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 <[email protected]>
> Signed-off-by: Jinjie Ruan <[email protected]>
> ---
> arch/arm64/Kconfig | 1 +
> arch/arm64/include/asm/thread_info.h | 62 ++++++++++++----------------
> 2 files changed, 28 insertions(+), 35 deletions(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 96fef01598be..33cf901fb1a0 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -224,6 +224,7 @@ config ARM64
> select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> select HAVE_BUILDTIME_MCOUNT_SORT
> select HAVE_EFFICIENT_UNALIGNED_ACCESS
> + select HAVE_GENERIC_TIF_BITS
> select HAVE_GUP_FAST
> select HAVE_FTRACE_GRAPH_FUNC
> select HAVE_FUNCTION_TRACER
> diff --git a/arch/arm64/include/asm/thread_info.h
> b/arch/arm64/include/asm/thread_info.h
> index f89a15dc6ad5..be1a0651cfe2 100644
> --- a/arch/arm64/include/asm/thread_info.h
> +++ b/arch/arm64/include/asm/thread_info.h
> @@ -58,42 +58,34 @@ void arch_setup_new_exec(void);
>
> #endif
>
> -#define TIF_SIGPENDING 0 /* signal pending */
> -#define TIF_NEED_RESCHED 1 /* rescheduling necessary */
> -#define TIF_NEED_RESCHED_LAZY 2 /* Lazy rescheduling needed */
> -#define TIF_NOTIFY_RESUME 3 /* callback before returning to user */
> -#define TIF_FOREIGN_FPSTATE 4 /* CPU's FP state is not current's */
> -#define TIF_UPROBE 5 /* uprobe breakpoint or singlestep */
> -#define TIF_MTE_ASYNC_FAULT 6 /* MTE Asynchronous Tag Check Fault */
> -#define TIF_NOTIFY_SIGNAL 7 /* signal notifications exist */
> -#define TIF_PATCH_PENDING 13 /* pending live patching update */
> -#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
> -#define TIF_FREEZE 19
> -#define TIF_RESTORE_SIGMASK 20
> -#define TIF_SINGLESTEP 21
> -#define TIF_32BIT 22 /* 32bit process */
> -#define TIF_SVE 23 /* Scalable Vector Extension in
> use */
> -#define TIF_SVE_VL_INHERIT 24 /* Inherit SVE vl_onexec across exec */
> -#define TIF_SSBD 25 /* Wants SSB mitigation */
> -#define TIF_TAGGED_ADDR 26 /* Allow tagged user addresses
> */
> -#define TIF_SME 27 /* SME in use */
> -#define TIF_SME_VL_INHERIT 28 /* Inherit SME vl_onexec across exec */
> -#define TIF_KERNEL_FPSTATE 29 /* Task is in a kernel mode FPSIMD
> section */
> -#define TIF_TSC_SIGSEGV 30 /* SIGSEGV on counter-timer
> access */
> -#define TIF_LAZY_MMU_PENDING 31 /* Ops pending for lazy mmu mode exit */
> +/*
> + * Tell the generic TIF infrastructure which bits arm64 supports
> + */
> +#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.
Otherwise:
Reviewed-by: Kevin Brodsky <[email protected]>
> +#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 \
