1 files changed, 53 insertions, 13 deletions

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index c836eb2dc44d..3d7810341b57 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -198,19 +198,45 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
 
 #include <uapi/linux/types.h>
 
-static __always_inline void __read_once_size(const volatile void *p, void *res, int size)
+#define __READ_ONCE_SIZE                                                \
+({                                                                      \
+        switch (size) {                                                 \
+        case 1: *(__u8 *)res = *(volatile __u8 *)p; break;              \
+        case 2: *(__u16 *)res = *(volatile __u16 *)p; break;            \
+        case 4: *(__u32 *)res = *(volatile __u32 *)p; break;            \
+        case 8: *(__u64 *)res = *(volatile __u64 *)p; break;            \
+        default:                                                        \
+                barrier();                                              \
+                __builtin_memcpy((void *)res, (const void *)p, size);   \
+                barrier();                                              \
+        }                                                               \
+})
+
+static __always_inline
+void __read_once_size(const volatile void *p, void *res, int size)
 {
-        switch (size) {
-        case 1: *(__u8 *)res = *(volatile __u8 *)p; break;
-        case 2: *(__u16 *)res = *(volatile __u16 *)p; break;
-        case 4: *(__u32 *)res = *(volatile __u32 *)p; break;
-        case 8: *(__u64 *)res = *(volatile __u64 *)p; break;
-        default:
-                barrier();
-                __builtin_memcpy((void *)res, (const void *)p, size);
-                barrier();
-        }
+        __READ_ONCE_SIZE;
+}
+
+#ifdef CONFIG_KASAN
+/*
+ * This function is not 'inline' because __no_sanitize_address confilcts
+ * with inlining. Attempt to inline it may cause a build failure.
+ *      https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
+ * '__maybe_unused' allows us to avoid defined-but-not-used warnings.
+ */
+static __no_sanitize_address __maybe_unused
+void __read_once_size_nocheck(const volatile void *p, void *res, int size)
+{
+        __READ_ONCE_SIZE;
+}
+#else
+static __always_inline
+void __read_once_size_nocheck(const volatile void *p, void *res, int size)
+{
+        __READ_ONCE_SIZE;
 }
+#endif
 
 static __always_inline void __write_once_size(volatile void *p, void *res, int size)
 {
@@ -248,8 +274,22 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
  * required ordering.
  */
 
-#define READ_ONCE(x) \
-        ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
+#define __READ_ONCE(x, check)                                           \
+({                                                                      \
+        union { typeof(x) __val; char __c[1]; } __u;                    \
+        if (check)                                                      \
+                __read_once_size(&(x), __u.__c, sizeof(x));             \
+        else                                                            \
+                __read_once_size_nocheck(&(x), __u.__c, sizeof(x));     \
+        __u.__val;                                                      \
+})
+#define READ_ONCE(x) __READ_ONCE(x, 1)
+
+/*
+ * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
+ * to hide memory access from KASAN.
+ */
+#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
 
 #define WRITE_ONCE(x, val) \
 ({                                                      \