Re: [PATCH 3/3] powerpc/mm: Implement CONFIG_DEBUG_RODATA on PPC32

[Christophe LEROY]

Le 19/04/2017 à 16:01, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@xxxxxx> writes:
>
> > diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
> > index 32509de6ce4c..4af81fb23653 100644
> > --- a/arch/powerpc/kernel/ftrace.c
> > +++ b/arch/powerpc/kernel/ftrace.c
> > @@ -526,7 +526,9 @@ void ftrace_replace_code(int enable)
> >   */
> >  void arch_ftrace_update_code(int command)
> >  {
> > +	set_kernel_text_rw();
> >  	ftrace_modify_all_code(command);
> > +	set_kernel_text_ro();
> >  }
>
> I'm not sure that's the right place for that.


I took arch/arm/ as model. It does the following. Is that wrong ?


static int __ftrace_modify_code(void *data)
{
	int *command = data;

	set_kernel_text_rw();
	ftrace_modify_all_code(*command);
	set_kernel_text_ro();

	return 0;
}

void arch_ftrace_update_code(int command)
{
	stop_machine(__ftrace_modify_code, &command, NULL);
}



> If you look at other arches they hook into ftrace_modify_code(), where
> you have the address that's being modified.

Ok, I will look at other arches.

Christophe