[PATCH] LoongArch: Fix build errors for CONFIG_RANDSTRUCT

[PATCH] LoongArch: Fix build errors for CONFIG_RANDSTRUCT

[Huacai Chen]

When CONFIG_RANDSTRUCT enabled, members of task_struct are randomized.
There is a chance that TASK_STACK_CANARY be out of 12bit immediate's
range and causes build errors. TASK_STACK_CANARY is naturally aligned,
so fix it by replacing ld.d/st.d with ldptr.d/stptr.d which have 14bit
immediates.

Cc: stable@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511240656.0NaPcJs1-lkp@intel.com/
Suggested-by: Rui Wang <wangrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 arch/loongarch/kernel/switch.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/loongarch/kernel/switch.S b/arch/loongarch/kernel/switch.S
index 9c23cb7e432f..3007e909e0d8 100644
--- a/arch/loongarch/kernel/switch.S
+++ b/arch/loongarch/kernel/switch.S
@@ -25,8 +25,8 @@ SYM_FUNC_START(__switch_to)
 	stptr.d a4, a0, THREAD_SCHED_CFA
 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP)
 	la	t7, __stack_chk_guard
-	LONG_L	t8, a1, TASK_STACK_CANARY
-	LONG_S	t8, t7, 0
+	ldptr.d	t8, a1, TASK_STACK_CANARY
+	stptr.d	t8, t7, 0
 #endif
 	move	tp, a2
 	cpu_restore_nonscratch a1
-- 
2.47.3

Re: [PATCH] LoongArch: Fix build errors for CONFIG_RANDSTRUCT

[Jiaxun Yang]

On Tue, 25 Nov 2025, at 4:25 PM, Huacai Chen wrote:
> When CONFIG_RANDSTRUCT enabled, members of task_struct are randomized.
> There is a chance that TASK_STACK_CANARY be out of 12bit immediate's
> range and causes build errors. TASK_STACK_CANARY is naturally aligned,
> so fix it by replacing ld.d/st.d with ldptr.d/stptr.d which have 14bit
> immediates.

Hi Huacai,

What about 32bit build in this case?

Thanks
Jiaxun

>

Re: [PATCH] LoongArch: Fix build errors for CONFIG_RANDSTRUCT

[Huacai Chen]

On Tue, Nov 25, 2025 at 9:49 PM Jiaxun Yang <jiaxun.yang@flygoat.com> wrote:
>
>
>
> On Tue, 25 Nov 2025, at 4:25 PM, Huacai Chen wrote:
> > When CONFIG_RANDSTRUCT enabled, members of task_struct are randomized.
> > There is a chance that TASK_STACK_CANARY be out of 12bit immediate's
> > range and causes build errors. TASK_STACK_CANARY is naturally aligned,
> > so fix it by replacing ld.d/st.d with ldptr.d/stptr.d which have 14bit
> > immediates.
>
> Hi Huacai,
>
> What about 32bit build in this case?
Use the same solution as other registers, please see:
https://lore.kernel.org/loongarch/20251122043634.3447854-7-chenhuacai@loongson.cn/T/#u

Huacai

>
> Thanks
> Jiaxun
>
> >