On Thu, Feb 18, 2016 at 07:48:35PM +0800, Zhi-zhou Zhang wrote:
> From: zhizhou <[email protected]>
>
> This patch is based on the implementation of arm. The generic
> current_pt_regs is implemented with current->stack. It need to access
> memory that would be too expensive.
Do you have any performance numbers?
> diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
> index e9e5467..1865d54 100644
> --- a/arch/arm64/include/asm/ptrace.h
> +++ b/arch/arm64/include/asm/ptrace.h
> @@ -185,5 +185,9 @@ static inline int valid_user_regs(struct user_pt_regs
> *regs)
>
> extern unsigned long profile_pc(struct pt_regs *regs);
>
> +#define current_pt_regs(void) ({ (struct pt_regs *) \
> + ((current_stack_pointer | (THREAD_SIZE - 1)) - 0xf) - 1; \
> +})
I don't think this works well with the separate IRQ stack that we merged
in 4.5-rc1. current_thread_info() explicitly uses "sp_el0" while
current_stack_pointer is just "sp" (though I don't think we ever use
current_pt_regs in interrupt context).
--
Catalin
