FTrace on MPC8xx

Joakim Tjernlund joakim.tjernlund at transmode.se
Fri Apr 15 18:46:05 EST 2011


Stefan Roese <ml at stefan-roese.de> wrote on 2011/04/15 09:22:42:
> Hi Joakim,
>
> On Thursday 14 April 2011 21:21:23 Joakim Tjernlund wrote:
> > > hmm, I guess 8xx really maps kernel RO as RO :) Try
> > >
> > > changing in pte-8xx.h:
> > >  - #define _PAGE_KERNEL_RO   (_PAGE_SHARED)
> > >  + #define _PAGE_KERNEL_RO   (_PAGE_RW |_PAGE_SHARED)
> >
> > hmm, I wonder if not this is the problem(in pte-common.h)
> > #if defined(CONFIG_KGDB) || defined(CONFIG_XMON) ||
> > defined(CONFIG_BDI_SWITCH) ||\ defined(CONFIG_KPROBES)
> > #define PAGE_KERNEL_TEXT   PAGE_KERNEL_X
> > #else
> > #define PAGE_KERNEL_TEXT   PAGE_KERNEL_ROX
> > #endif
> >
> > What is PAGE_KERNEL_TEXT for you?
> > I think it must be PAGE_KERNEL_X, otherwise kernel text will be readonly.
>
> Yes, that's it! Its PAGE_KERNEL_ROX right now. We need to add CONFIG_FTRACE or
> at least CONFIG_DYNAMIC_FTRACE to the #if statement above.
>
> Do you want to send a patch (since you detected the real problem)? Or should I
> do this?

Feel free to send it. I am barely managing my mail ATM.

 Jocke



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