plucky (2) UFFDIO_COPY.2const.gz

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