Clarify when __builtin_dynamic_object_size() is available. All our
supported Clang versions support it. GCC 12 and later support it. Link
to documentation for both.
Signed-off-by: Kees Cook <k...@kernel.org>
---
Cc: Miguel Ojeda <oj...@kernel.org>
Cc: Nathan Chancellor <nat...@kernel.org>
Cc: Nick Desaulniers <nick.desaulniers+l...@gmail.com>
Cc: Bill Wendling <mo...@google.com>
Cc: Justin Stitt <justinst...@google.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Marco Elver <el...@google.com>
Cc: Przemek Kitszel <przemyslaw.kits...@intel.com>
Cc: l...@lists.linux.dev
---
include/linux/compiler_types.h | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 501cffddc2f4..20881cc761fa 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -449,6 +449,11 @@ struct ftrace_likely_data {
/*
* When the size of an allocated object is needed, use the best available
* mechanism to find it. (For cases where sizeof() cannot be used.)
+ *
+ * Optional: only supported since gcc >= 12
+ *
+ * gcc: https://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html
+ * clang:
https://clang.llvm.org/docs/LanguageExtensions.html#evaluating-object-size
*/
#if __has_builtin(__builtin_dynamic_object_size)
#define __struct_size(p) __builtin_dynamic_object_size(p, 0)
--
2.34.1
