diff mbox series

[1/1] ACPI: Fix building with GCC 15

Message ID 20250414161644.30400-1-listout@listout.xyz
State New
Headers show
Series [1/1] ACPI: Fix building with GCC 15 | expand

Commit Message

Brahmajit Das April 14, 2025, 4:16 p.m. UTC
Since the Linux kernel initializes many non-C-string char arrays with
literals. While it would be possible to convert initializers from:
   { "BOOP", ... }
to something like:
   { { 'B', 'O', 'O', 'P' }, ... }
that is annoying.
Making -Wunterminated-string-initialization stay silent about char
arrays marked with nonstring would be much better.

Without the __attribute__((nonstring)) we would get the following build
error:

...
drivers/acpi/acpica/acpredef.h:903:11: error: initializer-string for array of ‘char’ truncates NUL terminator but destination lacks ‘nonstring’ attribute (5 chars into 4 available) [-Werror=unterminated-string-initialization]
  903 |         {{"_S3D", METHOD_0ARGS,
      |           ^~~~~~
drivers/acpi/acpica/acpredef.h:906:11: error: initializer-string for array of ‘char’ truncates NUL terminator but destination lacks ‘nonstring’ attribute (5 chars into 4 available) [-Werror=unterminated-string-initialization]
  906 |         {{"_S4D", METHOD_0ARGS,
      |           ^~~~~~

and,

...
drivers/acpi/acpica/nsrepair2.c:115:10: error: initializer-string for array of ‘char’ truncates NUL terminator but destination lacks ‘nonstring’ attribute (5 chars into 4 available) [-Werror=unterminated-string-initialization]
  115 |         {"_ALR", acpi_ns_repair_ALR},
      |          ^~~~~~
drivers/acpi/acpica/nsrepair2.c:116:10: error: initializer-string for array of ‘char’ truncates NUL terminator but destination lacks ‘nonstring’ attribute (5 chars into 4 available) [-Werror=unterminated-string-initialization]
  116 |         {"_CID", acpi_ns_repair_CID},
...

Upstream GCC has added this commit
622968990beee7499e951590258363545b4a3b57[0][1] which silences warning
about truncating NUL char when initializing nonstring arrays.

[0]: https://gcc.gnu.org/cgit/gcc/commit/?id=622968990beee7499e951590258363545b4a3b57
[1]: https://gcc.gnu.org/cgit/gcc/commit/?id=afb46540d3921e96c4cd7ba8fa2c8b0901759455

Thanks to Jakub Jelinek <jakub@gcc.gnu.org> for the gcc patch.

Signed-off-by: Brahmajit Das <listout@listout.xyz>
---
 drivers/acpi/acpica/aclocal.h   |  4 ++--
 drivers/acpi/acpica/nsrepair2.c |  2 +-
 drivers/acpi/tables.c           | 28 +++++++++++++++-------------
 include/acpi/actbl.h            |  3 ++-
 4 files changed, 20 insertions(+), 17 deletions(-)

Comments

David Laight April 15, 2025, 6:04 p.m. UTC | #1
On Mon, 14 Apr 2025 21:46:42 +0530
Brahmajit Das <brahmajit.xyz@gmail.com> wrote:

> Since the Linux kernel initializes many non-C-string char arrays with
> literals. While it would be possible to convert initializers from:
>    { "BOOP", ... }
> to something like:
>    { { 'B', 'O', 'O', 'P' }, ... }
> that is annoying.
> Making -Wunterminated-string-initialization stay silent about char
> arrays marked with nonstring would be much better.
...
> diff --git a/drivers/acpi/acpica/aclocal.h b/drivers/acpi/acpica/aclocal.h
> index 6f4fe47c955b..d2cda1b35e59 100644
> --- a/drivers/acpi/acpica/aclocal.h
> +++ b/drivers/acpi/acpica/aclocal.h
> @@ -293,7 +293,7 @@ acpi_status (*acpi_internal_method) (struct acpi_walk_state * walk_state);
>   * expected_return_btypes - Allowed type(s) for the return value
>   */
>  struct acpi_name_info {
> -	char name[ACPI_NAMESEG_SIZE];
> +	char name[ACPI_NAMESEG_SIZE] __attribute__((nonstring));

Doesn't than generate an 'unknown attribute' error on older compilers?

Does:
	typedef char char_nonstring __attribute__((nonstring));
	char_nonstring name[4] = "abcd";
work?

If so the attribute could even be applied to 'u8'.

	David
diff mbox series

Patch

diff --git a/drivers/acpi/acpica/aclocal.h b/drivers/acpi/acpica/aclocal.h
index 6f4fe47c955b..d2cda1b35e59 100644
--- a/drivers/acpi/acpica/aclocal.h
+++ b/drivers/acpi/acpica/aclocal.h
@@ -293,7 +293,7 @@  acpi_status (*acpi_internal_method) (struct acpi_walk_state * walk_state);
  * expected_return_btypes - Allowed type(s) for the return value
  */
 struct acpi_name_info {
-	char name[ACPI_NAMESEG_SIZE];
+	char name[ACPI_NAMESEG_SIZE] __attribute__((nonstring));
 	u16 argument_list;
 	u8 expected_btypes;
 };
@@ -370,7 +370,7 @@  typedef acpi_status (*acpi_object_converter) (struct acpi_namespace_node *
 					      converted_object);
 
 struct acpi_simple_repair_info {
-	char name[ACPI_NAMESEG_SIZE];
+	char name[ACPI_NAMESEG_SIZE] __attribute__((nonstring));
 	u32 unexpected_btypes;
 	u32 package_index;
 	acpi_object_converter object_converter;
diff --git a/drivers/acpi/acpica/nsrepair2.c b/drivers/acpi/acpica/nsrepair2.c
index 1bb7b71f07f1..a28b1fa2b1ea 100644
--- a/drivers/acpi/acpica/nsrepair2.c
+++ b/drivers/acpi/acpica/nsrepair2.c
@@ -25,7 +25,7 @@  acpi_status (*acpi_repair_function) (struct acpi_evaluate_info * info,
 				     return_object_ptr);
 
 typedef struct acpi_repair_info {
-	char name[ACPI_NAMESEG_SIZE];
+	char name[ACPI_NAMESEG_SIZE] __attribute__((nonstring));
 	acpi_repair_function repair_function;
 
 } acpi_repair_info;
diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index 2295abbecd14..27104cbb48b5 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -396,19 +396,21 @@  static u8 __init acpi_table_checksum(u8 *buffer, u32 length)
 }
 
 /* All but ACPI_SIG_RSDP and ACPI_SIG_FACS: */
-static const char table_sigs[][ACPI_NAMESEG_SIZE] __initconst = {
-	ACPI_SIG_BERT, ACPI_SIG_BGRT, ACPI_SIG_CPEP, ACPI_SIG_ECDT,
-	ACPI_SIG_EINJ, ACPI_SIG_ERST, ACPI_SIG_HEST, ACPI_SIG_MADT,
-	ACPI_SIG_MSCT, ACPI_SIG_SBST, ACPI_SIG_SLIT, ACPI_SIG_SRAT,
-	ACPI_SIG_ASF,  ACPI_SIG_BOOT, ACPI_SIG_DBGP, ACPI_SIG_DMAR,
-	ACPI_SIG_HPET, ACPI_SIG_IBFT, ACPI_SIG_IVRS, ACPI_SIG_MCFG,
-	ACPI_SIG_MCHI, ACPI_SIG_SLIC, ACPI_SIG_SPCR, ACPI_SIG_SPMI,
-	ACPI_SIG_TCPA, ACPI_SIG_UEFI, ACPI_SIG_WAET, ACPI_SIG_WDAT,
-	ACPI_SIG_WDDT, ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT,
-	ACPI_SIG_PSDT, ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT,
-	ACPI_SIG_IORT, ACPI_SIG_NFIT, ACPI_SIG_HMAT, ACPI_SIG_PPTT,
-	ACPI_SIG_NHLT, ACPI_SIG_AEST, ACPI_SIG_CEDT, ACPI_SIG_AGDI,
-	ACPI_SIG_NBFT };
+static const char table_sigs[][ACPI_NAMESEG_SIZE] __initconst
+	__attribute__((nonstring)) = {
+		ACPI_SIG_BERT, ACPI_SIG_BGRT, ACPI_SIG_CPEP, ACPI_SIG_ECDT,
+		ACPI_SIG_EINJ, ACPI_SIG_ERST, ACPI_SIG_HEST, ACPI_SIG_MADT,
+		ACPI_SIG_MSCT, ACPI_SIG_SBST, ACPI_SIG_SLIT, ACPI_SIG_SRAT,
+		ACPI_SIG_ASF,  ACPI_SIG_BOOT, ACPI_SIG_DBGP, ACPI_SIG_DMAR,
+		ACPI_SIG_HPET, ACPI_SIG_IBFT, ACPI_SIG_IVRS, ACPI_SIG_MCFG,
+		ACPI_SIG_MCHI, ACPI_SIG_SLIC, ACPI_SIG_SPCR, ACPI_SIG_SPMI,
+		ACPI_SIG_TCPA, ACPI_SIG_UEFI, ACPI_SIG_WAET, ACPI_SIG_WDAT,
+		ACPI_SIG_WDDT, ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT,
+		ACPI_SIG_PSDT, ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT,
+		ACPI_SIG_IORT, ACPI_SIG_NFIT, ACPI_SIG_HMAT, ACPI_SIG_PPTT,
+		ACPI_SIG_NHLT, ACPI_SIG_AEST, ACPI_SIG_CEDT, ACPI_SIG_AGDI,
+		ACPI_SIG_NBFT
+	};
 
 #define ACPI_HEADER_SIZE sizeof(struct acpi_table_header)
 
diff --git a/include/acpi/actbl.h b/include/acpi/actbl.h
index 451f6276da49..88ba1b978053 100644
--- a/include/acpi/actbl.h
+++ b/include/acpi/actbl.h
@@ -66,7 +66,8 @@ 
  ******************************************************************************/
 
 struct acpi_table_header {
-	char signature[ACPI_NAMESEG_SIZE];	/* ASCII table signature */
+	char signature[ACPI_NAMESEG_SIZE]
+		__attribute__((nonstring)); /* ASCII table signature */
 	u32 length;		/* Length of table in bytes, including this header */
 	u8 revision;		/* ACPI Specification minor version number */
 	u8 checksum;		/* To make sum of entire table == 0 */