netdev - RE: [PATCH 2/3] e1000e: Useset_memory_ro()/set_memory

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Message-ID: <B27EBC40D200ED48A3F4CC2EBEABAE0B15607F81@orsmsx501.amr.corp.intel.com>
Date:	Wed, 24 Sep 2008 11:13:04 -0700
From:	"Allan, Bruce W" <bruce.w.allan@...el.com>
To:	Kyle McMartin <kyle@...hat.com>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>
CC:	"jeff@...zik.org" <jeff@...zik.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
	"Ronciak, John" <john.ronciak@...el.com>
Subject: RE: [PATCH 2/3] e1000e: Useset_memory_ro()/set_memory_rw() to
	protect flash memory

It's a single page.

We have not been able to reproduce it in-house as yet.

-----Original Message-----
From: Kyle McMartin [mailto:kyle@...hat.com]
Sent: Wednesday, September 24, 2008 10:54 AM
To: Kirsher, Jeffrey T
Cc: jeff@...zik.org; mingo@...e.hu; davem@...emloft.net; netdev@...r.kernel.org; linux-kernel@...r.kernel.org; Brandeburg, Jesse; Ronciak, John; Allan, Bruce W
Subject: Re: [PATCH 2/3] e1000e: Useset_memory_ro()/set_memory_rw() to protect flash memory

On Tue, Sep 23, 2008 at 03:45:54PM -0700, Jeff Kirsher wrote:
> +#ifdef _ASM_X86_CACHEFLUSH_H
> +     set_memory_rw((unsigned long)hw->flash_address,
> +                   hw->flash_len >> PAGE_SHIFT);
> +#endif
>       writew(val, hw->flash_address + reg);
> +#ifdef _ASM_X86_CACHEFLUSH_H
> +     set_memory_ro((unsigned long)hw->flash_address,
> +                   hw->flash_len >> PAGE_SHIFT);
> +#endif
>  }

Hi Jeff,

You're making the entire read-only mapping read-write for the single
writel call... why not just limit it to the page that the writel is
targetting?

regards, Kyle
[sorry, I've only been following this at a glance, but it's somewhat
 important for rawhide... does someone have a way to reproduce this at
 whim? Has someone tried catching it using an IOMMU on one of the newer
 Intel boxes, if it is a DMA going awry?]
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