LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: "wangliang (C)" <wangliang101@huawei.com>
To: Luis Chamberlain <mcgrof@kernel.org>
Cc: "palmerdabbelt@google.com" <palmerdabbelt@google.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"linux@armlinux.org.uk" <linux@armlinux.org.uk>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	"Wangle (RTOS FAE)" <wangle6@huawei.com>,
	"Chenxin (RTOS)" <kepler.chenxin@huawei.com>,
	Nixiaoming <nixiaoming@huawei.com>,
	"Wangkefeng (OS Kernel Lab)" <wangkefeng.wang@huawei.com>
Subject: 答复: [PATCH v2] lib: Use PFN_PHYS() in devmem_is_allowed()
Date: Sat, 31 Jul 2021 02:04:02 +0000	[thread overview]
Message-ID: <6ce22e64615846968533b7d920bc431d@huawei.com> (raw)
In-Reply-To: <YQRUz9Uw9nfiLcgr@bombadil.infradead.org>

I'm glad to get the reply.
I found this problem not only with the arm, but also with the x86. Is it good to fixed both in only one patch? I found this problem in actual work. When CONFIG_STRICT_DEVMEM is enabled on the ARM and devmem is used to map a high address that is not in the iomem address range, an unexpected error indicating no permission is returned. Then i find the bug.

-----邮件原件-----
发件人: Luis Chamberlain [mailto:mcgrof@infradead.org] 代表 Luis Chamberlain
发送时间: 2021年7月31日 3:37
收件人: wangliang (C) <wangliang101@huawei.com>
抄送: palmerdabbelt@google.com; linux-kernel@vger.kernel.org; gregkh@linuxfoundation.org; linux@armlinux.org.uk; linux-arm-kernel@lists.infradead.org; stable@vger.kernel.org; Wangle (RTOS FAE) <wangle6@huawei.com>; Chenxin (RTOS) <kepler.chenxin@huawei.com>; Nixiaoming <nixiaoming@huawei.com>; Wangkefeng (OS Kernel Lab) <wangkefeng.wang@huawei.com>
主题: Re: [PATCH v2] lib: Use PFN_PHYS() in devmem_is_allowed()

On Fri, Jul 30, 2021 at 03:43:15PM +0800, Liang Wang wrote:
> The physical address may exceed 32 bits on ARM(when ARM_LPAE enabled), 
> use PFN_PHYS() in devmem_is_allowed(),

First off, good catch!

This should not be ARM specific, this should just say:

on 32-bit systems with more than 32 bits of physcial address

Also, towards then end then explain that in practice, yes, this is probably just ARM which is affected. By explaining this, it ensures folks are aware of the affected systems.

May be good to refer to commit 947d0496cf3e1 ("generic: make PFN_PHYS explicitly return phys_addr_t") which added the original PFN_PHYS() casting to phys_addr_t to resolve the same problem.

> or the physical address may overflow and be truncated.

Indeed. How did you find this issue? Can you describe that in the commit log? Was it a real world issue or did you do just code inspection? Or was there a bot which helped you?

> This bug was initially introduced from v2.6.37, and the function was 
> moved to lib when v5.11.
> 
> Fixes: 087aaffcdf9c ("ARM: implement CONFIG_STRICT_DEVMEM by disabling 
> access to RAM via /dev/mem")
> Fixes: 527701eda5f1 ("lib: Add a generic version of 
> devmem_is_allowed()")
> Cc: stable@vger.kernel.org # v2.6.37
> Signed-off-by: Liang Wang <wangliang101@huawei.com>

Other than that:

Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>

  Luis

  reply	other threads:[~2021-07-31  2:04 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-30  7:43 Liang Wang
2021-07-30 19:36 ` Luis Chamberlain
2021-07-31  2:04   ` wangliang (C) [this message]
  -- strict thread matches above, loose matches on Subject: below --
2021-07-31  2:16 撤回: " wangliang (C)
     [not found] <20210730064915.56249-1-wangliang101@huawei.com>
2021-07-30  7:04 ` Kefeng Wang
2021-08-04  0:20   ` Palmer Dabbelt
2021-08-04  5:03     ` Kefeng Wang

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=6ce22e64615846968533b7d920bc431d@huawei.com \
    --to=wangliang101@huawei.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=kepler.chenxin@huawei.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=mcgrof@kernel.org \
    --cc=nixiaoming@huawei.com \
    --cc=palmerdabbelt@google.com \
    --cc=stable@vger.kernel.org \
    --cc=wangkefeng.wang@huawei.com \
    --cc=wangle6@huawei.com \
    --subject='Re: 答复: [PATCH v2] lib: Use PFN_PHYS() in devmem_is_allowed()' \
    /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

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).