From: qiuxishi@huawei•com (Xishi Qiu)
To: linux-arm-kernel@lists•infradead.org
Subject: Have any influence on set_memory_** about below patch ??
Date: Thu, 14 Jan 2016 21:06:08 +0800 [thread overview]
Message-ID: <56979D40.4060602@huawei.com> (raw)
In-Reply-To: <56979621.1060102@huawei.com>
On 2016/1/14 20:35, Xishi Qiu wrote:
> 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?
>
Hi Mark,
Is the two approaches like following?
1. use create_mapping to map the data in read only, then use fixmap to create a
temp page table, and change the data when necessary.
2. use vmalloc, then we can use set_memory_ro to change the page table prot.
Thanks,
Xishi Qiu
> Thanks,
> Xishi Qiu
>
>> Thanks,
>> Mark.
>>
>> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-January/397320.html
>>
>> .
>>
>
>
next prev parent reply other threads:[~2016-01-14 13:06 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <5693A740.7070408@huawei.com>
[not found] ` <20160111133145.GM6499@leverpostej>
2016-01-12 1:20 ` Have any influence on set_memory_** about below patch ?? Xishi Qiu
2016-01-12 11:15 ` Mark Rutland
2016-01-13 4:10 ` Xishi Qiu
2016-01-13 11:22 ` Mark Rutland
2016-01-13 5:02 ` Xishi Qiu
2016-01-13 6:35 ` Xishi Qiu
2016-01-13 11:28 ` Mark Rutland
2016-01-27 1:18 ` Xishi Qiu
2016-01-27 11:25 ` Mark Rutland
2016-01-26 14:05 ` zhong jiang
2016-01-26 16:07 ` Mark Rutland
2016-01-13 10:30 ` Xishi Qiu
2016-01-13 11:18 ` Mark Rutland
2016-01-14 12:35 ` Xishi Qiu
2016-01-14 13:06 ` Xishi Qiu [this message]
2016-01-14 13:44 ` Mark Rutland
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