Re: Have any influence on set_memory_** about below patch ??

From	Xishi Qiu <qiuxishi@huawei.com>
Newsgroups	linux.kernel
Subject	Re: Have any influence on set_memory_** about below patch ??
Date	2016-01-14 13:40 +0100
Message-ID	<qQPm3-71u-23@gated-at.bofh.it> (permalink)
References	(1 earlier) <qPVWy-2fD-23@gated-at.bofh.it> <qPVWy-2fD-19@gated-at.bofh.it> <qQ59w-8S-29@gated-at.bofh.it> <qQr0n-6PJ-35@gated-at.bofh.it> <qQrD4-7jL-19@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 2016/1/13 19:18, Mark Rutland wrote:

> On Wed, Jan 13, 2016 at 06:30:06PM +0800, Xishi Qiu wrote:
>> Hi Mark,
>>
>> If I create swapper page tables by 4kb, not large page, then I use
>> set_memory_ro() to change the pate table flag, does it have the problem
>> too?
> 
> The splitting/merging problem would not apply.
> 
> However, you're going to waste a reasonable amount of memory by not
> using section mappings in the swapper, and we gain additional complexity
> in the page table setup code (which is shared with others things that
> want section mappings).
> 
> What are you exactly actually trying to achieve?
> 

If module allocates some pages and save data on them, and the data will
not be changed during the module running. So we want to use set_memory_ro()
to increase the security. If the data is changed, we can catch someone.

> What memory do you want to mark RO, and why?
> 

The key data, and it will not be changed during the running time.

>>From a previous discussion [1], we figured out alternative approaches
> for common cases. Do none of those work for your case?
> 

I have not read the patchset carefully, could you tell me the general meaning
of the approaches?

Thanks,
Xishi Qiu

> Thanks,
> Mark.
> 
> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-January/397320.html
> 
> .
>

Thread

Re: Have any influence on set_memory_** about below patch ?? Xishi Qiu <qiuxishi@huawei.com> - 2016-01-12 02:30 +0100
  Re: Have any influence on set_memory_** about below patch ?? Mark Rutland <mark.rutland@arm.com> - 2016-01-12 12:20 +0100
    Re: Have any influence on set_memory_** about below patch ?? Xishi Qiu <qiuxishi@huawei.com> - 2016-01-13 05:20 +0100
      Re: Have any influence on set_memory_** about below patch ?? Mark Rutland <mark.rutland@arm.com> - 2016-01-13 12:30 +0100
    Re: Have any influence on set_memory_** about below patch ?? Xishi Qiu <qiuxishi@huawei.com> - 2016-01-13 06:10 +0100
      Re: Have any influence on set_memory_** about below patch ?? Xishi Qiu <qiuxishi@huawei.com> - 2016-01-13 07:40 +0100
      Re: Have any influence on set_memory_** about below patch ?? Mark Rutland <mark.rutland@arm.com> - 2016-01-13 12:30 +0100
    Re: Have any influence on set_memory_** about below patch ?? Xishi Qiu <qiuxishi@huawei.com> - 2016-01-13 11:40 +0100
      Re: Have any influence on set_memory_** about below patch ?? Mark Rutland <mark.rutland@arm.com> - 2016-01-13 12:20 +0100
        Re: Have any influence on set_memory_** about below patch ?? Xishi Qiu <qiuxishi@huawei.com> - 2016-01-14 13:40 +0100
          Re: Have any influence on set_memory_** about below patch ?? Xishi Qiu <qiuxishi@huawei.com> - 2016-01-14 14:10 +0100
            Re: Have any influence on set_memory_** about below patch ?? Mark Rutland <mark.rutland@arm.com> - 2016-01-14 14:50 +0100

csiph-web