Re: [PATCH V2] LoongArch: Align ACPI structures if ARCH_STRICT_ALIGN enabled
From: Guenter Roeck
Date: Fri Sep 26 2025 - 14:27:10 EST
On 9/26/25 10:15, Xi Ruoyao wrote:
On Fri, 2025-09-26 at 07:31 -0700, Guenter Roeck wrote:
On Sun, Sep 21, 2025 at 09:07:38AM +0800, Huacai Chen wrote:
Hi, Nathan,
On Sun, Sep 21, 2025 at 7:48 AM Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
arch-specific kernel issue):
Hi Huacai,
On Wed, Sep 10, 2025 at 05:10:33PM +0800, Huacai Chen wrote:
ARCH_STRICT_ALIGN is used for hardware without UAL, now it only control
the -mstrict-align flag. However, ACPI structures are packed by default
so will cause unaligned accesses.
To avoid this, define ACPI_MISALIGNMENT_NOT_SUPPORTED in asm/acenv.h to
align ACPI structures if ARCH_STRICT_ALIGN enabled.
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Binbin Zhou <zhoubinbin@xxxxxxxxxxx>
Suggested-by: Xi Ruoyao <xry111@xxxxxxxxxxx>
Suggested-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
---
V2: Modify asm/acenv.h instead of Makefile.
arch/loongarch/include/asm/acenv.h | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/arch/loongarch/include/asm/acenv.h b/arch/loongarch/include/asm/acenv.h
index 52f298f7293b..483c955f2ae5 100644
--- a/arch/loongarch/include/asm/acenv.h
+++ b/arch/loongarch/include/asm/acenv.h
@@ -10,9 +10,8 @@
#ifndef _ASM_LOONGARCH_ACENV_H
#define _ASM_LOONGARCH_ACENV_H
-/*
- * This header is required by ACPI core, but we have nothing to fill in
- * right now. Will be updated later when needed.
- */
+#ifdef CONFIG_ARCH_STRICT_ALIGN
+#define ACPI_MISALIGNMENT_NOT_SUPPORTED
+#endif /* CONFIG_ARCH_STRICT_ALIGN */
#endif /* _ASM_LOONGARCH_ACENV_H */
I am seeing several ACPI errors in my QEMU testing after this change in
Linus's tree as commit a9d13433fe17 ("LoongArch: Align ACPI structures
if ARCH_STRICT_ALIGN enabled").
$ make -skj"$(nproc)" ARCH=loongarch CROSS_COMPILE=loongarch64-linux- clean defconfig vmlinuz.efi
kernel/sched/fair.o: warning: objtool: sched_update_scaling() falls through to next function init_entity_runnable_average()
mm/mempolicy.o: warning: objtool: alloc_pages_bulk_mempolicy_noprof+0x380: stack state mismatch: reg1[30]=-1+0 reg2[30]=-2-80
lib/crypto/mpi/mpih-div.o: warning: objtool: mpihelp_divrem+0x2d0: stack state mismatch: reg1[22]=-1+0 reg2[22]=-2-16
In file included from include/acpi/acpi.h:24,
from drivers/acpi/acpica/tbprint.c:10:
drivers/acpi/acpica/tbprint.c: In function 'acpi_tb_print_table_header':
include/acpi/actypes.h:530:43: warning: 'strncmp' argument 1 declared attribute 'nonstring' is smaller than the specified bound 8 [-Wstringop-overread]
530 | #define ACPI_VALIDATE_RSDP_SIG(a) (!strncmp (ACPI_CAST_PTR (char, (a)), ACPI_SIG_RSDP, (sizeof(a) < 8) ? ACPI_NAMESEG_SIZE : 8))
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/acpi/acpica/tbprint.c:105:20: note: in expansion of macro 'ACPI_VALIDATE_RSDP_SIG'
105 | } else if (ACPI_VALIDATE_RSDP_SIG(ACPI_CAST_PTR(struct acpi_table_rsdp,
| ^~~~~~~~~~~~~~~~~~~~~~
In file included from include/acpi/acpi.h:26:
include/acpi/actbl.h:69:14: note: argument 'signature' declared here
69 | char signature[ACPI_NAMESEG_SIZE] ACPI_NONSTRING; /* ASCII table signature */
| ^~~~~~~~~
From this link this seems a comiler issue (at least not an
https://github.com/AOSC-Tracking/linux/commit/1e9ee413357ef58dd902f6ec55013d2a2f2043eb
I see that the patch made it into the upstream kernel, now breaking both
mainline and 6.16.y test builds of loongarch64:allmodconfig with gcc.
Since this is apparently intentional, I'll stop build testing
loongarch64:allmodconfig. So far it looks like my qemu tests
are not affected, so I'll continue testing those for the time being.
See https://gcc.gnu.org/PR122073 and
https://github.com/acpica/acpica/pull/1050.
I understand that. Every compiler has bugs. Normally workarounds are implemented.
Since that won't happen here, my remedy is to stop testing the affected
configuration(s). I do this whenever I learn that a known problem won't be fixed.
The above is not a complaint, just an information.
Guenter