uffdio_writeprotect(2const)

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Options · 6

UFFDIO_WRITEPROTECT_MODE_WP	When this mode bit is set, the ioctl will be a write-protect operation upon the memory range specified by range. Otherwise it will be a write-unprotect operation upon the specified range, which can be used to resolve a userfaultfd write-protect page fault.
UFFDIO_WRITEPROTECT_MODE_DONTWAKE	When this mode bit is set, do not wake up any thread that waits for page-fault resolution after the operation. This can be specified only if UFFDIO_WRITEPROTECT_MODE_WP is not specified.
EINVAL	The start or the len field of the ufdio_range structure was not a multiple of the system page size; or len was zero; or the specified range was otherwise invalid.
EAGAIN	The process was interrupted; retry this call.
ENOENT	The range specified in range is not valid. For example, the virtual address does not exist, or not registered with userfaultfd write-protect mode.
EFAULT	Encountered a generic fault during processing.

NAME

UFFDIO_WRITEPROTECT - write-protect or write-unprotect a userfaultfd-registered memory range

LIBRARY

Standard C library (libc, -lc)

SYNOPSIS

bash

#include <linux/userfaultfd.h>\n  /* Definition of \nUFFD*\n constants */
\n#include <sys/ioctl.h>

bash

int ioctl(int \nfd\n, UFFDIO_WRITEPROTECT, ...);

bash

#include <linux/userfaultfd.h>

bash

struct uffdio_writeprotect {\n
\n    struct uffdio_range  range;\n  /* Range to change write permission*/
\n    __u64                mode;\n   /* Mode to change write permission */
\n};\n

DESCRIPTION

Write-protect or write-unprotect a userfaultfd-registered memory range registered with mode UFFDIO_REGISTER_MODE_WP.

There are two mode bits that are supported in this structure:

UFFDIO_WRITEPROTECT_MODE_WP: When this mode bit is set, the ioctl will be a write-protect operation upon the memory range specified by range. Otherwise it will be a write-unprotect operation upon the specified range, which can be used to resolve a userfaultfd write-protect page fault.
UFFDIO_WRITEPROTECT_MODE_DONTWAKE: When this mode bit is set, do not wake up any thread that waits for page-fault resolution after the operation. This can be specified only if UFFDIO_WRITEPROTECT_MODE_WP is not specified.

RETURN VALUE

On success, 0 is returned. On error, -1 is returned and errno is set to indicate the error.

ERRORS

EINVAL: The start or the len field of the ufdio_range structure was not a multiple of the system page size; or len was zero; or the specified range was otherwise invalid.
EAGAIN: The process was interrupted; retry this call.
ENOENT: The range specified in range is not valid. For example, the virtual address does not exist, or not registered with userfaultfd write-protect mode.
EFAULT: Encountered a generic fault during processing.

STANDARDS

Linux.

HISTORY

Linux 5.7.

EXAMPLES

See userfaultfd(2).