Merge branch 'compiler_types-add-endianness-dependent-__counted_by_-le-be'

Alexander Lobakin says:

====================
compiler_types: add Endianness-dependent __counted_by_{le,be}

Some structures contain flexible arrays at the end and the counter for
them, but the counter has explicit Endianness and thus __counted_by()
can't be used directly.

To increase test coverage for potential problems without breaking
anything, introduce __counted_by_{le,be} defined depending on platform's
Endianness to either __counted_by() when applicable or noop otherwise.
The first user will be virtchnl2.h from idpf just as example with 9 flex
structures having Little Endian counters.

Maybe it would be a good idea to introduce such attributes on compiler
level if possible, but for now let's stop on what we have.
====================

Link: https://lore.kernel.org/r/20240327142241.1745989-1-aleksander.lobakin@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 2abaa3a825a9..a29ba6ef1e27 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -282,6 +282,17 @@ struct ftrace_likely_data {
 #define __no_sanitize_or_inline __always_inline
 #endif
 
+/*
+ * Apply __counted_by() when the Endianness matches to increase test coverage.
+ */
+#ifdef __LITTLE_ENDIAN
+#define __counted_by_le(member)	__counted_by(member)
+#define __counted_by_be(member)
+#else
+#define __counted_by_le(member)
+#define __counted_by_be(member)	__counted_by(member)
+#endif
+
 /* Do not trap wrapping arithmetic within an annotated function. */
 #ifdef CONFIG_UBSAN_SIGNED_WRAP
 # define __signed_wrap __attribute__((no_sanitize("signed-integer-overflow")))