linux-kernel - Re: Dealing with the NMI mess

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20150907074218.GC19280@gmail.com>
Date:	Mon, 7 Sep 2015 09:42:18 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
Cc:	Borislav Petkov <bp@...en8.de>,
	Andy Lutomirski <luto@...capital.net>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Willy Tarreau <w@....eu>, Steven Rostedt <rostedt@...dmis.org>,
	X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Brian Gerst <brgerst@...il.com>
Subject: Re: Dealing with the NMI mess


* Maciej W. Rozycki <macro@...ux-mips.org> wrote:

>  I did some work on this a few years ago, including emulating DR0-7 accesses in 
> software down the JTAG handler upon a General Detect fault to keep the kernel 
> both happy and away from real debug registers. ;) Yes, you can debug any 
> software with this stuff, including the Linux kernel: set instruction and data 
> breakpoints, single-step it, poke at all hardware registers, including 
> descriptor registers not otherwise accessible (you can set funny modes for 
> segments, also in the 64-bit mode), etc.  One complication though is you operate 
> on physical addresses when poking at memory, you can't ask the CPU's MMU to 
> remap them for you (you can walk page tables manually of course, just as the MMU 
> would).

Essentially the ICE breakpoint instruction enters SMM mode?

Thanks,

	Ingo
--
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/