From: Catalin Marinas <catalin.marinas@arm.com>
To: Zhi-zhou Zhang <zhizhou.zh@gmail.com>
Cc: robin.murphy@arm.com, will.deacon@arm.com,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: add architecture specified current_pt_regs
Date: Thu, 18 Feb 2016 11:58:24 +0000 [thread overview]
Message-ID: <20160218115824.GA2538@e104818-lin.cambridge.arm.com> (raw)
In-Reply-To: <1455796115-7844-1-git-send-email-zhizhou.zh@gmail.com>
On Thu, Feb 18, 2016 at 07:48:35PM +0800, Zhi-zhou Zhang wrote:
> From: zhizhou <zhizhou.zh@gmail.com>
>
> 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
next prev parent reply other threads:[~2016-02-18 11:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-18 11:48 Zhi-zhou Zhang
2016-02-18 11:58 ` Catalin Marinas [this message]
2016-02-19 2:30 ` Zhi-zhou
2016-02-19 10:32 ` Will Deacon
2016-02-19 12:01 ` Zhizhou Zhang
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