linux-kernel - Re: [PATCH v2 03/13] x86: Add macro for 64bit entry startup

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:	Mon, 19 Nov 2012 15:13:25 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-kernel@...r.kernel.org, Matt Fleming <matt.fleming@...el.com>
Subject: Re: [PATCH v2 03/13] x86: Add macro for 64bit entry startup_64

On 11/19/2012 02:53 PM, Yinghai Lu wrote:
>>
>> We can't change the 0x200 value, ever, because there are already things
>> that use the 64-bit entry point.  As such, these macros and the bzImage
>> fields are pointless; let's not bother and instead document the 0x200 as
>> the permanently fixed address of the 64-bit entry point.
> 
> ok,
> 
> any other field, in header struct field that we can use to tell
> bzImage could be used that
> 0x200 directly?
> 
> hardware_subarch?
> 

There isn't one... this dates back all the way to the original x86-64
kernels.

Are you asking if we can tell this is a 64-bit kernel (as opposed to a
32-bit kernel, which obviously doesn't have a 64-bit entry point)?
Unfortunately there isn't an intentional one that I know of.  There
might be an accidental such indicator, but we'd have to go back to look
at 8+ years of kernels.  We can't even rely on a jmp instruction at the
address...

	-hpa

--
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/