* do_page_fault() doesn't attempt to take mmap_sem. This makes
* probe_kernel_address() suitable for use within regions where the caller
* already holds mmap_sem, or other locks which nest inside mmap_sem.
+ * This must be a macro because __get_user() needs to know the types of the
+ * args.
+ *
+ * We don't include enough header files to be able to do the set_fs(). We
+ * require that the probe_kernel_address() caller will do that.
*/
#define probe_kernel_address(addr, retval) \
({ \
long ret; \
+ mm_segment_t old_fs = get_fs(); \
\
+ set_fs(KERNEL_DS); \
pagefault_disable(); \
- ret = __get_user(retval, addr); \
+ ret = __get_user(retval, (__force typeof(retval) __user *)(addr)); \
pagefault_enable(); \
+ set_fs(old_fs); \
ret; \
})