Re: [RFC 17/17] x86/traps: Use a new on_thread_stack() helper to clean up an assertion

From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Juergen Gross <jgross@suse.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Kees Cook <keescook@chromium.org>
Subject: Re: [RFC 17/17] x86/traps: Use a new on_thread_stack() helper to clean up an assertion
Date: Tue, 12 Sep 2017 15:11:40 -0500	[thread overview]
Message-ID: <20170912201140.gcnjxdpzxhg4nyi5@treble> (raw)
In-Reply-To: <eabfbaaf295473e4d6fda700bb346af766fcee80.1504733277.git.luto@kernel.org>

On Wed, Sep 06, 2017 at 02:37:02PM -0700, Andy Lutomirski wrote:
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
>  arch/x86/include/asm/processor.h   | 17 +++++++++++++++++
>  arch/x86/include/asm/thread_info.h | 11 -----------
>  arch/x86/kernel/traps.c            |  3 +--
>  3 files changed, 18 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 4c137472f530..b6f8dc11c222 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -534,6 +534,23 @@ static inline unsigned long current_top_of_stack(void)
>  #endif
>  }
>  
> +static inline unsigned long current_stack_pointer(void)
> +{
> +	unsigned long sp;
> +#ifdef CONFIG_X86_64
> +	asm("mov %%rsp,%0" : "=g" (sp));
> +#else
> +	asm("mov %%esp,%0" : "=g" (sp));
> +#endif
> +	return sp;
> +}

I know you're just moving the function, but this function could also be
cleaned up by using _ASM_SP and getting rid of the ifdef.

-- 
Josh