linux-kernel - Re: another pagetable initialization crash on xen

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:	Wed, 30 Mar 2011 10:58:05 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Stefano Stabellini <stefano.stabellini@...citrix.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: another pagetable initialization crash on xen

On 03/30/2011 09:59 AM, Stefano Stabellini wrote:
> On Wed, 30 Mar 2011, Stefano Stabellini wrote:
>> I have another unrelated question: init_memory_mapping is called on the
>> range 0 - max_low_pfn, but that range usually includes a reserved region
>> below the first MB. On one machine of mine the IOAPIC mmio region falls
>> in that memory range therefore we are mapping the IOAPIC mmio region in
>> init_memory_mapping without going through the fixmap as we should.
>> This is causing problems on Xen, but I guess it could theoretically
>> cause problems on other platforms as well. Should we avoid reserved
>> memory regions below the first MB from the initial memory mappings?
>
> Sorry I mixed up frame numbers with physical addresses, so the IOAPIC
> mmio region is actually at 0xfec00000 where it should be but it gets
> mapped during the initial memory mapping (range 0 - 0x100000000).
> Is that supposed to happen? Shouldn't it go through the fixmap?

io apic addr is going through fixmap.

initial_memory_mapping will map to [0, max_mem_under_4g).
max_mem_under_4g is from E820 table searching.

later it will map [4g, max_mem_above_4g).

We do not map mmio gap between [max_mem_under_4g,4g)

Thanks

Yinghai
--
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/