linux-kernel - Re: [Fastboot] [CFT] ELF Relocatable x86 and x86

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]

Message-ID: <m1k65t2k8s.fsf@ebiederm.dsl.xmission.com>
Date:	Mon, 31 Jul 2006 21:44:03 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	vgoyal@...ibm.com, fastboot@...l.org, Horms <horms@...ge.net.au>,
	Jan Kratochvil <lace@...kratochvil.net>,
	Magnus Damm <magnus.damm@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [Fastboot] [CFT] ELF Relocatable x86 and x86_64 bzImages

"H. Peter Anvin" <hpa@...or.com> writes:

> Eric W. Biederman wrote:
>>
>>> Ok. I am decompressing the kernel to 16MB and after reducing 1MB of
>>> CONFIG_PHYSICAL_START I am left with 15MB which is not 4M aligned
>>> hence I seems to be running into it.
>>>
>>> I changed it to
>>>
>>> if ((u32)output) & 0x3fffff)
>>>
>>> and kdump kernel booted fine. But this will run into issues if I load
>>> kernel at 1MB.
>>>
>>> I got a dump question. Why do I have to load the kernel at 4MB alignment?
>>> Existing kernel boots loads at 1MB, which is non 4MB aligned and it works
>>> fine?
>> 4MB is a little harsh, but I haven't worked through what the exact rules
>> are, I know 4MB is the worst case alignment for arch/i386.
>>
>
> 4 MB would be worst case for i386; 2 MB for x86-64.  Actually the x86-64 worst
> case would be gigabyte, but that's more than a little bit extreme.

Yep and that is what a test for, except for the gigabyte case which we don't
currently implement.  Although I can imagine that gigabyte pages might
be interesting for the identity mapped part of the page table.

Eric
-
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/