Re: [GIT PULL] x86/kaslr for v3.14

From: Peter Zijlstra
Date: Tue Jan 21 2014 - 04:00:46 EST


On Mon, Jan 20, 2014 at 03:13:33PM -0800, H. Peter Anvin wrote:
> On 01/20/2014 03:12 PM, Linus Torvalds wrote:
> > On Mon, Jan 20, 2014 at 2:54 PM, Linus Torvalds
> > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> >> So I pulled this, but one question:
> >
> > .. oh, and since I decided to test it, and was looking for problems:
> > enabling kaslr breaks "perf". The *profile* looks fine, but the
> > disassembly doesn't work.
> >
> > I'm not entirely surprised. I decided I wanted to test it for a
> > reason, after all. So it's not unexpected, but perhaps people hadn't
> > thought about it, and clearly hadn't tested it.
> >
> > Kernel modules disassemble fine, so clearly perf knows about code that
> > moves around, but apparently it gets surprised when the core vmlinux
> > file disassembly doesn't match addresses.
> >
>
> So this is presumably something that needs to be fixed in perf?

Where do we learn about the offset from userspace?
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