linux-kernel - Re: [PATCH 1/6] syscalls: use uaccess_kernel in addr_limit_user

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Date:   Sat, 18 Jul 2020 07:54:37 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Christoph Hellwig <hch@....de>
Cc:     Nick Hu <nickhu@...estech.com>, Greentime Hu <green.hu@...il.com>,
        Vincent Chen <deanbo422@...il.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-riscv@...ts.infradead.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] syscalls: use uaccess_kernel in addr_limit_user_check

On 7/18/20 2:48 AM, Christoph Hellwig wrote:
> On Fri, Jul 17, 2020 at 06:38:50PM -0700, Guenter Roeck wrote:
>> Hi,
>>
>> On Tue, Jul 14, 2020 at 12:55:00PM +0200, Christoph Hellwig wrote:
>>> Use the uaccess_kernel helper instead of duplicating it.
>>>
>>> Signed-off-by: Christoph Hellwig <hch@....de>
>>
>> This patch causes a severe hiccup with my mps2-an385 boot test.
> 
> I guess that is a nommu config?
> 
Correct.

> Can you try this patch?
> 
> diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
> index b19c9bec1f7a63..cc7daf374a6eb6 100644
> --- a/arch/arm/include/asm/uaccess.h
> +++ b/arch/arm/include/asm/uaccess.h
> @@ -263,7 +263,7 @@ extern int __put_user_8(void *, unsigned long long);
>   */
>  #define USER_DS			KERNEL_DS
>  
> -#define uaccess_kernel()	(true)
> +#define uaccess_kernel()	(false)
>  #define __addr_ok(addr)		((void)(addr), 1)
>  #define __range_ok(addr, size)	((void)(addr), 0)
>  #define get_fs()		(KERNEL_DS)
> 

With this change, the error message is gone. However, it still does not
work. The image just hangs instead.

Guenter