user_access_begin  712 arch/x86/include/asm/uaccess.h static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len)
user_access_begin  719 arch/x86/include/asm/uaccess.h #define user_access_begin(a,b)	user_access_begin(a,b)
user_access_begin  368 include/linux/uaccess.h #define user_access_begin(ptr,len) access_ok(ptr, len)