[PATCH v3 24/25] compiler_attributes.h: Add __disable_sanitizer_instrumentation

[Marco Elver <elver@google.com>]

From: Alexander Potapenko <glider@google.com>

The new attribute maps to
__attribute__((disable_sanitizer_instrumentation)), which will be
supported by Clang >= 14.0. Future support in GCC is also possible.

This attribute disables compiler instrumentation for kernel sanitizer
tools, making it easier to implement noinstr. It is different from the
existing __no_sanitize* attributes, which may still allow certain types
of instrumentation to prevent false positives.

Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Marco Elver <elver@google.com>
---
v3:
* New patch.
---
 include/linux/compiler_attributes.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
index b9121afd8733..37e260020221 100644
--- a/include/linux/compiler_attributes.h
+++ b/include/linux/compiler_attributes.h
@@ -308,6 +308,24 @@
 # define __compiletime_warning(msg)
 #endif
 
+/*
+ * Optional: only supported since clang >= 14.0
+ *
+ * clang: https://clang.llvm.org/docs/AttributeReference.html#disable-sanitizer-instrumentation
+ *
+ * disable_sanitizer_instrumentation is not always similar to
+ * no_sanitize((<sanitizer-name>)): the latter may still let specific sanitizers
+ * insert code into functions to prevent false positives. Unlike that,
+ * disable_sanitizer_instrumentation prevents all kinds of instrumentation to
+ * functions with the attribute.
+ */
+#if __has_attribute(disable_sanitizer_instrumentation)
+# define __disable_sanitizer_instrumentation \
+	 __attribute__((disable_sanitizer_instrumentation))
+#else
+# define __disable_sanitizer_instrumentation
+#endif
+
 /*
  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute
  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute
-- 
2.34.0.rc2.393.gf8c9666880-goog