1 files changed, 50 insertions, 0 deletions

diff --git a/include/linux/kmemcheck.h b/include/linux/kmemcheck.h
index 093d23969b1b..47b39b7c7e84 100644
--- a/include/linux/kmemcheck.h
+++ b/include/linux/kmemcheck.h
@@ -33,6 +33,7 @@ void kmemcheck_mark_initialized_pages(struct page *p, unsigned int n);
 
 int kmemcheck_show_addr(unsigned long address);
 int kmemcheck_hide_addr(unsigned long address);
+
 #else
 #define kmemcheck_enabled 0
 
@@ -100,4 +101,53 @@ static inline void kmemcheck_mark_initialized_pages(struct page *p,
 
 #endif /* CONFIG_KMEMCHECK */
 
+/*
+ * Bitfield annotations
+ *
+ * How to use: If you have a struct using bitfields, for example
+ *
+ *     struct a {
+ *             int x:8, y:8;
+ *     };
+ *
+ * then this should be rewritten as
+ *
+ *     struct a {
+ *             kmemcheck_bitfield_begin(flags);
+ *             int x:8, y:8;
+ *             kmemcheck_bitfield_end(flags);
+ *     };
+ *
+ * Now the "flags_begin" and "flags_end" members may be used to refer to the
+ * beginning and end, respectively, of the bitfield (and things like
+ * &x.flags_begin is allowed). As soon as the struct is allocated, the bit-
+ * fields should be annotated:
+ *
+ *     struct a *a = kmalloc(sizeof(struct a), GFP_KERNEL);
+ *     kmemcheck_annotate_bitfield(a, flags);
+ *
+ * Note: We provide the same definitions for both kmemcheck and non-
+ * kmemcheck kernels. This makes it harder to introduce accidental errors. It
+ * is also allowed to pass NULL pointers to kmemcheck_annotate_bitfield().
+ */
+#define kmemcheck_bitfield_begin(name)  \
+        int name##_begin[0];
+
+#define kmemcheck_bitfield_end(name)    \
+        int name##_end[0];
+
+#define kmemcheck_annotate_bitfield(ptr, name)                          \
+        do if (ptr) {                                                   \
+                int _n = (long) &((ptr)->name##_end)                    \
+                        - (long) &((ptr)->name##_begin);                \
+                BUILD_BUG_ON(_n < 0);                                   \
+                                                                        \
+                kmemcheck_mark_initialized(&((ptr)->name##_begin), _n); \
+        } while (0)
+
+#define kmemcheck_annotate_variable(var)                                \
+        do {                                                            \
+                kmemcheck_mark_initialized(&(var), sizeof(var));        \
+        } while (0)                                                     \
+
 #endif /* LINUX_KMEMCHECK_H */