linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Yaohui Wang <yaohuiwang@linux.alibaba.com>
To: dave.hansen@linux.intel.com, luto@kernel.org,
	peterz@infradead.org, Thomas Gleixner <tglx@linutronix.de>,
	mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com
Cc: linux-kernel@vger.kernel.org, yaohuiwang@linux.alibaba.com
Subject: Re: [PATCH v3 0/2] x86/ioremap: fix boundary calculation and boundary judgment issues for ioremap()
Date: Thu, 1 Jul 2021 10:44:47 +0800	[thread overview]
Message-ID: <55fa4f7e-356b-8b41-0e06-efa5a065277a@linux.alibaba.com> (raw)
In-Reply-To: <20210621123419.2976-1-yaohuiwang@linux.alibaba.com>

Hi, maintainers,

It's been 10 days since I sent the patches at Jun 21st. Would you please
help to review them? Wish to hear your feedbacks, Thanks!


Yaohui

On 2021/6/21 20:34, Yaohui Wang wrote:
> ioremap_xxx() functions should fail if the memory address range contains
> normal RAM. But due to some boundary calculation and boundary judgment
> issues, the RAM check may be omitted for the very start or the very end
> page in the memory range. As a consequence, ioremap_xxx() can be applied
> to normal RAM pages by mistake. This raises the risk of misusing
> ioremap_xxx() functions on normal RAM ranges, and may incur terrible
> performance issues.
> 
> For example, suppose [phys_addr ~ phys_addr + PAGE_SIZE - 1] is a normal
> RAM page. Calling ioremap(phys_addr, PAGE_SIZE-1) will succeed (but it
> should not). This will set the cache flag of the phys_addr's directing
> mapping pte to be PCD. What's worse, iounmap() won't revert this cache
> flag in the directing mapping. So the pte in the directing mapping keeps
> polluted until workarounds are applied (by invoking ioremap_cache() on
> phys_addr) to fix the cache bit. If there is important data/code in the
> polluted page, which is accessed frequently, then the performance of the
> machine will drop terribly.
> 
> These two patches aim to address this issue.
> 
> Yahui Wang (2):
>    x86/ioremap: fix the pfn calculation mistake in __ioremap_check_ram()
>    kernel/resource: fix boundary judgment issues in find_next_iomem_res()
>      and __walk_iomem_res_desc()
> 
>   arch/x86/mm/ioremap.c | 16 ++++++++--------
>   kernel/resource.c     |  4 ++--
>   2 files changed, 10 insertions(+), 10 deletions(-)
> 
> 
> base-commit: 13311e74253fe64329390df80bed3f07314ddd61
> 

      parent reply	other threads:[~2021-07-01  2:44 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-21 12:34 [PATCH v3 0/2] x86/ioremap: fix boundary calculation and boundary judgment issues for ioremap() Yaohui Wang
2021-06-21 12:34 ` [PATCH v3 1/2] x86/ioremap: fix the pfn calculation mistake in __ioremap_check_ram() Yaohui Wang
2021-07-01 14:41   ` Dave Hansen
2021-07-02 10:05     ` Yaohui Wang
2021-07-02 14:49       ` Dave Hansen
2021-07-05  2:11         ` Yaohui Wang
2021-06-21 12:34 ` [PATCH v3 2/2] kernel/resource: fix boundary judgment issues in find_next_iomem_res() and __walk_iomem_res_desc() Yaohui Wang
2021-07-01 16:29   ` Dave Hansen
2021-07-01  2:44 ` Yaohui Wang [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=55fa4f7e-356b-8b41-0e06-efa5a065277a@linux.alibaba.com \
    --to=yaohuiwang@linux.alibaba.com \
    --cc=bp@alien8.de \
    --cc=dave.hansen@linux.intel.com \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).