Re: [PATCH v13 RESEND 13/14] arm64: Use generic TIF bits for common thread flags

[Jinjie Ruan <ruanjinjie@huawei.com>]

On 2026/3/20 1:07, Kevin Brodsky wrote:
> On 17/03/2026 09:20, Jinjie Ruan wrote:
>> Use the generic TIF bits defined in <asm-generic/thread_info_tif.h> for
>> standard thread flags (TIF_SIGPENDING, TIF_NEED_RESCHED, TIF_NOTIFY_RESUME,
>> TIF_RESTORE_SIGMASK, TIF_SINGLESTEP, etc.) instead of defining
>> them locally.
>>
>> Arm64-specific bits (TIF_FOREIGN_FPSTATE, TIF_MTE_ASYNC_FAULT, TIF_SVE,
>> TIF_SSBD, etc.) are renumbered to start at bit 16 to avoid conflicts.
>>
>> This enables RSEQ optimizations which require CONFIG_HAVE_GENERIC_TIF_BITS
>> combined with the generic entry infrastructure (already used by arm64).
>>
>> Cc: Thomas Gleixner <tglx@kernel.org>
>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>>  arch/arm64/Kconfig                   |  1 +
>>  arch/arm64/include/asm/thread_info.h | 62 ++++++++++++----------------
>>  2 files changed, 28 insertions(+), 35 deletions(-)
>>

[...]

>> + */
>> +#define HAVE_TIF_NEED_RESCHED_LAZY
>> +#define HAVE_TIF_RESTORE_SIGMASK
>> +#define HAVE_TIF_SINGLESTEP
>> +
>> +#include <asm-generic/thread_info_tif.h>
>> +
>> +#define TIF_FOREIGN_FPSTATE	16	/* CPU's FP state is not current's */
>> +#define TIF_MTE_ASYNC_FAULT	17	/* MTE Asynchronous Tag Check Fault */
>> +#define TIF_FREEZE		18
> 
> Turns out this flag became unused a long time ago, see commit
> d88e4cb67197 ("freezer: remove now unused TIF_FREEZE"), and it was
> probably reintroduced by mistake in the original arm64 implementation,
> commit b3901d54dc4f ("arm64: Process management"). Good opportunity to
> remove it I think.

Totally agree. Let's get rid of it. No point in keeping dead code.

Thanks for the review.

> 
> Otherwise:
> 
> Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
> 
>> +#define TIF_32BIT		19      /* 32bit process */
>> +#define TIF_SVE			20	/* Scalable Vector Extension in use */
>> +#define TIF_SVE_VL_INHERIT	21	/* Inherit SVE vl_onexec across exec */
>> +#define TIF_SSBD		22	/* Wants SSB mitigation */
>> +#define TIF_TAGGED_ADDR		23	/* Allow tagged user addresses */
>> +#define TIF_SME			24	/* SME in use */
>> +#define TIF_SME_VL_INHERIT	25	/* Inherit SME vl_onexec across exec */
>> +#define TIF_KERNEL_FPSTATE	26	/* Task is in a kernel mode FPSIMD section */
>> +#define TIF_TSC_SIGSEGV		27	/* SIGSEGV on counter-timer access */
>> +#define TIF_LAZY_MMU_PENDING	28	/* Ops pending for lazy mmu mode exit */
>>  
>> -#define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
>> -#define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
>> -#define _TIF_NEED_RESCHED_LAZY	(1 << TIF_NEED_RESCHED_LAZY)
>> -#define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
>> -#define _TIF_FOREIGN_FPSTATE	(1 << TIF_FOREIGN_FPSTATE)
>> -#define _TIF_PATCH_PENDING	(1 << TIF_PATCH_PENDING)
>> -#define _TIF_UPROBE		(1 << TIF_UPROBE)
>> -#define _TIF_32BIT		(1 << TIF_32BIT)
>> -#define _TIF_SVE		(1 << TIF_SVE)
>> -#define _TIF_MTE_ASYNC_FAULT	(1 << TIF_MTE_ASYNC_FAULT)
>> -#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
>> -#define _TIF_TSC_SIGSEGV	(1 << TIF_TSC_SIGSEGV)
>> +#define _TIF_FOREIGN_FPSTATE	BIT(TIF_FOREIGN_FPSTATE)
>> +#define _TIF_32BIT		BIT(TIF_32BIT)
>> +#define _TIF_SVE		BIT(TIF_SVE)
>> +#define _TIF_MTE_ASYNC_FAULT	BIT(TIF_MTE_ASYNC_FAULT)
>> +#define _TIF_TSC_SIGSEGV	BIT(TIF_TSC_SIGSEGV)
>>  
>>  #ifdef CONFIG_SHADOW_CALL_STACK
>>  #define INIT_SCS							\
>