RE: [PATCH 2/3] e1000e: Useset_memory_ro()/set_memory_rw() toprotect flash memory

[Allan, Bruce W]

It's a single page.

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

-----Original Message-----
From: Kyle McMartin [mailto:kyle@xxxxxxxxxx]
Sent: Wednesday, September 24, 2008 10:54 AM
To: Kirsher, Jeffrey T
Cc: jeff@xxxxxxxxxx; mingo@xxxxxxx; davem@xxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; 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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