diff options
| author | Kees Cook <kees@kernel.org> | 2025-03-10 14:42:48 -0700 |
|---|---|---|
| committer | Kees Cook <kees@kernel.org> | 2025-03-12 13:21:09 -0700 |
| commit | b688f369ae0d5d25865f5441fa62e54c7d5d0de6 (patch) | |
| tree | b2c790c78e9b3f143e89610b2022014d3fea9c6d | |
| parent | d70da12453ac3797e0c54884305ccc894e8c817b (diff) | |
compiler_types: Introduce __nonstring_array
GCC has expanded support of the "nonstring" attribute so that it can be
applied to arrays of character arrays[1], which is needed to identify
correct static initialization of those kinds of objects. Since this was
not supported prior to GCC 15, we need to distinguish the usage of Linux's
existing __nonstring macro for the attribute for non-multi-dimensional
char arrays. Until GCC 15 is the minimum version, use __nonstring_array to
mark arrays of non-string character arrays. (Regular non-string character
arrays can continue to use __nonstring.) Once GCC 15 is the minimum
compiler version we can replace all uses of __nonstring_array with just
__nonstring and remove this macro.
This allows for changes like this:
-static const char table_sigs[][ACPI_NAMESEG_SIZE] __initconst = {
+static const char table_sigs[][ACPI_NAMESEG_SIZE] __nonstring_array __initconst = {
ACPI_SIG_BERT, ACPI_SIG_BGRT, ACPI_SIG_CPEP, ACPI_SIG_ECDT,
Which will silence the coming -Wunterminated-string-initialization
warnings in GCC 15:
In file included from ../include/acpi/actbl.h:371, from ../include/acpi/acpi.h:26, from ../include/linux/acpi.h:26,
from ../drivers/acpi/tables.c:19:
../include/acpi/actbl1.h:30:33: warning: initializer-string for array of 'char' truncates NUL terminator but destination lacks 'nonstring' attribute (5 chars into 4 available) [-Wunterminated-string-initialization]
30 | #define ACPI_SIG_BERT "BERT" /* Boot Error Record Table */
| ^~~~~~ ../drivers/acpi/tables.c:400:9: note: in expansion of macro 'ACPI_SIG_BERT' 400 | ACPI_SIG_BERT, ACPI_SIG_BGRT, ACPI_SIG_CPEP, ACPI_SIG_ECDT,
| ^~~~~~~~~~~~~ ../include/acpi/actbl1.h:31:33: warning: initializer-string for array of 'char' truncates NUL terminator but destination lacks 'nonstring' attribute (5 chars into 4 available) [-Wunterminated-string-initialization]
31 | #define ACPI_SIG_BGRT "BGRT" /* Boot Graphics Resource Table */
| ^~~~~~
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1]
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20250310214244.work.194-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
| -rw-r--r-- | include/linux/compiler_types.h | 12 | ||||
| -rw-r--r-- | init/Kconfig | 3 |
2 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index 4ad3e900bc3d..e09d323be845 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -349,6 +349,18 @@ struct ftrace_likely_data { #endif /* + * Optional: only supported since gcc >= 15 + * Optional: not supported by Clang + * + * gcc: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 + */ +#ifdef CONFIG_CC_HAS_MULTIDIMENSIONAL_NONSTRING +# define __nonstring_array __attribute__((__nonstring__)) +#else +# define __nonstring_array +#endif + +/* * Apply __counted_by() when the Endianness matches to increase test coverage. */ #ifdef __LITTLE_ENDIAN diff --git a/init/Kconfig b/init/Kconfig index d0d021b3fa3b..723dc69507d6 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -129,6 +129,9 @@ config CC_HAS_COUNTED_BY # https://github.com/llvm/llvm-project/pull/112636 depends on !(CC_IS_CLANG && CLANG_VERSION < 190103) +config CC_HAS_MULTIDIMENSIONAL_NONSTRING + def_bool $(success,echo 'char tag[][4] __attribute__((__nonstring__)) = { };' | $(CC) $(CLANG_FLAGS) -x c - -c -o /dev/null -Werror) + config RUSTC_HAS_COERCE_POINTEE def_bool RUSTC_VERSION >= 108400 |