linux-kernel - Re: [RFC] [PATCH 2.6.37-rc5-tip 13/20] 13: x86: x86 specific probe handling

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:	Thu, 27 Jan 2011 22:23:16 -0800 (PST)
From:	Roland McGrath <roland@...hat.com>
To:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	Steven Rostedt <rostedt@...dmis.org>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Christoph Hellwig <hch@...radead.org>,
	Andi Kleen <andi@...stfloor.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	SystemTap <systemtap@...rces.redhat.com>,
	Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [RFC] [PATCH 2.6.37-rc5-tip 13/20] 13: x86: x86 specific probe
 handling

> Uprobes doesn't request/handle block-step for now. So can we postpone
> your suggested changes till uprobes needs to handle block-step?

That's not the issue.  The way the hardware works is that if the bit is set
in the MSR, then the TF eflags bit means block-step instead of single-step.
So if PTRACE_SINGLEBLOCK has been used (i.e. user_enable_block_step), then
this can interfere with your use of single-step.  You need to do the work
in the else branch of step.c:enable_step to ensure that the hardware is not
left in the state where it will do block-step instead of single-step when
uprobes wants a single-step done.


Thanks,
Roland
--
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/