UFFDIO_POISON - mark an address range as 'poisoned'

NAME  LIBRARY  SYNOPSIS  DESCRIPTION  RETURN VALUE  ERRORS  STANDARDS  HISTORY  EXAMPLES  SEE ALSO 

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NAME

UFFDIO_POISON − mark an address range as "poisoned"

LIBRARY

Standard C library (libc, −lc)

SYNOPSIS

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

int ioctl(int fd, UFFDIO_POISON, ...);

#include <linux/userfaultfd.h>

struct uffdio_poison {

		struct uffdio_range range;
		/* Range to install poison PTE markers in */
		__u64 mode; /* Flags controlling the behavior of poison */
		__s64 updated; /* Number of bytes poisoned, or negated error */

};

DESCRIPTION

Mark an address range as "poisoned". Future accesses to these addresses will raise a SIGBUS signal. Unlike MADV_HWPOISON this works by installing page table entries, rather than "really" poisoning the underlying physical pages. This means it only affects this particular address space.

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

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

The updated field is used by the kernel to return the number of bytes that were actually poisoned, or an error in the same manner as UFFDIO_COPY. If the value returned in the updated field doesn’t match the value that was specified in range.len, the operation fails with the error EAGAIN. The updated field is output-only; it is not read by the UFFDIO_POISON operation.

RETURN VALUE

On success, 0 is returned. In this case, the entire area was poisoned.

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

ERRORS

	EAGAIN		The number of bytes mapped (i.e., the value returned in the updated field) does not equal the value that was specified in the range.len field.
	EINVAL		Either range.start or range.len was not a multiple of the system page size; or range.len was zero; or the range specified was invalid.
	EINVAL		An invalid bit was specified in the mode field.
	EEXIST		One or more pages were already mapped in the given range.
	ENOENT		The faulting process has changed its virtual memory layout simultaneously with an outstanding UFFDIO_POISON operation.
	ENOMEM		Allocating memory for page table entries failed.
	ESRCH		The faulting process has exited at the time of a UFFDIO_POISON operation.

STANDARDS

Linux.

HISTORY

Linux 6.6.

EXAMPLES

See userfaultfd(2).

SEE ALSO

ioctl(2), ioctl_userfaultfd(2), userfaultfd(2)

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

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