linux-kernel - Re: [PATCH] arm64: add architecture specified current_pt

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20160218115824.GA2538@e104818-lin.cambridge.arm.com>
Date:	Thu, 18 Feb 2016 11:58:24 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	Zhi-zhou Zhang <zhizhou.zh@...il.com>
Cc:	robin.murphy@....com, will.deacon@....com,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] arm64: add architecture specified current_pt_regs

On Thu, Feb 18, 2016 at 07:48:35PM +0800, Zhi-zhou Zhang wrote:
> From: zhizhou <zhizhou.zh@...il.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