Re: [PATCH v13 RESEND 12/14] asm-generic: Move TIF_SINGLESTEP to generic TIF bits

[Kevin Brodsky <kevin.brodsky@arm.com>]

On 17/03/2026 09:20, Jinjie Ruan wrote:
> Currently, x86, ARM64, s390, and LoongArch all define and use
> TIF_SINGLESTEP to track single-stepping state.
>
> Since this flag is shared across multiple major architectures and serves
> a common purpose in the generic entry/exit paths, move TIF_SINGLESTEP
> into the generic Thread Information Flags (TIF) infrastructure.
>
> This consolidation reduces architecture-specific boilerplate code and
> ensures consistency for generic features that rely on single-step
> state tracking.
>
> Cc: Thomas Gleixner <tglx@kernel.org>
> Acked-by: Heiko Carstens <hca@linux.ibm.com> # s390
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>

Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>

> ---
>  arch/loongarch/include/asm/thread_info.h | 11 +++++------
>  arch/s390/include/asm/thread_info.h      |  7 +++----
>  arch/x86/include/asm/thread_info.h       |  6 ++----
>  include/asm-generic/thread_info_tif.h    |  5 +++++
>  4 files changed, 15 insertions(+), 14 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/thread_info.h b/arch/loongarch/include/asm/thread_info.h
> index 4d7117fcdc78..a2ec87f18e1d 100644
> --- a/arch/loongarch/include/asm/thread_info.h
> +++ b/arch/loongarch/include/asm/thread_info.h
> @@ -70,6 +70,7 @@ register unsigned long current_stack_pointer __asm__("$sp");
>   */
>  #define HAVE_TIF_NEED_RESCHED_LAZY
>  #define HAVE_TIF_RESTORE_SIGMASK
> +#define HAVE_TIF_SINGLESTEP
>  
>  #include <asm-generic/thread_info_tif.h>
>  
> @@ -82,11 +83,10 @@ register unsigned long current_stack_pointer __asm__("$sp");
>  #define TIF_32BIT_REGS		21	/* 32-bit general purpose registers */
>  #define TIF_32BIT_ADDR		22	/* 32-bit address space */
>  #define TIF_LOAD_WATCH		23	/* If set, load watch registers */
> -#define TIF_SINGLESTEP		24	/* Single Step */
> -#define TIF_LSX_CTX_LIVE	25	/* LSX context must be preserved */
> -#define TIF_LASX_CTX_LIVE	26	/* LASX context must be preserved */
> -#define TIF_USEDLBT		27	/* LBT was used by this task this quantum (SMP) */
> -#define TIF_LBT_CTX_LIVE	28	/* LBT context must be preserved */
> +#define TIF_LSX_CTX_LIVE	24	/* LSX context must be preserved */
> +#define TIF_LASX_CTX_LIVE	25	/* LASX context must be preserved */
> +#define TIF_USEDLBT		26	/* LBT was used by this task this quantum (SMP) */
> +#define TIF_LBT_CTX_LIVE	27	/* LBT context must be preserved */
>  
>  #define _TIF_NOHZ		BIT(TIF_NOHZ)
>  #define _TIF_USEDFPU		BIT(TIF_USEDFPU)
> @@ -96,7 +96,6 @@ register unsigned long current_stack_pointer __asm__("$sp");
>  #define _TIF_32BIT_REGS		BIT(TIF_32BIT_REGS)
>  #define _TIF_32BIT_ADDR		BIT(TIF_32BIT_ADDR)
>  #define _TIF_LOAD_WATCH		BIT(TIF_LOAD_WATCH)
> -#define _TIF_SINGLESTEP		BIT(TIF_SINGLESTEP)
>  #define _TIF_LSX_CTX_LIVE	BIT(TIF_LSX_CTX_LIVE)
>  #define _TIF_LASX_CTX_LIVE	BIT(TIF_LASX_CTX_LIVE)
>  #define _TIF_USEDLBT		BIT(TIF_USEDLBT)
> diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
> index 1bcd42614e41..95be5258a422 100644
> --- a/arch/s390/include/asm/thread_info.h
> +++ b/arch/s390/include/asm/thread_info.h
> @@ -61,6 +61,7 @@ void arch_setup_new_exec(void);
>   */
>  #define HAVE_TIF_NEED_RESCHED_LAZY
>  #define HAVE_TIF_RESTORE_SIGMASK
> +#define HAVE_TIF_SINGLESTEP
>  
>  #include <asm-generic/thread_info_tif.h>
>  
> @@ -69,15 +70,13 @@ void arch_setup_new_exec(void);
>  #define TIF_GUARDED_STORAGE	17	/* load guarded storage control block */
>  #define TIF_ISOLATE_BP_GUEST	18	/* Run KVM guests with isolated BP */
>  #define TIF_PER_TRAP		19	/* Need to handle PER trap on exit to usermode */
> -#define TIF_SINGLESTEP		21	/* This task is single stepped */
> -#define TIF_BLOCK_STEP		22	/* This task is block stepped */
> -#define TIF_UPROBE_SINGLESTEP	23	/* This task is uprobe single stepped */
> +#define TIF_BLOCK_STEP		20	/* This task is block stepped */
> +#define TIF_UPROBE_SINGLESTEP	21	/* This task is uprobe single stepped */
>  
>  #define _TIF_ASCE_PRIMARY	BIT(TIF_ASCE_PRIMARY)
>  #define _TIF_GUARDED_STORAGE	BIT(TIF_GUARDED_STORAGE)
>  #define _TIF_ISOLATE_BP_GUEST	BIT(TIF_ISOLATE_BP_GUEST)
>  #define _TIF_PER_TRAP		BIT(TIF_PER_TRAP)
> -#define _TIF_SINGLESTEP	BIT(TIF_SINGLESTEP)
>  #define _TIF_BLOCK_STEP		BIT(TIF_BLOCK_STEP)
>  #define _TIF_UPROBE_SINGLESTEP	BIT(TIF_UPROBE_SINGLESTEP)
>  
> diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
> index 0067684afb5b..f59072ba1473 100644
> --- a/arch/x86/include/asm/thread_info.h
> +++ b/arch/x86/include/asm/thread_info.h
> @@ -98,9 +98,8 @@ struct thread_info {
>  #define TIF_IO_BITMAP		22	/* uses I/O bitmap */
>  #define TIF_SPEC_FORCE_UPDATE	23	/* Force speculation MSR update in context switch */
>  #define TIF_FORCED_TF		24	/* true if TF in eflags artificially */
> -#define TIF_SINGLESTEP		25	/* reenable singlestep on user return*/
> -#define TIF_BLOCKSTEP		26	/* set when we want DEBUGCTLMSR_BTF */
> -#define TIF_ADDR32		27	/* 32-bit address space on 64 bits */
> +#define TIF_BLOCKSTEP		25	/* set when we want DEBUGCTLMSR_BTF */
> +#define TIF_ADDR32		26	/* 32-bit address space on 64 bits */
>  
>  #define _TIF_SSBD		BIT(TIF_SSBD)
>  #define _TIF_SPEC_IB		BIT(TIF_SPEC_IB)
> @@ -112,7 +111,6 @@ struct thread_info {
>  #define _TIF_SPEC_FORCE_UPDATE	BIT(TIF_SPEC_FORCE_UPDATE)
>  #define _TIF_FORCED_TF		BIT(TIF_FORCED_TF)
>  #define _TIF_BLOCKSTEP		BIT(TIF_BLOCKSTEP)
> -#define _TIF_SINGLESTEP		BIT(TIF_SINGLESTEP)
>  #define _TIF_ADDR32		BIT(TIF_ADDR32)
>  
>  /* flags to check in __switch_to() */
> diff --git a/include/asm-generic/thread_info_tif.h b/include/asm-generic/thread_info_tif.h
> index da1610a78f92..b277fe06aee3 100644
> --- a/include/asm-generic/thread_info_tif.h
> +++ b/include/asm-generic/thread_info_tif.h
> @@ -48,4 +48,9 @@
>  #define TIF_RSEQ		11	// Run RSEQ fast path
>  #define _TIF_RSEQ		BIT(TIF_RSEQ)
>  
> +#ifdef HAVE_TIF_SINGLESTEP
> +#define TIF_SINGLESTEP		12	/* reenable singlestep on user return*/
> +#define _TIF_SINGLESTEP		BIT(TIF_SINGLESTEP)
> +#endif
> +
>  #endif /* _ASM_GENERIC_THREAD_INFO_TIF_H_ */