NAME

kcopy — copy data between kernel addresses, guarding against faults

SYNOPSIS

#include <sys/types.h>
#include <sys/systm.h>

int
kcopy(const void *from, void *to, size_t count);

INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

PARAMETERS

from: Source kernel address of the copy.
to: Destination kernel address of the copy.
count: Number of bytes to copy.

DESCRIPTION

The kcopy() function copies count bytes from one kernel address to another. It performs the same copy as bcopy(9F), but guards against faults for the duration of the copy. A fault taken while copying is first handled as an ordinary page fault, so a copy involving pageable kernel memory succeeds when the fault can be resolved. A fault which cannot be resolved causes kcopy() to return an error, where bcopy(9F) would panic the system.

Both from and to must be kernel addresses. kcopy() must not be used to copy data to or from user address space; use copyin(9F) and copyout(9F) for that. If the source and destination areas overlap, the behaviour is undefined.

CONTEXT

The kcopy() function can be called from user or kernel context.

RETURN VALUES

Upon successful completion, the kcopy() function returns 0. Otherwise, a fault occurred that could not be resolved, and an error number describing the fault, most commonly EFAULT, is returned. Note that this differs from copyin(9F) and copyout(9F), which return -1 on failure.