is output-only; it is not read by the UFFDIO_COPY operation.

RETURN VALUE
       On success, 0 is returned.  In this case, the entire area was copied.

       On error, -1 is returned and errno is set to indicate the error.

ERRORS
       EAGAIN The number of bytes copied (i.e., the value returned in the copy
              field) does not equal the value that was specified in the len
              field.

       EINVAL Either dst or len was not a multiple of the system page size, or
              the range specified by src and len or dst and len was invalid.

       EINVAL An invalid bit was specified in the mode field.

       ENOENT (since Linux 4.11)
              The faulting process has changed its virtual memory layout
              simultaneously with an outstanding UFFDIO_COPY operation.

       ENOSPC (from Linux 4.11 until Linux 4.13)
              The faulting process has exited at the time of a UFFDIO_COPY
              operation.

       ESRCH (since Linux 4.13)
              The faulting process has exited at the time of a UFFDIO_COPY
              operation.

STANDARDS
       Linux.

HISTORY
       Linux 4.3.

EXAMPLES
       See userfaultfd(2).

SEE ALSO
       ioctl(2), ioctl_userfaultfd(2), userfaultfd(2)

       linux.git/Documentation/admin-guide/mm/userfaultfd.rst

Linux man-pages 6.9.1             2024-06-17               UFFDIO_COPY(2const)