Merge git://git.infradead.org/~dwmw2/random-2.6

[pandora-kernel.git] / include / linux / uaccess.h

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 67918c2..fec6dec 100644 (file)
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -65,15 +65,45 @@ static inline unsigned long __copy_from_user_nocache(void *to,
  * 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;                                    \
        })
 
+/*
+ * probe_kernel_read(): safely attempt to read from a location
+ * @dst: pointer to the buffer that shall take the data
+ * @src: address to read from
+ * @size: size of the data chunk
+ *
+ * Safely read from address @src to the buffer at @dst.  If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+extern long probe_kernel_read(void *dst, void *src, size_t size);
+
+/*
+ * probe_kernel_write(): safely attempt to write to a location
+ * @dst: address to write to
+ * @src: pointer to the data that shall be written
+ * @size: size of the data chunk
+ *
+ * Safely write to address @dst from the buffer at @src.  If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+extern long probe_kernel_write(void *dst, void *src, size_t size);
+
 #endif         /* __LINUX_UACCESS_H__ */