linux-kernel - Re: [RFC] [PATCH 2.6.37-rc5-tip 14/20] 14: uprobes: Handing int3 and singlestep exception.

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: <20110126151418.GL19725@linux.vnet.ibm.com>
Date:	Wed, 26 Jan 2011 20:44:18 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
	Linux-mm <linux-mm@...ck.org>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Christoph Hellwig <hch@...radead.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Oleg Nesterov <oleg@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	SystemTap <systemtap@...rces.redhat.com>,
	Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [RFC] [PATCH 2.6.37-rc5-tip 14/20] 14: uprobes: Handing int3
 and singlestep exception.

* Peter Zijlstra <peterz@...radead.org> [2011-01-26 11:17:11]:

> On Wed, 2011-01-26 at 14:22 +0530, Srikar Dronamraju wrote:
> > * Peter Zijlstra <peterz@...radead.org> [2011-01-25 14:56:19]:
> > 
> > > On Thu, 2010-12-16 at 15:29 +0530, Srikar Dronamraju wrote:
> > > > +               down_read(&mm->mmap_sem);
> > > > +               for (vma = mm->mmap; vma; vma = vma->vm_next) {
> > > > +                       if (!valid_vma(vma))
> > > > +                               continue;
> > > > +                       if (probept < vma->vm_start || probept > vma->vm_end)
> > > > +                               continue;
> > > > +                       u = find_uprobe(vma->vm_file->f_mapping->host,
> > > > +                                       probept - vma->vm_start);
> > > > +                       if (u)
> > > > +                               break;
> > > > +               }
> > > > +               up_read(&mm->mmap_sem); 
> > > 
> > > One has to ask, what's wrong with find_vma() ?
> > 
> > Are you looking for something like this.
> > 
> >        down_read(&mm->mmap_sem);
> > 	for (vma = find_vma(mm, probept); ; vma = vma->vm_next) {
> > 	       if (!valid_vma(vma))
> > 		       continue;
> > 	       u = find_uprobe(vma->vm_file->f_mapping->host,
> > 			       probept - vma->vm_start);
> > 	       if (u)
> > 		       break;
> >        }
> >        up_read(&mm->mmap_sem); 
> 
> How could you ever need to iterate here? There is only a single vma that
> covers the probe point, if that doesn't find a uprobe, there isn't any.

Agree.
So it simplifies to 

        down_read(&mm->mmap_sem);
 	vma = find_vma(mm, probept);
        if (valid_vma(vma)) {
 	       u = find_uprobe(vma->vm_file->f_mapping->host,
 			       probept - vma->vm_start);
        }
        up_read(&mm->mmap_sem); 

-- 
Thanks and Regards
Srikar
--
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/