Re: [PATCH v2 1/7] arm64: add CPU field to struct thread_info

Christophe Leroy
2021-09-30T13:07:32Z

Le 30/09/2021 à 14:58, Ard Biesheuvel a écrit :
> The CPU field will be moved back into thread_info even when
> THREAD_INFO_IN_TASK is enabled, so add it back to arm64's definition of
> struct thread_info.
>
> Note that arm64 always has CONFIG_SMP=y so there is no point in guarding
> the CPU field with an #ifdef.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Acked-by: Mark Rutland <mark.rutland@arm.com>
> ---
> arch/arm64/include/asm/thread_info.h | 1 +
> arch/arm64/kernel/asm-offsets.c | 1 +
> 2 files changed, 2 insertions(+)
>
> diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
> index 6623c99f0984..c02bc8c183c3 100644
> --- a/arch/arm64/include/asm/thread_info.h
> +++ b/arch/arm64/include/asm/thread_info.h
> @@ -42,6 +42,7 @@ struct thread_info {
> void *scs_base;
> void *scs_sp;
> #endif
> + u32 cpu;
> };
>
> #define thread_saved_pc(tsk) \
> diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
> index 551427ae8cc5..cee9f3e9f906 100644
> --- a/arch/arm64/kernel/asm-offsets.c
> +++ b/arch/arm64/kernel/asm-offsets.c
> @@ -29,6 +29,7 @@ int main(void)
> DEFINE(TSK_ACTIVE_MM, offsetof(struct task_struct, active_mm));
> DEFINE(TSK_CPU, offsetof(struct task_struct, cpu));
> BLANK();
> + DEFINE(TSK_TI_CPU, offsetof(struct task_struct, thread_info.cpu));

Why adding that now ? For powerpc you do the switch in 5.

> DEFINE(TSK_TI_FLAGS, offsetof(struct task_struct, thread_info.flags));
> DEFINE(TSK_TI_PREEMPT, offsetof(struct task_struct, thread_info.preempt_count));
> #ifdef CONFIG_ARM64_SW_TTBR0_PAN
>