Messages in this thread | | | Date | Fri, 14 Mar 2014 15:08:24 -0400 | From | Dave Jones <> | Subject | Re: [RFC] improve_stack: make stack dump output useful again |
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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
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