linux-kernel - Re: [PATCH] EFI: Do not use __pa() to get the physical address of an ioremapped memory range

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 2 Sep 2011 13:12:06 +0800
From:	huang ying <huang.ying.caritas@...il.com>
To:	Matt Fleming <matt@...sole-pimps.org>
Cc:	Zhang Rui <rui.zhang@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Matthew Garrett <mjg59@...f.ucam.org>
Subject: Re: [PATCH] EFI: Do not use __pa() to get the physical address of an
 ioremapped memory range

On Thu, Sep 1, 2011 at 8:28 PM, Matt Fleming <matt@...sole-pimps.org> wrote:
> On Thu, 2011-09-01 at 16:14 +0800, Zhang Rui wrote:
>> On Thu, 2011-09-01 at 14:55 +0800, Zhang, Rui wrote:
>> > From: Zhang Rui <rui.zhang@...el.com>
>> > Date: Wed, 31 Aug 2011 09:59:01 +0800
>> > Subject: Do not use __pa() to get the physical address of an ioremapped memory range.
>> >
>> > set_memory_uc uses __pa() to translate the virtual address to the physical address.
>> > This breaks a EFI_MEMORY_MAPPED_IO memory region in my case as it was ioremapped first.
>> >
>> oops, wrong patch was attached.
>>
>> here is the correct patch.
>>
>> From: Zhang Rui <rui.zhang@...el.com>
>> Date: Wed, 31 Aug 2011 09:59:01 +0800
>> Subject: Do not use __pa() to get the physical address of an ioremapped memory range.
>>
>> set_memory_uc uses __pa() to translate the virtual address to the physical address.
>> This breaks a EFI_MEMORY_MAPPED_IO memory region in my case as it was ioremapped first.
>
> Hmm.. does anyone know why we ioremap_cache() the memory on
> CONFIG_X86_32 instead of ioremap_nocache()? In the case of
> EFI_MEMORY_MAPPED_IO the memory really needs to be uncached. Then if
> we've ioremap'd the memory we should skip set_memory_uc() altogether,
> no?

Because whether the mapping should be cached is determined by md->attr
instead of md->type.  And besides UC, we may add WC, etc support.

Best Regards,
Huang Ying
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/