Add a inlined __ variant of copy_from_user_nmi. The inlined variant allows
the user to:
- batch the access_ok() check for multiple accesses
- avoid having a pagefault_disable/enable() on every access if the
caller already ensures disabled page faults due to its context.
- get all the optimizations in copy_*_user() for small constant sized
transfers
It is just a define to __copy_from_user_inatomic().
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1445551641-13379-1-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
#undef __copy_from_user_overflow
#undef __copy_to_user_overflow
+/*
+ * We rely on the nested NMI work to allow atomic faults from the NMI path; the
+ * nested NMI paths are careful to preserve CR2.
+ *
+ * Caller must use pagefault_enable/disable, or run in interrupt context,
+ * and also do a uaccess_ok() check
+ */
+#define __copy_from_user_nmi __copy_from_user_inatomic
+
#endif /* _ASM_X86_UACCESS_H */