[PATCH] LoongArch: Fix bitflag conflict for TIF_FIXADE

[PATCH] LoongArch: Fix bitflag conflict for TIF_FIXADE

[Yao Zi]

After LoongArch was converted to use the generic TIF bits in commit
f9629891d407 ("loongarch: Use generic TIF bits"), its TIF_FIXADE flag
takes the same bit with TIF_RESTORE_SIGMASK in thread_info.flags.

Such conflict causes TIF_FIXADE being considered cleared when
TIF_RESTORE_SIGMASK is cleared during deliver of a signal. And since
TIF_FIXADE determines whether unaligned access emulation works for a
task, userspace making use of unaligned access will receive unexpected
SIGBUS (and likely terminate) after receiving its first signal.

This conflict looks like a simple typo, let's just switch to a free bit.

Fixes: f9629891d407 ("loongarch: Use generic TIF bits")
Signed-off-by: Yao Zi <ziyao@disroot.org>
---

Note the problematic commit is contained in next-20250918, but not
master.

 arch/loongarch/include/asm/thread_info.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/loongarch/include/asm/thread_info.h b/arch/loongarch/include/asm/thread_info.h
index def7cb14467e..4d7117fcdc78 100644
--- a/arch/loongarch/include/asm/thread_info.h
+++ b/arch/loongarch/include/asm/thread_info.h
@@ -77,7 +77,7 @@ register unsigned long current_stack_pointer __asm__("$sp");
 #define TIF_NOHZ		16	/* in adaptive nohz mode */
 #define TIF_USEDFPU		17	/* FPU was used by this task this quantum (SMP) */
 #define TIF_USEDSIMD		18	/* SIMD has been used this quantum */
-#define TIF_FIXADE		10	/* Fix address errors in software */
+#define TIF_FIXADE		19	/* Fix address errors in software */
 #define TIF_LOGADE		20	/* Log address errors to syslog */
 #define TIF_32BIT_REGS		21	/* 32-bit general purpose registers */
 #define TIF_32BIT_ADDR		22	/* 32-bit address space */
-- 
2.50.1

Re:[PATCH] LoongArch: Fix bitflag conflict for TIF_FIXADE

[Wentao Guan]

Hello,

nice catch:)

Reviewed-by: Wentao Guan <guanwentao@uniontech.com>

BRs
Wentao Guan

Re: [PATCH] LoongArch: Fix bitflag conflict for TIF_FIXADE

[Huacai Chen]

On Fri, Sep 19, 2025 at 8:58 PM Yao Zi <ziyao@disroot.org> wrote:
>
> After LoongArch was converted to use the generic TIF bits in commit
> f9629891d407 ("loongarch: Use generic TIF bits"), its TIF_FIXADE flag
> takes the same bit with TIF_RESTORE_SIGMASK in thread_info.flags.
>
> Such conflict causes TIF_FIXADE being considered cleared when
> TIF_RESTORE_SIGMASK is cleared during deliver of a signal. And since
> TIF_FIXADE determines whether unaligned access emulation works for a
> task, userspace making use of unaligned access will receive unexpected
> SIGBUS (and likely terminate) after receiving its first signal.
>
> This conflict looks like a simple typo, let's just switch to a free bit.
>
> Fixes: f9629891d407 ("loongarch: Use generic TIF bits")
> Signed-off-by: Yao Zi <ziyao@disroot.org>
> ---
>
> Note the problematic commit is contained in next-20250918, but not
> master.
It will be more beautiful if this patch is squashed to the original one.

Huacai

>
>  arch/loongarch/include/asm/thread_info.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/loongarch/include/asm/thread_info.h b/arch/loongarch/include/asm/thread_info.h
> index def7cb14467e..4d7117fcdc78 100644
> --- a/arch/loongarch/include/asm/thread_info.h
> +++ b/arch/loongarch/include/asm/thread_info.h
> @@ -77,7 +77,7 @@ register unsigned long current_stack_pointer __asm__("$sp");
>  #define TIF_NOHZ               16      /* in adaptive nohz mode */
>  #define TIF_USEDFPU            17      /* FPU was used by this task this quantum (SMP) */
>  #define TIF_USEDSIMD           18      /* SIMD has been used this quantum */
> -#define TIF_FIXADE             10      /* Fix address errors in software */
> +#define TIF_FIXADE             19      /* Fix address errors in software */
>  #define TIF_LOGADE             20      /* Log address errors to syslog */
>  #define TIF_32BIT_REGS         21      /* 32-bit general purpose registers */
>  #define TIF_32BIT_ADDR         22      /* 32-bit address space */
> --
> 2.50.1
>

[tip: core/core] LoongArch: Fix bitflag conflict for TIF_FIXADE

[tip-bot2 for Yao Zi]

The following commit has been merged into the core/core branch of tip:

Commit-ID:     3ec09344b01a15901ba824e877a0562ed8103e27
Gitweb:        https://git.kernel.org/tip/3ec09344b01a15901ba824e877a0562ed8103e27
Author:        Yao Zi <ziyao@disroot.org>
AuthorDate:    Fri, 19 Sep 2025 12:58:29 
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Sat, 20 Sep 2025 09:55:56 +02:00

LoongArch: Fix bitflag conflict for TIF_FIXADE

After LoongArch was converted to use the generic TIF bits in commit
f9629891d407 ("loongarch: Use generic TIF bits"), its TIF_FIXADE flag
takes the same bit with TIF_RESTORE_SIGMASK in thread_info.flags.

Such conflict causes TIF_FIXADE being considered cleared when
TIF_RESTORE_SIGMASK is cleared during deliver of a signal. And since
TIF_FIXADE determines whether unaligned access emulation works for a
task, userspace making use of unaligned access will receive unexpected
SIGBUS (and likely terminate) after receiving its first signal.

This conflict looks like a simple typo, switch it to the free bit 19.

Fixes: f9629891d407 ("loongarch: Use generic TIF bits")
Signed-off-by: Yao Zi <ziyao@disroot.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Wentao Guan <guanwentao@uniontech.com>
---
 arch/loongarch/include/asm/thread_info.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/loongarch/include/asm/thread_info.h b/arch/loongarch/include/asm/thread_info.h
index def7cb1..4d7117f 100644
--- a/arch/loongarch/include/asm/thread_info.h
+++ b/arch/loongarch/include/asm/thread_info.h
@@ -77,7 +77,7 @@ register unsigned long current_stack_pointer __asm__("$sp");
 #define TIF_NOHZ		16	/* in adaptive nohz mode */
 #define TIF_USEDFPU		17	/* FPU was used by this task this quantum (SMP) */
 #define TIF_USEDSIMD		18	/* SIMD has been used this quantum */
-#define TIF_FIXADE		10	/* Fix address errors in software */
+#define TIF_FIXADE		19	/* Fix address errors in software */
 #define TIF_LOGADE		20	/* Log address errors to syslog */
 #define TIF_32BIT_REGS		21	/* 32-bit general purpose registers */
 #define TIF_32BIT_ADDR		22	/* 32-bit address space */