lkml.org 
[lkml]   [2014]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC] improve_stack: make stack dump output useful again
On Fri, Mar 14, 2014 at 11:31:11AM -0700, Kees Cook wrote:
> On Thu, Mar 13, 2014 at 4:12 PM, Dave Jones <davej@redhat.com> wrote:
> > On Thu, Mar 13, 2014 at 03:03:41PM -0700, Linus Torvalds wrote:
> >
> > > You need to look at the *symbol* number. In this output:
> > >
> > > [<ffffffff810020c2>] do_one_initcall+0xc2/0x1e0
> > >
> > > that "ffffffff810020c2" is crap, and is going away. The address that
> > > is meaningful and valid is the "do_one_initcall+0xc2" part.
> > >
> > > *That* is the part you'd use to parse in user space.
> > >
> > > Try it today with the CONFIG_RANDOMIZE_BASE option to see. Using the
> > > hex number doesn't *work*.
> >
> > That reminds me, perf top is still busted when this option is enabled.
>
> Hrm, works for me. I'm not very familiar with what to expect, but
> comparing output between kaslr boot and nokaslr boot, it looks the
> same to me.

ok, nokalsr makes it work too.
Booting with that and using the perf binary from 3.14rc6 , I just see..

9.30% [kernel] [k] 0xffffffffaf18e887
7.98% [kernel] [k] 0xffffffffaf3276c7
6.10% [kernel] [k] 0xffffffffaf18dd3a
4.39% [kernel] [k] 0xffffffffaf327717
1.71% [kernel] [k] 0xffffffffaf18e89c
1.52% [kernel] [k] 0xffffffffaf3276cc

Curiously, if I use the perf binary from 3.13, I see everything lumped together as..

95.89% [kernel].exit.text [k] 0x000000002e586c26

(When kaslr is disabled both binaries work fine)

Also maybe related: The rc6 binary claims it can't read symbols from vmlinux
when kaslr is enabled.

Dave



\
 
 \ /
  Last update: 2014-03-14 21:01    [W:0.102 / U:0.528 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site