x86: acpi: Annotate struct acpi_table_header with __packed

GCC 9.2 starts complaining about possible pointer misalignment of
pointers to the unpacked (alignment=4) structures in the packed
(alignment=1) ones:

  CC      arch/x86/cpu/tangier/acpi.o
arch/x86/cpu/tangier/acpi.c: In function ‘acpi_create_fadt’:
arch/x86/cpu/tangier/acpi.c:22:37: warning: taking address of packed
member of ‘struct acpi_fadt’ may result in an unaligned pointer value
[-Waddress-of-packed-member]
  22 |  struct acpi_table_header *header = &(fadt->header);

  CC      arch/x86/lib/acpi_table.o
arch/x86/lib/acpi_table.c: In function ‘acpi_create_spcr’:
arch/x86/lib/acpi_table.c:366:37: warning: taking address of packed
member of ‘struct acpi_spcr’ may result in an unaligned pointer value
[-Waddress-of-packed-member]
  366 |  struct acpi_table_header *header = &(spcr->header);

Fix the potential issues by annotating embedded structures with
__packed even though they are packed naturally.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: add GCC version number in the commit message]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

diff --git a/arch/x86/include/asm/acpi_table.h b/arch/x86/include/asm/acpi_table.h
index 02aea127c1a26a28fd1969d1c1d45708a3eed7c4..7588913f937022dd533e8789126a368332b1a15a 100644 (file)
--- a/arch/x86/include/asm/acpi_table.h
+++ b/arch/x86/include/asm/acpi_table.h
@@ -34,7 +34,7 @@ struct acpi_rsdp {
 };
 
 /* Generic ACPI header, provided by (almost) all tables */
-struct acpi_table_header {
+struct __packed acpi_table_header {
        char signature[4];      /* ACPI signature (4 ASCII characters) */
        u32 length;             /* Table length in bytes (incl. header) */
        u8 revision;            /* Table version (not ACPI version!) */