[PATCH 5.10 14/54] compiler_attributes.h: move __compiletime_{error|warning}

Greg Kroah-Hartman
2022-10-13T18:14:57Z

From: Nick Desaulniers <ndesaulniers@google.com>

commit b83a908498d68fafca931e1276e145b339cac5fb upstream.

Clang 14 will add support for __attribute__((__error__(""))) and
__attribute__((__warning__(""))). To make use of these in
__compiletime_error and __compiletime_warning (as used by BUILD_BUG and
friends) for newer clang and detect/fallback for older versions of
clang, move these to compiler_attributes.h and guard them with
__has_attribute preprocessor guards.

Link: https://reviews.llvm.org/D106030
Link: https://bugs.llvm.org/show_bug.cgi?id=16428
Link: https://github.com/ClangBuiltLinux/linux/issues/1173
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
[Reworded, landed in Clang 14]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/compiler-gcc.h | 3 ---
include/linux/compiler_attributes.h | 24 ++++++++++++++++++++++++
include/linux/compiler_types.h | 6 ------
3 files changed, 24 insertions(+), 9 deletions(-)

--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -54,9 +54,6 @@

#define __compiletime_object_size(obj) __builtin_object_size(obj, 0)

-#define __compiletime_warning(message) __attribute__((__warning__(message)))
-#define __compiletime_error(message) __attribute__((__error__(message)))
-
#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
#define __latent_entropy __attribute__((latent_entropy))
#endif
--- a/include/linux/compiler_attributes.h
+++ b/include/linux/compiler_attributes.h
@@ -30,6 +30,7 @@
# define __GCC4_has_attribute___assume_aligned__ (__GNUC_MINOR__ >= 9)
# define __GCC4_has_attribute___copy__ 0
# define __GCC4_has_attribute___designated_init__ 0
+# define __GCC4_has_attribute___error__ 1
# define __GCC4_has_attribute___externally_visible__ 1
# define __GCC4_has_attribute___no_caller_saved_registers__ 0
# define __GCC4_has_attribute___noclone__ 1
@@ -37,6 +38,7 @@
# define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8)
# define __GCC4_has_attribute___no_sanitize_undefined__ (__GNUC_MINOR__ >= 9)
# define __GCC4_has_attribute___fallthrough__ 0
+# define __GCC4_has_attribute___warning__ 1
#endif

/*
@@ -137,6 +139,17 @@
#endif

/*
+ * Optional: only supported since clang >= 14.0
+ *
+ * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-error-function-attribute
+ */
+#if __has_attribute(__error__)
+# define __compiletime_error(msg) __attribute__((__error__(msg)))
+#else
+# define __compiletime_error(msg)
+#endif
+
+/*
* Optional: not supported by clang
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute
@@ -273,6 +286,17 @@
#define __used __attribute__((__used__))

/*
+ * Optional: only supported since clang >= 14.0
+ *
+ * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warning-function-attribute
+ */
+#if __has_attribute(__warning__)
+# define __compiletime_warning(msg) __attribute__((__warning__(msg)))
+#else
+# define __compiletime_warning(msg)
+#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
*/
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -281,12 +281,6 @@ struct ftrace_likely_data {
#ifndef __compiletime_object_size
# define __compiletime_object_size(obj) -1
#endif
-#ifndef __compiletime_warning
-# define __compiletime_warning(message)
-#endif
-#ifndef __compiletime_error
-# define __compiletime_error(message)
-#endif

#ifdef __OPTIMIZE__
# define __compiletime_assert(condition, msg, prefix, suffix) \