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