53 lines
1.4 KiB
C
53 lines
1.4 KiB
C
/*
|
|
* User address space access functions.
|
|
*
|
|
* For licencing details see kernel-base/COPYING
|
|
*/
|
|
|
|
#include <linux/uaccess.h>
|
|
#include <linux/export.h>
|
|
|
|
#include <asm/tlbflush.h>
|
|
|
|
/**
|
|
* copy_from_user_nmi - NMI safe copy from user
|
|
* @to: Pointer to the destination buffer
|
|
* @from: Pointer to a user space address of the current task
|
|
* @n: Number of bytes to copy
|
|
*
|
|
* Returns: The number of not copied bytes. 0 is success, i.e. all bytes copied
|
|
*
|
|
* Contrary to other copy_from_user() variants this function can be called
|
|
* from NMI context. Despite the name it is not restricted to be called
|
|
* from NMI context. It is safe to be called from any other context as
|
|
* well. It disables pagefaults across the copy which means a fault will
|
|
* abort the copy.
|
|
*
|
|
* For NMI context invocations this relies on the nested NMI work to allow
|
|
* atomic faults from the NMI path; the nested NMI paths are careful to
|
|
* preserve CR2.
|
|
*/
|
|
unsigned long
|
|
copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
|
|
{
|
|
unsigned long ret;
|
|
|
|
if (__range_not_ok(from, n, TASK_SIZE))
|
|
return n;
|
|
|
|
if (!nmi_uaccess_okay())
|
|
return n;
|
|
|
|
/*
|
|
* Even though this function is typically called from NMI/IRQ context
|
|
* disable pagefaults so that its behaviour is consistent even when
|
|
* called from other contexts.
|
|
*/
|
|
pagefault_disable();
|
|
ret = __copy_from_user_inatomic(to, from, n);
|
|
pagefault_enable();
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(copy_from_user_nmi);
|